Topic:"System Reliability" in M12842

REDACTED CI C0083591 Attachment 1 Page 3 of 39 REDACTED (CONFIDENTIAL INFORMATION REMOVED) guy replacements, and customer owned equipment such as the gang-operated switch is not included in these estimates. - The cost estimate to complete...

AI summary The document outlines interconnection requirements for a solar project, including a $1,062,874 cost estimate, compliance with NSPI standards, flicker emission management, power factor specifications, and electrical safety protocols. NSPI retains operational control over high-voltage equipment and may disconnect the facility if flicker issues persist. The Interconnection Customer must adhere to electrical codes and obtain permits.

4.1 Adverse System Impacts The Generating Facility must not adversely affect the Distribution System or service to any other connected customers or facilities.

AI summary The Generating Facility must not adversely affect the Distribution System or service to other connected customers or facilities, emphasizing the need to prevent negative impacts on grid reliability and customer service.

4.3 Grounding Requirements Following the addition of any Interconnection Customer Interconnection Facilities and a Generating Facility to the Distribution System, the system must remain effectively grounded at all locations, in all sustain...

AI summary The section outlines grounding requirements for the distribution system after adding interconnection and generating facilities, emphasizing the necessity of effective grounding under all conditions to prevent overstressing surge arrestors. It references NSPI's DSIR for further details.

4.4 Interconnection Transformer Configuration The Generating Facility interconnection transformer shall not cause voltage disturbances or disrupt coordination of Distribution System ground fault protection. The interconnection transformer...

AI summary The interconnection transformer for the generating facility must not cause voltage disturbances or disrupt ground fault protection. The specified transformer is a 2500 kVA, 0.6kV–12.47kV Y-Yg padmount unit, as proposed by the Interconnection Customer.

4.7 Off-Nominal Frequency Operation The transmission system in Nova Scotia is synchronously connected to the North American grid via three transmission ties to New Brunswick and the HVDC link to Newfoundland. As a result, frequency rarely...

AI summary Nova Scotia's transmission system is connected to the North American grid, but can operate independently as an electrical island, leading to frequency variations. Standards from NPCC, NERC, IEEE, and CSA dictate required generator frequency tripping settings in such scenarios.

4.10 Thermal Limits and Overcurrent Protection Thermal limits of NSPI equipment shall not be exceeded as a result of the addition of the generating facility. Protection shall be provided to detect and cease energization for all phase-to-ph...

AI summary NSPI equipment thermal limits must not be exceeded by new generating facilities. Overcurrent protection is required to detect and stop energization for phase-to-phase and phase-to-ground faults on the NSPI Distribution System.

4.11 Protection of Equipment and Fault Detection The Interconnection Customer must ensure that their protection devices will detect abnormal system conditions and isolate their facilities from the NSPI Distribution System including, but no...

AI summary The Interconnection Customer is required to ensure their protection devices detect abnormal system conditions such as over/under frequency, voltage, and anti-islanding, and isolate their facilities from the NSPI Distribution System to maintain reliability and safety.

4.12 Automatic Start/Restart of Generation Facilities Individual generators are permitted to automatically start or restart after tripping from the Distribution System. This automatic restart may occur only after the Distribution System vo...

AI summary Generators may automatically restart after tripping from the Distribution System only if voltages are restored, frequencies stabilize at 60 Hz, and a 5-minute delay has passed. This ensures system stability and safety following disruptions.

4.13 Protection Coordination The protection systems installed by the Interconnection Customer shall coordinate with NSPI's protection facilities. The Interconnection Customer shall submit details of the protection facilities and proposed s...

AI summary The Interconnection Customer must coordinate protection systems with NSPI's facilities, submitting details and proposed settings for review and acceptance. Revisions to settings also require NSPI approval, ensuring compatibility and reliability within the power grid.

4.14.1 Voltage Flicker The Interconnection Customer is to ensure that the operation of the Generating Facility does not cause voltage variations on the Distribution System that result in objectionable lamp flicker to other connected custom...

AI summary The Interconnection Customer must ensure their Generating Facility does not cause voltage variations leading to lamp flicker on NSPI's Distribution System. Voltage variations are measured at the POI, with IEEE 1547-2018 setting acceptable flicker limits (Pst95% ≤ 0.35, Plt95% ≤ 0.25) to prevent objectionable flicker.

REDACTED CI C0083591 Attachment 1 Page 16 of 39 REDACTED (CONFIDENTIAL INFORMATION REMOVED) Where Pst is the emission limit for the short-term flicker severity and Plt is the long-term flicker severity. In computing the flicker emission le...

AI summary The document specifies that flicker emission limits (Pst for short-term and Plt for long-term flicker severity) apply only during periods when the Generating Facility is operational, and these limits must be observed for all consecutive operational periods.

