N-2NSPML (BW) RIRs 1-22 - Redacted
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20 2018 2019 2020 2021 2022 2023 2024 2025 Bipole availability 74.1% 88.3% 94.6% 59.8% 94.0% 94.8% 94.22% 97.04% Monopole availability 90.4% 99.9% 100.0% 96.7% 100% 99.9% 99.99% 100.0% Energy availability 82.2% 94.13% 97.27% 79.1% 97.13% 9...
AI summary The table presents availability percentages for Bipole, Monopole, and Energy from 2018 to 2025, along with Forced Energy Unavailability (FEU) rates. Availability rates fluctuate over the years, with Monopole showing the highest availability and FEU rates generally decreasing over time.
NSPML Responses to Bates White Information Requests 1 c-d) 4 the land portions. 5 6 Response U-18: 7 8 The target availability for the Labrador Island Link, Labrador Transmission Assets and Muskrat 9 Falls is 98 - 99.9% and the Maritime Li...
AI summary The document outlines the target availability percentages for various power transmission assets, including the Labrador Island Link, Labrador Transmission Assets, Muskrat Falls, and the Maritime Link, based on engineering estimates. The availability of the AC system on Newfoundland is compared to that of Nova Scotia's AC systems.
Page 1 of 1 1 Q. Please provide any studies of reliability for the post Muskrat Falls project and 2 Labrador Island Link project. 3 4 5 A. Please refer to the following attached reports: 6 7 PUB‐NLH‐212 Attachment 1: "Technical Note Labrad...
AI summary The document presents a question and answer related to reliability studies for the post-Muskrat Falls project and the Labrador Island Link project. The answer refers to two technical reports attached to PUB-NLH-212, dated October 30, 2011, and April 10, 2012, which assess the impacts of the HVdc link on the Island Interconnected System.
The addition of a 900 MW HVdc transmission line between Muskrat Falls in Labrador and Soldiers Pond on the Island portion of the province Province has raised concerns regarding the impact that such a significant change will have on the rel...
AI summary The addition of a 900 MW HVdc transmission line between Muskrat Falls and Soldiers Pond has raised concerns about its impact on the reliability of the Island Interconnected System. This technical note aims to assess the system reliability, interrelationships affecting it, and the impact of the proposed transmission line.
SYSTEM RELIABILITY INTERRELATIONSHIPS To understand the concept of system reliability and overall impact the addition of a 900 MW HVdc transmission link between Labrador and Newfoundland will have on the Island Interconnected Transmission...
AI summary The text explains the need to understand interrelationships between system planning, transmission line design, and system operations to assess how a 900 MW HVdc transmission link between Labrador and Newfoundland will impact the Island Interconnected Transmission System's reliability.
Generation Planning Generation planning for the Island Interconnected System ensures that there is sufficient generation, both capacity (MW) and energy (MWh) to supply the load as provided in load forecasts for future years. NLH uses an in...
AI summary Generation planning for Nova Scotia's Island Interconnected System ensures sufficient capacity (MW) and energy (MWh) to meet load forecasts using the Strategist® program. Key criteria include a LOLH target of ≤2.8 hours/year and firm energy capability. Deficiencies trigger additions of energy sources or low-cost combustion turbines, with iterations for least-cost expansion. LOLH excludes grid outage rates.
Transmission Planning Transmission planning at NLH follows traditional transmission planning practices similar to, but less stringent than, that found in North American Electric Reliability Corporation (NERC) Transmission Planning Standard...
AI summary NLH's transmission planning follows deterministic practices ensuring no load loss for transmission line failures but permits under-frequency load shedding for generator outages. This deviation from NERC standards is due to the Island System's isolation and cost constraints, requiring standby generation to meet LOLH targets.
Reference to Annex C indicates that: - The area surrounding the Churchill River is considered to have a loading condition of medium loading B; - The area traversed by the proposed HVdc line from Muskrat Falls to the Strait of Belle Isle is...
AI summary The text outlines loading conditions for different regions in Newfoundland and Labrador, specifying ice thickness requirements from Table 30. Medium loading B (12.5 mm), heavy loading (12.5 mm), and severe loading (19 mm) are assigned to specific geographic areas, including the Churchill River, HVdc transmission route, and the Bonavista/Avalon Peninsulas.
Section 10 of C22.3 No. 1‐06 states: The reliability‐based method should be used for supply lines greater than 70 kV phase‐to‐phase, in areas where significant amounts of meteorological data are readily available. This method may also be u...
AI summary Section 10 of C22.3 No. 1‐06 mandates the use of a reliability-based method for supply lines exceeding 70 kV phase-to-phase, contingent on availability of meteorological data. The method is also applicable for lines designed for specific climatic loads or calibrated with existing lines demonstrating long-term satisfactory performance.
CAN/CSA C22.3 No. 60826:06 International Standard CEI/IEC 60826:2003 (third edition, 2003‐10) has been adopted as CAN/CSA C22.3 No. 60826:06 Design criteria of overhead transmission lines with Canadian deviations and has been approved as a...
AI summary The Canadian standard CAN/CSA C22.3 No. 60826:06 adopts the CEI/IEC 60826:2003 international standard for overhead transmission line design, emphasizing reliability-based methods. It outlines criteria for designing lines using meteorological and strength data, with notes on applicability for specific climatic loads and design consistency.
Section 4.3 goes on to state: The objective of the design criteria described in this standard is to provide for reliable and safe lines. The reliability of lines is achieved by providing strength requirements of the line components larger...
AI summary The text outlines design criteria for transmission lines to ensure reliability against climatic loads, using return periods (e.g., 1:50, 1:500 years) to define required strength. It emphasizes higher reliability standards for critical lines and provides Canadian-specific ice thickness calculations for different return periods.
NLH Line Design At this point it is worth describing how each of the above noted standards has impacted transmission line design within the Island Interconnected System. The 230 kV transmission lines on the Avalon Peninsula are used to dis...
AI summary The document details historical transmission line design practices on the Avalon Peninsula, highlighting how ice storm failures led to upgrades. Original 230 kV lines used 25 mm ice thickness, but failures from 1970-1998 revealed insufficient design. NLH reinforced lines for a 1:50 year return period (66-75 mm ice) between 1998-2002, improving reliability.
System Operations With all equipment available and in service the Island Interconnected System operates at its most reliable level as the generation planning exercise ensures there is sufficient generation to meet the load even for loss of...
AI summary The Island Interconnected System maintains reliability through generation and transmission planning, ensuring sufficient capacity to handle single equipment losses. Forced outages and maintenance require System Operations to reconfigure the grid, scheduling maintenance to preserve backup capacity during unplanned outages.
IMPACT OF THE LABRADOR – ISLAND HVdc LINK ON ISLAND SYSTEM RELIABILITY The Labrador – Island HVdc Link has the following nominal ratings: - ±320 kV operating voltage (bipole); - 2 x 450 MW, 1406 A per pole; - 900 MW at Muskrat Falls; - 92....
AI summary The Labrador-Island HVdc Link's 900 MW capacity and 92.1 MW losses impact Island System Reliability, modeled as a generator with a forced outage rate. Additional 50 MW combustion turbines are required to maintain LOLH below 2.8 hours/year. Generation planning ensures firm energy supply until 2036, with future sources like Portland Creek and wind needed thereafter.
Pole Outages CIGRE 2010 paper B4_209_2010 "A survey of the Reliability of HVdc Systems Throughout the World During 2007 – 2008" provides the latest available outage statistics for HVdc transmission systems worldwide. It must be noted that...
AI summary The text discusses reliability concerns for HVdc transmission systems, referencing CIGRE 2010 outage statistics. It highlights potential pole outages in the Labrador–Island HVdc Link, their impact on system frequency, and measures like temporary ratings (2 p.u. for 10 minutes) to prevent under-frequency load shedding. The proposed system's operational parameters and mitigation strategies are detailed.
Pole Outages – Maritime Link In Service Of the 807.9 MW delivered to Soldiers Pond, 162.2 MW is assigned to supply the Emera block, leaving 645.7 MW as the peak deliveries to the Island Interconnected System. For loss of a pole the Emera b...
AI summary The document analyzes the impact of pole outages on the Maritime Link HVdc system, noting a 27.5 MW shortfall during monopolar operation. However, spinning reserves and 150 MW of combustion turbine capacity (including new units) ensure no under-frequency load shedding, maintaining system reliability for the Island Interconnected System.
Pole Outages – No Maritime Link Should the Maritime Link component of Phase I of the Lower Churchill Project not proceed, operation of the Labrador – Island Link would be somewhat modified. Under the Maritime Link scenario, System Operatio...
AI summary The document discusses the operational implications of not proceeding with the Maritime Link component of the Lower Churchill Project, emphasizing the need for increased spinning reserve capacity on the Labrador–Island Link to maintain system reliability. It highlights the role of NERC standards in ensuring no load loss from single pole outages and NLH's alignment with these criteria through curtailment strategies.
Bipole Outages The CIGRE statistics for bipole outages of two terminal HVdc systems with one converter per pole are summarized in Table 1. The data indicates an average bipole outage rate varying from zero per year to a high of 0.42 outage...
AI summary CIGRE statistics show bipole outages for HVdc systems range from 0 to 0.42 per year, with durations of 1.03–2.27 hours. Outages trigger curtailments and load-tripping via SPS to prevent blackouts. Restoration under 3 hours is deemed acceptable due to backup generation and import coordination via the Maritime Link.
Table 1 Summary of Frequency and Duration of Forced Bipole Outages 2 Terminal Systems – 1 Converter per Pole Average 1988 – 2008 System Years Frequency Duration – hours Skagerrak 1 & 2 20 0.13 1.03 Square Butte 18 0.42 2.27 CU 20 0.28 1.66...
AI summary The document presents data on forced outages for HVdc transmission lines from 1988 to 2008, highlighting the concerns related to the Labrador – Island HVdc Link due to its length and environmental conditions. The CIGRE statistics do not provide long-term averages, and no system is a direct comparison to the Labrador – Island Link. Table 2 provides 2007–2008 data, but causes of outages are not reported.
Bipole Outages – Maritime Link In Service For loss of the bipole, NERC transmission planning standards permit planned and controlled load loss in order to maintain system stability. In the context of the Labrador – Island Link loss of the...
AI summary The document discusses the implications of a bipole outage on the Labrador-Island Link and the Maritime Link. It outlines how a special protection scheme would manage load loss and system stability, and notes that Nova Scotia must plan for the loss of 500 MW from the Maritime Link without load loss, while Newfoundland and Labrador Hydro must ensure no adverse impact on neighboring systems.
Bipole Outages – No Maritime Link Without the Maritime Link, the available generation to supply the Island Interconnected System following a bipole outage to the Labrador – Island Link equal 1468.5 MW. Given that the 2017 load forecast for...
AI summary The document analyzes the capacity shortfall in the Island Interconnected System during a bipole outage without the Maritime Link, highlighting a 235.5 MW shortfall and 637 hours of exposure in 2017. It also compares the risk of outages in the existing Island Isolated System, noting a 1.97% probability of unsupplied energy in 2012 due to simultaneous failure of TL202 and TL206.
- 1: Isolated Island Alternative includes a new 170 MW CCCT in 2022 bringing 465.5 MW Thermal to 635.5 MW - 2: Hardwoods 50 MW CT to retire in 2022 - 3: For BDE WAV 230 kV transmission line transfer capability add 328 MW In essence the 201...
AI summary The text discusses the impact of transmission line failures on energy availability in the Isolated Island Scenario compared to the Interconnected Scenario. It highlights that the loss of TL202 and TL206 would result in significantly higher unsupplied energy than the loss of the Labrador – Island Link. The analysis also considers the increased generating capacity east of Bay d'Espoir and the probability of unsupplied energy in 2017.
the 1:25 year design for TL202 and TL206, the probability of unsupplied energy in 2017 for the Isolated Island Scenario is 0.0987 \ 0.04 = 0.00394 or 0.39%. The resultant availability equals 99.6%9 . Table 5 summarizes the exposure levels...
AI summary The analysis compares energy availability and exposure levels under Isolated Island and Interconnected Scenarios, noting reduced exposure in the Isolated Scenario due to capacity additions (e.g., retiring 50 MW Hardwoods CT and building a 170 MW CCCT). The Interconnected Scenario shows rising exposure until 2037 due to delayed capacity additions, though availability remains higher than current Isolated Scenario levels.
lues for the Island Interconnected Scenario are greater than the availability value today for loss of TL202 and TL206. System Planning Department, Newfoundland and Labrador Hydro October 30, 2011 9 Assumes 230 kV transmission line construc...
AI summary The text discusses system availability comparisons for the Island Interconnected Scenario, noting higher values than current levels for loss of TL202 and TL206. It references a 230 kV transmission line design assumption and highlights potential reliability improvements from the Maritime Link during Labrador-Island Link outages between 2017-2027.
Level of Exposure and Unsupplied Energy Table 5 Year Load Forecast Island Standby Generation Level of Exposure Load Exceeds Generation Availability % Unsupplied Energy Worst 2 wk Window MW GWh MW Annual Hours Annual % MWh % of Annual Isola...
AI summary The table presents data on the level of exposure and unsupplied energy for different years and scenarios, including isolated island and interconnected island conditions, with varying levels of standby generation and outage scenarios. It includes metrics such as load forecast, availability percentages, and unsupplied energy in MWh.
- 1: 230 kV transmission line Bay d'Espoir to Western Avalon is built prior to 2017 increasing transfer to east coast for loss of TL202 and TL206. - 2: 170 MW CCCT in 2022 at Holyrood and Hardwoods 50 MW CT retired in 2022 - 3: 50 MW CT in...
AI summary This text discusses the retirement and replacement of various power generation units and transmission lines, as well as the need for additional capacity by 2036-2037 to meet LOLH targets. It highlights the retirement of older units and the planned installation of new CCCT units.
rates of all other generating units to derive the LOLH expectation target. Based upon the Strategist ® analysis, the LOLH target is not exceeded until 2036 requiring additional capacity in 2036‐2037. To eliminate the hours of exposure to z...
AI summary The document discusses the LOLH expectation target and the need for additional capacity by 2036-2037. It evaluates the cost and impact of installing combustion turbines to mitigate exposure to unsupplied load during a permanent bipole outage, suggesting incremental additions over time as a more cost-effective approach.
Table 8 Level of Exposure and Unsupplied Energy Known Avalon Peninsula Icing Events No Maritime Link 50 MW Combustion Turbines Added Year Load Forecast Island Standby Generation Level of Exposure Load Exceeds Generation Availability % Unsu...
AI summary The table presents data on the level of exposure and unsupplied energy for the Avalon Peninsula under different icing events scenarios with the addition of 50 MW combustion turbines. It includes metrics such as load forecast, standby generation, availability percentage, and unsupplied energy across multiple years from 2017 to 2037.
- 11: Portland Creek at 23 MW and new CCCT at 170 MW Added Table 9 Level of Exposure and Unsupplied Energy Known Avalon Peninsula Icing Events With Maritime Link 50 MW Combustion Turbines Added Year Load Forecast Island Standby Level of Ex...
AI summary The text discusses the addition of a 23 MW Portland Creek and a 170 MW Combined Cycle Combustion Turbine (CCCT) in the context of energy generation and exposure levels. It includes a table showing load forecasts, standby generation, level of exposure, availability, and unsupplied energy for various years, highlighting changes in generation capacity and reliability over time.
HVdc Line Design Load The final question with respect to the reliability of the Labrador – Island Link relates to the exposure of the approximately 1100 km of overhead transmission line and how to prevent failure. In the context of the los...
AI summary The reliability of the Labrador–Island Link's HVdc transmission line is questioned, focusing on design standards to prevent failure. Alternate generation and transmission planning processes are considered to ensure capacity and energy availability during repairs, with the central issue being the required construction standard for the HVdc line.
SUMMARY To date the generation planning process incorporates the forced outage rate and associated impacts of the HVdc transmission line between Labrador and the Island portion of the Province along with appropriate capacity and energy sou...
AI summary The generation planning process incorporates forced outage rates and capacity additions for the Labrador–Island HVdc transmission line, ensuring compliance with NERC reliability standards. Low-probability outage events may result in minimal unserved energy (under 0.4% annually), mitigated through load rotation rather than additional combustion turbines to minimize customer costs.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVdc ISLAND LINK SLI Document No.: 505573-480A-47ER-0017-00 Nalcor Reference No.: ILK-SN-CD-8000-EL-SY-0004-01-B1
AI summary This document outlines the reliability and availability assessment of the HVdc Island Link, focusing on technical standards and system performance. It references key organizations and standards relevant to the project's evaluation.
Date: 10-Apr-2012 Prepared by: Peter Anderson 2 COMPONE NT RELIABILITY 4
AI summary The document is a prepared chunk from a regulatory proceeding, authored by Peter Anderson, and focuses on component reliability, with a heading date of 10-Apr-2012. The content is sparse and appears to be a fragment or placeholder.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 4 2 COMPONENT RELIABILITY
AI summary This section discusses the reliability and availability assessment of the HVDC Island Link, focusing on component reliability. It includes document numbers, revision details, and a date.
Table 2-1: Summary of FOR and FU (per terminal) Period Outage FOR (%) FU(hrs/yr) 2007 Pole 0.15 13 Bipole 0.0003 0.02 2008 Pole 0.38 34 Bipole 0.0002 0.02 1988-2008 Pole 0.49 43.4 Bipole 0.003 0.27 The average failure rate per terminal ove...
AI summary Table 2-1 provides a summary of FOR (Forced Outage Rate) and FU (Forced Unavailability) for pole and bipole outages from 2007 to 2008 and over the 1988-2008 period. It includes average failure rates and repair times for pole and bipole outages.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 5 Thus, for a 2-terminal bipole, the estimated average rel...
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, focusing on estimated average reliability indicators for a 2-terminal bipole. It includes document numbers, revision details, and a date.
- 4 pole outages per year with a repair time of 21 hours per outage (FOR=0.98%) - 0.4 bipole outages per year with a repair time of 1.3 hours per outage (FOR=0.006%) The same source also provides information on the breakdown of forced ener...
AI summary The text discusses forced outages and forced energy unavailability (FEU) in converter stations, highlighting the impact of major components such as converter transformers and dc smoothing reactors. It also mentions that providing spare units improves station availability.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 6 Spare Converter Transformer
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, focusing on the spare converter transformer. It includes document numbers, revision details, and page information.
λ = Failure rate (1-phase) = 0.01 f/yr N = No. of Components = 6 R1 = Repair Time (replacement with spare) = 168 hrs R2 = Repair Time at Factory = 4380 hrs With no spare, Average outage time per pole = 0.01x3x4380 = 131 hrs/yr With one spa...
AI summary The text calculates the average outage time per pole for a system with and without spare components, showing that having a spare significantly reduces outage time. It also references CIGRE statistics on the impact of having spare transformer units and smoothing reactors in HVDC converter stations.
Table 2-2: Converter Unavailability Item Performance Indicator Spare Transformer No Yes Yes Spare Smoothing Reactor No No Yes Terminal Unavailability 3.04% 0.94% 0.21% Hours/ Year 266 82.5 18.6 Based on the above information, it is recomme...
AI summary The text discusses the reliability performance of converter stations, recommending spare units at each terminal to improve reliability. It references statistics from prior years to support the recommendation.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 7 Table 2-3: Converter Reliability (Average 2007-2008) Out...
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, focusing on converter reliability based on historical data from 2007-2008. It highlights that while technological improvements may lead to lower failure rates, historical data is used for conservative estimates. The document also notes the difference in accessibility between the two converter stations, which may affect repair times.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 8 Table 2-4: HVdc Transmission Line Outage Statistics System Length...
AI summary The document presents a reliability and availability assessment of the HVDC Island Link, including outage statistics for various HVDC transmission lines. It provides average outage rates and durations, and calculates expected reliability performance for a 1,100 km route length.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 9 A report by C-Core [4] examined the incidence of iceberg strikes...
AI summary A report by C-Core examined the incidence of iceberg strikes on submarine cables, concluding that the expected failure rates for such events would be significant, as part of the reliability and availability assessment of the HVDC Island Link.
- 0.004 failures/year for a single cable - 0.002 failures/year for 2 cables - 0.001 failures/year for 3 cables Repair times for cables in the Strait of Belle Isle could be very long and a repair time of 6 months (4,380 hours) has been assu...
AI summary The text calculates the failure rates and reliability of a cable system in the Strait of Belle Isle, considering both independent cable failures and iceberg strikes. It provides failure rates for different numbers of cables, repair times, and downtime, concluding with the FOR (Forced Outage Rate) for different failure scenarios.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 10 2.4 Electrode Line
AI summary This document discusses the reliability and availability assessment of the HVDC Island Link, focusing on the Electrode Line section. It includes technical details related to the project and is part of a larger assessment report.
Given the above considerations, it is considered that the reliability related to the complete loss of the Island Link will not be significantly influenced by the reliability of the electrode lines at either terminal.
AI summary The text states that the reliability of the electrode lines at either terminal will not significantly impact the reliability related to the complete loss of the Island Link.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 12 3 COMPOSITE SYSTEM
AI summary The document presents a reliability and availability assessment of the HVDC Island Link, focusing on the composite system analysis. It includes technical details and evaluations related to the system's performance and reliability.
3.1 HVdc Overhead Line and Submarine Cable First, it is necessary to determine the composite reliability indices associated with each parallel pole element (L1, C1+2, and L2 in series). Since the failure of any one of these elements will r...
AI summary The document discusses the calculation of composite reliability indices for HVdc overhead line and submarine cable elements, considering failure rates, repair times, and downtime, with special attention given to the impact of iceberg strikes on submarine cables.
Table 3-1: Reliability Performance of One Pole of the HVdc Line Element Failure Rate (f/yr) Repair Time (hrs) Downtime (hrs/yr) L1-388 km 0.741 1.78 1.32 C-Submarine cable 0.0022 4,163 9.24 L2-680 km 1.3 1.78 2.31 Total 2.042 6.3 12.87 REL...
AI summary Table 3-1 presents the reliability performance of one pole of the HVdc line, including failure rates, repair times, and downtime for various elements such as L1-388 km, C-Submarine cable, and L2-680 km. The data highlights the reliability and availability assessment of the HVDC Island Link.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 14 The reliability indices for the coincident, independent failure...
AI summary The document discusses the reliability indices for the coincident, independent failure of two poles in parallel within the HVDC Island Link project. It references specific document numbers and dates, indicating a technical assessment of reliability and availability.
