Topic:"System Reliability" in M11307

MODELING APPROACH Capacity expansion and production cost optimization modeling developed least-cost portfolios for each scenario. The scenarios are compliant with current legislation, including the 2030 environmental policy targets of coal...

AI summary The modeling approach outlines least-cost portfolios for scenarios compliant with 2030 environmental targets (coal phase-out, 80% renewable electricity) and net-zero timelines (2035, 2050). It evaluates resource strategies (with/without Atlantic Loop), electrification pace, and sensitivities, producing results like NPVRR, emissions, reserve margins, and generation profiles.

KEY FINDINGS Based on the common themes observed, the following are the key guiding principles to inform the Action Plan and Roadmap Items: - Variable renewable capacity additions are required to meet the 2030 targets. Up to 1500MW of addi...

AI summary Key findings emphasize the need for 1500MW additional wind, 200MW solar, and 100-900MW firm capacity by 2030. Battery storage (≥100MW) and the Reliability Tie are critical across scenarios. The Atlantic Loop reduces costs/emissions with government support. Synchronous condensers and SMRs (late 2030s) address system reliability and decarbonization. NS Power updated its 2020 IRP based on 2023 modeling.

CAPACITY ADDITIONS The optimized capacity additions highlight the transition of the power system to an increased penetration of variable renewable energy, backed by fast acting firm capacity resources (Battery and Combustion Turbine) as th...

AI summary The text discusses capacity additions in Nova Scotia's power system, emphasizing variable renewable energy integration with fast-acting firm resources (batteries, combustion turbines) and low-cost fuel conversions (coal-to-gas/oil). These measures ensure reliability during peak demand and resource unavailability, aligning with sensitivity scenarios and common industry observations.

Fast Acting Generation • All scenarios add new fast acting generation resources in the range of generally 300MW to 900MW by 2030. Installed capacity is influenced by the range in assumptions of firm peak load growth across scenarios. - Mos...

AI summary The text outlines the addition of 300-900MW of fast-acting generation by 2030, with No Atlantic Loop scenarios requiring 450MW more than With Atlantic Loop scenarios. These resources operate flexibly with low capacity factors to integrate variable renewables and meet peak demand.

GENERATION MIX The evergreen IRP modeling results demonstrate that annual generation profiles are increasingly decarbonized through the planning horizon in line with environmental policy changes in 2030 and 2035 (please refer toFigure 4)....

AI summary The document discusses the decarbonization of Nova Scotia's generation mix through 2030 and 2035, emphasizing wind energy's role, curtailment rates (10–45%), and emission reductions. Gas resources are used in peaking capacity, with lower emissions in all scenarios compared to 2005 levels.

ITEM 1: REGIONAL INTEGRATION STRATEGY Develop a Regional Integration Strategy to provide access to firm capacity and low-carbon energy while increasing the reliability of Nova Scotia's interconnection with North America. With virtually no...

AI summary Nova Scotia aims to develop a Regional Integration Strategy to secure firm capacity and low-carbon energy, enhance interconnection reliability with North America, and address the phase-out of coal generation. The strategy emphasizes access to renewable markets and system reliability independent of the Atlantic Loop for wind integration.

Item 1a: Reliability Tie Continue to develop the Reliability Tie via an appropriate regulatory process with target in-service date of 2028.

AI summary The document proposes continuing the development of the Reliability Tie through a regulatory process, with a target in-service date of 2028. The focus is on ensuring system reliability through this infrastructure project.

Item 2b: Data Collection Continue to collect detailed data, including data on the quantity, flexibility and hourly load shape of incremental electrification demand, to assist with further system planning work. Updated 14 IRP Action Plan an...

AI summary The document emphasizes the need to collect detailed data on electrification demand, including quantity, flexibility, and hourly load shape, to support system planning. It references the Atlantic Clean Power Roadmap and updates to the Integrated Resource Plan (IRP) Action Plan.

Item 3c: Fast Acting Generating Capacity Initiate development of new fast-acting generating capacity resourcesto address growing demand, balance variable renewable generation, and maintain the reliability of the Nova Scotia system. Scope w...

AI summary The initiative aims to develop 300MW of fast-acting generating capacity by 2027 and an additional 300-600MW by 2030 to meet growing demand, balance variable renewable energy, and ensure system reliability. Fuel flexibility, including hydrogen, is emphasized, with existing combustion turbines sustained through the planning horizon.

Item 3d: Procurement Strategy for Variable Renewable Resources Develop a procurement plan for incremental variable renewable resources, targeting approximately 1000MW[5](#page-15-7) by 2030. Anticipated renewable procurements and programs,...

AI summary The document outlines a procurement plan targeting 1000MW of variable renewable resources by 2030, leveraging programs like Green Choice, Community Solar, and Renewable to Retail. It emphasizes regular procurements, engineering resources, and studies to reduce curtailment of renewable generation.

Item 3g: Synchronous Condensers Complete generator site-specific system impact studies for new variable renewable generation to assess the need for synchronous condenser support. Progress the development of 100 - 200MVA of synchronous cond...

AI summary The document outlines the need to conduct site-specific system impact studies for new variable renewable generation and to develop 100-200MVA of synchronous condensers by 2030 to ensure grid reliability and stability as renewable energy penetration increases.

an and should be welcome to bid in such an RFP, allowing for a fair and complete comparison of these alternatives to minimize cost and risk to ratepayers while meeting system reliability requirements. Third, to the extent NSPI conducts tec...

AI summary The text emphasizes NSPI's need to use competitive procurement to compare resource alternatives, avoid restrictive RFP quantity targets, and consider market-driven pricing. It highlights IRP scenarios showing how wind and battery cost variations affect project timelines and retirement schedules, advocating for flexible procurement designs like 'price-to-beat' benchmarks. Regional cooperation via external control areas is also recommended to incentivize transmission investments.

ers used in the 2020 IRP ($1.7 billion in 2019 dollars). 13 NSPI's modeling of the Atlantic Loop relied upon forecasts of ISO New England market prices for energy and capacity. 14 In our view, NSPI's attempt to model regional solutions was...

AI summary The Atlantic Loop project faces significant cost increases (from $2.9B to $7.5B) and risks, raising concerns about its affordability and reliability. NSPI's modeling relies on ISO New England market forecasts, but uncertainties persist. The Board emphasizes the need for rigorous cost-risk analysis and regional integration solutions to optimize costs for ratepayers.

2. Reliability Tie and Regional Integration NSPI continues to show need for the development of the Reliability Tie, and the IRP modeling results reflect the inclusion of the Tie, with an in-service date of 2028. Action Plan Item 1a is deve...

AI summary NSPI emphasizes the necessity of the Reliability Tie for wind resource integration by 2028, with IRP modeling supporting its inclusion. By 2030, 2,000 MW of wind capacity is required. Synapse recommends prioritizing the Tie's development. The Action Plan also includes exploring Atlantic Loop integration.

B. Atlantic Loop NS Power confirmed that it has chosen a "No Atlantic Loop" reference scenario (CE1-E1-R2) for planning purposes. (Response to Comments, p. 11) It declined to comment on the likelihood of a contract (or other commitment) fo...