Table 8: Limits for Rapid Voltage Changes ΔV/ V (%) Occurrences 2.5% ≤ 1 time / hr 2.0% ≤ 5 times / hr 1.0% ≤ 50 times / hr 0.5% ≤ 500 times / hr Dynamic Voltage Changes must be ≤ 2.5% 4.15 Voltage & Current Distortion

AI summary Table 8 outlines the limits for rapid voltage changes, specifying the maximum percentage change (ΔV/ V) and the allowable number of occurrences per hour. It also notes that dynamic voltage changes must not exceed 2.5%. Section 4.15 discusses voltage and current distortion.

4.16 Voltage Regeneration Sustained voltage regeneration from the Interconnection Customer's Interconnection Facilities following the loss of a supply phase on the Distribution System is not permitted. Regenerated voltages may not be well...

AI summary The document prohibits sustained voltage regeneration after a supply phase loss on the Distribution System, citing risks of unregulated voltages and inadequate protection. Interconnection Customers must assess and mitigate voltage regeneration risks in their facility design. Generator transformers can regenerate voltage to varying degrees, requiring interconnection protection to detect phase loss.

5.1 Configuration and Grounding NSPI's primary Distribution System is a 3-phase, 4-wire multi-grounded common neutral system ("effectively grounded-wye"). This generally provides a single intentional ground path for short-circuit currents...

AI summary NSPI's distribution system uses a 3-phase, 4-wire effectively grounded-wye configuration, ensuring a single ground path for short-circuit currents. Adding generating facilities requires maintaining effective grounding and compliance with DSIR Section 6.3 for short-circuit protection and device coordination.

5.5 Voltage Flicker Emission Limits at POI Flicker data was not available for the proposed solar generator. The flicker value must adhere to the allowable flicker emission limits (Pst 95% ≤ 0.35) as per DSIR Section 6.14.1.

AI summary The proposed solar generator lacks available flicker data, requiring compliance with DSIR Section 6.14.1's Pst 95% ≤ 0.35 flicker emission limit at the Point of Interconnection (POI).

5.6 Voltage Unbalance The voltage profile for distribution circuit between the and the POI is shown in Figure 5 under peak load conditions with generators online. Figure 5: Voltage Profile at POI The average voltage unbalance at the solar...

AI summary The voltage profile at the solar generator POI on a 12.47 kV system shows an average unbalance of 0.53% under peak load conditions, with variations influenced by load, time of day, and season. Figure 5 illustrates the voltage distribution profile.

REDACTED CI C0083591 Attachment 1 Page 20 of 39 REDACTED (CONFIDENTIAL INFORMATION REMOVED) NSPI distribution circuits typically experience less than 3% voltage unbalance (defined as the maximum deviation from the average phase-to-phase vo...

AI summary NSPI distribution circuits typically maintain less than 3% voltage unbalance but cannot guarantee this under all conditions. The Interconnection Customer is responsible for ensuring solar generators can operate within these voltage parameters.

5.7 Voltage Regulation and Voltage Dip As per Section 6.17 of the DSIR, all inverter based Generating Facilities shall be CSA certified and meet the functional requirements of CSA C22.3 No. 9:20 "Interconnection of distributed energy resou...

AI summary The Petpeswick Solar farm's voltage changes under load conditions are analyzed to ensure compliance with CSA standards. Load flow simulations show voltage fluctuations within allowable limits (≤2.5%), confirming the project's compatibility with the distribution system under both heavy and light load scenarios.

6.4 Operational Control of Electrical Lines and Equipment NSPI shall have operational control over any Interconnection Facilities it deems necessary to ensure reliability or serviceability of the Distribution System. Operational Control of...

AI summary NSPI retains operational control over Interconnection Facilities deemed necessary to ensure the reliability and serviceability of the Distribution System. The text emphasizes NSPI's authority in managing electrical infrastructure to maintain system integrity.

REDACTED CI C0083591 Attachment 1 Page 25 of 39 REDACTED (CONFIDENTIAL INFORMATION REMOVED) The Interconnection Customer shall pay a capital contribution for any required line extensions, upgrades, and right-of-way acquisition necessary to...

AI summary The Interconnection Customer must cover capital contributions for line extensions, upgrades, and right-of-way acquisition, while NSPI manages maintenance at their request. Compliance with technical requirements, power factor specifications, and flicker emission mitigation is mandated. NSPI reserves the right to disconnect if flicker issues persist.

Commercial Information Items 1, 2, 3 and 4: Partial confidentiality was applied to costs associated with materials, contracts, freight, consulting, licensing and software details provided in the capital work orders. To protect value for cu...

AI summary NS Power seeks confidentiality for supplier pricing and contract details to prevent competitive disadvantage and higher costs for customers. Vendors also request confidentiality for proprietary information. System security concerns necessitate confidentiality for distribution system impact studies to protect reliability and reduce external threats.