3.2 Converters Similarly, the coincident failure of both converters in independent mode can be calculated as: $$\lambda_T = (1.64)^2 \cdot (2x13.8)/8760 = 0.0084 \text{ f/yr}$$ $$r_T = (13.8)^2/(2x13.8) = 6.9 \text{ hrs}$$ $$U_T = 0.0086x7...
AI summary The text presents mathematical calculations for converter reliability, including failure rates (λ_T = 0.0084 f/yr), repair time (r_T = 6.9 hrs), and unavailability (U_T = 0.06 hrs/yr). These metrics assess the performance of converters operating in independent mode, relevant to system reliability analysis in power infrastructure.
3.3 Electrode Lines As mentioned above, the link can still be operated at full power or reduced power even for the complete loss of the electrode line at either end of the link. As such, the reliability of the electrode line is considered...
AI summary The reliability of the electrode line is deemed to have no significant impact on the composite reliability of the link, as the link can operate at full or reduced power even with the complete loss of an electrode line at either end.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 15 3.4 Complete System
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, focusing on the complete system. It includes technical details related to the HVDC transmission system and its components.
For the failure of both lines/cables (P1+P2) or both converters (CP+CP), in series with the common-mode failure of both poles due to converter faults (BP) and main line faults (BPL1 and BPL2), the composite reliability of the Island Link i...
AI summary The composite reliability of the Island Link is discussed in the context of failures in both lines/cables, converters, and common-mode failures due to converter faults and main line faults.
Table 3-2: Composite Island Link Bi-pole Reliability Element Failure Rate Repair Time Downtime (f/yr) (hrs) (hrs/yr) % of Total BP-Muskrat Falls 0.24 0.13 0.031 0.3 CP+CP-Muskrat Falls 0.0084 6.86 0.057 0.6 BPL1-388 km 0.074 24 1.776 18.6...
AI summary Table 3-2 presents the reliability data for the Composite Island Link Bi-pole, including failure rates, repair times, downtime, and percentages of total downtime for various elements. The composite forced unavailability and FOR is calculated as 0.109%.
It is clear from the above results that the major contributors to the unavailability of the Island Link are the common-mode failure of both poles of the overhead line (representing nearly 52% of the total unavailability) and the independen...
AI summary The major contributors to the unavailability of the Island Link are common-mode failures of both poles of the overhead line and coincident failures of both poles in the overhead and submarine cable sections. The reliability indices for these failures are uncertain due to limited operating experience, and repair time significantly affects overall unavailability.
3.5 Reduced Power Operation The scheduled maintenance would typically be of the order of 3 days per pole per year, assuming that maintenance work would be carried out at both terminal stations and on each line (pole) at the same time. With...
AI summary The text discusses scheduled maintenance and forced outage scenarios for the Island Link, focusing on reliability indices associated with reduced power operation. It considers single contingency events that lead to the loss of one pole, such as converter failures or permanent outages of the main DC line.
Table 3-3: Reduced Power Capability Modes (Mono-polar) Element Failure Rate(f/yr) Repair Time(hrs) Downtime(hrs/yr) Scheduled Maintenance 2.0 72 144 Converter-Muskrat Falls 1.64 13.8 22.42 Pole 1 2.04 6.3 12.87 Pole 2 2.04 6.3 12.87 Conver...
AI summary Table 3-3 details the reduced power capability modes for mono-polar systems, including failure rates, repair times, and downtime for various elements. The composite unavailability and FOR is calculated as 2.45% based on total downtime of 214.6 hours per year.
Thus, the actual availability of the Island Link at full power capacity is 100-0.109-2.45 = 97.44%. If the use of the station ground for mono-polar operation is not allowed in the event of the loss of the electrode line, the above values w...
AI summary The document discusses the availability of the Island Link at full power capacity, noting it is 97.44%. It also considers the impact of potential failures in the electrode line conductors, particularly the Muskrat Falls electrode line, which has a higher significance due to its length.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 17 24 hours and a downtime of 4.8 hours/year. If these values are a...
AI summary The reliability and availability assessment of the HVDC Island Link indicates an increase in the forced outage rate (FOR) from 2.45% to 2.51% when considering additional downtime and operational hours.
The impact of the repair time for the common-mode failure of both circuits of either the Muskrat Falls electrode line or the main dc line is dominant to the point where the total forced unavailability can be approximated as being proportio...
AI summary The text discusses the relationship between repair time for common-mode failures in HVDC lines and the resulting forced unavailability. It shows that forced unavailability is proportional to repair time, and provides a formula to calculate unavailability based on repair time. A target reliability can be achieved by limiting repair time to specific thresholds.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 18 4 CONCLUSIONS & RECOMMENDATIONS
AI summary This section presents conclusions and recommendations from the reliability and availability assessment of the HVDC Island Link. It discusses the performance and reliability of the system, including key metrics such as reliability and availability, and provides recommendations for improvements.
Objective 1: To develop R&A performance indices for converter stations Using historical information compiled by CIGRE from HVdc installations throughout the world over the period 1988-2008, failure rates and repair times were estimated for...
AI summary The objective is to develop reliability and availability performance indices for converter stations using historical data from HVdc installations worldwide between 1988 and 2008, focusing on the Island Link converter stations.
Table 4-1: Converter Reliability (Average 2007-2008) Outage FOR (%) FU(hrs/yr) F/yr Repair Time (hrs) Pole 0.265 24 1.64 13.8 Bipole 0.00025 0.02 0.24 0.13 Objective 2: To develop R&A performance indices for the HVdc transmission line from...
AI summary The document presents Table 4-1, which outlines the reliability of converters during 2007-2008, including metrics like FOR and FU. It also mentions the objective to develop R&A performance indices for the HVdc transmission line from Muskrat Falls to Soldiers Pond.
- To assess the improvements that could be made in the above indices considering design aspects such as the provision of spare equipment, over-rated equipment, etc., - To assess the composite R&A performance indices of the complete HVdc Is...
AI summary The text discusses assessing improvements in reliability and availability (R&A) performance indices for the HVdc Island Link from Muskrat Falls to Soldiers Pond, considering design aspects like spare and over-rated equipment.
Table 4-2: Reliability Performance of the HVdc Line Element Failure Rate (f/yr) Repair Time (hrs) Downtime (hrs/yr) L1-388 km 0.741 1.78 1.32 C-Submarine cable 0.0022 4,163 9.24 L2-680 km 1.3 1.78 2.31 Total 2.042 6.3 12.87 The associated...
AI summary Table 4-2 presents the reliability performance of the HVdc line, including failure rates, repair times, and downtime for different elements. The total forced outage rate (FOR) is reported as 0.147%.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 19 Table 4-3: Composite Island Link Reliability Element Fa...
AI summary This table presents the reliability and availability assessment of the HVDC Island Link, including failure rates, repair times, and downtime percentages for various components. The overall FOR is 0.109%, and the availability is 99.89%.
4.1 Conclusions The provision of a spare transformer of each type and a spare smoothing reactor at each converter station will significantly improve the availability of the converters. This has become common practice in recent HVdc schemes...
AI summary The provision of spare transformers and smoothing reactors at converter stations is expected to enhance the reliability of the Island Link HVdc system. Predicted forced unavailability is approximately 0.1% overall and less than 2.5% for full power capability.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 20 maintenance being 1.64%. However, both of the values fo...
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, highlighting that maintenance being 1.64% and forced unavailability values are heavily dependent on average repair times for pole outages and common-mode failures.
It has been shown that a linear relationship exists between these repair times and the unavailability of the Island Link. Once a target reliability has been decided on, the maximum repair time can be determined. The overall unavailability...
AI summary The text discusses the relationship between repair times and the unavailability of the Island Link, noting that repair times for submarine cables have minimal impact due to redundancy, but repair times for overhead line failures significantly affect overall unavailability. Repair times for single pole outages are estimated at 1.78 hours, while common-mode failures are assumed at 24 hours.
Table 4-5: Variation in Overall FOR with DC Overhead Line Repair Time Repair Time(hrs) FOR(%) 24 (1 day) 0.112 48 (2 days) 0.179 72 (3 days) 0.251 96 (4 days) 0.33 120 (5 days) 0.416 144 (6 days) 0.507 168 (1 week) 0.605 336 (2 weeks) 1.46...
AI summary The table shows the relationship between repair time for DC overhead line faults and the forced outage rate (FOR). As repair time increases, the FOR rises non-linearly, indicating the impact of repair time on system reliability and availability.
4.2 Recommendations At each converter station, a spare converter transformer of each type (single phase) and a spare smoothing reactor should be provided. This will significantly improve the availability of the converters. Other critical c...
AI summary The recommendations emphasize the need for spare components at converter stations to improve system reliability and availability, particularly focusing on converter transformers and smoothing reactors, as well as other long-lead-time items determined by the converter supplier.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 22 5 REFERENCES
AI summary This document presents a reliability and availability assessment of the HVDC Island Link, including reference materials related to the project. It includes document numbers and dates, indicating the context and source of the assessment.
- 1) Nalcor Energy-Lower Churchill Project, :Basis of Design, Document LCP-PT-ED-0000-EN-RP-0001-O1. - 2) A Survey of the Reliability of HVDC Systems throughout the World during 2007 2008, M.G. Bennett, N.S.Dhaliwal, A. Leirbukt CIGRE 2010...
AI summary The document lists several references related to HVDC systems and reliability studies, including a survey of HVDC system reliability, a report on the Lower Churchill Project, and studies on iceberg risks to subsea cables in the Strait of Belle Isle.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 A APPENDIX A
AI summary The document provides an appendix related to the reliability and availability assessment of the HVDC Island Link, with specific reference numbers and a revision history. It is part of a technical evaluation process.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 A-1 Individual Components
AI summary The document presents a reliability and availability assessment of the HVDC Island Link, focusing on individual components. It includes document numbers, dates, and page references, indicating a technical evaluation of the system's reliability.
Components in Series In a system where the failure of any single component will result in failure of the system, the components are said to be connected in series, using the analogy of an electrical circuit. In such a system, the total sys...
AI summary This section explains the concept of components in series, where the failure of any single component leads to system failure. The total system failure rate and downtime are calculated as the sum of the individual components' failure rates and downtimes, respectively. An example with two components illustrates the calculation.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 A-2 Components in Parallel
AI summary This document discusses the reliability and availability assessment of the HVDC Island Link, focusing on components in parallel. It includes document numbers, revision details, and a date.
In a system where multiple components must fail to result in failure of the system, the components are said to be connected in parallel, again using the analogy of an electrical circuit. For a two component system, two possible failure mod...
AI summary The document explains the calculation of system failure rates and downtime for components connected in parallel. It provides mathematical formulas to determine total failure rates, downtime, and average repair time based on individual component failure rates and repair times.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 B APPENDIX B
AI summary The document presents an appendix titled 'Reliability & Availability Assessment of the HVDC Island Link,' which is part of a technical evaluation related to the High Voltage Direct Current (HVDC) transmission system. The appendix includes document numbers, revision details, and a date.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 B-1 CIGRE Historical Data 1988-2008 per Terminal
AI summary The document presents a reliability and availability assessment of the HVDC Island Link, referencing CIGRE historical data from 1988 to 2008 per terminal. It includes document numbers, revision details, and a date, indicating it is part of a technical evaluation process.
Labrador-Island Link
AI summary The Labrador-Island Link (LIL) is a proposed High Voltage Direct Current (HVDC) transmission project connecting Newfoundland and Labrador to the Island of Newfoundland, aiming to enhance grid reliability and facilitate renewable energy integration. The initiative involves Nova Scotia Power Marketing Limited (NSPML) and Newfoundland and Labrador Hydro (NLH), with regulatory considerations under the Utility and Review Board (UARB).
1.1 900 MW Test and Software All software functionality required for operation up to 900 MW was proven and accepted as satisfactory during pole overload tests in winter 2023 prior to the April 2023 commissioning; however, as committed, con...
AI summary Software for the Labrador-Island Link (LIL) was tested up to 900 MW in winter 2023, but high-power testing remains postponed until 2026 due to system reliability priorities. Software issues with General Electric (GE) delayed installation, with a new version expected by late 2025 and installation planned for Spring 2026 once system conditions allow.
1.2 Operations During the fourth quarter of 2025, there were two trip events on the LIL as described in the Rolling 12 for the twelve months ended December 31, 2025. The first event occurred on October 7, 2025, when Pole 1 tripped while in...
AI summary Two trip events occurred on the Labrador-Island Link (LIL) in Q4 2025. The first involved Pole 1 tripping due to a voltage differential, causing an underfrequency load shedding event. The second event saw Pole 1 blocking and tripping, transferring load to Pole 2 with no customer impact. Both incidents were resolved through repairs and relay replacement.
Soldiers Pond Synchronous Condensers Outside of planned outages, the Soldiers Pond Synchronous Condensers ("SCs") have been in continuous operation at all times since the last LIL update, with the exception of one event on SC2 and one even...
AI summary The Soldiers Pond Synchronous Condensers experienced two incidents in 2025: SC2 failed to start due to a loss of excitation fault, and SC3 shut down during maintenance due to LLD trip levels. Both were resolved without customer impact. Hydro's operational data is reported in the Rolling 12 report.
NSPML Application to Review the Holdback Mechanism (NSEB M12696) NSPML Responses to Bates White Information Requests NON-CONFIDENTIAL Request IR-05 3 a) Please confirm that NSPML's requested relief associated with Good Utility Practice 4 i...
AI summary NSPML is requesting a review of the Holdback Mechanism and has responded to information requests regarding the LIL's performance, including its inability to operate at full capacity due to software issues and the classification of planned and extreme weather-related outages as good utility practice.
NSPML Responses to Bates White Information Requests 1 ii. Explanation of the "software update" and why the update was needed. 17 with a generating capacity of 824 MW and an annual estimated energy production of 4.9 18 TWh (an average of 60...
AI summary The document discusses NSPML's responses to information requests, including an explanation of a software update and its necessity. It mentions generating capacity, energy production, system losses, and storage limitations at Muskrat Falls, along with reserve limits and asset status on regional systems.
NON-CONFIDENTIAL 1 2023. At that time the LIL was (and continues to be) operational as a critical piece of the 2 regional system. Work since that time has been part of normal and routine maintenance, or 3 to augment functionality or correc...
AI summary The Labrador-Island Link (LIL) remains operational with routine maintenance and improvements. NSPML argues an icing event constitutes 'exceptional circumstances' warranting relief, noting past extreme weather events without outages. NLH's response to the event had limited downtime, showcasing robust emergency protocols.
PARTIALLY CONFIDENTIAL 1 • Nova Scotians incurring 20 percent of the cost of the Lower Churchill Project to 2 secure 20 percent of the output. 3 4 NSPML reaffirms its belief that customers have received the collective contractual bargain 5...
AI summary NSPML asserts customers received the 'collective contractual bargain' post-LIL commissioning, emphasizing 35 years of renewable energy from the NS Block and its role in avoiding fossil fuel units. The NS Block's dispatchable energy supports system reliability and integration, with deferred energy fully delivered. NS Power plans increased use of dispatchability as wind capacity expands.
Page 851 - lines 14 to 22 14 MR. YOUNGER: And I understand that 15 you're going to get the energy. My concern is you 16 know, we just had a fairly lengthy discussion about the 17 need to back up wind energy. And my concern is that you 18 s...
AI summary Mr. Younger expresses concern about the reliability of wind energy and the need for backup supply, emphasizing that energy shortages over short or extended periods must be addressed. Mr. Sidebottom responds by stating that the proposed Link will meet the 20 percent planning reserve and will be more reliable than the generator it replaces, citing typical forced outage rates for industry generators.
Hydropower in the United States is used extensively for power system flexibility and resilience. - » In many parts of the country, hydropower provides more frequency regulation and reserves than its share of installed capacity. - » In near...
AI summary Hydropower in the U.S. provides significant power system flexibility and resilience, contributing disproportionately to frequency regulation, hourly ramping flexibility, and black start resources despite representing less than 6.7% of total electricity generation capacity.
, the extent of operational constraints due to non-power purposes (e.g., flood control, irrigation, recreation) of the dams, and the generation fuel mix in the BA help explain some of the variability. USACE Pressbooks: https://cdm16021.con...
AI summary The text discusses factors influencing hydropower variability, including non-power dam uses (flood control, recreation) and fuel mix in balancing authorities (BAs). It references EIA data on 2019 one-hour ramping performance for hydropower (including PSH) and natural gas fleets across 18 BAs, highlighting capacity distribution and high-frequency ramping metrics.
IN MULTIPLE ISOs. THE SHARES OF FREQUENCY REGULATION AND RESERVES PROVIDED BY HYDROPOWER ARE MUCH HIGHER THAN HYDROPOWER'S SHARE OF INSTALLED CAPACITY - For instance, in the Pennsylvania- Jersey-Maryland (PJM) Interconnection, hydropower s...
AI summary Hydropower contributes disproportionately to frequency regulation and reserves in ISOs like PJM compared to its installed capacity share. Data from 2014-2019 shows hydropower's reserve contribution declined, while EIA reporting requirements (effective 2018) enabled more detailed analysis. Hydropower provides 40% of U.S. black start resources despite representing <10% of generation capacity.
008 is one of the key drivers for the generally low wholesale electricity price levels in Figure 23. In the Pacific Northwest and the SPP territory, large growth in installed wind capacity has also contributed to the low prices. The cost-b...
AI summary Federal hydropower prices show less year-to-year variation than wholesale market prices. Eastern PMAs (SWPA, SEPA) have higher average rates than wholesale prices since 2011, while BPA and WAPA align with regional prices. Revenue variability for SWPA and SEPA is greater due to factors like rainfall dependence and drought resilience. PMAs are considering ISO/RTO market participation to adapt to changing market structures.
5. U.S. Hydropower and PSH Cost and Performance Metrics This chapter reports a wide array of metrics regarding hydropower cost and performance. It provides updates on databases of U.S. hydropower construction and O&M costs. Then, it turns...
AI summary The chapter details U.S. hydropower and PSH metrics, including construction and O&M costs, generation trends, capacity factors, availability factors by region and season, and grid reliability contributions through ramping and ancillary services.
ary (Powerex Corporation) 64 2018 State of the Market Report for the New York ISO Markets 65 https://www.cer-rec.gc.ca/nrg/ntgrtd/mrkt/snpsht/2020/01-01lctrctyxprtmprt-eng.html Treaty modernization discussions center around post-2024 flood...
AI summary Treaty modernization discussions focus on post-2024 flood control provisions, U.S. compensation for downstream power benefits, and ecosystem improvements. The U.S. argues for revising the Canadian entitlement calculation, while Canada claims current compensation doesn't fully account for Treaty impacts. Hydropower generation correlates variably with drought conditions across regions.
EFFECTS OF EXTREME HYDROLOGICAL CONDITIONS ON HYDROPOWER Given drought's unpredictability and its dependence not only on atmospheric variables but also on soil moisture and land surface conditions, the relationship between drought and clim...
AI summary The text examines how extreme hydrological conditions, such as droughts and floods, impact hydropower generation. It highlights the complexity of drought-climate change relationships, the need for downscaled climate models, and projected shifts in hydropower output due to changing precipitation and temperature patterns. Mitigation strategies like operational adjustments and infrastructure investments are discussed.
nnual gross PSH generation by region (2003–2019) Source: EIA Form 923 (2003–2018), EIA Form 923 Early Release (2019) Note: The Northwest region was excluded because it has a very small PSH capacity. Despite the Southwest having 70% more PS...
AI summary The text analyzes PSH generation trends (2003–2019), noting regional disparities in capacity factors, drought impacts on Southwest facilities like J S Eastwood, and Midwest outages at Ludington and Taum Sauk. Southwest plants operated at lower capacity factors despite higher capacity, while drought effects were less severe than for hydropower.
ercentages experiencing drought conditions in the Pacific Northwest and California HUC-2 regions-which contain 55% of installed hydropower capacity in the United States-were 3% in 2006 and 0% in 2011. Figure 40 also shows that every year h...
AI summary The text discusses variations in hydropower capacity factors across U.S. regions, influenced by drought conditions, operational modes, ownership types, and market structures. Northern regions (Northwest, Midwest, Northeast) have higher average capacity factors (43-45%) compared to southern regions (Southwest, Southeast at 27-32%), with resource quality and market dynamics contributing to the disparity.
5.5 Availability Factors In 2016–2018, availability factors remained stable for small (< 10 MW) and large units (> 100 MW) but continued decreasing for medium-sized units (10–100 MW). As shown in Section 5.4, the average capacity factor fo...
AI summary Availability factors for hydropower units in 2016–2018 showed stability for small and large units but declines for medium-sized units. The text distinguishes capacity factors from availability factors, emphasizing their different implications for performance evaluation. NERC collects and publishes availability data through GADS, though unit identifiers are anonymized.
ES are investigating the constraints (mechanical, hydrological, institutional) shaping the use of hydropower and PSH capabilities and seeking to align their use with the evolving needs of the grid. 78 Availability factors exhibit more seas...
AI summary The analysis examines seasonal variations in hydropower and PSH availability factors, highlighting hydropower's dependence on hydrological conditions versus PSH's ability to schedule outages. Data from NERC GADS (2005-2018) shows 28% of U.S. hydropower and 55% of PSH units reported availability factors, with PSH exhibiting less seasonal variability.
5.6 Hydropower Operation Flexibility Power system flexibility is the ability to effectively cope with variations in the supply or demand of electricity (International Energy Agency, 2019). Mismatches between supply and demand take place at...
AI summary Hydropower flexibility is critical for balancing electricity supply and demand, especially with variable renewables. Flexibility varies by facility design and operational constraints, while increased use for grid services may accelerate equipment degradation. Metrics like ramping, ancillary services, and unit starts are used to assess U.S. hydropower's contribution to grid reliability.
5.6.1 Ramping (hourly frequency) The average and range of one-hour ramps of electricity production performed by the hydropower fleet (including PSH) vary widely across BAs. In 34 out of 36 BAs analyzed, hourly ramps were larger (and their...
AI summary Hydropower (including PSH) exhibits larger and more variable one-hour production ramps compared to natural gas in 34 of 36 BAs analyzed, potentially impacting grid reliability and management strategies.
Variable renewable penetration does not help explain cross-sectional variability in average one-hour ramps across the BAs. Variable renewable energy (solar and wind) penetration is another BA attribute that is useful to investigate in rela...
AI summary The analysis finds no strong correlation between variable renewable energy penetration and cross-sectional variability in average one-hour hydropower ramps across balancing authorities (BAs). Only one of 11 BAs with high hydropower ramping has significant solar/wind penetration. Sub-hourly ramp data, critical for flexibility products, remains uncomputable with available hourly data.
5.6.3 Contribution to Provision of Ancillary Services With increasing variable renewable energy penetration, maintaining the reliability and resilience of the grid, which is underpinned by various ancillary services and dispatchable genera...