AI summary NS Power has selected a 'No Atlantic Loop' planning scenario, while Bates White highlights financial risks and recommends joint dispatch with New Brunswick. NS Power's valuation methods for bi-directional transactions are criticized as inadequate, with concerns over reliance on uncertain forecasts. The Atlantic Loop's potential benefits and costs are debated, including impacts on system costs and renewable integration.

E. Reliability Tie As we noted in our comments on the modeling results, NS Power has delayed the earliest complefion date of the reliability fie (a second 345 kV AC transmission line from Onslow, NS to Salisbury, NB) unfil at least 2027, r...

AI summary NS Power has delayed the completion of a 345 kV AC transmission line (reliability tie) from Onslow, NS to Salisbury, NB until 2027 due to capital constraints linked to Bill 212. The project, vital for wind integration, is expected to file for review in 2024 with an in-service date of 2028. NS Power and the Board are urged to expedite its review.

F. Enhanced Operafional Pracfices We recommended in earlier comments that NS Power enhance its operafional pracfices to support more complex commitment and dispatch decisions and to reduce the cost of maintaining system reliability. NS Pow...

AI summary Recommends enhancing NS Power's operational practices for reliability and complex decisions. NS Power's response is limited to reducing curtailment of variable renewables, not comprehensive updates.

Reflections on the Evergreen IRP Analysis General Comments on the Update Process, Reasonability of Analysis and Key Findings Comments from Board Counsel's consultants and many participants were generally positive with respect to the qualit...

AI summary Board Counsel consultants Synapse and Bates White generally support the Evergreen IRP Update's analysis and key findings, though Synapse notes limitations. Both emphasize the need for ongoing monitoring of factors like hydrogen industry development impacting electricity demand and low-carbon fuel supply.

l to offset a portion of the requirement for other new firm capacity resources. NS Power acknowledges this request and will investigate avenues for completing this work prior to the next IRP analysis. NS Power notes that a firm capacity be...

AI summary NS Power acknowledges a request to offset firm capacity requirements and will investigate options before the next IRP. It emphasizes the value of 18MW-40MW firm capacity and plans to proceed with 300MW of new fast-acting generation by 2027, citing feedback from PHP and Eastward Energy that further study is unnecessary due to timelines and system needs.

Specific Recommendations: Future Analysis & Action Plan Items All Source RFP Process Bates White and Grid Strategies on behalf of the Consumer Advocate recommend all source RFP processes to acquire generation and infrastructure assets deem...

AI summary The Consumer Advocate recommends all-source RFP processes to meet decarbonization targets, while NS Power anticipates multiple procurements, some managed by the Province. NSUARB approval is required for capital investments, with stakeholder engagement. The Electrification Study will be published in 2023, and wind integration studies will address curtailment reduction and system reliability.

that correctly iden�fying the need for capacity is paramount for all subsequent IRP runs. The study should also ask whether energy to meet those peak demands should be stored in a batery, a tank, a lake or in a regionally linked, diversifi...

AI summary The text discusses the importance of accurately identifying capacity needs for Integrated Resource Plan (IRP) runs and explores options for storing energy to meet peak demands. It also highlights the need to understand how customer behavior may change with increasing carbon prices and the impact of decarbonization policies on NS Power and Eastward. Additionally, the reliability tie project is mentioned as vital for integrating wind power.

batery energy storage, PHP is concerned with further study that could poten�ally delay firm inprovince resources which will be required to maintain the reliability of the system, especially with the addi�on of significantly greater amounts...

AI summary The document discusses concerns about delaying the development of firm in-province resources due to potential further studies, particularly in the context of integrating non-dispatchable renewables. It emphasizes the need for expeditious action to maintain system reliability, referencing the Evergreen IRP Update's requirement for 300 MW of new fast-acting generation by 2027. The document also addresses the planning reserve margin, noting the shift from a 20% ICAP to a 9% UCAP planning reserve margin after stakeholder feedback and the 2019 Planning Reserve Margin and Capacity Value Study.

will be released to stakeholders for their review and NS Power will request feedback on the findings. will be evaluated by further study work (Updated Ac�on Plan page 7), including generator site– specific system impact studies for new var...

AI summary The document discusses the need for further study on the impact of adding more variable renewable generation, particularly the potential need for synchronous condensers, and the implications of the Federal Clean Electricity Regulations on natural gas peaking capacity in Nova Scotia. PHP emphasizes the importance of a system-wide approach to assess these issues.

batery energy storage, PHP is concerned with further study that could poten�ally delay firm inprovince resources which will be required to maintain the reliability of the system, especially with the addi�on of significantly greater amounts...

AI summary PHP is concerned about potential delays in building firm in-province resources due to further study on battery energy storage, which could affect system reliability with increased non-dispatchable renewables. The Evergreen IRP Update requires 300 MW of new fast-acting generation by 2027. Future modeling refinement will not eliminate the need for new firm capacity to maintain reliability.

While batery storage does assist with the curtailment issues, wind integra�on and capacity, and addi�onal batery storage is called for in the No Loop scenarios, NSPI lays out in some detail in its responses to stakeholder comments (see pag...

AI summary The text discusses the limitations of battery storage in replacing fast-acting generation and the need for synchronous condensers to support wind integration by 2030. NSPI explains that battery storage has duration limitations and must be supplemented with other resources during peak periods. PHP highlights the addition of 80 MVA of synchronous condensers for wind integration.

will be released to stakeholders for their review and NS Power will request feedback on the findings. will be evaluated by further study work (Updated Ac�on Plan page 7), including generator site– specific system impact studies for new var...

AI summary The document discusses the evaluation of new variable renewable generation and the need for synchronous condensers, as well as the impact of the Federal Clean Electricity Regulations on natural gas peaking capacity in Nova Scotia. PHP suggests a system-wide review of synchronous condensers and NS Power confirms its participation in stakeholder processes regarding the regulations.

Large Scale Integration of Inverter Based Resources in Nova Scotia Frequency Control and System Strength Assessment Initial Findings and Recommendations Report Number: 083-2023-TSMG October 23, 2023 Manitoba Hydro International Ltd. Nova S...

AI summary This report, titled 'Large Scale Integration of Inverter Based Resources in Nova Scotia,' focuses on assessing frequency control and system strength for integrating inverter-based resources into the grid. It is authored by Manitoba Hydro International Ltd. and Nova Scotia Power Inc., highlighting technical and operational considerations for grid reliability.

Executive Summary Nova Scotia is on a path to build a cleaner, greener future for the province, phasing out coal and working towards 80% renewable energy by 2030. Inverter-based generation will displace conventional synchronous machine-bas...

AI summary Nova Scotia aims for 80% renewable energy by 2030, transitioning from coal and conventional generation to inverter-based systems. This shift requires addressing technical challenges through system studies, including EMT analyses. Initial findings were released due to delays in plant models, with an updated report pending. Mitigation measures are emphasized to ensure grid reliability.

Recommendations Stable and Reliable Integration of Renewables - Verify network response for high Rate of Frequency (RoCoF) system disturbances through EMT simulations. Based on study to date, there are significant concerns for the ability...