AI summary Hydropower's flexibility and ancillary service capabilities are critical for grid reliability with high renewable penetration. While hydropower offers rapid startup, black start, and voltage control, constraints like multi-purpose dams and water availability limit its operational flexibility. PJM and EIA data highlight its technical advantages but note challenges in prioritizing electricity generation.
MULTIPURPOSE CONSTRAINTS TO HYDROPOWER OPERATIONAL FLEXIBILITY Protection of fish and wildlife is an important priority shaping hydropower operations in many parts of the United States. In the lower Snake and lower Columbia dams that are p...
AI summary The text discusses how fish and wildlife protection measures, such as water spilling for juvenile fish passage in the Federal Columbia River Power System, constrain hydropower operational flexibility. A 2018 collaborative agreement among federal agencies, states, and tribal nations introduced flexible spill timing, improving hydropower efficiency metrics like generation during peak load hours and mileage per megawatt. This balance between environmental and operational goals is highlighted.
In ISO-NE, at least two thirds of hydropower capacity receive uplift revenue and provide reserves and voltage control. Market data from ISOs/RTOs help document hydropower's versatility in the provision of grid services. Figure 53 shows how...
AI summary In ISO-NE, two-thirds of hydropower capacity receives uplift revenue for grid services like reserves and voltage control. Market data shows hydropower's role in spinning reserves, regulation, and black start capabilities, with trends linked to solar/wind penetration and NERC standard revisions. Figure 53 (FERC Electric Quarterly Report) illustrates service provision from 2008-2017.
te: Natural gas includes the contribution from combustion turbines and combined cycles; however, it should be noted that a small portion of the fuel used by (dual-fired) combustion turbines is diesel. CAISO is a leading market in decarboni...
AI summary CAISO's hydropower provides significant ancillary services, including regulation and spinning reserve, even during droughts. Hydropower (including PSH) outperformed its capacity share in regulation and spinning reserve, while natural gas and batteries also contribute. Droughts reduced regulation down but not other services, highlighting hydropower's flexibility for solar integration.
8. External Reviewer Recommendations Regarding Future Reports As in previous editions of the Hydropower Market Report, this document has benefitted from significant review and input from a diverse set of external reviewers. Not only have r...
AI summary External reviewers recommended future analyses on hydropower R&D trends, unit outage causes, operational pattern changes, hydrologic metrics, and capital expenditure drivers. These topics aim to enhance understanding of innovation, reliability, market adaptations, and investment priorities in hydropower and pumped storage.
erhard, A., and R. Naude. 2016. "The South African Renewable Energy Independent Power Producer Procurement Programme: A Review and Lessons Learned." Journal of Energy in South Africa 27, no.4: 1–14. European Small Hydropower Association. 2...
AI summary The text references studies and reports on hydropower, renewable energy programs, regulatory processes, and environmental considerations, including South African IPP procurement, European small hydropower, FERC licensing, fish passage in the Columbia River, Bonneville Power Administration's flexible assets, drought analysis, hydropower rights in Europe, and black start resources.
NERC Generating Availability Data System The sample size for the NERC GADS dataset is not constant over time. Until 2011, hydropower plant owners were reporting to NERC on a voluntary basis. Reporting became mandatory for units greater tha...
AI summary The NERC GADS dataset's sample size has evolved over time, with mandatory reporting starting in 2012 for units >50 MW and 2013 for units >20 MW. The analysis highlights challenges in data anonymity, segmentation of hydropower vs. PSH units, and the impact of changing sample composition on interpreting availability trends.
1.0 Introduction and Summary of Findings - 2 Early in 2020, Newfoundland and Labrador Hydro ("Hydro") commissioned Haldar & Associates Inc. - 3 ("Haldar & Associates") to undertake an "Assessment of Labrador Island Transmission Link (LIL)...
AI summary Newfoundland and Labrador Hydro commissioned an assessment of the Labrador Island Transmission Link's reliability under climatological loads. The assessment evaluated the design against CSA 60826 standards and considered both damage and ultimate limit states, resulting in a baseline reliability of a 1:72 year return period under CSA standards and a 1:160 year return period under ULS analysis.
11 1.2 Ultimate Limit States - 12 The ULS is outside the CSA standard. This scenario was considered as the governing component of the - 13 LIL is the OPGW, and considering a return period and failure rate on the governing component only do...
AI summary The analysis examines the Ultimate Limit State (ULS) for the Labrador-Island Link (LIL), considering structural failure scenarios beyond CSA standards. By increasing strength factors to maximum limits, the ULS scenario indicates a 1:160-year return period with a 0.48% annual failure rate, highlighting risks to power delivery reliability.
6 1.3 Segmented Line Lengths versus Full Line Length - 7 In line with CSA standards, the LIL reliability has been assessed based on segmented line lengths (i.e., 11 - 8 individual line segments based on geographical region) versus the full...
AI summary The document discusses reliability assessments of the Labrador-Island Link (LIL) using segmented line lengths versus full line lengths, referencing CSA standards. Haldar & Associates emphasize the importance of full line length analysis, noting increased failure probability compared to global infrastructure benchmarks. Pre-CSA design considerations did not standardize full line length assessments, and current adoption remains unclear.
20 2.0 Background - 21 The original design of the LIL was considered to be equal to or greater than Hydro's historical - 22 transmission line designs, which are deemed to have a 1:50 year return period based on historical - 23 design pract...
AI summary The Labrador-Island Link (LIL) was originally designed using historical transmission standards (CSA 22.3 No.1) and later assessed under CSA 60826. A 2014/2015 study by SNC Lavalin found a 1:150 year return period, with some sections at 1:500. Hydro later conducted a comprehensive reliability assessment of all infrastructure components, adhering to CSA 60826 principles.
2.1 EFLA Assessment of As-Designed Structural Capacity of the Labrador-Island Link - 12 In the first stage of the reliability assessment undertaken by Hydro, EFLA Consulting Engineers ("EFLA") - 13 was engaged to complete a comprehensive r...
AI summary EFLA Consulting Engineers assessed the Labrador-Island Link's structural capacity against CSA standards, finding a 1:150 year return period. However, rime icing was excluded as CSA lacks specific requirements. SNC Lavalin's peer review identified discrepancies due to differing ice load inputs and calculation methods based on CSA interpretations.
2.2 EFLA's Rime Ice Modelling - 23 To further its understanding of rime ice impacts on the LIL, Hydro subsequently contracted EFLA to - 24 complete weather forecasting modelling of the LIL's Alpine regions, which would be necessary to - 25...
AI summary Hydro contracted EFLA to model rime ice impacts on the Labrador-Island Link (LIL) using historical and forecasting data. The 2020 findings confirmed the original line routing avoided high-exposure areas, resulting in significantly lower rime ice loading (up to six times less) and improved reliability in remote Alpine zones.
3.0 Assessment of Labrador Island Transmission Link (LIL) Reliability in Consideration of Climatological Loads - Haldar & Associates Assessment - 21 The Haldar & Associates Assessment considered the impact of two types of icing on the stru...
AI summary Haldar & Associates assessed the Labrador Island Transmission Link (LIL) HVdc line's reliability under glaze and rime icing scenarios, identifying failure probabilities leading to extended outages. The study followed CSA 60826 guidelines and incorporated EFLA's rime ice evaluation.
3.1 CSA 60826 Analysis - 29 Based on CSA 60826, the Haldar & Associates Assessment indicates that the as-built LIL has a return - 30 period of approximately 1:72 years and an estimated annual failure rate of 1.10% where the CSA standard is...
AI summary The Haldar & Associates Assessment, based on CSA 60826, evaluates the Labrador-Island Link (LIL) and concludes its mechanical failure limits are not expected to be reached due to a 60% OPGW tension limit (vs. CSA's 75%), providing a safety margin. While extended outages are unlikely, persistent environmental conditions could cause operational issues.
3.2 Ultimate Limit State Analysis - The return period and failure rates under an ULS was also considered to provide a more complete picture of the considerations necessary with respect to the LIL reliability. The ULS analysis was undertake...
AI summary The ULS analysis of the LIL infrastructure assesses extreme loading scenarios, identifying a 1:160-year return period and 0.48% annual failure rate. Design differences from typical utility practices are noted, with Hydro asserting that mechanical failures are unlikely to cause extended outages due to buffer capacity. Operational protocols and ice removal techniques are highlighted as mitigation strategies.
3.3 Line Length Consideration - 21 The Haldar & Associates Assessment identified long line length as a consideration of the LIL structural - 22 reliability. The CSA standard does not require analysis of the impact of line length on reliabi...
AI summary The Haldar & Associates Assessment highlights that longer line lengths decrease reliability, as noted in their analysis of the Labrador-Island Link (LIL). While the CSA standard does not require line length analysis, Haldar identifies this as a shortcoming, citing annual failure rates under different scenarios.
4.0 Additional Considerations - 5 The Haldar & Associates Assessment identified additional considerations related to the as-built design of - 6 the LIL which are suggested for further investigation. These recommendations were identified as...
AI summary Hydro is evaluating additional design considerations for the Labrador-Island Link (LIL) identified by Haldar & Associates, including icing effects and wind factors. Further engineering assessments are needed to validate adjustments, with Hydro consulting Nalcor Energy and reporting to the Board.
4.1 Effect of Large Diameter Pole Conductor - 2 CSA states that an ice load adjustment can be made if the cable diameter is different than the diameter - 3 of modelling rod that was used in the measurements or during simulations. Since the...
AI summary The text discusses adjusting ice load calculations for large-diameter pole conductors compared to a 25mm standard rod used in CSA simulations. Haldar & Associates recommends an engineering assessment to improve reliability by addressing reduced ice accumulation impacts on the existing LIL design.
4.2 Unbalanced Loading - 13 CSA 60826 suggests that unequal ice accumulations or shedding in adjacent spans will induce critical - 14 out-of-balance longitudinal loads on the supports. This loading can occur either during ice accretion or...
AI summary The text discusses unbalanced ice loading on the Labrador-Island Link (LIL) infrastructure, referencing CSA 60826 standards and Haldar & Associates' recommendations. It highlights discrepancies between CSA guidelines, Hydro's past practices, and the LIL's design, which includes anti-cascading towers. Haldar & Associates argues for deterministic load treatment and further studies due to Labrador's colder climate, increasing ice residence time and risk.
5.0 Conclusion - 26 The Haldar & Associates Assessment was undertaken to identify the overall structural reliability of the - 27 LIL with respect to the probability of failure based on the integrity of the system components and - 28 consid...
AI summary The Haldar & Associates Assessment evaluated the structural reliability of the Labrador-Island Link (LIL), considering climatological conditions, icing events, and compliance with CSA 60826 standards to determine the likelihood of failure and extended outages.
Attachment 1 Assessment of Labrador Island Transmission Link (LIL) Reliability in Consideration of Climatological Loads NSPML 2026 Holdback Mechanism BW IR-15 Attachment 1 Page 22 of 134
AI summary This attachment assesses the reliability of the Labrador Island Transmission Link (LIL) under climatological load conditions. It references the NSPML 2026 Holdback Mechanism and is part of Bates White's IR-15 submission.
Assessment of Labrador Island Transmission Link (LIL) Reliability in Consideration of Climatological Loads Prepared By: Asim Haldar, Ph.D., P. Eng. Principal Investigator Haldar & Associates Inc. St. John's NL Report Prepared for Newfoundl...
AI summary This document assesses the reliability of the Labrador Island Transmission Link (LIL) under climatological load conditions. Prepared by Asim Haldar for Newfoundland and Labrador Hydro (NLH) on March 10, 2021, it evaluates how climatic factors impact transmission reliability.
REPORT DISCLAIMER This report contains information about the Labrador Island Link (" LIL ") reliability study (the " Report "). The Report uses data specifically related to the structural analysis of the LIL, which was provided by Newfound...
AI summary This disclaimer accompanies a reliability study of the Labrador Island Link (LIL), funded by Newfoundland and Labrador Hydro and Nalcor Energy. It limits liability for damages arising from the report's use and notes its submission to the Public Utility Board. The study focuses on structural analysis data provided by the contributing entities.
Executive Summary This report presents the impact of two types of icing on the structural reliability of the Labrador-Island Link (LIL) HVdc transmission line. The two types of icing are (a) glaze icing due to freezing precipitation and (b...
AI summary This report evaluates the structural reliability of the Labrador-Island Link (LIL) HVdc transmission line under glaze and rime icing conditions. It assesses failure rates, validates LIL design against CSA 60826-2010, and compares failure rates normalized by line length with operational data. The study informs reliability planning by quantifying outage risks from extreme weather.
1.1 Impact of Weather Events on Power Delivery Since the commissioning of Hydro's (NLH's) transmission lines in the 60's, much of NLH's system has experienced ice storms and severe ice loadings. The original design wind and ice loads for t...
AI summary The text discusses the historical impact of ice storms on Newfoundland and Labrador Hydro's (NLH) transmission lines, referencing original design standards (CSA C 22.3 No.1) and documented failures since the 1960s. It highlights design load assumptions, ice accumulation issues, and specific failures in regions like the Avalon Peninsula and Buchan's Plain, emphasizing infrastructure vulnerabilities to weather events.
1.2 Labrador Island Transmission Line (LIL) System Configuration The ± 350 kV HVdc line route extends from the Muskrat Falls generating station in Labrador to the Strait of Belle Isle, before passing under the Strait of Belle Isle via an u...
AI summary The Labrador Island Transmission Line (LIL) is a ±350 kV HVdc system connecting Muskrat Falls to Newfoundland, passing through regions prone to severe icing. It includes key components like converter stations and integrates with NLH's AC network, spanning 1093 km with 388 km in Labrador and 705 km in Newfoundland.
to validate the design for an increased return period based on ice and wind loads; however, the clearances due to increased sag and due to swing angles need to be addressed (serviceability criteria)". Mr. Alteen's submission from Newfoundl...
AI summary The text addresses the need to validate design for increased return periods due to ice and wind loads, emphasizing clearances for sag and swing angles. Mr. Alteen's submission highlights reliability concerns for the Labrador Island Transmission Link (LIL) and the Isthmus zone's critical corridor post-Holyrood decommissioning, noting Nalcor's oversight in considering line length in reliability assessments.
1.4 Return Period Concept in Selecting Overhead Line Design Loads One of the major concerns that has been raised during the review and information gathering process is that LIL did not strictly meet the CSA C 22.3 60826-06 standard and tha...
AI summary The text discusses concerns that the Labrador Island Transmission Link (LIL) did not meet CSA C 22.3 60826-06 standards, leading to underestimated design loads. Nalcor responded by citing a 50-year return period, operational experience of NLH, and Hydro's risk assessments. The CSA standard requires higher reliability (Level III) unless justified by studies. Methodologies by Haldar (1990s–2020s) are cited for cost-risk optimization in line design.
1.5 Objective of this Study The primary objective of this report is to assess the structural reliability of the LIL considering two predominant types of icing to which the line is exposed. These are (a) glaze icing due to freezing precipit...
AI summary The study assesses the structural reliability of the Labrador Island Transmission Link (LIL) against glaze and rime icing, using CSA 60826-2010 standards. It evaluates failure rates under various scenarios, conducts a sensitivity analysis, and benchmarks against operational data to inform system planning reliability.
1.6 Scope of this Study This study evaluated the overall line reliability of LIL with respect to the likelihood of failure based on a range of climatological loading scenarios. This report includes the inputs and data from the following re...
AI summary This study evaluates the line reliability of the Labrador Island Transmission Link (LIL) under climatological loading scenarios, incorporating structural capacity assessments, rime icing recalibration, and benchmarking against utility operational data. Findings will inform failure likelihood, repair rates, and outage duration calculations.
1.7 EFLA (2020) Report on Strength Assessment of LIL – Summary With respect to first item under the "Scope of the Study", EFLA has submitted a report in April 2020 entitled "Structural Capacity of as-built Design of the LIL following CSA C...
AI summary The EFLA (2020) report found that the Labrador Island Transmission Link (LIL) design did not meet the 500-year return period load effect, instead meeting the CSA 150-year standard in most cases, except specific zones where OPGW and hardware failed. The study excluded rime icing and unbalanced ice loads, recommending an impact study on OPGW loss.
1.8 Deliverables - Baseline LIL reliability (and probability of failure and failure rate) that considers two types of icing exposures and associated climatic hazard exposures - A targeted sensitivity of the following parameters is included...
AI summary The deliverables focus on assessing LIL reliability under icing conditions, sensitivity analyses for terrain, topography, and ice-wind interactions, justification for extreme ice loads, OPGW loading issues, and uncertainty in rime ice modeling. Clearance issues from Section 1.3 are excluded.
1.9 Layout of the Report Section 1 provides a brief historical background of this project and the objective and the primary focus of this study. This section also presents a high-level chronological overview on the Nalcor's submissions to...
AI summary The report outlines a structured analysis of the Labrador Island Transmission Link (LIL) design, focusing on reliability, system planning, and CSA standard compliance. It emphasizes the impact of line length on reliability for a long HVdc radial line, critiques CSA 60826-2010, and benchmarks against NLH's operational experience. Key themes include reliability-based design, transmission planning, and system reliability considerations.
2.0 Basic System Design Concept In overhead line design, reliability is determined by assigning a fixed return period to extreme climatic events, such as wind, ice, and combined wind and ice loads. This implies some expected failure rate d...
AI summary The section discusses reliability and security in power system design, emphasizing overhead line reliability through return periods for extreme weather and structural security measures like containment structures. It outlines BEPS planning criteria (N-1, N-2, N-1-1) and contrasts reliability (probabilistic) with security (deterministic) in power networks versus structural design.
Mechanical System Reliability : Reliability of a line is defined as the probability that the line will perform under specified conditions for a specified period, normally defined as the service life. Security : Security is often referred a...
AI summary The text defines reliability as a line's probability of performing under specified conditions and security as its ability to withstand catastrophic failures. Mitigation strategies include designing suspension structures with adequate longitudinal RSL and inserting anti-cascading towers (stop towers) every 20-25 towers to prevent cascade failures.
Power System The primary function of an electric power system is to economically supply electrical energy to its customer with adequate reliability and service continuity. Billinton and Allan (2007) describe the system reliability in terms...
AI summary The power system's primary function is to supply reliable electrical energy. System adequacy ensures meeting load demand, while security addresses transient disturbances. The author suggests integrating reliability and security through an availability model considering failure and repair rates.
2.2 Selection of Optimum Return Period The initial line cost (LCOS) will increase as the reliability increases, and the future failure cost (DCOST) will decrease as line reliability increases. An optimum reliability can be found by balanci...
AI summary The text discusses balancing initial line costs (LCOS) and future failure costs (DCOST) to determine optimal reliability for a HVdc transmission system. It references studies by Haldar and others, emphasizing probabilistic models, risk assessment, and the impact of the Maritime link on risk reduction. The Avalon upgrade study highlights the need for economic justification of reliability improvements, including customer interruption costs.
2.3 Reliability Worth - Acceptable Value Determination of line reliability (failure rate, ) can be estimated (in ranges) with some degree of confidence, in contrast to line security risk, where the design philosophy is strictly determinist...
AI summary The text discusses the determination of line reliability and its impact on system parameters such as LOLE and EENS under extreme weather conditions. It references studies on reliability assessment and outlines the classification of BEPS and local disturbances, emphasizing the importance of assessing structural reliability in response to climatological loads.
482 Table 2.1 Degree of Severity for BES Disturbances and Local Disturbances (Billinton and 483 Wangdoe, 2006) Degree of Description BES Local security Disturbance Disturbance (System (MW Minutes) minutes) Degree 0 -an unreliability condit...
AI summary This table outlines the degree of severity for Bulk Electric System (BES) and local disturbances, categorizing them based on the duration of unreliability and the impact on customers. It defines four degrees of severity, from acceptable conditions to very serious impacts.
2.5 Reliability Model – System Level In system design, there are two fundamental systems: series and parallel. A series system fails when any member has failed. This is also a characteristic of the "weakest-link" system.
AI summary The system-level reliability model distinguishes between series and parallel systems, noting that series systems fail when any component fails, embodying the 'weakest-link' characteristic. This foundational concept informs reliability analysis in power system design.
2.5.1 Reliability Model – System vs. Component It is known that for a series system, the system reliability is always less than the individual component reliability and the system fails when any one of its components fails. On the other ex...
AI summary This section explains system reliability differences between series and parallel configurations. Series systems (e.g., cable systems) fail with any single component failure, while parallel systems (e.g., transmission towers) maintain functionality through redundancy. Reliability decreases in series systems with added components, whereas parallel systems improve with redundancy.
Table 3.1 Relationship between Lifetime Reliability and Return Period (T) Return Period, T 50 150 500 Reliability During 0.36 0.71 0.90 50-year Asset Life $(0.50)^ $ (1.3) POF during Asset's 0.64 0.29 0.10 Life (50 years) \ Bracketed value...
AI summary Table 3.1 illustrates the relationship between lifetime reliability and return period (T) for a 50-year asset life. It shows reliability during different return periods and the probability of failure (POF) during the asset's life, with a reliability index provided for one of the values.
3.2 Introduction – CSA 60826-06/10 Under reliability class of loads, CSA 60826-10 stipulates that extreme ice, extreme wind, two types of combined wind and ice loads, and unbalanced ice load cases be considered in line design. CSA also rec...
AI summary CSA 60826-06/10 outlines reliability design standards for power lines, emphasizing extreme weather load cases, return period values for HV lines, and climatological parameters. It distinguishes between damage limit state (DLS) for reliability analysis and security load failure criteria, noting that DLS violations do not always equate to structural failure. The standard lacks national maps for rime icing, a significant hazard for the LIL line.
663 Table 3.2 Design Requirement for the System (CSA 60826, 2010) Condition Type of Load Required Performance Corresponding Limit State Reliability Climatic Loads with a Return Period, T years To ensure reliable and safe power transmission...
AI summary The text discusses the design requirements for transmission systems based on CSA 60826-10, emphasizing reliability, security, and safety. It highlights the difference between theoretical and practical approaches to modeling transmission tower reliability, including the use of parallel and series systems, as well as simulation techniques for analyzing failure modes.
3.4 Limit States of Transmission Lines –Examples
AI summary The section provides examples of limit states for transmission lines, focusing on technical criteria and safety margins relevant to power system reliability and infrastructure design standards.
3.4.1 Damage Limit State (DLS) Three 735kv lines run parallel from the Churchill Falls generating station to the Hydro Quebec Montagnasis substation and serve to transport power to the Hydro Quebec system. These lines have experienced seve...
AI summary The text details two incidents (1995 and 1997) where severe icing on 735kV lines from Churchill Falls to Hydro Quebec caused flashovers and outages due to Damage Limit State (DLS) violations. Icing led to ground wire sagging, phase-ground short circuits, and line outages. The 1995 event involved a failed U-bolt, while the 1997 incident required cutting the ground wire to restore power.
Manitoba Hvdro + 500kV HVdc Lines Manitoba Hydro HVDC transmission system consists of three Bipole lines called Bipole I(BP1), Bipole II (BP2), and Bipole III (BP3) respectively. Bipoles I and II were built in the 70's and 80's (?) while B...
AI summary Manitoba Hydro's HVDC transmission system, including Bipole I, II, and III, faces reliability risks from severe weather events. A 1996 microburst caused simultaneous failures of Bipoles I and II, leading to a 2020 MW outage and four-day power restoration. The incident prompted significant R&D investments to mitigate High Intensity Wind (HIW) impacts on transmission infrastructure.
Churchill Falls 735kV Lines In the December 27, 1995 storm, several line trips and subsequent clearing were first experienced on line 7051 and, on the following day, lines 7052 and 7053 experienced outages. The heavy icing caused a ground...
AI summary A 1995 storm caused line outages on Churchill Falls 735kV Lines due to heavy icing, leading to a ground wire detachment from a tower via broken U-bolts. The 1997 failure, initially classified as DLS, resulted in line decommissioning after OHGW removal.
3.5 Typical Asset Component State Classification – Reliability Index and POF Reliability indices are a relative measure of component's POF and provide a qualitative measure of the expected performance. A structure support system (SS) or a...
AI summary This section discusses reliability indices and probability of failure (POF) for infrastructure components, classifying asset states based on these metrics. It highlights that low reliability indices correlate with higher failure risks, using examples like transmission lines (POF 0.02–0.001) and offshore structures (beta ≥5). Design criteria like N-1/N-2 and CSA 60826 standards are referenced for reliability targets.
3.6 Review of CSA 60826 (2010) In the CSA standard, the line is considered a system that consists of many major components (subsystems), such as supports, foundations, conductors, insulators, and hardware. Each component can be further bro...
AI summary The CSA 60826 (2010) standard outlines transmission line design, emphasizing system reliability through component strength exceeding weather-related loads, with figures illustrating system hierarchy and connectivity.
3.6.1 Design Equation CSA 60826 (2010) provides a framework where the semi-probabilistic design equation is given in terms of the load effect on a component and the strength of the component. The basic equation relates the characteristic s...
AI summary CSA 60826 (2010) outlines a semi-probabilistic design equation (R_C ≥ Q_T) for structural reliability, assuming Gumbel and normal distributions for load and strength, respectively. It specifies COV ranges for accuracy but highlights limitations when load COV exceeds 0.5, such as with ice thickness, leading to potential POF estimation errors. The approach's reliance on distribution assumptions may introduce variability in reliability assessments.
4.0 Loading and Strength of LIL Line Overhead lines are normally designed for two types of loads, (1) reliability (normal) loads and (2) security loads. During the operation of the asset, normal loads—sometimes called probabilistic climato...
AI summary The text discusses the design of overhead transmission lines for reliability and security loads, emphasizing challenges in meteorological data collection, reliance on Environment Canada weather maps, and the impact of under/overestimating wind and ice loads on line reliability and capital costs.
4.1 Glaze Ice Loads Freezing precipitation usually occurs when a cold air mass with temperature less than or equal to 0° C is positioned below a layer of warm air through which rain or drizzle is falling. When the liquid droplets pass from...
AI summary The text explains glaze ice formation on conductors and OPGW due to freezing precipitation, detailing supercooled droplet behavior, freezing conditions, and density. It references CSA 60826-10 standards and includes a figure comparing ice thickness values with EFLA 2020 design parameters.
4.2 Rime Ice Loads Rime icing results from accretion of super cooled water droplets which freeze immediately upon contact with a surface. The density of rime ice varies depending on the size and speed with which the supercooled water dropl...
AI summary Rime ice forms when supercooled water droplets freeze on surfaces, influenced by wind velocity, temperature, droplet size, and liquid water content. The text explains rime ice density ranges, formation parameters, and provides an equation for ice accretion rates, referencing studies by Haldar et al (2016) and the CEATI TODEM 3384 Report.
4.2.1 Rime Icing Forecast along LIL Route in Zones 2, 5, and 7 (EFLA, 2021) CSA 60826-10 does not provide any rime ice map as it does for glaze icing. EFLA-KVT was retained by NLH to develop the rime icing loads (in-cloud icing loads) on t...
AI summary The study by EFLA-KVT for NLH on rime icing along the LIL route in Zones 2, 5, and 7 used monitoring stations, hindcast data, and the Makkonnen model. The model overpredicted icing compared to test data, highlighting the need for accurate forecasting in transmission planning.
4.3 Wind Loads The design wind speed and pressure used in the reliability analysis are based on CSA 60826-10 for 50, 150, and 500-year return period values and is presented in Figure 4.8. $\begin{array}{c} 1047 \\ 1048 \end{array}$ Figure...
AI summary The section outlines wind load design parameters for reliability analysis, referencing CSA 60826-10 standards for 50, 150, and 500-year return periods. It includes figures detailing wind pressure ratios and rime ice data from numerical weather models, citing EFLA reports from 2020 and 2021.
4.5.1 Brief Review of Design Philosophy for Unbalanced Ice Loads including NLH's Design Brief In Newfoundland and Labrador Hydro (NLH), unbalanced ice loads have always played a significant role because of the harsh environment and towers...
AI summary NLH's design philosophy for unbalanced ice loads emphasizes conservative load considerations, including full and partial ice thickness scenarios, and evolved from historical practices (SAE towers) to modern standards (e.g., NLH A1-2200-T-546). Load combinations for all phase configurations are analyzed to ensure structural safety.
4.6 Strength of Component The assessment of the characteristic strength of each component and the load effects on this component, following equation (3.3) in Section 3, is necessary to develop the reliability calculation model. Figure 4.9...
AI summary The reliability calculation model requires assessing component strength and load effects using equation (3.3). Figure 4.9 illustrates key components in support and wire subsystems across segments, highlighting critical elements for analysis.
5.0 LIL Reliability Assessment The POF and the reliability of LIL under two different types of icing scenarios is determined in this section based on the reliability of individual line segment's exposure to these icing phenomena. A line se...
AI summary The document assesses the reliability of the Labrador Island Transmission Link (LIL) under icing scenarios by analyzing individual line segments and subsystems. It models reliability using the 'weakest link' concept, categorizing segments into glaze and rime icing zones, and distinguishes between series and parallel system configurations for reliability calculations.
5.1 LIL Modelled as a Series System The LIL is modelled as a series system and the system acts as a "weak link" because the system fails and may lose its functionality if one of the line element fails. The series system model is described...
AI summary The Labrador Island Transmission Link (LIL) is modeled as a series system where failure of any component leads to system failure. Reliability is analyzed using N-1/N-2 criteria, with equations for upper and lower bounds of failure probability based on Cornell (1967). Mechanical failures can cause prolonged outages despite electrical redundancy.
5.1.1 Correlation Issue – Among Key Elements Figure 4.7 presents the element layout diagram used to determine the correlation value of a typical segment. Ten key elements are considered for two sub-systems. The selection of ten elements is...
AI summary The text discusses a correlation study among key system elements under extreme ice load conditions, highlighting a correlation value generally above 0.90. It outlines reliability analysis methods, including mathematical bounds for failure probabilities across multiple load cases and subsystems, referencing diagrams and equations for calculation.
5.2 LIL Reliability – System Approach Very long lines are often divided into several segments (several weather zones) because of different loading criteria for various weather zones. Lines below 200km in a severe climatic zone may be desig...
AI summary The section discusses modeling the reliability of the Labrador Island Transmission Link (LIL) by segmenting long transmission lines into weather zones, calculating segment failure probabilities, and applying reliability formulas (e.g., equation 5.5) to assess system-wide reliability under various loading conditions like wind and ice.
5.3 Regional Grouping Considering Multiple Segments Under Various Weather Zones In a technical note, Thomas (2011) outlined the justification for selecting the 50-year return period for LIL and showed that the higher return period could no...
AI summary The text discusses the design and reliability considerations for the Labrador Island Transmission Link (LIL), emphasizing the 50-year return period for its design. It highlights concerns about forced outages in HVDC lines due to length, environmental factors, and repair times, referencing Thomas (2011) and the CIGRE report. The author stresses the need to adjust design loads based on line length to maintain reliability.
5.3.1 Determination of Reliability for LIL (Assumptions for Various Levels) - Level 1 (No regional grouping, full correlation along the entire line length and among elements, no distinction made between different exposure levels, e.g., ici...
AI summary The document outlines four levels of reliability assessment for the Labrador Island Transmission Link (LIL), varying by regional grouping, correlation assumptions, and exposure distinctions (e.g., icing types). Each level corresponds to specific base cases and scenarios, with figures illustrating regional groupings and reliability outcomes.
6.0 Summary Results for Various Zones In this section, summary results are presented for the following load cases and are presented following the Figure 3.1 and the methodology outlined in Sections 4 and 5. This analysis uses the following...
AI summary Section 6.0 presents reliability analysis results for load cases (extreme wind, ice, and unbalanced ice loads) impacting line reliability in glaze and rime icing zones. The author argues unbalanced ice loads should be excluded from reliability calculations, citing Section 6.1.3. Data from 29 segments (22 glaze, 7 rime) is analyzed, referencing methodology from Sections 4 and 5.
6.1 CSA RBD Analysis – Reliability Classes of Loads Based on the structural reliability analysis conducted by the author, all components meet CSA 150-year return period except OPGW and electrode lines in few segments. These analyses are ap...
AI summary The analysis concludes that all components meet CSA 150-year return period standards except OPGW and electrode lines in some segments, applicable to normal climatological loads under reliability class classifications.
6.1.1 CSA RBD Analysis – Reliability Classes of Loads (Glaze Icing) Figure 6.2 summarizes the results for the glaze icing zones. Figure 6.2 Annual POF Under Glaze Icing Figure 6.3 shows that in all segments, foundation POF's are higher tha...
AI summary The analysis of glaze icing zones reveals that foundation failure probabilities (POF) exceed tower POF in most segments, contradicting industry standards where towers should fail first. Similar trends are observed in cable systems versus structural supports, highlighting reliability concerns in infrastructure design under glaze icing conditions.
6.1.2 CSA RBD Analysis – Reliability Classes of Loads (Rime Icing) Figure 6.4 summarizes the results for rime icing zones. Here, sequence of failure between tower and foundation is acceptable, POF of tower is significantly higher compared...
AI summary The analysis examines reliability classes of loads under rime icing conditions, highlighting higher probability of failure (POF) for towers compared to foundations. Figures 6.4 and 6.5 illustrate POF thresholds exceeding 0.01 for specific components like S2-541 (UBI) and OPGW/strain hardware under rime icing, with detailed data points provided.
6.1.3 CSA RBD Analysis – Unbalanced Loads due to Ice Shedding Unbalanced ice load analyses consist of two parts. In the first part, we compare the effects of UBI on two towers selected in the Labrador region deterministically. In this case...
AI summary The analysis of unbalanced ice loads on two Labrador towers is divided into deterministic and probabilistic methods. The first part compares use factors of critical tower members, while the second part uses probabilistic analysis to assess UBI effects.
6.1.3.1 Deterministic Analysis – LIL DESIGN Using NLH Criteria In this section, we compare the analysis results of the two critical towers located in Zones 1 and 3a respectively. These towers are in Labrador and each tower carry five cable...
AI summary This section compares the structural integrity of two critical towers under LIL and NLH design criteria. NLH criteria result in significantly higher use member factors (UF) exceeding 100% for multiple members, with probability of failure (POF) at 1% and 2% respectively. The analysis suggests potential structural risks under specific load combinations, highlighting design concerns for towers in Zones 1 and 3a.
1619 6.3.1 DLS Criterion 1614 1616 1618 1620 Table 6.2 presents the summary results that provide POF for LIL under various scenarios outlined in Table 6.1. The POF presented considers the load effect and strength interference following Fig...
AI summary This section discusses the calculation of probability of failure (POF) for the Long International Line (LIL) under various scenarios, referencing CSA 60826-10 for return period estimation. It highlights that the return period depends on uncertainties in load effect and strength, and provides a 72-year return period based on a semi-probabilistic calculation for glaze icing.
Table 6.3 POF, Failure Rate Determined for Various Scenarios (ULS) RISK of EXC RISK of EXCEEDING ULS - CSA 60826 (5 and 50 Years) Scenario # POF- Annual 5 Years (%) 50 Years (%) Failure Rate (%) 1 0.00474 2 21 0.48 1A 0.00543 3 24 0.54 2 0...
AI summary The table compares the probability of failure (POF) under different scenarios for the Ultimate Load Specification (ULS) and the Design Load Specification (DLS). It highlights that POF under ULS is 43% of that under DLS in Scenario #1. The text also notes that a full ULS system reliability analysis has not been conducted and should be done before generation expansion planning.
7.0 Sensitivity Study This section presents the sensitivity of some key parameters regarding the load effects and strength on LIL POF and reliability. In section 1, the author listed several issues that were raised through RFI process. Upo...
AI summary This sensitivity study evaluates key parameters affecting load effects and reliability of the Labrador Island Transmission Link (LIL) power outage frequency (POF). Case studies assess terrain roughness, wind speed, ice loads, and uncertainties in rime ice predictions. Collaboration with NLH is noted, with item 3 excluded due to WRF model alignment with CSA standards.
7.1 Terrain Roughness To address the effects of terrain roughness (Type B vs. Type C) and topographical issue with respect to "wind speed up effect", the profile of the line on the top of the Hawke Hill is selected. This site is 25km of we...
AI summary The analysis examines terrain roughness (Type B vs. C) and topographic effects on wind load at Hawke Hill, focusing on tower S5-494. CSA 60826-10 defines wind speed calculations, with Nalcor using terrain type C (factor 0.85) for LIL design. The study highlights increased failure probability under Type B terrain but deems it acceptable. The site's open exposure justifies Type B classification despite prior line failures.
7.3.1 S2-541 Tower (Zone 3a) 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 Results of the analyses show that the POF is...
AI summary The analysis reveals that S2-541 tower in Zone 3a has a significantly higher Probability of Failure (POF) under combined wind and ice loads compared to baseline scenarios. This increases the overall POF for the Labrador Island Transmission Link (LIL) and highlights the need for revised design standards considering increased reference wind speeds and terrain roughness.
7.3.2 S5-468 Tower (Zone 11-4) A similar observation is also made on POF for one critical tower in Segment 11-4, S5-468. The POF has also increased significantly from 0.2% to 1.1% (5 times, for load cases 100/40 and 100/50) under combined...
AI summary The analysis highlights increased POF (Probability of Failure) and UF (Unavailability Factor) for S5-468 Tower under combined ice + wind loads, particularly for load cases 85/40. The critical 'tower mast member' is overloaded, necessitating closer examination and adjustments to wind speed factors in Labrador and exposed ice regions due to higher ice residence times. Recommendations include reassessing reliability under DLS/ULS criteria and conducting progressive collapse analyses for critical towers on escarpments or hills.
7.4.1 Review Literature and show the effects on Thickness (Reduction in Transverse Load) Clause 6.3.4.1 of CSA states that an ice load adjustment can be made if the cable diameter is different than the diameter of rod that was used in the...
AI summary The text discusses adjusting ice load calculations for cables with diameters different from the standard 25mm rod used in CSA maps. A Kd factor of 1.33 is applied, and studies show larger cables have less ice accretion. Environment Canada simulations confirm a 30% reduction in icing for a 56.9mm conductor compared to CSA predictions, impacting design ice thickness for LIL lines.
7.4.2 Revision of Avalon Load Based on Lower Failure Rate Value The above load on the Avalon can also be justified based on 1996 Avalon study. During this study, design loads for upgrading and for a short section of a new line on the Avalo...
AI summary The Avalon load revision is based on updated failure rate data from 2004-2023, adjusting the 1996 study's 50-year ice load estimate from 68mm to 48mm. This reflects a 30% reduction due to a revised 11-year failure interval, considering one major icing failure post-2004 upgrades, and accounts for spatial factors observed over 30 years of operational data.
7.5 Underestimation of OPGW Icing Clause 6.3.4.1 suggests considering equivalent conductor load in the design of OPGW in the same span. Research by McComber et al and others (2001) have shown that the OPGW cable has lower torsional rigidit...
AI summary Research by McComber et al (2001) indicates that OPGW cables, with lower torsional rigidity than pole conductors, accrete more ice initially but may catch up over time. Designing OPGW to the same ice thickness as conductors is currently considered best practice, though further field validation is needed. Alternative mitigation strategies, such as increasing torsional rigidity at critical points, are suggested as cost-effective solutions.
7.6 Rime Icing on LRM – (EFLA & KVT Study, Full Effects of Topography and Terrain Characteristics) Several studies have been presented as part of this LIL project to assess rime ice loads on the LIL. As reported in Section 4, the recent st...
AI summary The section discusses studies on rime ice loads for the Labrador Island Transmission Link (LIL) using the WRF model, noting the use of USGS landuse data but omission of topographic effects like escarpments. The author recommends a separate study for glaze icing.
7.7 Variation of COV of Strength on Reliability All the COV's that were used in the reliability assessment were taken from CSA 60826-10 following Table 19 in the standard. However, the author has done some literature search and noted that...
AI summary The text discusses variations in the Coefficient of Variation (COV) of strength parameters affecting reliability assessments, referencing CSA 60826-10 standards. Sensitivity analyses show a 10% reduction in Probability of Failure (POF) for compression members with increased mean strength and a significant POF increase for foundations when COV rises from 0.2 to 0.3, as illustrated in figures.
8.0 Review of Hydro's Operational Experiences and Benchmarking This section presents a review of past line failures that NLH experienced during the operation of transmission line assets during the past 50 years. The objective here is to un...
AI summary This section reviews NLH's transmission line failures over 50 years, analyzing outage hours per 100km and comparing data with national averages (CEA) and CSA 60826-10 standards. It evaluates reliability on the Avalon Peninsula and against a Canadian utility's upgraded line under extreme ice loads.
8.3.1 East Coast Failures (Avalon Peninsula, Haldar 1988, 1996, 2006) The line failures on the Avalon Peninsula occurred in 1970, 1984, 1988, and 1994 (Haldar, 1995). Figure 8.3 depicts the observed glaze ice sample on conductor during the...
AI summary The Avalon Peninsula experienced multiple transmission line failures between 1970 and 1994 due to ice overload, leading to conductor/hardware failures and cascading outages. Design weaknesses and underestimated ice loads (up to 50mm radial glaze ice) were identified, prompting a revision of design standards to 63mm ice thickness. Failures included bridge collapses, tower failures, and significant repair costs, highlighting systemic infrastructure vulnerabilities.
8.3.2 West Coast Failure (TL 228, Haldar 1990) The 230kV line (TL 228) which runs from Buchans to Massey Drive on the west coast of Newfoundland, was commissioned in 1967. Since its commissioning, the line has experienced several major fai...
AI summary The 230kV Buchans-Massey Drive transmission line (TL 228) on Newfoundland faced repeated failures from 1967-1990 due to ice accumulation and wind. Upgrades in 1990-1991, including mid-span towers to shorten spans, resolved the issue. Post-upgrade, no damage has occurred, with ice load models estimating 75mm radial ice as the design threshold.
8.3.3 Northern Peninsula (TL 247 & 248, Hannah et al.) Lines designed and operating at present on the Northern Peninsula have a large dispersion in ice loadings, varying from 0.3 to 4 inches of radial ice. This corresponds to 13.0 to 102mm...
AI summary The Northern Peninsula power lines (TL 247 & 248) exhibit significant ice loading variations (0.3–4 inches radial ice, 1.5–30kg/m load) across 69kV–230kV systems. The Deer Lake–Cat Arm line, designed for 4-inch ice loads (30kg/m), includes a NW-SE segment critical for NE wind-driven freezing precipitation, justifying its higher design standard.
8.4 Benchmarking Outage Data (Before and after Upgrade, Edwards, 2021) The cumulative weather related line outage hours between 1980-1999 were approximately 6700 hours and between 2000-2020, approximately 2765 hours. The high value in the...
AI summary This section compares weather-related and non-weather-related line outage hours in Newfoundland and Labrador (NL) and Canada from 1980–2020. Outage hours decreased significantly after 2000 due to NLH's upgrades, with a notable 2010 spike from a TL208 failure. Data normalization against CEA benchmarks highlights improved system reliability post-2000.
8.5.1 Line from a Canadian Utility To compare the reliability of LIL with other utility lines, the author decided to benchmark the structural reliability of an important line in Canada. This is a line from a 700 MW generating station in No...
AI summary The reliability of a 700 MW Canadian transmission line (connected to a 230kV grid) was benchmarked against the Labrador Island Link (LIL). Analysis using CSA 60826-10 showed low annual failure probability with high safety margins, attributed to security-load-driven design rather than reliability-based factors. Four load scenarios (ice, wind, combined, unbalanced ice) were evaluated.
8.5.2 Comparison of Avalon Upgrade Steel Transmission Line and LIL This section compares the structure support system and cable system reliability comparison for the Avalon upgrades and the LIL on the Avalon Peninsula for extreme ice load....
AI summary The section compares the Avalon Upgrade and LIL transmission lines, noting LIL's higher structural reliability under extreme ice loads but lower cable system reliability. Avalon's design prioritized cost control by limiting conductor tension, while LIL's balanced design maintains failure sequence. Historical NLH upgrades post-2001 improved system performance, though LIL still lags behind a Canadian utility's reliability benchmarks.
8.6 LIL Outage/Failure Rate – Comparison of Results with Published Data A transmission line outage can be caused by (1) electrical fault and (2) permanent faults caused by mechanical damage/failure of line components. Electrical faults are...
AI summary The section discusses LIL outage/failure rates, comparing them with published data. It explains causes of outages, differentiates between electrical and mechanical faults, mentions statistical data from studies, and notes the lack of guidance for mechanical failures. The permanent failure rate is estimated at 0.03/year/100km.
9.1 Summary This report assesses the impact of two types of icing on the structural reliability (and probability of failure) of the LIL HVdc line. The two types of icing are (a) glaze icing due to freezing precipitation and (b) rime icing...
AI summary This report evaluates the structural reliability of the LIL HVdc line under glaze and rime icing scenarios, validating its design against CSA 60826-2010. It calculates failure rates (λ) and repair rates (μ) for system planning, benchmarks LIL performance against utility outage data, and discusses Hydro's operational experience with transmission lines.