AI summary The recommendations focus on ensuring stable integration of renewables by addressing RoCoF risks, upgrading grid interconnection standards, and conducting detailed studies. Concerns include existing RoCoF limits potentially causing cascade tripping, the need for IEEE 1547-2018 alignment, and MHI's proposals for grid study updates. NSPI is urged to review system guidelines and perform incremental studies for each generation/load wave.

Resource Planning for High IBR Penetration Update IBR and inertia constraints for resource planning based on the findings herein. At the present time, studies indicate that there is no hard limit on IBR penetration and dispatch if there is...

AI summary The document discusses updating resource planning for high IBR penetration, emphasizing the need for inertia and system strength metrics. It recommends a sliding scale for inertia/FFR, maintaining inertia requirements even with two tielines, and introducing SCMVA as a new metric for system strength in future grid planning.

Good Planning Practices to Integrate Renewables in Nova Scotia • Perform an annual assessment of NSPI System Inertia and Strength in the 10-year horizon to identify potential issues. See Section [2.2.](#page-18-0) Include FOR and planned m...

AI summary The document outlines planning practices for integrating renewables in Nova Scotia, emphasizing annual system inertia assessments, model requirements for grid connections, system studies for western Nova Scotia's load and hydro generation, and maintaining SCMVA levels to ensure grid reliability.

System Operator Support to Transition to High IBR Grid - Develop a methodology to estimate the minimum SCMVA and SCR online prior to the addition of additional IBR (WEC, BESS, HVDC etc.) to the NSPI grid. - Develop a methodology to estimat...

AI summary The document outlines the need to develop methodologies for estimating SCMVA, SCR, and inertia online to ensure grid stability before integrating additional IBR (e.g., WEC, BESS, HVDC) into the NSPI grid. It also emphasizes updating operating guidelines and conducting EMT studies to address fault ride-through, control interactions, and system oscillations from expanded IBR interconnections.

Acronyms Acronym Term BES Bulk Electric System BESS Battery Energy Storage System CI Control Interaction EMT Electromagnetic Transient FACTS Flexible AC Transmission System FFR Fast Frequency Response IBR Inverter Based Resource LVRT Low V...

AI summary The document outlines the acronyms and terminology used in the analysis of frequency control and system strength within the Bulk Electric System (BES), including terms related to power electronics, energy storage, and system impact studies.

[Appendix B: Sensitive SCMVA Buses](#page-58-0) - Table B 1: SCMVA Sensitive Buses, 2023 Typical SCMVA - Table B 2: SCMVA Sensitive Buses, 2023 Minimum SCMVA, 2 thermals, ML - Table B 3: SCMVA Sensitive Buses, 2030 SCMVA, RoCoF Case 511 -...

AI summary Appendix B presents tables analyzing Short Circuit MVA (SCMVA) sensitivity for critical buses in Nova Scotia's power system under various scenarios (2023/2030, thermal limits, tie lines, inertia levels). The data reflects system stability considerations for the Bulk Electric System (BES) under different operational conditions.

[Appendix C: SCR Sensitive Facilities](#page-59-0) - Table C 1: SCR Sensitive Sites, Existing Typical - Table C 2: SCR Sensitive Sites, Existing Minimum Transmission Level Voltage - Table C 3: SCR Sensitive Sites, 2030 RoCoF Case 511 - Tab...

AI summary Appendix C presents tables detailing SCR (Short Circuit Ratio) sensitive facilities under various scenarios, including existing transmission levels, 2030 RoCoF Case 511, and minimum SCMVA conditions. These tables assess system stability risks associated with low SCR values in the Nova Scotia power grid.

List of Tables and Figures Table 1: Minimum Inertia for Frequency Control, First Iteration15 Table 2: Minimum Inertia and FFR Required for Frequency Control 17 Table 3: Most Severe RoCoF, 2023 Grid18 Table 4: First Iteration for 2030 RoCoF...

AI summary The document provides a list of tables and figures related to frequency control, inertia requirements, and grid stability, including tables on minimum inertia, FFR support, and RoCoF, as well as figures illustrating voltage waveforms, simulation results, and frequency response. The introduction section is referenced but not detailed in this chunk.

1.1 Background Most power systems in North America, Europe, Australia, and the Middle East have seen increased penetration of renewable energy-based generation of from 10% to 30% over the past decade. In 2021, close to 30% of NSPI electric...

AI summary The document discusses the increasing penetration of renewable energy, particularly inverter-based generation, and its technical challenges on power systems. NSPI aims for 80% renewable electricity by 2030, but this may reduce system inertia, short circuit levels, and cause instability issues like fault recovery and torsional oscillations, requiring mitigation measures.

1.1.1 Frequency Control In an electrical system, generation and load must be balanced at all times to maintain system stability. Load is the demand for electricity at any instance in time. Generation is the electrical energy to supply the...

AI summary The text explains the importance of balancing generation and load to maintain system frequency (60Hz) in Nova Scotia. Traditional synchronous generators provide Synchronous Inertial Response (SIR) to stabilize frequency during disturbances, while Inverter-Based Resources (IBR) like wind and solar lack inherent inertia but can be programmed for fast frequency response. Effective RoCoF management is critical to prevent equipment trips and maintain stability.

1.1.2 System Strength In an electric system, to be able to transmit power to the customer load, the voltage level on the transmission grid must be maintained within a specific range. When there is a system disturbance,such as lightning str...

AI summary The document explains system strength in electric grids, emphasizing the role of Short Circuit MVA (SCMVA) and the impact of replacing synchronous generators with Inverter-Based Resources (IBRs). Synchronous machines historically provided high SCMVA, but IBRs offer only 10-20% of that support, weakening system stability and increasing voltage volatility during disturbances.

1.2 Scope The following scope will be investigated to ensure a stable NSPI system as it transitions to large scale integration of renewables:

AI summary The scope of the proceeding focuses on ensuring the stability of Nova Scotia Power Inc.'s (NSPI) system as it transitions to large-scale renewable energy integration, emphasizing system reliability and grid management challenges associated with renewable energy adoption.

1.2.1 Frequency Control - Perform an assessment to determine minimum inertia required to maintain frequency stability for the Nova Scotia system under existing and 2030 load and generation dispatch scenarios. - Perform detailed system simu...

AI summary The section outlines tasks related to assessing frequency stability in Nova Scotia's power system, identifying stability and RoCoF concerns through simulations, and recommending mitigation strategies for system design and plant ride-through capabilities under current and 2030 scenarios.

1.2.2 System Strength - Perform a screening level assessment to benchmark 2023 SCMVA levels at 69, 138 and 230 KV buses. - Document minimum SCMVA at load sensitive locations. - Document minimum SCR at all Wind Plants, SVC and HVDC location...

AI summary The document outlines a system strength assessment for Nova Scotia's grid, focusing on benchmarking SCMVA/SCR levels, identifying IBR connection issues, and recommending support measures like BESS or synchronous condensers to maintain reliability by 2030. Initial findings are published ahead of full EMT study results.

2 Assessment Metrics and Methodologies The metrics and methodologies described below are utilized for this study. The assessment is looking at 2030 and aims to identify any deficiencies in frequency and voltage control due to the changing...

AI summary The study assesses 2030 system challenges in frequency and voltage control due to evolving generation fleets, applying Nova Scotia UARB standards. Traditional methods like load flow and short circuit analysis are combined with new methodologies for IBR integration.