9.2 Conclusions Results of the LIL system reliability study clearly show that the "wire support system" contributes significantly in the reliability analysis. Under combined load cases for glaze icing and for rime icing, elements in OPGW a...
AI summary The LIL system reliability study highlights the wire support system's critical role in reliability analysis. Combined load cases for glaze and rime icing significantly impact OPGW and electrode line systems, affecting LIL reliability under CSA 60826-10 damage limit state criteria.
9.2.1 Probability of Failure (POF) -DLS Based on our study we find the POF of LIL can range from little over 1% for Scenario # 1 to 5% for Scenario # 4D (Table 6.2). Each scenario considers a set of assumptions and these are presented in T...
AI summary The study evaluates the Probability of Failure (POF) for the Labrador Island Transmission Link (LIL) under four scenarios, ranging from 1% to 5%. Key factors include icing types, weather zones, and correlation assumptions. The LIL's reliability is emphasized as distinct due to its length, power transfer capability, and exposure to two icing types. The cable system is identified as weaker than structural supports, contradicting industry practices. Reducing unavailability requires improved monitoring and maintenance.
9.2.2 Probability of Failure (POF) -ULS at a High Level A high level Ultimate Limit State (ULS) analysis for cable systems provides a relative comparison of the risk levels between DLS and ULS and shows that POF under ULS is almost forty-t...
AI summary A high-level ULS analysis shows POF under ULS is 43% of DLS risk, translating to a 160-year return period. The LIL design is vulnerable to ice shedding, failing CSA and Hydro standards, with weaknesses in load combinations for unbalanced ice loads, particularly in Labrador's harsh environments.
9.3 Recommendations Based on this study, the decision to make appropriate generation expansion study should not be done strictly based on DLS criteria satisfying CSA 60826-10 rather by doing a full ULS analysis of the structure-cable syste...
AI summary The study recommends moving beyond DLS criteria (CSA 60826-10) for generation expansion studies, emphasizing the need for a comprehensive ULS analysis of the structure-cable system and its impact on LIL failure rates. Current ULS assessments lacked consideration of system coupling effects, necessitating future studies to refine LIL POF calculations.
10.0 References - Alteen, Peter 2018 Written Submission on Behalf of Newfoundland Power Inc. to Commission of Inquiry respecting the Muskrat Falls Project. - ASCE Manual Practice No. 74 2010 Guidelines for Electrical Transmission Line Stru...
AI summary The references list technical documents, studies, and reports on power system reliability, structural design, and transmission line assessments. Key entities include Newfoundland Power Inc., Commonwealth Associates, EFLA, and Newfoundland and Labrador Hydro. Topics focus on system reliability and grid modernization.
Quarterly Report on Asset Performance in Support of Resource Adequacy for the Twelve Months Ended December 31, 2025
AI summary The document is a quarterly report from Nova Scotia Power Marketing Limited (NSPML) detailing asset performance metrics for the twelve months ending December 31, 2025, with a focus on resource adequacy. It likely includes data on forced outages, energy unavailability, and other reliability indicators critical to grid stability.
Quarterly Report on Asset Performance in Support of Resource Adequacy for the Twelve Months Ended December 31, 2025 - hydraulic units and, historically, was used for the thermal units; however, it does not apply to CTs - because of their o...
AI summary The report discusses metrics like DAUFOP and EqFOR for assessing forced outages and deratings in generating units and the Labrador-Island Link (LIL). It highlights that DAUFOP applies to combustion turbines (CTs) and thermal units under standby operations, while EqFOR measures LIL's performance. The LIL's maximum continuous rating is currently 700 MW.
1 Assumptions Used in Hydro's Assessment of System 2 Reliability and Resource Adequacy - 3 Hydro continually assesses the reliability of its system and its ability to meet customer requirements, - filing both near- and long-term assessment...
AI summary Hydro assesses system reliability and resource adequacy, filing reports with the Board of Commissioners of Public Utilities. As part of the Reliability and Resource Adequacy Study Review proceeding, Hydro outlines the process for determining forced outage rates for near-term reliability assessments and long-term resource adequacy analysis. These assumptions are reviewed annually.
Table 1: Hydro's Reliability and Resource Adequacy Study Analysis Values – Generating Units (%) Near-Term Resource Planning Asset Type Measure Analysis Value Analysis Value Hydraulic: Regulated DAFOR 2.50 3.03 Hydraulic: Muskrat Falls DAFO...
AI summary Table 1 presents reliability and resource adequacy study analysis values for generating units, including DAFOR and DAUFOP metrics for various asset types such as hydraulic and thermal units. The data shows different analysis values for near-term and resource planning scenarios.
Quarterly Report on Asset Performance in Support of Resource Adequacy for the Twelve Months Ended December 31, 2025 - 3.03%. The DAFOR value was based on historical data reflective of Hydro's maintenance program over - the long term. - For...
AI summary The report analyzes forced outage rates (FOR) for hydroelectric facilities, noting that Muskrat Falls uses historical data for near-term rates, while long-term planning assumes regulated maintenance standards. Holyrood TGS's reliability concerns under standby operations necessitate DAUFOP over DAFOR, with a 20% FOR recommendation and 34% sensitivity. Operations remain base-loaded due to LIL's early-stage performance.
Table 2: Hydro's Reliability and Resource Adequacy Study Analysis Values – LIL (%) Base Planning Range of Planning Asset Type Measure Analysis Value Analysis Values LIL EqFOR 5 1–10 14 Assessment of the remaining useful life for the Hardwo...
AI summary Table 2 presents analysis values for the Labrador Island Transmission Link (LIL) reliability and resource adequacy study, including an Equivalent Forced Outage Rate (EqFOR) of 5% in the base planning scenario, with a range of 1–10%. The document also notes ongoing assessments of the remaining useful life and capital operating costs for certain assets up to 2035.
- 5 performance improved for the current period, when compared to the previous period. - 6 The DAUFOP performance for the Happy Valley GT and the Hardwoods and Stephenville GTs has - 7 improved for the current period, while the Holyrood CT...
AI summary Performance metrics for various generating units and the Labrador Island Transmission Link (LIL) have improved in the current period compared to the previous period, with the exception of the Holyrood CT, which saw a decline. The LIL's performance has improved, with no significant impacts to the EqFOR due to operational events.
1 Hydraulic Unit DAFOR Performance – Regulated Hydro - 2 Detailed results for the current period and the previous period are presented in Table 5 and Chart 1. - 3 These results are compared to Hydro's near-term and resource planning analys...
AI summary The document presents detailed results comparing the current and previous periods' hydraulic unit DAFOR performance to Hydro's near-term and resource planning analysis values for forced outage rates, as used in the 2024 Resource Plan and the November 2025 Near-Term Report. Units exceeding established values are discussed.
4.1 Granite Canal Facility 1 9 - 2 The Granite Canal unit DAFOR of 5.21% for the current period is above the resource planning analysis - 3 value of 3.03% and the near-term planning analysis value of 2.50% for an individual hydraulic unit....
AI summary The Granite Canal Facility's DAFOR (5.21%) exceeds planning analysis thresholds (3.03% and 2.50%) due to nine forced outages, including three post-filing. Outages occurred on October 6, 2025 (communications issues) and October 20/December 26, 2025 (vibration trips in hydraulic rough zone).
4.2 Paradise River Facility - 10 The Paradise River unit DAFOR of 2.84% for the current period is above the near-term planning analysis - 11 value of 2.50% but is below the resource planning analysis value of 3.03% for an individual hydrau...
AI summary The Paradise River Facility's DAFOR of 2.84% exceeds near-term planning analysis values (2.50%) but remains below resource planning analysis thresholds (3.03%). The elevated rate resulted from four forced outages, with no additional outages since the last filing.
1 5.1 Muskrat Falls Unit 3 - 2 The Muskrat Falls Unit 3 DAFOR of 2.51% is below the resource planning analysis value of 3.03%, but is - 3 above the near-term planning analysis value of 2.30% for an individual Muskrat Falls unit. This eleva...
AI summary The DAFOR for Muskrat Falls Unit 3 is 2.51%, above the near-term planning value of 2.30% due to three forced outages, but below the resource planning value of 3.03%. No new outages have occurred since the last filing.
6.1 Holyrood TGS Unit 1 - Considering individual thermal unit performance, the DAFOR of 39.12% for Unit 1 at the Holyrood TGS is - above the near-term and resource planning analysis value of 20.00% for a unit at the Holyrood TGS; - however...
AI summary Holyrood TGS Unit 1 experienced elevated DAFOR (39.12%) due to a 2024 turbine overhaul and recurring control valve issues causing derates to 105 MW and 160 MW. Outages and maintenance delays impacted performance, with investigations ongoing for condenser back pressure and air in-leakage.
Table 9: Happy Valley GT DAUFOP GT Unit Maximum Continuous Unit Rating (MW) 12 months Ended Dec 2024 (%) 12 months Ended Dec 2025 (%) Near-Term Planning and Resource Planning Analysis Value (%) Happy Valley 25 6.29 10.57 4.65
AI summary Table 9 provides the Derated Adjusted Utilization Forced Outage Probability (DAUFOP) for the Happy Valley Gas Turbine (GT) unit, showing a 6.29% forced outage probability for the 12 months ending December 2024 and 10.57% for the 12 months ending December 2025, with a near-term planning value of 4.65%.
7.1 Happy Valley Gas Turbine - 2 The Happy Valley GT DAUFOP was 10.57% for the current period, which is above the near-term and - 3 resource planning analysis value of 4.65%. This decline in performance is a result of outages experienced -...
AI summary The Happy Valley Gas Turbine's DAUFOP was 10.57%, exceeding the 4.65% resource planning analysis value. This is attributed to outages on July 12, 2025, causing four hours of downtime due to two start-up failures, significantly impacting performance due to low operating time.
7.2 Holyrood Combustion Turbine - 9 The Holyrood CT DAUFOP was 25.13% for the current period, which is above the near-term and resource - 10 planning analysis value of 4.90%. This decline in performance is the result of forced outages, as...
AI summary The Holyrood Combustion Turbine's performance is below expected standards, with a DAUFOP of 25.13%, significantly higher than the planning value of 4.90%. This is attributed to forced outages, including an unexpected extension of maintenance from October 27 to November 12, 2025.
3 Labrador-Island Link EqFOR Performance - The EqFOR for the LIL was 0.96% 19 4 for the current period, as shown in Table 11. This is below the range - 5 of values used by Hydro in the resource planning analysis scenarios.
AI summary The Equivalent Forced Outage Rate (EqFOR) for the Labrador Island Transmission Link (LIL) was reported at 0.96% for the current period, which is below the range of values used by Hydro in resource planning analysis scenarios.
Table 11: LIL EqFOR (%) 12 Months Ended 12 Months Ended Base Planning Analysis Range of Planning Analysis Asset Type Measure Dec 2024 Dec 2025 Value Values LIL EqFOR 3.37 0.96 5 1–10 - 6 The availability of the three Soldiers Pond Synchron...
AI summary Table 11 presents the Equivalent Forced Outage Rate (EqFOR) for the Labrador Island Transmission Link (LIL) over two 12-month periods and includes planning analysis values. The availability of the Soldiers Pond Synchronous Condensers is noted as critical to system reliability.
Quarterly Report on Asset Performance in Support of Resource Adequacy for the Twelve Months Ended December 31, 2025, Appendix B
AI summary This document is a quarterly report on asset performance supporting resource adequacy for the twelve months ending December 31, 2025, presented as Appendix B. It likely details generator availability, outage rates, and reliability metrics critical to Nova Scotia's electricity system.
Introduction - The Muskrat Falls Assets, made up of the Labrador-Island Link ("LIL"), which includes the Soldiers Pond - Synchronous Condensers ("SCs"), the Labrador Transmission Assets and the Muskrat Falls Hydroelectric - Generating Faci...
AI summary The Muskrat Falls Assets, including the Labrador-Island Link and hydroelectric facilities, face early operational challenges due to manufacturing defects and equipment failures following a 'bathtub-shaped curve.' Newfoundland and Labrador Hydro addresses these issues through maintenance, capital projects, and engineering studies to improve long-term asset reliability.
Forced Outages - Outside of planned outages, the Soldiers Pond SCs have operated continuously during the quarter, with - the exception of one event on SC2 and one event on SC3. The first event occurred on November 7, 2025, - when SC2 faile...
AI summary The Soldiers Pond SCs experienced two forced outages during the quarter: SC2 failed to start due to a loss of excitation fault on November 7, 2025, and SC3 was shut down for planned maintenance on December 17, 2025, with liquid level detectors tripping. Both issues were resolved without customer impact.
Cable Switching - As reported in Hydro's final 2024–2025 Winter Readiness Report, 3 new equipment was successfully - installed to mitigate cable switching transients at the LIL Transition Compounds in mid-October 2024. - Since that time, H...
AI summary Hydro installed new equipment to mitigate cable switching transients at LIL Transition Compounds in 2024 but identified an icing issue with disconnects. General Electric developed an improved ice guard design, with installation planned for early 2026. Hydro has implemented temporary operating procedures to ensure winter reliability.
Replacement of Direct Current Current Transformers - In 2023, the OEM and Hydro determined that very low air temperatures at Muskrat Falls Converter - Station were influencing the measurement accuracy of DCCTs 4 , resulting in false protec...
AI summary In 2023, OEM and Newfoundland and Labrador Hydro identified that low temperatures at Muskrat Falls Converter Station caused DCCT measurement inaccuracies, leading to false protection trips. A 2024 study highlights the need for DCCT replacement to ensure reliability.
Conductor Testing - Following a bipole trip on March 30, 2024, line patrol determined that the electrode conductor was - broken and damaged during an ice storm at several locations in southern Labrador. As a result, - conductor testing was...
AI summary Following a bipole trip in March 2024, conductor testing in southern Labrador found no material issues with the electrode conductor. Failure was attributed to overload, consistent with past findings, with cyclic loading from ice and wind potentially contributing to fatigue. Additional testing revealed no significant new findings.
Optimizing Clamp Designs - During December 2022, March 2024, and January 2025, there were issues with the electrode conductor - during significant ice loading, the root cause of which was determined to be overloading due to ice and - ice s...
AI summary Issues with electrode conductors due to ice loading led to the installation of three alternative clamp designs on ten structures. These designs aim to reduce stresses and improve performance. A DCCT replacement is planned for 2026, with reference to a report from Newfoundland and Labrador Hydro.
Quarterly Report on Asset Performance in Support of Resource Adequacy for the Twelve Months Ended December 31, 2025, Appendix B - 2025, with the assemblies to be purchased and installed as required through a capital project. 9 - Additional...
AI summary The report details infrastructure upgrades including a 2025 capital project for conductor assemblies, 2024 OPGW suspension clamp procurement installed in 2025, and enhanced testing protocols. Hydro emphasizes emergency preparedness and reliability measures through its Emergency Response Plan and material stockpiling to prevent service disruptions.
Top Plate Design - In December 2022, there were two incidents impacting two adjacent structures of the LIL where the - connection of the top plate of the OPGW suspension detached from the tower, falling onto the cross - arm. Analysis was c...
AI summary The text details incidents in December 2022 involving top plate detachment on the Labrador-Island Link (LIL), leading to an analysis identifying 63 towers (A3/A4) requiring reinforcement. By 2024, 61 towers were repaired, with remaining work planned for 2026-2028. Other tower types (A2, B1, B2) may require future repairs if deformation occurs, with designs completed in Q3 2025.
4.3 High-Power Testing - As previously reported in Hydro's final 2025–2026 Winter Readiness Report, 12 the high-power test of the - LIL has been postponed because of Hydro's prioritization of reliable service to customers during the - wint...
AI summary The high-power test of the Labrador-Island Link (LIL) has been postponed until Q1 2026 to prioritize winter service reliability and reservoir management. Prerequisites include system conditions, coordination with neighbors, and risk mitigation.
4.4 Software - The new LIL software was commissioned in October 2024. This software, as with the previous version, - allows for full operation of the LIL up to 900 MW. Through dynamic commissioning, non-critical - software-related issues w...
AI summary The new LIL software, commissioned in October 2024, allows operation up to 900 MW but faces issues requiring collaboration with GE. A version control error in April 2025 led to removal, with a new version delivered in Q4 2025. Installation is delayed until mid-2026 due to system constraints in the Newfoundland and Labrador Interconnected System and neighboring provinces.
4.5 Engineering Studies and Reports - Since the commissioning of LIL in April 2023, Hydro has gained valuable insight into LIL operations. Using - Hydro's operating experience and recommendations from its investigations, supplemented by th...
AI summary Hydro has identified three potential reinforcements to the Labrador-Island Link (LIL) post-commissioning in 2023 to enhance reliability, address failure modes, and mitigate risks. Engineering assessments, including ice load reviews, mid-span structures, and electrode conductor relocations, have been completed, with cost estimates evaluated through Q4 2025. Findings are summarized in Attachment 1.
4.7 Restoration Plans and Operational Strategy - In addition to engineering studies to inform potential reinforcements to mitigate the risk of component - failures and outages, Hydro is currently in the process of contracting a consultant...
AI summary Hydro is updating restoration plans with a consultant to address geographic and weather challenges, evaluate alternative restoration approaches, and analyze time and cost-benefit factors for improving restoration efficiency and effectiveness.
Conclusion - Hydro recognizes the criticality of the Muskrat Falls Assets to the supply of the Island Interconnected - System, which helps to limit the thermal generation required from the Holyrood TGS and impacts the - overall reliability...
AI summary Hydro acknowledges the importance of Muskrat Falls Assets to the Island Interconnected System, reducing reliance on Holyrood TGS thermal generation and enhancing grid reliability. Hydro will monitor asset performance to address early-life issues from manufacturing or component defects.
1.0 Introduction - The Labrador-Island Link ("LIL") is an important transmission line for the provincial energy grid due to its - power carrying capacity that is used to deliver a large portion of the winter peak energy and demand to - the...
AI summary The Labrador-Island Link (LIL) is critical to Nova Scotia's energy grid, with past failures attributed to icing and unbalanced loading. Newfoundland and Labrador Hydro conducted investigations, leading to a 2026–2028 capital project to reinforce the line, including tower modifications, damping systems, and electrode conductor relocations to enhance reliability.
Number of Date Location Number of Damaged EL Crossarms Locations of Damaged EL Conductor Number of Damaged OPGW Peaks Number of Damaged OPGW Top Plates Approximate Radial Equivalent Ice Thickness (mm)4 Approximate Weight of Ice on EL Condu...
AI summary The table presents data on the number of damaged electrical infrastructure components, including crossarms, conductor, and OPGW peaks and top plates, across different locations and dates, along with ice thickness and weight measurements. This data is relevant to understanding the impact of ice loading on power infrastructure.
5 Ice Monitoring - 6 A total of three sensors were installed on structures 514 (central Labrador), 1224 (southern Labrador) - 7 and 2597 (central Newfoundland) in 2025 to monitor ice load and galloping.
AI summary Three sensors were installed in 2025 on structures located in central Labrador (514), southern Labrador (1224), and central Newfoundland (2597) to monitor ice load and galloping, aiming to enhance infrastructure reliability in these regions.
5.1.4 Reinforcement and Re-design of OPGW Peaks and EL Crossarms - This alternative would include replacing the existing electrode crossarms and OPGW peak with new - reinforced sections and adding reinforcing members to the existing cage....
AI summary This section discusses reinforcing OPGW peaks and EL crossarms with new reinforced sections and additional members to address ice and unbalanced ice loads. The alternative is low-cost per structure ($36,000 for both components, $29,000 for crossarms alone) but does not resolve electrode conductor failures. Installation can occur during monopole outages.
5.3 Scope of Work - The project scope includes procurement and installation work on a total of 309 Type A1 towers, as - follows: - Replacement of OPGW peaks, EL crossarms, and EL assemblies for 186 towers: - o 18 A1 towers from structure 1...
AI summary The project involves replacing OPGW components and reinforcing towers across specific line sections, prioritizing areas with past failures. Material procurement includes reinforcement for ice load risks, with repairs deemed non-urgent due to no outage risk. Selection criteria prioritize sections with multiple past events.
3.2 $4-576 (2543) Tower position S4-576 (2543) was chosen due to long weight spans on both sides of the tower, as shown in Table 4. To avoid weight spans imbalance, it was decided to add two mid-span structures; one in the back span (BS) a...
AI summary Tower position S4-576 (2543) was selected due to long weight spans on both sides, necessitating mid-span structures to balance loads. Long spans create high vertical loads during ice events, leading to local peak failures despite no electrodes being present.
3.3 S4-598 (2565) Tower S4-598 (2565) has no electrodes strung, and it was chosen due to its location on a downhill with increasing stationing, which causes high longitudinal loads due to the weight span imbalance with a ratio of approxima...
AI summary Tower S4-598 (2565) lacks electrodes and experiences high longitudinal loads due to a downhill location and weight span imbalance (ratio ~2.4) during 'Max ice' weather. Similar issues were observed in towers S4-502 (2469) and S4-576 (2543) under unbalanced ice conditions, indicating potential structural vulnerabilities.
3.5 S1-370 (371) Tower S1-370 (371) has electrode wires strung, with a weight span imbalance ratio of approximately 2.4 for the 'Max ice' weather case. These conditions increase longitudinal loads during an ice event. A possible solution t...
AI summary Tower S1-370 (371) exhibits a weight span imbalance ratio of 2.4 during 'Max ice' conditions, increasing longitudinal loads. A proposed mid-span structure aims to address the imbalance, but terrain challenges may hinder visibility and cause uplift risks.
3.7 REINFORCED MODEL OVERSTRESSES
AI summary Section 3.7 discusses the issue of a reinforced model being overstressed, potentially impacting system reliability or capacity. The context includes technical and regulatory terms related to energy systems, but no specific claims or arguments are detailed in the provided text.
1.0 INTRODUCTION NL Hydro has experienced several performance issues with the electrodes that are mounted on the same towers as the pole conductors (tower type A1) for the Labrador-Island Transmission Link, +/- 350 kV HVDC. Electrode perfo...
AI summary NL Hydro's Labrador-Island Transmission Link (LIL) HVDC infrastructure faces electrode performance issues, including conductor failure and structural failures. The memo evaluates solutions, proposing two approaches: one low-effort, high-priority fix and a more comprehensive but labor-intensive alternative.
2.0 WORK COMPLETED TO DATE Extensive study of the performance issues has previously been completed by NL Hydro and the root cause of most of the issues is that the line has experienced weather loading events that exceeded the initial desig...
AI summary NL Hydro's studies identified that performance issues in the line stem from weather loading events exceeding initial design assumptions, specifically electrode suspension longitudinal loading during icing events. Reports from 2021 and 2024 detail failures related to ice storms and tower damage.
3.2 ELECTRODE CONDUCTOR DROP The electrode conductor drop on the tower type A1 electrical clearance drawing ILK-JY-SD-6200-TL-D99-0012-01-A3 is listed as 270 mm. This value is dependent on the vertical departure angle and describes decreas...
AI summary The electrode conductor drop on tower type A1 is specified as 270 mm based on vertical departure angles under 0°C, no ice, no wind, and max sag FE conditions. The maximum considered vertical departure angle is 14°, with a 15° case potentially neglected due to its correlation with weight span and transverse swing angles. The as-built conductor drop is adjusted to 200 mm.
3.4 VERTICAL AND HORIZONTAL SEPARATIONS TO POLE CONDUCTORS Tower type A1 design requirements drawing ILK-SN-CD-6200-TL-DD-0112-01-C4 outlines the required separation between the electrode and the poles. The limitations are as follows: - Ho...
AI summary The text outlines design requirements for vertical and horizontal separations between electrode and pole conductors, referencing specific drawings and calculations. It highlights that existing designs exceed minimum vertical separation due to shorter-than-anticipated pole insulator strings, but warns that lengthening electrode insulators or increasing horizontal offsets could violate these limits. The analysis emphasizes the need to study galloping ellipse clearance to assess acceptability of potential encroachments.
3.6 OPTION 1 PERMISSIBLE INCREASE The permissible increase for option 1 was determined to be 295 mm governed by the maximum wind swing case with electrical clearance to the cage, see Figure 5. Note that the EDT (0°C, 0 Pa) limit at 11° tra...
AI summary The permissible increase for Option 1 is set at 295 mm, determined by the maximum wind swing case with electrical clearance to the cage. The EDT and REDUCED WIND SWING limits are not shown as they are covered by the MAXIMUM WIND SWING limit. Electrode shielding improves with longer insulator lengths, as detailed in Figure 5.
3.7 OPTION 2 PERMISSIBLE INCREASE The tower type A1 reinforcement scope showed significant overusages in most of the electrode cross-arm members that are not easily addressed with reinforcement. For this reason, it is more economical to de...
AI summary Option 2 for tower reinforcement prioritizes cross-arm replacement over reinforcement due to overusage in electrode cross-arm members. The permissible increase is 325 mm, governed by maximum wind swing cases, with potential for an additional 50 mm if the climbing bolt is removed, as confirmed by NL Hydro.
4.0 LONGITUDINAL ARTICULATION ANGLE One of the field observations from existing conditions is contact of the bottom insulator unit and the electrode conductor under longitudinal loading cases. Based on the geometry from the electrode insul...
AI summary The document discusses the permissible longitudinal articulation angle for insulator units under load, noting a maximum of 50° before contact. Design requirements specify 33°, within the permissible range, but a failure case showed 60°, leading to proposed hardware modifications to increase articulation beyond 70°, confirmed by SLACAN.
4.2 Option 2: Midspan Structures Installation The cost of installing new midspan structures is approximately $328,662.00 per tower + $315,000.00 + $700,000.00 . Assumptions were made in the development of this estimate which can be reviewe...
AI summary The cost of installing midspan structures is approximately $1.3 million per tower, factoring in inflation and structure type assumptions. Construction may require outages on the Labrador-Island Link (LIL), potentially adding $500,000/day in costs, necessitating further investigation into feasibility and financial impacts.
er types (A1, A2, A3, A4, B1, B2, C1, C2, D1, D2, and E1) were designed to meet the loading requirements, which consist of a specified wind load, ice load, and combination of both applied to the line. There have been a number of failures t...
AI summary Transmission line failures in central Labrador (2021, 2022) caused damage to electrode crossarms and conductors due to unbalanced ice loads exceeding design specifications (50 mm radial glaze ice). Events involved ice thicknesses of 54-72 mm, with damage attributed to ice shedding on A1-type towers.
2. Sections for Consideration Due to the cost of building a wood pole line from Muskrat Falls to the start of the existing wood pole electrode line at structure 1229 (approximately 376 km), the removal of the electrode line from L3501/2 wi...
AI summary The document discusses the removal of 85 km of electrode line (L3501/2) due to high costs and factors like past failures, high icing, elevation changes, and galloping risks. Six sections are recommended for removal, with Figure 2 summarizing the criteria.
3. Analysis The failure investigations of damage to the towers and conductors in past events determined the root cause was overloading due to unbalanced ice loads. To determine the benefits of removing the electrode conductor from the towe...
AI summary The analysis examines power line failures caused by unbalanced ice loads, comparing scenarios with and without electrode conductors. Removing electrodes significantly reduces structural failures under balanced ice loads (60-70 mm), though failures increase beyond 70 mm. Results highlight infrastructure reliability concerns under extreme ice conditions.
Under unbalanced ice load (UBL) with 70 mm of ice: - structures with the electrode: - o the percentage of structure failure range between 77% to 91% for all load cases, - structures without the electrode - o on the OPGW (G) the percentage...
AI summary Under 70 mm unbalanced ice load, structures with electrodes show 77–91% failure rates, while those without have 68–86% failures on OPGW (G), and no failures on EL1, EL2, P1, and P2.
Under unbalanced ice load (UBL) with 80 m of ice: - structures with the electrode: - o 95% of structures failed for all load cases, - structures without the electrode: - o on the OPGW (g) the percentage of structure failure for 70/100% unb...
AI summary Structural failure rates under unbalanced ice loads (UBL) with 80 m of ice show that removing electrodes significantly reduces failures. With electrodes, 95% of structures failed, while without electrodes, failures ranged from 32% to 36% on specific components. Balanced ice loads also revealed higher failure rates with electrodes, emphasizing the benefit of electrode removal for structural integrity.
Muskrat Falls Generation As reported in its most recent Rolling 12 report, the Muskrat Falls Hydroelectric Generating Station ("Muskrat Falls") total plant DAFOR 6 performance through the end of the second quarter of 2024 was 0.42%, which...
AI summary The Muskrat Falls Hydroelectric Generating Station's DAFOR performance was 0.42% through Q2 2024, significantly below Canada's average of 5.70%. Newfoundland and Labrador Hydro will update performance metrics and winter readiness in upcoming reports. Hydro continues submitting quarterly updates despite a proposal to discontinue them, integrating Muskrat Falls reporting into regular operational filings.
NSPML Responses to Bates White Information Requests
AI summary NSPML is responding to information requests from Bates White, a consulting firm, as part of a regulatory proceeding. The document outlines technical and operational details related to energy generation, grid reliability, and regulatory compliance in Nova Scotia.
N-4NSPML (IG) RIRs 1-26 - Redacted
70 passages
NON-CONFIDENTIAL c) An example would be an outage taken for which there is no technical reason why an outage is required to complete the work identified (changing a lightbulb in a hallway). None of the outages from May 2023 to the present...
AI summary NSPML argues that non-winter outages are less harmful to customers and that outage timing is more important than quantity. They assert that outages during non-winter periods are technically necessary and that holdback disallowances do not reflect actual harm. NSPML aligns with NLH on preferring non-winter outages due to lower system urgency and energy value variances.
NON-CONFIDENTIAL 1 Over the winter period, NLH (and NS Power) generally avoid planned outages with the 2 exception being if weather permits a short outage without risk to the system. The outages 3 during the winter period have predominantl...
AI summary NSPML asserts that winter outages were primarily due to extreme weather and addressed promptly. System reliability is maintained through reserve generation equivalent to the largest unit, including the NS Block. NSPML emphasizes a case-by-case evaluation for defining 'exceptional circumstances' related to inclement weather.
PARTIALLY CONFIDENTIAL - Capacity of the NS Block has been at a level that allows NS Power (and now the IESO-NS) to treat the NS Block in the same manner as its other generation assets for short-, mid- and long-term planning. Yes, there ha...
AI summary NSPML argues that the NS Block's capacity is integrated with Nova Scotia's generation assets, resulting in minimal outage impacts and benefits exceeding costs. It notes that planned outages by NLH during non-winter periods have not caused system outages and that the holdback is tied to the Lower Churchill Project's performance.
1 Planned Outages: Start Date and Time End Date and Time Duration [h] Cause Identified Date 6-18-23 16:00 6-26-23 23:00 199 Non-critical punch list, SCADA & electrol line fault indicator 01-May-23 130 Preparation for final software update,...
AI summary The table outlines multiple planned outages with dates, durations, and causes, including software updates, maintenance, and repairs. Notably, the March 2024 transmission repair was the only outage with less than 30 days' notice, highlighting potential reliability concerns and regulatory considerations.
NSPML Responses to Industrial Group Information Requests 1 Request IR-09: 2 3 4 Reference: Preamble: N-01 Application, pages 21-22; and Footnote 26. The Application states that April 2024 fell short of the 90% threshold due to 5 extreme we...
AI summary The document discusses NSPML's response to an information request regarding a transmission line outage caused by extreme weather conditions, specifically icing, on NLH facilities. The request inquires about the design criteria of the transmission line, whether similar issues have occurred elsewhere, and details about the outage starting March 30, 2024.
third party in connection with the March–April 2024 29 icing event, including any findings comparing actual weather conditions to design criteria and 30 any recommendations for design upgrades. 1 2 3 A. a) Line L3501/2 is the 350 kV HVdc o...
AI summary The third party inquired about the March–April 2024 icing event's impact on the 350 kV HVdc transmission line L3501/2, including design criteria comparisons and upgrade recommendations. The line spans 1,100 km through three meteorological zones, with 19 loading zones and 11 tower types. Damage occurred to specific towers during the incident.
ds and utility experience. Structure numbers that sustained damage 10 during the April 2024 incident are str. 1218–1228 and 1232, located on the south coast of Labrador in an average loading zone.1 11 12 The main root cause of the damage t...
AI summary Structural damage to power line L3501/2 occurred due to ice loads exceeding design specifications (100–125 mm radial ice) and potential galloping-induced cyclic loading. The incident, located on Labrador's south coast, prompted a 2024–2025 capital project to implement mitigation measures, with CSA 22.3 No. 60826 referenced for load standards.
1 c) Due to site conditions, limited access, and the extent of damage, repairs could not be undertaken immediately; the two impacted customers restored their service through their own backup power source. Repairs were completed and power w...
AI summary Due to site conditions and damage, repairs were delayed, but customers used backup power. On March 29, 2024, a recloser failure in Hampden caused a power outage affecting multiple areas due to heavy freezing rain and tree contact with lines. Power was restored on March 31, 2024.
1.0 Introduction - The Labrador-Island Link ("LIL") is an important transmission line for the provincial energy grid due to its - power carrying capacity that is used to deliver a large portion of the winter peak energy and demand to - the...
AI summary The Labrador-Island Link (LIL) transmission line has experienced ten failures over five years due to icing-related overloading. Investigations identified root causes and led to a 2026–2028 capital project to strengthen the line through infrastructure upgrades, including ice monitoring, tower modifications, and electrode conductor reconfiguration to enhance reliability and reduce failure risks.
Optimizing Clamp Designs - Three alternative suspension clamps were installed on the electrode conductor at 10 structures in 2024, - and will be inspected annually for performance. These alternative clamp designs are intended to reduce - s...
AI summary The document discusses the installation and evaluation of alternative suspension clamps on electrode conductors to reduce stresses from oscillations and unbalanced icing. Redesigned clamps and tower reinforcements based on ice load studies are proposed to enhance system reliability and address overloading risks.
5.1.4 Reinforcement and Re-design of OPGW Peaks and EL Crossarms - This alternative would include replacing the existing electrode crossarms and OPGW peak with new - reinforced sections and adding reinforcing members to the existing cage....
AI summary This section discusses reinforcing OPGW peaks and EL crossarms with new reinforced sections and additional members to address ice load issues from past events. The reinforcement can be installed during monopole outages at a relatively low cost per structure, though it does not resolve electrode conductor failures. Estimated costs are $36,000 per structure for both components and $29,000 for only the crossarm.
5.2 Recommended Alternative - The recommended alternative is the Reinforcement and Re-design of OPGW Peaks and EL Crossarms - with Re-design of the EL Assembly for most sections, with two exceptions. The combination of these - alternatives...
AI summary The recommended alternative involves reinforcing and redesigning OPGW peaks and EL crossarms, with exceptions in specific sections due to higher icing and existing infrastructure. This approach is deemed more cost-effective than alternatives like mid-span structures or removing conductor.
- 2 There have been 10 failure events on L3501/2 over the past five years. These failures were localized - 3 issues, affecting a small number of transmission line components. Due to the importance of L3501/2 to - 4 the provincial energy gr...
AI summary Over the past five years, there have been 10 failure events on L3501/2, primarily due to overloading from ice accumulation and unbalanced ice loads. A 2024–2025 capital project addressed some recommendations, while others will be implemented in a 2026–2028 project, including tower reinforcement and conductor modifications to improve reliability and reduce ice-related failure risks.
3.2 $4-576 (2543) Tower position S4-576 (2543) was chosen due to long weight spans on both sides of the tower, as shown in Table 4. To avoid weight spans imbalance, it was decided to add two mid-span structures; one in the back span (BS) a...
AI summary Tower position S4-576 (2543) was selected due to long weight spans on both sides, necessitating mid-span structures to balance loads. Long spans create high vertical loads during ice events, leading to local peak failures despite no electrodes being present on the tower.
1.0 INTRODUCTION NL Hydro has experienced several performance issues with the electrodes that are mounted on the same towers as the pole conductors (tower type A1) for the Labrador-Island Transmission Link, +/- 350 kV HVDC. Electrode perfo...
AI summary NL Hydro reports performance issues with electrodes on the Labrador-Island Transmission Link's HVDC towers, including conductor failure and structural failures. A technical memo proposes two improvement strategies: one low-cost, minimal-effort solution for critical issues, and a more comprehensive approach requiring additional field work.
2.0 WORK COMPLETED TO DATE Extensive study of the performance issues has previously been completed by NL Hydro and the root cause of most of the issues is that the line has experienced weather loading events that exceeded the initial desig...
AI summary The line L3501/2 experienced performance issues due to weather loading events exceeding initial design assumptions, primarily caused by electrode suspension longitudinal loading during icing events. Reports from 2021 and 2024 detail the damage and root causes, including unbalanced ice accumulation and shedding.
4.1 Option 1: Wood Pole Line Installation The two methods utilized to develop cost estimates for Option 1: Wood Pole Line Installation result in total costs of $262,663.58/km and $313,379.68/km (+ mob and demob) respectively. These two val...
AI summary Option 1: Wood Pole Line Installation has two cost estimates ($262,663.58/km and $313,379.68/km) due to factors like inflation assumptions (general 2x, wood 1.3x), an emergency work markup (1.5x), and pole density estimates. Emergency work uncertainty and potential outage impacts from construction are noted as additional considerations.
er types (A1, A2, A3, A4, B1, B2, C1, C2, D1, D2, and E1) were designed to meet the loading requirements, which consist of a specified wind load, ice load, and combination of both applied to the line. There have been a number of failures t...
AI summary The document details transmission line failures in central Labrador due to ice events between 2021 and 2022. Electrode crossarms and conductors were damaged by unbalanced ice loads exceeding design specifications (50 mm radial glaze ice). Ice loads measured 54–72 mm (0.88–0.9 g/cm³ density) during events, leading to failures on A1-type towers with electrode conductors.
3. Analysis The failure investigations of damage to the towers and conductors in past events determined the root cause was overloading due to unbalanced ice loads. To determine the benefits of removing the electrode conductor from the towe...
AI summary The analysis evaluates structural failure risks in power line towers under balanced and unbalanced ice load scenarios with and without electrode conductors. Removing electrodes significantly reduces failure rates (e.g., 5-80% failures with electrodes vs. 0% without for 60-70 mm ice loads). Over 70 mm balanced ice causes near-total failures regardless of electrode presence, highlighting critical infrastructure vulnerabilities.
Under unbalanced ice load (UBL) with 70 mm of ice: - structures with the electrode: - o the percentage of structure failure range between 77% to 91% for all load cases, - structures without the electrode - o on the OPGW (G) the percentage...
AI summary Under 70 mm unbalanced ice load (UBL), structures with the electrode show 77-91% failure rates, while those without the electrode have 68-86% failures on OPGW (G). No failures are reported on EL1, EL2, P1, and P2. This highlights structural vulnerability under UBL conditions.
Under unbalanced ice load (UBL) with 80 m of ice: - structures with the electrode: - o 95% of structures failed for all load cases, - structures without the electrode: - o on the OPGW (g) the percentage of structure failure for 70/100% unb...
AI summary Structures with electrodes exhibit significantly higher failure rates under unbalanced ice loads (UBL) compared to those without electrodes. For 80 mm UBL, 95% of structures with electrodes failed, while failures on OPGW and other components were 82% and 32-36% respectively. Removing electrodes reduces failures, particularly under balanced and unbalanced ice loads, indicating a safety benefit.
Attachment 2 L3501/2 Failure Investigation Ice Storm Southern Labrador ILK-EG-ED-6200-TL-H15-0007-01
AI summary This document outlines an investigation into the failure of L3501/2 (Pole 1 and 2 of the line) caused by an ice storm in Southern Labrador. The focus is on assessing the impact of the ice storm on the infrastructure and identifying the root causes of the failure.
Introduction - On Saturday March 30, 2024, Pole 2 tripped at 06:45. Pole 1 tripped at 06:52 on electrode line fault - protection. From a patrol of the line it was discovered that the electrode conductor was broken and - damaged at several...
AI summary On March 30, 2024, Pole 2 tripped at 06:45 and Pole 1 at 06:52 due to an electrode line fault, causing damage to the electrode conductor, steel lattice towers, and OPGW. Ice accumulation on the lines was noted as a contributing factor.
Purpose - Considering the importance of L3501/2 to the provincial energy grid and the need to understand the - line's performance, a detailed failure investigation was completed to determine the root cause of the - failures and to conclude...
AI summary The document outlines a failure investigation of the L3501/2 350 kV HVdc transmission line to determine root causes and preventive measures. Key components include failure analysis, weather impacts, construction quality, maintenance, material testing, and load analysis.
Weather Information - There were observations of significant icing on the lines on March 30th , as shown in [Figure 10.](#page-158-2) - Observations at site estimated the ice thickness on the conductor to be approximately 120–140 mm of - r...
AI summary The document details ice accumulation observations on a transmission line, including 120–140 mm radial ice thickness on conductors and 100–125 mm from an OPGW sample. Weather data from Blanc Sablon indicates colder temperatures and higher precipitation near the damaged structures compared to the weather station, with 55–60 mm precipitation recorded around the failure time.
Summary and Conclusions - The main root cause of the damage to the tower electrode crossarms, the OPGW tower peaks, and the - electrode conductor was an overload failure due to ice loads exceeding the design for this section of the - line....
AI summary The damage to the transmission line tower electrode crossarms, OPGW tower peaks, and electrode conductor was caused by ice loads exceeding design specifications. Ice loads of 100–125 mm with lower density than the design load of 50 mm (0.9 g/cm³) led to overload failure. Modeling suggests unbalanced ice loads and temperatures near zero contributed to the damage. Material testing confirmed ductile failure from overloading and wind-induced galloping.
Recommendations - Recommendations for consideration to prevent future failures and better understand the issue with the - line include the following: - Monitoring of ice conditions along the line; - Strengthening of the tower to withstand...
AI summary The recommendations focus on preventing transmission line failures by monitoring ice conditions, strengthening towers against unbalanced ice loads, modifying line designs to reduce tower stress, evaluating alternative suspension assemblies, and using radiography to assess conductor issues. Monitoring methods include patrols, test spans, and ice load equipment to inform future upgrades.
Appendix A NL Hydro Transmission Line Failure (Conductor EL-1 and EL-2 at Suspension Tower 1225) report by Wayland Engineering Ltd.
AI summary Report on NL Hydro's transmission line failure involving conductors EL-1 and EL-2 at Suspension Tower 1225, prepared by Wayland Engineering Ltd.
NL HYDRO TRANSMISSION LINE FAILURE (Conductor EL-1 and EL-2 at Suspension Tower 1225) Prepared By: K.J. KarisAllen, P.Eng. Wayland Engineering Ltd. Unit 9B, 2 Beechville Park Drive Beechville, NS B3T 1L7 Prepared For: Maria Veitch, P.Eng....
AI summary This document reports a transmission line failure involving conductors EL-1 and EL-2 at Suspension Tower 1225. Prepared by Wayland Engineering Ltd. for Newfoundland and Labrador Hydro, it details an incident requiring engineering analysis and potential remediation efforts.
on and wind velocities reported suggests that the line was operating in excess of the design criteria both on the day prior to and during the day of the failures sustained by conductors EL-1 and EL-2. Figure 1-1 is a map showing the genera...
AI summary The text details conductor failures (EL-1 and EL-2) on a 350 kV HVdc line, attributing them to wind velocities exceeding design criteria and asymmetric ice accumulation causing galloping vibrations. NL Hydro reported prior observations of galloping near Tower #1225, with conductors installed in 2017 and subjected to seven years of service.
ct at the site. Figure 2-2 also shows the relative vertical position of the steel reinforcing core, which showed evidence of migration towards the lower circumferential surface of the EL-1 wire clamp. The wire clamp was subsequently remove...
AI summary The document details the preliminary examination of failed conductor EL-1, revealing fracture failures in aluminum strands and evidence of strand-to-strand fusing on the lower surface. Metallurgical analysis of these failures is discussed in Section 4.1, focusing on the damage mechanisms observed during the conductor's failure event.
d that at Tower #1225 (Table 1-1 and Figure 1-2), the EL-2 line damage consisted of stripped and birdcaged outer conductors, which suggests that the steel reinforcing core remained intact at the site. The wire clamp and Stockbridge damper...
AI summary The analysis of failed conductor EL-2 at Tower #1225 reveals stripped outer conductors, fracture failures in aluminum strands, and evidence of strand-to-strand fusing. Fractures exhibited tapered intervals and oblique planes, while fusing increased near the wire clamp's outboard end. Metallurgical characterization of these failures is detailed in Section 4.2.
5.2 General Discussion The physical, chemical and metallurgical evidence indicates that the mechanism responsible for the failure of conductors EL-1 and EL-2 at Tower #1225 is consistent with ductile limit load fracture of the aluminum con...
AI summary The failure of conductors EL-1 and EL-2 at Tower #1225 is attributed to ductile limit load fracture caused by excessive ice accumulation (100–125 mm) and wind speeds (70–60 km/h), exceeding design criteria. Cyclic loading from wind-induced galloping likely contributed, with steel core migration reducing conductor strength. Radiographic imaging is suggested for detecting core migration.