2.1 Frequency Control As noted in Section 1.1.1, SIR is an immediate response provided by conventional synchronous machines. It is not a synthesized response through control actions but rather the natural response of a synchronous machine....

AI summary The text discusses the importance of synchronous inertial response (SIR) for system stability and the risks posed by converter-based IBR generators lacking SIR. It highlights NSPI's concerns about future grid reliability with high renewable penetration, emphasizing the need for inertia and FFR to manage RoCoF and maintain frequency stability.

2.2 System Strength As noted in Section [1.1.2](#page-10-0), for the connection of additional IBR generation, the SCMVA is predominantly known to as System Strength in industry. Typically, the SCMVA is estimated by calculating the fault cu...

AI summary The document explains system strength in power grids using SCMVA and SCR metrics. Low SCR (short circuit ratio) indicates weak system strength, leading to potential issues like fault recovery challenges, unstable oscillations, and voltage control difficulties. SCR classifications (high >3, low 2-3, very low <2) are referenced for industry guidance.

2.3 Iterative Assessment The initial assessment and metrics used for these studies follow the traditional load flow and dynamics methodologies with the intent to then take critical cases into PSCADTM for EMT analysis. Upon examination of t...

AI summary The text discusses an iterative assessment process for grid stability, focusing on the challenges of maintaining system inertia and frequency response with the integration of inverter-based resources (IBR). It highlights the need to decouple frequency control requirements from system strength requirements and outlines a multi-step approach to ensure system reliability.

3 Frequency Control Assessment in PSS®E For frequency control assessment, the Nova Scotia grid will experience the greatest frequency deviation and potential high RoCoF when it separates from the North American grid. - The critical dynamic...

AI summary The Nova Scotia grid may experience significant frequency deviation and high RoCoF when it separates from the North American grid, with the loss of transmission lines L-8001 and L-6613 being a critical contingency. UFLS is expected under this scenario.

3.1 Frequency Excursion Damping Boundary cases for light load and peak load for the 2030 load conditions, with maximum renewables online, were run. Simulations were run iteratively to get the online synchronous generation dispatched to the...

AI summary Simulations were conducted to assess frequency excursion damping under light and peak load conditions for 2030, with maximum renewable energy online. Cases were iteratively evaluated, and ten cases met basic criteria for further assessment, focusing on grid requirements for frequency control.

- The light load cases were run with 6 variations. In light load, NSPI has sufficient wind and imports to serve load with 100% renewable energy. Hydro resources are offline. Variations of FFR and inertia were simulated with the goal of tak...

AI summary The text discusses simulations of light load and winter peak scenarios in Nova Scotia's power system, analyzing the use of wind, hydro, and battery energy storage systems (BESS) for stability and inertia. It also examines the impact of losing the New Brunswick tieline with high Nova Scotia imports.

o meet the load, while reducing the thermal units, new wind and BESS was added to the simulation cases. Load Flow and Dynamic assessment was performed for the loss of NB tieline with high NS imports. Case 5, with a low amount of inertia on...

AI summary The document discusses grid simulations analyzing the impact of reducing thermal units and adding renewable resources like wind and BESS. It highlights voltage issues under winter peak load conditions and the potential of FFR from IBRs to reduce reliance on synchronous resources for frequency control in the 2030 grid.

- System load 2145 MW (2030 peak as forecast in 2020), including PHP at 152 MW - ML at 152 MW with 50 MW FFR for case 101, ML at 150 MW without FFR for case 102, offline for case 103 - NB imports at 296 MW - Wind: approximately 474 MW exis...

AI summary The document discusses system load and generation capacity in Nova Scotia, including the impact of reduced inertia and the importance of RoCoF (Rate of Change of Frequency) in system studies. It highlights the planned wind additions and the role of FFR in maintaining system stability.

3.2 RoCoF Historically, there have been RoCoF requirements for generation facilities and some protection devices to ensure they function as expected during frequency swings. The requirements are as needed to stay online for a grid with goo...

AI summary The document discusses the Rate of Change of Frequency (RoCoF) requirements for the Nova Scotia Power Inc. (NSPI) grid, analyzing how changes in grid inertia due to the phasing out of synchronous generation and the increase of renewable generation affect RoCoF. Simulations show varying RoCoF values under different load and generation scenarios, with a 500ms sample time used for calculations.

Table 3: Most Severe RoCoF, 2023 Grid Case Load Total Inertia (MW s) ML FFR RoCoF 2 Light Load 2224 Offline 1.4 11 Summer Peak Load 2487 Offline 2.3 Case 2 is a light load case with three large units on as per the existing operating guidel...

AI summary Table 3 presents the most severe Rate of Change of Frequency (RoCoF) in the 2023 grid, showing values of 1.4 and 2.3 for two different load cases. Case 2 is described as a light load case with three large units operating according to existing guidelines.

Case 11 dispatch is the worst case achievable under existing transmission system configuration and operating guideline for 3 thermal units and ML on for inertia: - The maximum load that could be served with imports, wind and the minimum th...

AI summary The text discusses the worst-case scenario for Case 11 dispatch, analyzing the maximum load that can be served under existing transmission system configurations and operating guidelines. It highlights the need for sufficient inertia and Fast Frequency Response (FFR) to maintain a RoCoF of under 2.5 Hz/s on a 500ms sample time, aligning with 2023 dispatch conditions and recommending further study on appropriate RoCoF metrics for Nova Scotia.

ned with what could be experienced with 2023 dispatch conditions and operating guidelines. That said, it is recommended that further study on an appropriate RoCoF metric for Nova Scotia be undertaken. The GHD survey [12] found that of the...

AI summary The document discusses the need for further study on an appropriate RoCoF metric for Nova Scotia, referencing existing studies and guidelines. It highlights the importance of understanding RoCoF ride-through capabilities of legacy and DER generation sources and the implications of different RoCoF thresholds on transmission system design and grid stability.

Table 4: First Iteration for 2030 RoCoF Case Load Total Inertia (MW s) ML FFR RoCoF 51 Light Load 1044 50MW 2.65 52 Light Load 1102 0MW 3.41 53 Light Load 1603 offline 2.32 101 Peak Load 2404 50MW 3.02 102 Peak Load 2404 0MW 3.27 103 Peak...

AI summary The text discusses the analysis of RoCoF (Rate of Change of Frequency) under various load conditions and the impact of BESS (Battery Energy Storage System) FFR (Fast Frequency Response) support. Tables show the initial and revised inertia levels and RoCoF values, with BESS significantly reducing RoCoF. The study indicates that integrating BESS with FFR capabilities can reduce the inertia required for maintaining RoCoF below 2.5 Hz/s.

4 System Strength Assessment in PSS®E A minimum level of System Strength is required for the power system to remain stable during system disturbances. A minimum level is also required for inverter-based facilities to stay online during sys...

AI summary The document discusses the importance of system strength in maintaining power system stability during disturbances and the testing conducted on the NSPI grid using a full contingency set based on 2020 IRP studies. Six cases were analyzed for system strength under different load conditions.

4.1 Existing Fault Level Assessment To understand the System Strength of the 2023 Nova Scotia grid, an "average" day dispatch was taken as the benchmark for existing SCMVA. Dispatch for benchmarking SCMVA has 3 thermal units, ML, all hydro...