PARTIALLY CONFIDENTIAL 1 Request IR-14: 2 3 Reference: N-01 Application, p. 28, lines 23–26. 4 Preamble: The Application states that any planned outage near the end of a calendar 5 month is likely to result in a holdback disallowance despi...
AI summary The document discusses a regulatory inquiry regarding planned outages near the end of a calendar month and their potential impact on holdback disallowance under the ECA. It requests detailed explanations and quantitative support for the assertion that such outages may increase the risk of breaching the 90% delivery threshold.
Article 1. Definitions Adverse System Impact shall mean the negative effects due to technical or operational limits on conductors or equipment being exceeded that may compromise the safety and reliability of the electric system. Affected S...
AI summary Article 1 defines key terms for regulatory proceedings, including 'Adverse System Impact,' 'Affected System,' 'Affiliate,' 'Ancillary Services,' and 'Applicable Reliability Standards.' These definitions establish foundational terminology for evaluating interconnection impacts, system reliability, and compliance with technical and legal requirements.
- 9.3 Transmission Provider Obligations. Transmission Provider shall cause the Transmission System and Transmission Provider's Interconnection Facilities to be operated, maintained and controlled in a safe and reliable manner and in accord...
AI summary The document outlines obligations under a Large Generator Interconnection Agreement (LGIA), specifying that the Transmission Provider must operate and maintain transmission systems safely, while the Interconnection Customer must comply with Balancing Authority Area requirements. It also addresses synchronization, reactive power, and power factor design criteria.
9.7.1 Outages. - 9.7.1.1 Outage Authority and Coordination. Each Party may in accordance with Good Utility Practice in coordination with the other Party remove from service any of its respective Interconnection Facilities or Network Upgrad...
AI summary Section 9.7.1 outlines procedures for outage coordination between Transmission Provider and Interconnection Customer. Parties may remove facilities from service for maintenance, requiring mutual agreement absent emergencies. Transmission Provider must post outages on OASIS, while Interconnection Customer must submit 24-month maintenance schedules, subject to rescheduling for system reliability.
9.7.4 System Protection and Other Control Requirements. - 9.7.4.1 System Protection Facilities. Interconnection Customer shall, at its expense, install, operate and maintain System Protection Facilities as a part of the Large Generating Fa...
AI summary The section outlines requirements for System Protection Facilities, mandating the Interconnection Customer to install, operate, and maintain these facilities at their expense. The Transmission Provider must also install such facilities on their systems if required by the interconnection. Both parties must design and coordinate protection systems according to Good Utility Practice.
- 13.2 Obligations. Each Party shall comply with the Emergency Condition procedures of the applicable ISO/RTO, the Electric Reliability Organization, Applicable Laws and Regulations, and any emergency procedures agreed to by the Joint Oper...
AI summary Article 13 outlines obligations during emergencies, requiring compliance with ISO/RTO and Electric Reliability Organization procedures. Transmission Provider and Interconnection Customer must notify each other promptly of emergencies affecting facilities, detailing the condition, impact, and corrective actions. Immediate action requires Transmission Provider's consent unless urgent.
Security Arrangements Details Infrastructure security of Transmission System equipment and operations and control hardware and software is essential to ensure day-to-day Transmission System reliability and operational security. FERC will e...
AI summary FERC requires Transmission Providers and market participants to comply with infrastructure security recommendations from the President's Critical Infrastructure Protection Board and future best practices from the electric reliability authority, ensuring physical, operational, and cybersecurity standards for public utilities.
i. Low Voltage Ride-Through (LVRT) Capability A wind generating plant shall be able to remain online during voltage disturbances up to the time periods and associated voltage levels set forth in the standard below. The LVRT standard provid...
AI summary Wind generating plants must remain online during voltage disturbances up to specified time periods and voltage levels, as outlined in the LVRT standard, which includes both transition and post-transition period requirements.
Post-transition Period LVRT Standard All wind generating plants subject to FERC Order No. 661 and not covered by the transition period described above must meet the following requirements: 1. Wind generating plants are required to remain i...
AI summary Wind generating plants not under FERC Order No. 661's transition period must meet LVRT standards, including remaining online during faults and post-fault voltage recovery. Existing units at the Appendix G LVRT Standard's effective date are exempt, while replacements must comply. Compliance may involve generator performance or additional equipment like Static VAR Compensators.
b) In addition to the factors identified in part (a), Concentric considers the following additional factors to be relevant in evaluating whether a planned outage falls within good utility practice: • Consistency with reliability objectives...
AI summary Concentric evaluates planned outages by considering their consistency with reliability objectives and coordination with regional system operators to ensure they align with broader system needs and enhance safe and reliable power system operations.
CONFIDENTIAL (Attachment Only) 1 Request IR-25: 2 3 Reference: N-01, Application, Attachment 1, Concentric Evidence. 4 Preamble: In responding to Q38, Concentric relies on NERC outage statistics and HVDC 5 benchmarking to support the view...
AI summary In response to Request IR-25, Concentric refers to NERC outage statistics and HVDC benchmarking to justify planned outages as normal and expected, and argues that the Board's monthly performance threshold for NS Block deliveries should account for such outages as part of good utility practice.
9.2.1 The Cigré Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 Contents xiii 9.2.2 Failure Statistics for Large HVDC Cable Projects 242 9.2.3 Definition of Reliability Terms . 244 9.2.4 Reliability of Some Sp...
AI summary The text outlines the structure of a document discussing Cigré studies, focusing on topics such as failure statistics for HVDC cable projects, reliability terms, environmental impacts of submarine power cables, and various anecdotes related to cable installations. It includes sections on environmental assessment, cable design, and recycling.
1.2 Connection of Autonomous Grids Since the advent of powerful submarine cables many grids have been interconnected, using different techniques. Submarine cables connect grids of different countries (To name a few: UK – France, Sweden – G...
AI summary The text discusses interconnecting autonomous grids via submarine HVDC cables, enabling shared generation capacity, green power trading, efficient spinning reserves, and exploiting price volatility. Examples include NorNed and other long HVDC systems, highlighting benefits for reliability, resource sharing, and market operations.
1.5 Short-Haul Crossings Hundreds of submarine power cables have been installed to transport power across rivers, channels, straits, fjords, or bays. Though overhead lines can be used for crossings up to 3 km (e.g. Messina Strait, Italy) i...
AI summary The text discusses the use of submarine cables for short-haul crossings over water bodies, highlighting their advantages over overhead lines in terms of visibility, maintenance, and reliability. Examples include the St. Lawrence River and Ems River crossings, with the latter's blackout incident underscoring the risks of overhead lines. Trenchless methods are suitable for shorter crossings, while longer ones require traditional submarine cable laying.
used in fluid-filled cables, predominantly linear alkylbenzene mixtures (LAB). As LAB is compatible with mineral oils it is also suitable for refilling and refurbishment of existing oil-filled cables. During operation, the oil is pressuriz...
AI summary The text discusses the use of linear alkylbenzene (LAB) in fluid-filled paper-insulated oil-filled cables, emphasizing its compatibility with mineral oils for refurbishment. It explains how pressure maintenance in submarine cables prevents gas bubble formation, partial discharges, and insulation breakdown, while ensuring positive overpressure against seawater ingress to avoid water damage.
ves at a steady-state indicated by curve no. 5 in Fig. 3.6. In the steady-state value the conductor temperature has arrived at 90◦C and the cable surface (armoring) temperature is at 46◦C. 8 Let us go back to the situation of curve no. 3 i...
AI summary The text discusses temporary overload scenarios for cables, emphasizing conductor temperature limits (90°C) and thermal reserves. It explains that overload can be applied temporarily (0.5–2 hours) before reaching design limits, with distinct considerations for HVDC cables due to insulation temperature differences. Equations and figures illustrate steady-state and transient temperature behaviors.
3.3.2 The Weibull Distribution Electric breakdown is a statistic process. Repeating the same experiment with equal samples and test conditions will result in a statistic distribution of results. The Weibull distribution is widely used to d...
AI summary The Weibull distribution models electric breakdown as a statistical process, characterized by parameters η (scale) and β (shape). The probability density function and cumulative distribution are provided, along with a figure illustrating experimental results on Weibull paper.
3.3.3.1 Overvoltages During testing and operation of submarine power cables a number of different voltage shapes can occur. Power frequency overvoltages can occur during a singlephase-to-ground cable failure until the fault is cleared. Dep...
AI summary The text discusses overvoltages in submarine power cables, including power frequency overvoltages during faults, abnormal operation conditions, and voltage impulses from switching or lightning. It emphasizes the risks of insulation ageing and breakdown, the importance of system studies for protection measures, and references testing standards for lightning and switching impulse tests.
3.3.7 Availability and Reliability The choice of the insulation wall thickness is as much an asset management task as it is an engineering task. Considering the Weibull plots of the cable insulation material, the cable designer will chose...
AI summary The text discusses the engineering and asset management considerations for submarine cable insulation thickness, balancing reliability against costs. It highlights the use of Weibull plots to determine insulation thickness, the trade-off between thicker insulation (reducing breakdown risk) and increased material costs, and operational rules to mitigate failure risks through temperature and voltage control.
5.2.1 Development Tests The development of new cable types, or the extension of existing cable types to new sizes or ratings, may require comprehensive testing of materials, components, and production processes. Many of the new materials a...
AI summary The development of new or extended cable types requires comprehensive testing of materials, components, and production processes, particularly for submarine cables due to higher repair costs and outages. Tests include dielectric properties, ageing performance, mechanical stress, corrosion, and fatigue, ensuring reliability and performance under various conditions.
gh resolution, relatively small transducers, and can thus be mounted on VOO mobilized 11 fath equals 6 ft. Conversion information is given in the Useful Tables chapter. 6.2 Bathymetry 155 for the task. This advantage has to be paid for wit...
AI summary The text discusses bathymetry methods for submarine power cable projects, highlighting multibeam echo sounders (MBES) and side-scan sonar. It emphasizes accuracy ranges (0.5–1% of water depth), operational limitations in shallow vs. deep waters, and the ability to detect obstacles like shipwrecks and boulders. Survey specifications for subcontracted marine surveys are also outlined.
7.1.4 Laying of Submarine Power Cables Submarine cables on drums, e.g. for in-field cables, can be installed from barges with simpler navigation equipment. A drum pay-off and a linear machine with brake are necessary. The cable runs over a...
AI summary The text describes the process of laying submarine power cables using barges, emphasizing the need for anchors, tugboats, and specialized vessels. It highlights risks of damaging existing infrastructure, slow progress (1–2 km/day), and challenges with visibility for ROV cameras in certain waters.
7.1.7 Weather Weather is the cable crew's worst enemy. Countless are the hours during which an armada of cable laying vessels and working boats has been rolling idly in waves and wind for hours, days, or even weeks until useful weather app...
AI summary Weather significantly disrupts cable laying operations, causing costly delays and operational challenges. The unpredictability of wave and wind patterns complicates planning, as safe laying depends on statistical wave movements rather than direct wind or wave measurements. 'Waiting on weather' is highlighted as a major operational inefficiency.
7.1.7.4 Other Impacts of Wind and Waves Vessel movements can introduce adverse effects on cable laying beyond the tensional force on the cable: Crew work ability . Many seamen suffer from seasickness. In heavy weather, 10– 30% of the crew...
AI summary Vessel movements during cable laying pose risks due to crew sickness in heavy weather, dangers from unsecured cables and equipment, and potential loss of vessel position. These factors can lead to safety hazards, operational delays, and legal consequences for prioritizing cost over crew safety.
7.2 Protection of Submarine Power Cables Submarine cables are precious assets and need to be protected from external hazards. The 1986 Cigré study [14] presents a comprehensive compilation of submarine cable faults and protection methods....
AI summary Submarine power cables require protection from external hazards through four steps: route selection, cable armoring, seafloor protection (e.g., burial), and post-installation monitoring. Proper protection enhances system reliability and reduces repair/maintenance costs, as highlighted by the 1986 Cigré study.
8.1.3 Damage by Fishing Equipment To understand the risks of damages to submarine cables some words should be mentioned about the most common fishing techniques, which may affect submarine cables. The speed of Otter trawling (Fig. 8.2) is...
AI summary The text details how fishing methods like otter trawling, beam trawling, and dredging pose risks to submarine cables through physical contact and force. It highlights specific hazards from trawl doors, anchors, and gear recovery operations, while noting that deeply buried cables are less vulnerable. A case study from Japan's Seto Inland Sea illustrates cable damage and mitigation efforts.
8.1.6 Other Damage Anchors and fishing activities account for the largest portion of submarine cable damages. A minor share is caused by other factors, this portion being smaller for submarine power cables since they are stronger than tele...
AI summary The text discusses various causes of submarine cable damage, including anchors, fishing, free spans leading to vortex-induced vibrations, ship collisions, geo-hazards like landslides and volcanic activity, and shipwrecks with unexploded ordnance. These factors contribute to the degradation and failure of submarine cables, impacting transmission infrastructure and system reliability.
Operation and Maintenance: Reliability
AI summary This section introduces the topic of operation and maintenance focusing on reliability in the context of Nova Scotia's regulatory proceedings. It likely discusses measures and standards to ensure the reliability of electrical systems, though specific details are not provided in the given text.
9.1.2.3 Partial Discharge Monitoring Partial discharge (PD) monitoring of power cable systems has achieved a sophisticated level. Defects, inhomogenities and other flaws can be evaluated with on-line PD detection systems. PD activities on...
AI summary Partial discharge (PD) monitoring in power cables is advanced but faces challenges in detecting signals over long submarine cables due to signal attenuation. The text raises concerns about TSO managers' decision-making when PD activity is detected, questioning whether to interrupt operations for repairs or wait for potential failures.
9.1.4 LPOF, SCOF and SCFF Cables Fluid-filled (FF) and oil-filled (OF) cables require the monitoring of the oil-pressure feeding system. Since the performance of these cables is critically depending on the prevailing oil pressure, it must...
AI summary The text discusses the importance of monitoring oil pressure in LPOF, SCOF, and SCFF cables to detect damage and maintain system reliability. It emphasizes the need for degassed dielectric fluid, SCADA integration, and regional collaboration among cable operators to manage potential leaks and ensure timely repairs.
9.2 Reliability of Submarine Cables Submarine power cables are often a special asset in the basket of TSOs and might deserve closer attention. The operating utilities are very much interested in a troublefree operation because repair is ex...
AI summary Submarine cables are critical for TSOs due to their lack of redundancy and high repair costs. Failures can disrupt islands, offshore platforms, or power trading revenues. Operators are reluctant to report failures, though Cigré Study Group B1 enables confidential reporting to mitigate shareholder concerns.
9.2.2 Failure Statistics for Large HVDC Cable Projects The failure rate calculated from the data given in Table 9.2 is 0.264 failures/year/100 cable kilometres for mechanical faults and 0.0143 failures/year/100 cable kilometres for other f...
AI summary The failure rate for large HVDC cable projects is 0.264 mechanical failures/year/100 km and 0.0143 other failures/year/100 km. The 1964–1988 Kontiskan 1 project significantly contributed to these rates, with its many mechanical failures. Poor engineering and unsuitable installation methods are identified as primary causes of cable failures.
Reliability terms can be expressed in many different terms. For a correct comparison of information from different sources, it is important to use a well-defined terminology. Reliability The probability that a cable is fulfilling its purpo...
AI summary The text discusses the importance of standardized terminology for reliability in power systems, defining key terms such as reliability, availability, outage, and failure rate. It provides mathematical expressions and definitions to ensure consistent comparison of reliability data across different sources.
9.2.4.3 Fox Islands Four SC submarine cables were laid between Rockport, Maine, USA, and the Fox Islands in 1976. The 10.4 miles of 34.5 kV circuit replaced on-island diesel generation. The cable system was stricken by 45 faults until deco...
AI summary Four 34.5 kV submarine cables between Rockport, Maine, and Fox Islands (1976) had 45 faults over 28 years, resulting in nine faults per year per 100 km—far exceeding Cigré's global average of 0.32 faults per year per 100 km, indicating the system's poor reliability and possibly the worst record globally.
9.2.4.4 Long Island Seven single-core high-pressure oil-filled 138 kV cables were installed under the Long Island Sound and commissioned in 1969. At that time it was the longest oil-filled submarine cable in the world [9]. Eighty percent o...
AI summary The 1385 cable system under Long Island Sound, commissioned in 1969, faced frequent failures due to corrosion and external damage, costing over $45 million in repairs since 1990. It was replaced by three 3C 138 kV cables buried six feet deep, improving reliability.
11.3 The Pilot I had overseen the design, testing, and part of production of this powerful submarine cable. Now I was on board one of the largest cable ships of the world with more than 6000 t capacity, to watch the installation. After yea...
AI summary The narrative describes the installation of a submarine cable, highlighting the role of the 'pilot' (cable laying chief) and an anecdote about a past incident where four 230 kV cables broke due to a telephone cable ship's error. The pilot, who was involved in both events, ensured the current cable's smooth installation.
NON-CONFIDENTIAL 1 Request IR-26: 2 3 Reference: N-01, Application, Attachment 1, Concentric Evidence, page 33/36 (pdf page 4 70) 5 Preamble: Concentric recommends that outage months should be "excluded from the 6 calculation of the 12-mon...
AI summary The document requests specific mathematical adjustments and worked calculations to exclude outage months from the 12-month reliability thresholds, focusing on months such as July 2023 and March 2024. It references the NSPML Application to Review the Holdback Mechanism (NSEB M12696).
N-5NSPML (NSEB) RIRs 1-19 - Redacted
65 passages
NSPML Responses to NSEB Information Requests 1 Request IR-12: 2 3 Reference: Exhibit N-1, Testimony of Danielle S. Powers, Attachment 1, p. 17 of 36: 4 • Ms. Power states, "Planned outages to address necessary repairs, upgrades, and 5 main...
AI summary NSPML clarifies that planned outages, while standard for maintenance, do not inherently indicate good utility practice. The response emphasizes that 'planned' refers to scheduling coordination, not the cause or prior practices.
NON-CONFIDENTIAL 1 made by qualified engineers as part of that approved design, and Ms. Powers is not aware 2 of any finding by a regulatory body, independent engineer, or other authority that the 3 approved design criteria were inconsiste...
AI summary Ms. Powers asserts that the Labrador Island Link's design criteria were consistent with good utility practice, emphasizing rigorous engineering standards and regulatory oversight rather than individual weather events. She disputes claims of a 'climate severity limitation' and argues that climate awareness did not necessitate revised design criteria.
NON-CONFIDENTIAL 1 Request IR-17: 2 3 Please provide detailed reasons for the causes of the failure to achieve 90% base contract 4 delivery in five out of the six months following the "Compliance Period", including how the 5 underlying cau...
AI summary NSPML explains that outages in May, July, August, September, and October 2024 were due to planned maintenance, repairs, and software upgrades for the Labrador Island Link (LIL). These activities were conducted in accordance with standard practices and were necessary for winter preparation. The outages were not attributed to poor utility practices.
- 3 On pages 11 and 12, NSPML stated "…the LIL had (and continues to have) a high reliability - 4 level when available for service (i.e. outside planned outage periods). Specifically, the LIL's - 5 equivalent Forced Outage Rate (eqFOR) has...
AI summary The document references the Labrador Island Link (LIL) and its equivalent Forced Outage Rate (eqFOR), noting that it has been below 3% since commissioning in April 2023. Questions are raised about the original forecast for eqFOR and the reasons for any changes from that forecast.
Page 1 of 1 1 Q. Please provide any studies of reliability for the post Muskrat Falls project and 2 Labrador Island Link project. 3 4 5 A. Please refer to the following attached reports: 6 7 PUB‐NLH‐212 Attachment 1: "Technical Note Labrad...
AI summary The document requests studies on the reliability of the post-Muskrat Falls project and the Labrador Island Link project. The response refers to two technical reports dated 2011 and 2012 that assess the impacts of the HVdc link on the Island Interconnected System.
SYSTEM RELIABILITY INTERRELATIONSHIPS To understand the concept of system reliability and overall impact the addition of a 900 MW HVdc transmission link between Labrador and Newfoundland will have on the Island Interconnected Transmission...
AI summary The text explains the need to understand system reliability and the impact of a 900 MW HVdc transmission link between Labrador and Newfoundland on the Island Interconnected Transmission System. It highlights the interrelationships between system planning, transmission line design, and system operations.
Generation Planning Generation planning for the Island Interconnected System ensures that there is sufficient generation, both capacity (MW) and energy (MWh) to supply the load as provided in load forecasts for future years. NLH uses an in...
AI summary NLH uses Strategist® for generation planning, ensuring the Island Interconnected System meets LOLH targets (≤2.8 hours/year) and firm energy requirements. Capacity shortfalls are addressed with low-cost combustion turbines, while energy deficiencies trigger additional energy sources. Grid forced outage rates are excluded from LOLH calculations.
Transmission Planning Transmission planning at NLH follows traditional transmission planning practices similar to, but less stringent than, that found in North American Electric Reliability Corporation (NERC) Transmission Planning Standard...
AI summary NLH's transmission planning follows traditional practices less stringent than NERC standards, emphasizing deterministic stability with no load loss for transmission line failures. Unlike NERC, NLH permits under-frequency load shedding for generator outages due to the Island System's isolation and cost constraints. Planning considers peak/light load conditions and includes provisions for standby generation during prolonged outages.
Section 10 of C22.3 No. 1‐06 states: The reliability‐based method should be used for supply lines greater than 70 kV phase‐to‐phase, in areas where significant amounts of meteorological data are readily available. This method may also be u...
AI summary Section 10 of C22.3 No. 1-06 mandates the use of reliability-based methods for high-voltage (70 kV+) supply lines in regions with abundant meteorological data. It also permits application for lines designed with specific climatic loads, relying on prior experience or calibration with historically reliable lines.
Section 4.3 goes on to state: The objective of the design criteria described in this standard is to provide for reliable and safe lines. The reliability of lines is achieved by providing strength requirements of the line components larger...
AI summary The text outlines design criteria for transmission line reliability, emphasizing strength requirements to withstand climatic loads with defined return periods (e.g., 1:50, 1:150, 1:500 years). It notes that higher reliability standards (longer return periods) are recommended for critical lines, with specific ice thickness values provided for Canada. Variations in reliability standards across countries are acknowledged.
NLH Line Design At this point it is worth describing how each of the above noted standards has impacted transmission line design within the Island Interconnected System. The 230 kV transmission lines on the Avalon Peninsula are used to dis...