AI summary The document discusses the existing fault level assessment for the 2023 Nova Scotia grid, using an 'average' day dispatch as a benchmark for SCMVA. It notes that wind generation is excluded to avoid including legacy wind's fault current contribution. The assessment is a high-level screening metric, with detailed studies planned for future grid conditions.

4.2 Minimum SCMVA for Sensitive Facilities While the above metric will be a measure of overall SCMVA and a measure of change over time, it will be necessary to monitor the minimum SCMVA for sensitive facilities such as manufacturing plants...

AI summary This section discusses the importance of monitoring the minimum SCMVA for sensitive facilities like manufacturing plants and HVDC facilities to ensure continued grid reliability. If future reductions in SCMVA are anticipated, studies will be conducted, and mitigation measures will be taken to maintain reliability.

4.4 System Support Requirements System Strength requirements will be driven by the need to support existing facilities as the grid transitions to high renewables as well as to strengthen the grid to support the addition of significant quan...

AI summary System strength requirements are necessary to support existing grid facilities during the transition to high renewable energy integration and to strengthen the grid for the addition of significant Inverter-Based Resources (IBR) to meet Nova Scotia Power Inc. (NSPI), provincial, and federal targets.

4.4.1 Post Contingency Voltage Support To maintain post contingency voltage within the range required by NSPI, NPCC and NERC criteria, reactor and capacitor banks were added at several locations in the province. For the winter peak cases,...

AI summary To maintain post contingency voltage within required ranges, NSPI added reactor and capacitor banks at various locations in Nova Scotia. These additions were effective for many scenarios, but future load growth may necessitate dynamic reactive power support if growth exceeds current forecasts.

4.4.2 SCMVA for Sensitive Buses With all contingencies solving well for the 6 cases, a comparative look at the SCMVA for sensitive buses was run. See [Appendix B: Sensitive SCMVA Buses](#page-58-0) for the tables of values. As can be seen...

AI summary The analysis examines the Short Circuit MVA (SCMVA) for sensitive buses under different generation dispatch scenarios. It highlights the need for inertia support, particularly with a second 345kV tieline to New Brunswick, and notes that synchronous condensers are currently the preferred mechanism for grid support.

4.4.4 IBR SCR As noted in Section [4.4.3,](#page-31-0) SCR has limitations in its usefulness as a screening metric for the connection of additional IBR. However, it is still a measure of a wind facility's ability to ride through system eve...

AI summary The document discusses the Short Circuit Ratio (SCR) as a metric for assessing the ability of Inverter-Based Resources (IBR) to ride through system events. It outlines current SCR ranges, the intent to maintain SCR at the Point of Interconnection (POI) for legacy IBR plants, and the need for system studies to determine grid support requirements as the grid evolves.

4.4.5 Stability Requirement When sufficient inertia, FFR and reactive support was added to meet criteria (Frequency, Voltage, and RoCoF, SCMVA etc) as defined in this report there were no observed stability issues in PSS®E. Stability and C...

AI summary The document discusses the stability requirements for the power system, noting that sufficient inertia, fast frequency response (FFR), and reactive support were added to meet defined criteria. Stability and control interactions are best observed in EMT simulations and require further analysis in PSCADTM.

5 Frequency Control and System Strength Assessment in PSCADTM First Stage studies, RMS analysis in PSS®E, have been completed as detailed in the sections above. Stage Two focused on EMT analysis in PSCAD are ongoing. As there are significa...

AI summary First Stage studies using RMS analysis in PSS®E have been completed, with significant findings reported. Stage Two, focusing on EMT analysis in PSCAD, is ongoing, and an updated report will be issued upon completion.

5.3 Detailed PSCADTM Simulation Detailed PSCADTM simulations are used to identify stability and fault ride though concerns and further assess potential RoCoF concerns. EMT simulations have become critical when integrating PE inverter-based...

AI summary Detailed PSCADTM simulations are used to assess stability, fault ride-through, and RoCoF concerns when integrating inverter-based resources (IBR) into AC networks. Traditional RMS simulations may miss critical design considerations, and EMT simulations are essential for identifying system challenges. Increasing short circuit levels and using synchronous support are recommended solutions, though new transmission may not be economically viable. Future NSPI grid analysis will explore IBR controls for system inertia and strength.

5.4.1 Fault Ride-Through NERC Reliability Standard PRC-024-2 describes how generator protective relays should be set such that generating units remain connected during frequency and voltage excursions (see [Figure 5)](#page-37-2). The curv...

AI summary This section discusses the challenges of meeting Low Voltage Ride Through (LVRT) requirements under weak grid conditions for inverter-based plants. It highlights issues such as limitations in Phase Locked Loop response and the impact of plant tripping on voltage control and system stability.

5.4.2 Control Interactions Control Interactions (CI) is a specific issue that can impact the coordinated operation of Power Electronic devices in a local area. Control systems of dynamic devices can interact in an undesirable manner result...

AI summary Control Interactions (CI) can lead to unstable oscillations in power systems, especially with fast-acting reactive power controllers and dynamic devices like wind and solar. The Maritime Link HVDC is designed to avoid adverse interactions with thermal plants. Mitigation requires detailed studies and vendor collaboration.

5.4.3 Sub Synchronous Control Interaction When an IBR is connected to a network, the voltage and phase at the IBR terminals are each sensitive not only to the inverter output but also to the output from other nearby IBR projects or FACTS d...

AI summary The document discusses Sub-Synchronous Control Interaction (SSCI) when Inverter-Based Resources (IBRs) are connected to a network, particularly near series compensated lines. It highlights the potential for negative damping effects from IBRs, such as Type 3 wind units, and notes that Nova Scotia Power Inc. (NSPI) is considering series compensated lines in some studies, requiring SSCI analysis.

SSTI due to interaction with power electronic converters: Power electronic converters and their controls can interact with the natural modes of generator shafts and give rise to poorly damped mechanical shaft oscillations. A main objective...

AI summary This section discusses the potential for Sub-synchronous Torsional Interaction (SSTI) caused by the interaction between power electronic converters and generator shafts, leading to poorly damped mechanical oscillations. The focus is on investigating these impacts through Electromagnetic Transient (EMT) studies, particularly in proximity to generating stations and transmission systems.

Torsional interactions due to network resonance conditions: In addition to SSTI due to interactions with power electronic converters, transient torque magnitude and damping can be negatively affected when series compensated transmission ar...

AI summary The text discusses how torsional interactions can occur due to network resonance conditions, particularly when series compensated transmission lines are near generators. These interactions can cause unstable resonant conditions that affect thermal generators and their mechanical systems, especially when the natural frequency of the mechanical system aligns with the complement of sub-synchronous network resonant frequencies.

5.4.5 IBR Low Frequency Oscillations According to field results and detailed simulation-based studies, the operation of many inverter-based devices in a weak network area can result in sustained low-frequency oscillations. The oscillation...

AI summary The document discusses the potential for low-frequency oscillations (8 Hz – 12 Hz) caused by inverter-based resources (IBRs) in weak network areas, a concern first observed in Australia around 2019. These oscillations, though small and stable, may cause visible flicker. Solutions such as SVC and STATCOM are suggested for system strength issues.