AI summary The document discusses the evolution of 230 kV transmission line design on the Avalon Peninsula, highlighting historical ice storm failures due to inadequate design standards (1:10 return period) and subsequent upgrades to a 1:50 return period (60–75 mm radial ice) to improve reliability. Reinforcements between 1998–2002 addressed extreme ice events (up to 150 mm) and aligned with CSA C22.3 standards.
System Operations With all equipment available and in service the Island Interconnected System operates at its most reliable level as the generation planning exercise ensures there is sufficient generation to meet the load even for loss of...
AI summary The Island Interconnected System maintains reliability through generation and transmission planning, ensuring sufficient capacity to handle single equipment failures and maintenance. System Operations schedules maintenance to preserve standby capacity, mitigating risks from forced outages and unplanned losses.
IMPACT OF THE LABRADOR – ISLAND HVdc LINK ON ISLAND SYSTEM RELIABILITY The Labrador – Island HVdc Link has the following nominal ratings: - ±320 kV operating voltage (bipole); - 2 x 450 MW, 1406 A per pole; - 900 MW at Muskrat Falls; - 92....
AI summary The Labrador-Island HVdc Link's impact on the Island Interconnected System's reliability is analyzed, including its modeling as a generator with a forced outage rate, the need for 50 MW combustion turbines to maintain LOLH below 2.8 hours/year, and sufficient generating capacity until 2036. Transmission planning criteria ensure reliable integration.
Pole Outages CIGRE 2010 paper B4_209_2010 "A survey of the Reliability of HVdc Systems Throughout the World During 2007 – 2008" provides the latest available outage statistics for HVdc transmission systems worldwide. It must be noted that...
AI summary The document discusses HVdc system reliability, citing CIGRE 2010 data on pole outages and their impact on the Labrador-Island Link. It highlights risks of under-frequency load shedding and system instability from pole failures, proposing temporary and continuous rating requirements to maintain reliability. The Labrador-Island Link's design includes specific voltage and power ratings for both bipole and monopolar operations.
Pole Outages – Maritime Link In Service Of the 807.9 MW delivered to Soldiers Pond, 162.2 MW is assigned to supply the Emera block, leaving 645.7 MW as the peak deliveries to the Island Interconnected System. For loss of a pole the Emera b...
AI summary The document discusses the impact of pole outages on power delivery via the Maritime Link, noting a 27.5 MW shortfall during monopolar operation. However, spinning reserves and planned combustion turbine startups (up to 150 MW) are expected to prevent under-frequency load shedding, ensuring system reliability despite the shortfall.
Pole Outages – No Maritime Link Should the Maritime Link component of Phase I of the Lower Churchill Project not proceed, operation of the Labrador – Island Link would be somewhat modified. Under the Maritime Link scenario, System Operatio...
AI summary The absence of the Maritime Link would require the Labrador–Island Link to manage spinning reserve differently to prevent under-frequency load shedding. Without the Maritime Link, 154 MW of reserve must be carried on the Labrador–Island Link or 180.7 MW on the Island Interconnected System. NERC standards mandate no load loss from HVdc pole outages, which NLH aims to meet through curtailment and synchronous condensers.
Bipole Outages The CIGRE statistics for bipole outages of two terminal HVdc systems with one converter per pole are summarized in Table 1. The data indicates an average bipole outage rate varying from zero per year to a high of 0.42 outage...
AI summary The document discusses CIGRE statistics on bipole outages for HVdc systems, noting average outage rates (0–0.42 per year) and durations (1.03–2.27 hours). It outlines scenarios where outages trigger a special protection scheme to manage load and prevent blackouts, with a restoration time under 2 hours deemed acceptable.
Summary of Forced Table Outages and 2 Durations for Overhead Transmission Lines Project 2007 2008 Number Duration Number Duration Skagerrak 1 & 2 0 0.0 0 0.0 Square Butte 2 194.6 1 64.5 CU 1 0.1 0 0.0 New Zealand Pole 2 1 0.3 5 9.3 Nelson...
AI summary The table summarizes forced outages and their durations for overhead transmission lines in various projects from 2007 to 2008. It notes that short-duration outages may be due to temporary issues like lightning, while longer outages, such as those on the Square Butte system, were likely caused by tower failures requiring repairs.
Bipole Outages – Maritime Link In Service For loss of the bipole, NERC transmission planning standards permit planned and controlled load loss in order to maintain system stability. In the context of the Labrador – Island Link loss of the...
AI summary The document discusses the implications of a bipole outage on the Maritime Link, highlighting how NERC transmission planning standards allow for controlled load loss to maintain stability. It outlines measures such as a special protection scheme to trip the Avalon Peninsula load and the planning requirements for Nova Scotia and Newfoundland and Labrador Hydro to ensure system stability.
Bipole Outages – No Maritime Link Without the Maritime Link, the available generation to supply the Island Interconnected System following a bipole outage to the Labrador – Island Link equal 1468.5 MW. Given that the 2017 load forecast for...
AI summary The document analyzes the potential impact of a bipole outage on the Island Interconnected System without the Maritime Link, highlighting a 235.5 MW capacity shortfall and a 0.14% probability of unsupplied energy in 2017. It also compares this scenario with the existing Island Isolated System, noting a higher risk of unsupplied energy in the event of simultaneous failures of transmission lines TL202 and TL206.
- 1: Isolated Island Alternative includes a new 170 MW CCCT in 2022 bringing 465.5 MW Thermal to 635.5 MW - 2: Hardwoods 50 MW CT to retire in 2022 - 3: For BDE WAV 230 kV transmission line transfer capability add 328 MW In essence the 201...
AI summary The document discusses the impact of transmission line failures on energy availability, comparing the 2017 loss of the Labrador – Island Link to the simultaneous failure of TL202 and TL206. Calculations show that the latter would result in significantly higher unsupplied energy, highlighting the importance of transmission capacity and reliability.
the 1:25 year design for TL202 and TL206, the probability of unsupplied energy in 2017 for the Isolated Island Scenario is 0.0987 \ 0.04 = 0.00394 or 0.39%. The resultant availability equals 99.6%9 . Table 5 summarizes the exposure levels...
AI summary The analysis compares exposure levels and reliability under Isolated Island and Interconnected Scenarios, highlighting that capacity additions (e.g., 170 MW CCCT) reduce unsupplied energy risks in the Isolated Island Scenario. In contrast, the Interconnected Scenario shows increasing exposure due to delayed capacity additions until 2036-2037, though annual exposure remains below current Isolated Island levels.
ater than the availability value today for loss of TL202 and TL206. 9 Assumes 230 kV transmission line constructed between Bay d'Espoir and Western Avalon built to a 1:50 year design load. Finally, if one considers the addition of the Mari...
AI summary The text discusses potential improvements in system exposure during a Labrador-Island Link bipole outage by leveraging the Maritime Link import capabilities, highlighting grid reliability considerations from 2017 to 2027.
Level of Exposure and Unsupplied Energy Table 5 Year Load Forecast Island Standby Generation Level of Exposure Load Exceeds Generation Availability % Unsupplied Energy Worst 2 wk Window MW GWh MW Annual Hours Annual % MWh % of Annual Isola...
AI summary The table presents data on load forecasts, standby generation, level of exposure, availability percentages, and unsupplied energy for different years and scenarios, including isolated island outages and interconnected island outages with the Bipole and Maritime Link in service. It highlights trends in energy demand, generation capacity, and reliability over time.
- 1: 230 kV transmission line Bay d'Espoir to Western Avalon is built prior to 2017 increasing transfer to east coast for loss of TL202 and TL206. - 2: 170 MW CCCT in 2022 at Holyrood and Hardwoods 50 MW CT retired in 2022 - 3: 50 MW CT in...
AI summary The text outlines the retirement and replacement of various power generation units and transmission lines, with a focus on the 230 kV transmission line and the retirement of combustion turbine units. It also discusses LOLH calculations and the need for additional capacity in 2036–2037 based on the Strategist ® analysis.
rates of all other generating units to derive the LOLH expectation target. Based upon the Strategist ® analysis, the LOLH target is not exceeded until 2036 requiring additional capacity in 2036‐2037. To eliminate the hours of exposure to z...
AI summary The text discusses the LOLH expectation target derived from the Strategist ® analysis, indicating that the target is not exceeded until 2036. It also evaluates the cost and impact of adding combustion turbines incrementally to manage exposure to unsupplied load in the event of a permanent bipole outage, showing that incremental additions are more cost-effective than a wholesale 800 MW plant.
n observed icing events in one of the most heavily loaded sections of the HVdc route. For the refined icing event analysis the following periods are extracted for the annual load shape for evaluation: - Based upon the load shape presented...
AI summary The document analyzes icing events on the HVdc route, selecting specific periods in February, April, and December for evaluation. It highlights a significant reduction in exposure hours and an increase in availability when considering only icing load conditions, not winter peak loads. Tables 8 and 9 provide exposure and unsupplied energy calculations with and without the Maritime Link.
Table 8 Level of Exposure and Unsupplied Energy Known Avalon Peninsula Icing Events No Maritime Link 50 MW Combustion Turbines Added Year Load Forecast Island Standby Generation Level of Exposure Load Exceeds Generation Unsupplied Energy W...
AI summary Table 8 presents data on the level of exposure and unsupplied energy for the Avalon Peninsula during icing events, with and without the Maritime Link and 50 MW combustion turbines. It includes metrics such as load forecasts, standby generation, load exceeding generation, and unsupplied energy percentages for various years from 2017 to 2037.
- 11: Portland Creek at 23 MW and new CCCT at 170 MW Added Table 9 Level of Exposure and Unsupplied Energy Known Avalon Peninsula Icing Events With Maritime Link 50 MW Combustion Turbines Added Year Load Forecast Island Standby Level of Ex...
AI summary The document discusses the addition of new generation capacity, including the Portland Creek at 23 MW and a new CCCT at 170 MW, and evaluates the level of exposure and unsupplied energy under different scenarios with the Maritime Link and 50 MW combustion turbines added. It includes data for various years from 2017 to 2037.
HVdc Line Design Load The final question with respect to the reliability of the Labrador – Island Link relates to the exposure of the approximately 1100 km of overhead transmission line and how to prevent failure. In the context of the los...
AI summary The document focuses on ensuring the reliability of the Labrador-Island Link's HVdc line, emphasizing the need to determine construction standards to prevent failures and ensure alternate energy sources are available during repairs.
SUMMARY To date the generation planning process incorporates the forced outage rate and associated impacts of the HVdc transmission line between Labrador and the Island portion of the Province along with appropriate capacity and energy sou...
AI summary The generation planning process considers the forced outage rate of the Labrador Island Link HVdc transmission line and incorporates capacity/energy additions to meet LOLH and energy balance criteria. Transmission planning aligns with NERC standards, with low-probability outage events resulting in <1% unserved energy. Nalcor opts for load rotation over additional combustion turbines to minimize customer costs due to the low impact of potential outages.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 i Revision Remarks o N By Verif. Appr. Date 00 PA RA SS 10...
AI summary The document outlines a reliability and availability assessment of the HVDC Island Link, including system components, reliability calculations, and historical data. It is part of a technical report with appendices and references, and includes a mention of the NSPML 2026 Holdback Mechanism NSEB IR-18 Attachment 1.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 iii List of Tables Table 2-1: Summary of FOR and FU (per t...
AI summary The document provides an introduction to the reliability and availability assessment of the HVDC Island Link, focusing on converter reliability, transmission line outages, and overall system performance metrics. It includes a list of tables summarizing key data related to reliability and availability.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 2 Figure 1-1: Project Area Map
AI summary The document presents a reliability and availability assessment of the HVDC Island Link project, including a project area map and document details such as revision numbers and dates.
Table 2-1: Summary of FOR and FU (per terminal) Period Outage FOR (%) FU(hrs/yr) 2007 Pole 0.15 13 Bipole 0.0003 0.02 2008 Pole 0.38 34 Bipole 0.0002 0.02 1988-2008 Pole 0.49 43.4 Bipole 0.003 0.27 The average failure rate per terminal ove...
AI summary Table 2-1 summarizes the failure rates (FOR) and forced outage hours (FU) for pole and bipole outages from 1988 to 2008. Pole outages had higher failure rates and longer repair times compared to bipole outages.
- 4 pole outages per year with a repair time of 21 hours per outage (FOR=0.98%) - 0.4 bipole outages per year with a repair time of 1.3 hours per outage (FOR=0.006%) The same source also provides information on the breakdown of forced ener...
AI summary The document discusses forced energy unavailability (FEU) in converter stations, noting that converter transformers and DC smoothing reactors are major contributors. Providing spare units for these components significantly improves station availability, as illustrated in an example.
Table 2-2: Converter Unavailability Item Performance Indicator Spare Transformer No Yes Yes Spare Smoothing Reactor No No Yes Terminal Unavailability 3.04% 0.94% 0.21% Hours/ Year 266 82.5 18.6 Based on the above information, it is recomme...
AI summary The table presents converter unavailability statistics, including spare transformer and smoothing reactor availability. It recommends providing spare units at each terminal to improve reliability, citing performance indicators from 2007 and 2008 for converter stations with spare units.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 8 Table 2-4: HVdc Transmission Line Outage Statistics Syst...
AI summary The document presents a reliability and availability assessment of the HVDC Island Link, including outage statistics for various HVDC transmission lines. The average outage frequency and duration are used to estimate the reliability performance for a 1,100 km route.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 9 A report by C-Core [4] examined the incidence of iceberg strikes...
AI summary A report by C-Core examined the incidence of iceberg strikes on submarine cables, concluding that the expected failure rates for such events would be as outlined in the document.
- 0.004 failures/year for a single cable - 0.002 failures/year for 2 cables - 0.001 failures/year for 3 cables Repair times for cables in the Strait of Belle Isle could be very long and a repair time of 6 months (4,380 hours) has been assu...
AI summary The text calculates failure rates for cables in the Strait of Belle Isle, considering both independent failures and iceberg strikes. It evaluates the probability of losing a single pole due to cable faults and the complete loss of the link, providing failure rates, repair times, and downtime for different scenarios.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 10 2.4 Electrode Line
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, specifically focusing on the Electrode Line section. It provides technical details related to the system's performance and reliability.
3.1 HVdc Overhead Line and Submarine Cable First, it is necessary to determine the composite reliability indices associated with each parallel pole element (L1, C1+2, and L2 in series). Since the failure of any one of these elements will r...
AI summary The text discusses the calculation of composite reliability indices for parallel pole elements in HVdc systems, including failure rates, repair times, and downtime for overhead lines and submarine cables, with specific considerations for iceberg strikes affecting multiple cables.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 14 The reliability indices for the coincident, independent failure...
AI summary This document discusses the reliability indices for the coincident, independent failure of two poles in parallel within the HVDC Island Link. It provides technical details related to the reliability and availability assessment of the HVDC system.
3.2 Converters Similarly, the coincident failure of both converters in independent mode can be calculated as: $$\begin{split} &\lambda_T = (1.64)^2.(2x13.8)/8760 = 0.0084 \text{ f/yr} \\ &r_T = (13.8)^2/(2x13.8) = 6.9 \text{ hrs} \\ &U_T =...
AI summary The text presents mathematical calculations for converter failure rates, including failure frequency (λ_T), repair time (r_T), and unavailability (U_T), using specific numerical values and formulas. The focus is on quantifying reliability metrics for converters in an HVdc system.
3.3 Electrode Lines As mentioned above, the link can still be operated at full power or reduced power even for the complete loss of the electrode line at either end of the link. As such, the reliability of the electrode line is considered...
AI summary The electrode line's reliability does not significantly affect the composite reliability of the link, as the link can operate at full or reduced power even with the complete loss of an electrode line at either end.
For the failure of both lines/cables (P1+P2) or both converters (CP+CP), in series with the common-mode failure of both poles due to converter faults (BP) and main line faults (BPL1 and BPL2), the composite reliability of the Island Link i...
AI summary The document discusses the composite reliability of the Island Link in the event of failures in both lines/cables, converters, and poles due to converter and main line faults.
Table 3-2: Composite Island Link Bi-pole Reliability Element Failure Rate Repair Time Downtime (f/yr) (hrs) (hrs/yr) % of Total BP-Muskrat Falls 0.24 0.13 0.031 0.3 CP+CP-Muskrat Falls 0.0084 6.86 0.057 0.6 BPL1-388 km 0.074 24 1.776 18.6...
AI summary Table 3-2 presents the reliability data for the Composite Island Link Bi-pole, including failure rates, repair times, and downtime contributions for various elements. The total forced unavailability and FOR is calculated as 0.109%.
It is clear from the above results that the major contributors to the unavailability of the Island Link are the common-mode failure of both poles of the overhead line (representing nearly 52% of the total unavailability) and the independen...
AI summary The major contributors to the unavailability of the Island Link are common-mode failures of both poles of the overhead line and coincident failures of both poles in the overhead and submarine cable sections. The reliability indices for these failures are uncertain due to limited operating experience, and repair time significantly influences overall unavailability.
3.5 Reduced Power Operation The scheduled maintenance would typically be of the order of 3 days per pole per year, assuming that maintenance work would be carried out at both terminal stations and on each line (pole) at the same time. With...
AI summary The section discusses scheduled maintenance and forced outages of the Island Link, focusing on reliability indices during reduced power operation. It highlights scenarios such as the loss of a converter or a pole, and references tables for reliability data.
Table 3-3: Reduced Power Capability Modes (Mono-polar) Element Failure Rate(f/yr) Repair Time(hrs) Downtime(hrs/yr) Scheduled Maintenance 2.0 72 144 Converter-Muskrat Falls 1.64 13.8 22.42 Pole 1 2.04 6.3 12.87 Pole 2 2.04 6.3 12.87 Conver...
AI summary Table 3-3 outlines the reduced power capability modes for mono-polar systems, including scheduled maintenance and converter failures. It calculates the composite unavailability and FOR at 2.45% based on downtime data.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 17 24 hours and a downtime of 4.8 hours/year. If these val...
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, noting a 24-hour operation and a downtime of 4.8 hours per year. Adding these values to those in Table 3-3 increases the overall FOR from 2.45% to 2.51%.
The impact of the repair time for the common-mode failure of both circuits of either the Muskrat Falls electrode line or the main dc line is dominant to the point where the total forced unavailability can be approximated as being proportio...
AI summary The document discusses the relationship between repair time for common-mode failures in HVDC transmission lines and the resulting forced unavailability. It highlights that total forced unavailability is proportional to repair time, and that maintaining reliability targets requires keeping repair times within specific limits.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 18 4 CONCLUSIONS & RECOMMENDATIONS
AI summary The document presents conclusions and recommendations from a reliability and availability assessment of the HVDC Island Link. It discusses the technical evaluation of the system's performance and reliability.
- To assess the improvements that could be made in the above indices considering design aspects such as the provision of spare equipment, over-rated equipment, etc., - To assess the composite R&A performance indices of the complete HVdc Is...
AI summary The text focuses on evaluating improvements to reliability and availability (R&A) performance indices for the HVDC Island Link, considering design aspects like spare and over-rated equipment, and assessing the composite R&A performance of the complete HVDC system from Muskrat Falls to Soldiers Pond.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 19 Table 4-3: Composite Island Link Reliability Element Fa...
AI summary This table presents a reliability and availability assessment of the HVDC Island Link, detailing failure rates, repair times, and downtime contributions for various elements of the system. The overall FOR is 0.109%, and the availability is calculated as 99.89%.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 20 maintenance being 1.64%. However, both of the values fo...
AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, focusing on maintenance rates and forced unavailability, which depend on average repair times for pole outages and common-mode failures.
It has been shown that a linear relationship exists between these repair times and the unavailability of the Island Link. Once a target reliability has been decided on, the maximum repair time can be determined. The overall unavailability...
AI summary The text discusses the relationship between repair times and the unavailability of the Labrador Island Link. It highlights that increasing repair times for common-mode failures significantly increases overall unavailability, while spare submarine cables reduce sensitivity to repair times for submarine cable failures.
Table 4-5: Variation in Overall FOR with DC Overhead Line Repair Time Repair Time(hrs) FOR(%) 24 (1 day) 0.112 48 (2 days) 0.179 72 (3 days) 0.251 96 (4 days) 0.33 120 (5 days) 0.416 144 (6 days) 0.507 168 (1 week) 0.605 336 (2 weeks) 1.46...
AI summary Table 4-5 illustrates the variation in Overall Forced Outage Rate (FOR) based on DC overhead line repair time, showing increasing FOR as repair time increases. This data is presented in the context of the NSPML 2026 Holdback Mechanism NSEB IR-18 Attachment 1.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Revision Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 21 The relationship is not linear, as may be expected, but...
AI summary The reliability and availability assessment of the HVDC Island Link indicates that the relationship between unavailability and repair time for overhead dc line section faults is not linear, highlighting the dependence of unavailability on repair time.
4.2 Recommendations At each converter station, a spare converter transformer of each type (single phase) and a spare smoothing reactor should be provided. This will significantly improve the availability of the converters. Other critical c...
AI summary The text recommends providing spare components at converter stations to improve converter availability and reliability, with specific mention of converter transformers and smoothing reactors. Other long-lead-time components should also be considered for on-site spares based on reliability targets.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 22 5 REFERENCES
AI summary The document provides a reliability and availability assessment of the HVDC Island Link, including references and documentation details. It outlines the technical and regulatory context for the project.
RELIABILITY FORMULAE
AI summary The text introduces the topic of reliability formulae, which are essential for assessing the performance and reliability of power systems. These formulae help in evaluating system reliability, outage probabilities, and other critical metrics.
Components in Series In a system where the failure of any single component will result in failure of the system, the components are said to be connected in series, using the analogy of an electrical circuit. In such a system, the total sys...
AI summary The text explains the concept of components in series within a system, where the failure of any single component leads to system failure. It calculates the total system failure rate and downtime as the sum of individual component failure rates and downtimes, using a numerical example for illustration.
RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 A-2 Components in Parallel
AI summary This document discusses the reliability and availability assessment of the HVDC Island Link, focusing on components in parallel. It outlines the technical aspects and considerations related to the system's reliability.
2 Terminal Systems - 1 Converter per Pole 2007 2008 Ave age 198 38-2008 Name Po ole Bipo le Po ole Bipo ole Years Po ole Bip ole fp dp fb db fp dp fb db fp dp fb db Skagerrak 1 & 2 1.25 3.1 0 0 2 3.8 0.5 1 20 1.54 17.1 0.13 1.03 Square But...
AI summary The document provides a table with data on terminal systems and converter performance, including forced outage rates and downtime statistics. It also includes a response from NSPML to an information request regarding the availability of market-priced energy for Nova Scotia customers, citing the Energy Access Agreement (EAA) as a contingency measure.