5.4.6 RoCoF The addition of IBR and the subsequent phasing out of conventional generation in Nova Scotia has potential to adversely impact the system RoCoF. This in turn will have impacts on the stable operation of IBRs that are based on g...

AI summary The integration of Inverter-Based Resources (IBR) in Nova Scotia's grid, along with the phase-out of traditional generation, may negatively impact the system's Rate of Change of Frequency (RoCoF). This could affect the stable operation of IBRs and legacy plants during frequency events. Manitoba Hydro International (MHI) recommends surveys and EMT simulations to better understand RoCoF impacts and ensure system reliability.

6.1.3 Fast Frequency Response [Figure 6](#page-49-0) in Section [7.1.2](#page-48-0) demonstrates the ability of FFR from an IBR in damping a frequency deviation for a system disturbance. FFR from HVDC, BESS and other fast acting devices wi...

AI summary This section discusses the role of Fast Frequency Response (FFR) from Inverter-Based Resources (IBR), HVDC, and Battery Energy Storage Systems (BESS) in stabilizing frequency deviations in Nova Scotia's power system during generation disturbances. These systems offer flexibility in rapidly adjusting power injection or consumption based on the state of charge.

6.2 BESS BESS can support the management of the energy supply in a renewable energy dominated NSPI system. Additionally, with appropriate specifications, the fast-acting nature of BESS inverters can also be used to mitigate stability relat...

AI summary Battery Energy Storage Systems (BESS) are highlighted for their ability to manage energy supply in a renewable energy-dominated Nova Scotia Power Inc. (NSPI) system and mitigate stability concerns through fast-acting inverters. They are considered a strong near-term candidate for providing grid-forming and virtual synchronous machine response.

6.3 Synchronous Condensers The addition of synchronous condensers at selected locations in an electrical system is an effective technical solution to facilitate high IBR penetration. It is expected that additional synchronous support will...

AI summary Synchronous condensers are being considered for installation in the NSPI grid to support system strength and accommodate high IBR penetration. Research is ongoing with vendors to understand design options, and EMT models are being assessed for their value in enhancing system stability and frequency response.

6.6 Transmission Connections New transmission paths will generally strengthen a power system. The more the ties between areas of a power system the stronger the ability of the system to withstand grid events. For Nova Scotia, additional tr...

AI summary New transmission connections can enhance power system resilience by reducing RoCoF and increasing SCMVA near tie line termini. Two areas in Nova Scotia are identified as having potential to improve grid stability and support IBR resources under various system conditions.

6.6.1 Second Tie with NB The addition of a second 345kV transmission line to New Brunswick would improve System Strength available from New Brunswick in the Onslow area and reduce the impact of the most critical contingency of the present...

AI summary Adding a second 345kV transmission line to New Brunswick would improve system strength in the Onslow area and reduce RoCoF during high imports. However, this may reduce system strength if synchronous units are offline, potentially affecting WEC facilities at lower voltage levels.

7 Findings and Recommendations This study scope includes full EMT assessment. Due to delay in getting adequate EMT generation and load facility models, it was determined that the initial findings and recommendation should be published imme...

AI summary The study scope includes a full EMT assessment, but due to delays in obtaining adequate models, initial findings and recommendations are being published immediately. An updated report will follow once EMT studies are complete. Findings are based on technical literature, industry expert discussions, and PSS®E studies on inertia and SCMVA for current and projected 2030 systems.

7.1 Findings NSPI can incorporate renewables, in particular IBR resources, limited only by the load to be served and the best economic dispatch to meet target metrics for renewables. There will be technical challenges and the grid will nee...

AI summary NSPI can integrate renewable energy sources, particularly inverter-based resources, up to the limits of load demand and economic dispatch. However, technical challenges and grid support requirements will increase as legacy plants are phased out or converted to alternate fuels, though the transition is deemed achievable with current and emerging technologies.

7.1.2 Minimum System Inertia and FFR The PSC study [23] performed for NSPI in 2019 documented the following: - A minimum of 3266 MW.sec of synchronous inertia will be required for steady state operation. - o Synchronous condensers generall...

AI summary The document discusses the minimum system inertia and Fast Frequency Response (FFR) requirements for Nova Scotia Power Inc. (NSPI), noting that a minimum of 3266 MW.sec of synchronous inertia is required for stable operation. It highlights various sources of inertia and FFR, including thermal units, hydro plants, biomass facilities, and the Maritime Link. The approach to maintaining inertia is based on RoCoF limits and current operating guidelines.

7.1.4 Operability As the grid moves to higher penetration of IBR, reduced SCMVA that occurs due to forced outages and planned maintenance will need an assessment for SCMVA and IBR stability. This may be in the form of updated guidelines or...

AI summary As the grid integrates more IBR, reduced SCMVA from forced outages and maintenance requires assessment for stability. This may involve updated guidelines or real-time studies, with increased need for real-time data visibility for inertia and SCMVA at critical buses for Transmission Operations staff.

7.2.1 Stable and Reliable Integration Recommendations to facilitate the integration of renewables on the timelines in place for Nova Scotia: - Based on study to date, there are significant concerns for the ability of the existing and futur...

AI summary The document outlines recommendations to ensure stable and reliable integration of renewable energy sources into Nova Scotia's grid. Key concerns include managing high RoCoF events, updating interconnection requirements, and addressing grid support needs as synchronous plants retire. Studies and system upgrades are recommended to mitigate risks of cascading tripping and maintain grid reliability.

7.2.2 Resource Planning for High IBR Penetration Recommendations to facilitate current and future economic generation dispatch for increased renewables on the timelines in place for Nova Scotia: - Update IBR and inertia constraints for Ple...

AI summary The document discusses resource planning for high Inverter-Based Resources (IBR) penetration in Nova Scotia, emphasizing the need to update models, incorporate frequency response, and maintain system strength through inertia or Frequency Response (FFR) as key metrics for stable grid operation.

7.2.3 Good Planning Practice Recommendations to implement good planning practices to the integration of renewables in Nova Scotia: - MHI recommends performing an annual assessment of NSPI System Inertia and Strength requirements in the 10-...

AI summary The text outlines recommendations for good planning practices in integrating renewables into Nova Scotia's grid, including annual assessments of system inertia, updated model requirements for load and generation, system studies for load growth and hydro availability, and maintaining SCMVA levels.

7.2.4 System Operator Transition to High IBR Grid Recommendations to support the System Operator transition to a grid with high IBR online. - Develop a methodology to estimate the minimum SCMVA and SCR online prior to the addition of addit...

AI summary The text outlines recommendations for the System Operator's transition to a grid with high Inverter-Based Resources (IBR). It suggests developing methodologies to estimate minimum Short Circuit MVA (SCMVA) and inertia, as well as reviewing and updating operating guidelines for the NSPI grid ahead of the next round of Transmission connected IBR integration.

8 References - [1] "Fast Frequency Response Concepts and Bulk Power System Reliability Needs", NERC Inverter-Based Resource Performance Task Force, March 2020 - [2] "Experiences with Wind Power Plants with Low SCR", Lessons learned from th...

AI summary The document provides a list of references related to power system reliability, renewable energy integration, and grid management, including studies on inverter-based resources, system strength, and high-voltage direct current (HVDC) systems.

benefits and costs of an additional electric vehicle or heat pump on Nova Scotia's Grid? This serves as a complement to IRP PLEXOS analysis of the total impacts of electrification loads on the grid. weighted averages of marginal emissions...

AI summary The analysis examines the grid impacts of scaling electric vehicles and heat pumps, noting that marginal emissions and costs depend on energy prices, carbon policies, and efficiency measures. System-level load and peak load impacts are emphasized, with scenarios excluding energy efficiency effects. The study focuses on building heat pumps and EVs, excluding other sectors.

ch as green hydrogen to meet system peaks. (Note that net ratepayer impacts will depend on utility revenues, a function of rate design, from electrified load relative to the costs to serve that load.) Figure ES-5. Noncoincident peak impact...

AI summary The key finding emphasizes that transportation electrification investments yield benefits exceeding costs for drivers, ratepayers, and Nova Scotia. The text highlights ratepayer impacts influenced by utility revenues and rate design, with figures illustrating noncoincident peak impacts and future heating load projections from building electrification.

pumps and dual-fuel heat pumps will be essential to mitigate peak load impacts. Equally important will be coupling new heat pumps with continued building shell and other energy efficiency measures. Current performance heat pumps can genera...

AI summary The document discusses the significant peak load impacts of current heat pumps and highlights the benefits of adopting high-performance and dual-fuel heat pumps to reduce these impacts. It notes that electrification at scale could increase winter peak loads, necessitating new generation and infrastructure investments, which may reduce ratepayer benefits unless best-in-class heat pumps are incentivized.

Long-Term Strategy and Planning Recommendation 5. Fully incorporate electrification strategy findings, including peak impacts and mitigation strategies, into utility planning models. - Model impacts on resource needs and costs : Reliably s...

AI summary The recommendation emphasizes the need to fully incorporate electrification strategy findings into utility planning models, focusing on resource needs, reliability impacts, and affordability. It highlights the importance of modeling peak load impacts, evaluating reliability benefits of managed loads, and assessing the equity and affordability implications of electrification.

Transmission System Design and SMEs - Developing good quality EMT simulations models: - o Faster response to grid disturbances - o Higher frequency oscillatory response - o Work with IC, OEM, Simulation and EMT consultants - Existing Plant...

AI summary The document outlines the development of EMT simulation models to enhance grid response, the modeling of existing and new plant technologies, and the importance of accurate load modeling, including non-traditional loads like EVs and hydrogen.

Iterative Assessment for EMT Studies FREQUENCY CONTROL ASSESSMENT IN PSS®E SYSTEM STRENGTH ASSESSMENT IN PSS®E TRADITIONAL PSS®E SIMULATION FREQUENCY CONTROL AND SYSTEM STRENGTH ASSESSMENT IN PSCADTM

AI summary The document outlines iterative assessment methods for Electromagnetic Transient (EMT) studies, focusing on frequency control and system strength evaluations using PSS®E and PSCADTM tools. It highlights traditional simulations and assessments specific to power system stability and reliability.

Stage 1, Iterative Assessment FREQUENCY CONTROL ASSESSMENT IN PSS®E SYSTEM STRENGTH ASSESSMENT IN PSS®E TRADITIONAL PSS®E SIMULATION FREQUENCY CONTROL AND SYSTEM STRENGTH ASSESSMENT IN PSCADTM CRITICAL DYNAMIC CONTINGENCY CRITICAL DYNAMIC...

AI summary This section of the document outlines various technical assessments related to frequency control, system strength, and critical dynamic contingencies using simulation tools like PSS®E and PSCADTM. It includes case development and fast frequency response considerations.

Case Total Inertia (MWs) ML FFR 51 1044 50MW 52 1102 0MW 53 1603 - 101 2381 50MW 102 2381 0MW 103 3158 -

AI summary The document presents a table with case numbers, total inertia in MWs, and ML FFR values, indicating variations in inertia and FFR across different cases. The data appears to relate to power system analysis or grid stability considerations.

Case Total Inertia (MWs) ML FFR RoCoF (Hz/s) 51 1044 50MW 2.65 52 1102 0MW 3.31 53 1603 - 2.32 101 2381 50MW 3.10 102 2381 0MW 3.27 103 3158 - 2.48 Case Total Inertia (MWs) ML FFR RoCoF (Hz/s) 511 1565 50MW 1.91 521 1890 0MW 2.09 531 2586...

AI summary The text presents tables with case numbers, total inertia (MWs), ML FFR, and RoCoF (Hz/s) values. These tables likely relate to technical analyses of power system stability and performance under different scenarios.

System Strength Assessment in PSS®E EXISTING FAULT LEVEL ASSESSMENT MINIMUM SCMVA FOR SENSITIVE FACILITIES

AI summary The document discusses the existing fault level assessment and minimum short-circuit MVA (SCMVA) requirements for sensitive facilities within the context of system strength evaluation using PSS®E. The analysis focuses on technical parameters critical to grid stability and protection coordination.

Stage 2, Iterative Assessment FREQUENCY CONTROL ASSESSMENT IN PSS®E SYSTEM STRENGTH ASSESSMENT IN PSS®E TRADITIONAL PSS®E SIMULATION FREQUENCY CONTROL AND SYSTEM STRENGTH ASSESSMENT IN PSCADTM

AI summary The document outlines simulations in PSS®E and PSCADTM for frequency control and system strength assessments, focusing on grid stability and reliability during iterative regulatory evaluations. Technical analyses are emphasized without explicit stakeholder claims or regulatory references.

Stage 2, 12 Hz system wide oscillation There is a possibility that this is a real issue since the investigation was performed using a very weak dispatch.

AI summary The document raises concerns about a potential real issue with a 12 Hz system-wide oscillation, citing that the investigation used a very weak dispatch method. A figure (Figure 2) is referenced but not described in detail.

Stage 2, Voltage collapse Systemwide (or partial) voltage collapse post contingency

AI summary The document discusses Stage 2 analysis of systemwide or partial voltage collapse following a contingency, supported by referenced figures. No detailed technical discussion or conclusions are present in the text.

Stage 2, Voltage Phase Angle Change

AI summary The document focuses on analyzing voltage phase angle change in Stage 2, referencing figures related to electromagnetic transient (EMT) simulations. The content emphasizes technical aspects of power system stability and grid behavior under specific conditions.

General Findings - IBR for Frequency Support Grid Following Limits - IBR for System Strength - Minimum Inertia and FFR - o Non traditional sources can reduce the need for synchronous support - o A sliding load/IBR generation online scale w...

AI summary The document discusses technical aspects of inverter-based resources (IBR) for frequency support and system strength, the development of a sliding load/IBR generation scale, EMT model quality, and operability considerations including dispatch guidelines, inertia, and uncontrolled distributed energy resources (DER).

Recommendations - Stable and Reliable Operation - o RoCoF review for existing plant - o TSIR and DSIR revision for high IBR - o Studies for each wave of change, IBR, plant retirements, load growth - Resource Planning, Update IBR and Inerti...

AI summary The document outlines recommendations for ensuring grid stability with high Inverter-Based Resources (IBR), including RoCoF reviews, system strength assessments, inertia constraint updates, real-time operational tools, and black start protocols for dual grids. It emphasizes planning practices for load growth and IBR integration.

- NS Power also addressed concerns about its pace to address 2030 decarbonization targets, including phasing out coal-fired generation and attaining 80% of renewables on the system. The Utility submitted that its Evergreen IRP process, inc...

AI summary NS Power outlined its Evergreen IRP process and 'Path to 2030' plan to meet 2030 decarbonization targets, including phasing out coal and achieving 80% renewables. It committed to detailed capital investment reporting, external studies on electrification strategies, and collaboration with the Province on procurement. Stakeholders emphasized the need for multi-stakeholder analysis of Hybrid Peak Mitigation and the importance of the Reliability Tie project and federal Clean Electricity Regulations.

End Effects NSP concludes that: "the Atlantic Loop shows lower system costs and lower overall emissions than the without Atlantic Loop scenarios", however, this conclusion is apparently based on the 25 year NPV with end effects. Of note in...

AI summary NSP argues the Atlantic Loop reduces system costs and emissions over 25 years with end effects, but NRR emphasizes prioritizing near-term decisions due to rapid tech/fuel price changes and the value of future flexibility. NSP's conclusion relies on long-term NPV calculations, while NRR stresses short-to-medium term relevance.

tlantic loop scenarios, but also an updated IRP analysis of battery energy storage capacity prior to significant commitment to reach the 2029 or 2030 CT addition levels seen in the CE1–E1–R2 scenario. While PHP understands Synapse's view w...

AI summary PHP expresses concern that further studies on battery storage may delay critical in-province resources needed for system reliability, emphasizing the urgency of building 300 MW of new fast-acting generation by 2027. Synapse questions the robustness of results attributing capacity value to battery storage, while PHP argues delays could jeopardize reliability.

3. Federal Clean Energy Regulations NSPI's roadmap item 5 indicates in part tracking the development of the Federal Clean Energy Regulations and monitoring for limitations on the use of gas and oil-fired generation beyond those already con...

AI summary NSPI and PHP discuss the potential impact of Federal Clean Energy Regulations on Nova Scotia's natural gas peaking capacity, critical for reliable electricity supply. PHP supports NSPI's efforts to comment on draft regulations to ensure amendments align with provincial needs.

Hybrid Peak Mitigation Eastward notes NSPI's support at page 4 of its responses to stakeholder comments, in direct response to a question from Eastward, for a multi stakeholder process to further analyze the issue of hybrid peak mitigation...

AI summary NSPI and Eastward Energy support a third-party-led multi-stakeholder process to analyze hybrid peak mitigation, citing benefits in avoiding new capacity costs and aligning with Québec's climate and cost strategies. The Board's 2023 decision on coordinated planning is referenced, alongside examples from Manitoba Hydro and BC Hydro. Eastward emphasizes collaboration with energy providers and impartial third-party reviews.

Fast Acting Generation and Coal to Gas Conversions NSPI Action Plan Item 3c includes the initial development of approximately 300MW of new fastacting generating capacity by 2027 and an additional 300-600MW by 2030, to address growing deman...

AI summary NSPI plans to develop 300-900MW of fast-acting generation by 2030, emphasizing fuel flexibility and hydrogen. Synapse questions the robustness of coal-to-gas conversions and battery storage, while Eastward supports natural gas and hydrogen as critical for reliability. The IRP Evergreen Update highlights the need for flexible resources to integrate renewables.

Robust reliability analysis is required to confirm IRP conclusions The SBA has previously provided comments on the importance of continuing NSPI's analysis of system reliability with the growth in inverter-based resources. NSPI used some i...

AI summary The SBA emphasizes the need for continued analysis of system reliability as inverter-based resources grow, noting that NSPI's initial modeling requires further validation. The SBA highlights the value of collaboration in the Evergreen IRP process for transitioning to a no-coal/net-zero grid.

Appendix: ESC Submission on 2023 Evergreen IRP Action Plan & Roadmap Update (M11307) - 1. " In the Nova Scotia context with the expected increase in variable renewable energy resources, expansion of transmission ties, and phase out of coal...

AI summary ESC argues that energy storage will play a critical role in Nova Scotia's energy future due to increasing renewables and coal phase-out. They highlight storage's contributions to firm capacity, peak shaving, and reduced wind curtailment, noting the current IRP underestimates its potential due to modeling limitations.

- firming of energy import and export assumptions. They recommended NS Power re-run the analysis of the Atlantic Loop as more information becomes available. - Synapse recommended that the development of the Reliability Tie continues to be...

AI summary Synapse recommends NS Power re-analyze the Atlantic Loop, prioritize the Reliability Tie, develop solar/wind procurement strategies, and address curtailment. They support electrification planning and 4-hour battery storage by 2030. E1 agrees with Synapse's recommendations for IRP implementation and action plan items.

- 8. It is recommended that DSM activities not tested in the 2022 Evergreen IRP be considered separate and distinct, when compared with the results of the 2022 IRP associated with DSM in particular. - 9. E1 recommends a thorough and transp...

AI summary E1 recommends treating untested DSM activities in the 2022 IRP separately, emphasizes stakeholder engagement for avoided cost analysis, and requests NS Power to address DERs, electrification, demand response valuation, and emission intensity reduction strategies. E1 also advocates for studying DERs' full costs/benefits and aligning avoided cost methodologies with system build-out projections.

solar (or to 38 MW, if four-hour storage is paired with 300MW of solar), NS Power is concerned this would potentially amount to "double counting" of wind + storage and solar + storage diversity credits, and may result in "over-crediting" t...

AI summary NS Power expresses concern over potential 'double counting' of diversity credits when pairing four-hour storage with both wind and solar, risking over-crediting. Synapse, E1, and NRR recommend expanding the Capacity Study to assess interactions among solar, wind, battery, and demand response. NS Power plans to investigate but will proceed with adding 300MW of fast-acting generation by 2027, supported by PHP and Eastward Energy, arguing the diversity benefit is insufficient to displace new capacity needs.

Effective Load Carrying Capability (ELCC) Study Scope Memo February 6, 2025 In its Decision letter of May 23, 2024, regarding NS Power's 2023 Evergreen IRP Update (Matter M11307), the Board highlighted certain Synapse recommendations and s...

AI summary The Nova Scotia Utility and Review Board directed NS Power to update its ELCC study to assess interactive effects of wind, solar, battery storage, and demand response. NS Power supports the update, plans to develop a scope of work by year-end, and proposes three study topics: resource interaction analysis, demand response ELCC recalibration, and seasonal ELCC assessment. The Board emphasized refining diversity benefits and aligning with current programs.

Area of Focus 6.0 – Review of System Planning Related Values - (6.1) review of system planning related values as applicable to TVP (and the technologies that deliver the load shifting such as batteries) including avoided costs and Effectiv...

AI summary The document discusses the review of system planning values for TVP and load-shifting technologies like batteries, emphasizing avoided costs and ELCC. It highlights the importance of Summer-specific reliability assessments by NPCC and NERC for NS Power's contributions. NS Power seeks stakeholder feedback on its ELCC study scope by February 21, 2025.