Update on System Protection Working Group Meeting
This update covers discussions on the impact of Inverter-Based Resources (IBR) on ERCOT Grid Protection, including short circuit modeling, protection best practices, interconnection requests, and more. Details on Protection System Misoperations from 2014 to 2019, with a focus on Q4 2019, are also provided, highlighting the number of misoperations and categories by failure type, relay system, and equipment protected.
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Presentation Transcript
System Protection Working Group (SPWG) Update to ROS May 07, 2020 Chair: John Karlik, PE Vice-Chair: Vincent Roberts, PE
SPWG Meeting Meeting held on March 4, 2020 Topics Discussed: Impact of Inverter-Based Resources (IBR) on ERCOT Grid Protection 2019 Q4 Protection System Misoperations Next meeting is scheduled July 22-23, 2020
Impact of IBRs on ERCOT Grid Protection
Impact of IBRs on ERCOT Grid Protection ERCOT provided background information to SPWG members and discussions were held concerning the following: Short circuit modeling Protection best practices Facility interconnection requests Action Items Survey TSPs regarding concerns and issues surrounding IBRs Hold an SPWG workshop to discuss survey results and determine if further action is required
2019 Q4 Protection System Misoperations
Protection System Misoperations 2019 Q4 Q4 2019 # of Misoperations Total 22 168 345 kV 5 43 138 kV 16 121 < 100 kV 1 4 By Category Failure to Trip 2 9 Slow Trip 1 1 Unnecessary Trip during Fault 13 87 Unnecessary Trip Non Fault 6 71 SPS 0 0 By Relay System Type Electromechanical 2 18 Solid State 0 1 Microprocessor 16 115 Other/ N/A 4 34 By Equipment Protected Line 11 65 Transformer 2 26 Generator 0 12 Shunt/Series Capacitor 1 4 Shunt/Series Reactor 0 2 Dynamic VAR system 2 9 Bus 1 12 Breaker 4 31
Regional Misoperation Rate Comparison Regional Misoperation Rates 16% 13.48% 14% 13.33% 12.19% 11.75% 11.75% 11.62% 12% 11.16% 10.57% 10.34% 9.66% 10% 9.10% 8.92% 8.90% 8.50% 8.05% 7.85% 7.81% 7.77% 7.66% 7.59% 8% 7.41% 7.36% 7.31% 7.19% 7.12% 7.05% 6.67% 6.56% 6.41% 5.91% 5.74% 5.62% 6% 5.53% 5.34% 4% 2% 0% MRO NPCC RF SERC TRE WECC NERC 2014 Q4 - 2015 Q3 2015 Q4 - 2016 Q3 2016 Q4 - 2017 Q3 2017 Q4 - 2018 Q3 2018 Q4 - 2019 Q3
Protection System Misoperations 2019 Q4 Summary of Human Performance Issues noted for 2019 Q4: - A 138kV line misoperated during a fault due to out-of-date firmware. - A 138kV line breaker overtripped during a fault due to an unintentionally grounded coaxial cable due to an as-left personnel error. Failure to Trip/Slow Trip Misoperations in 2019 Q4: - 138kV capacitor bank protection failed to trip during a fault due to a block trip function that was inadvertently set too low - A wind plant feeder breaker failed to trip during a fault due to a bad cable
Corrective Action Plan Metrics CAP Duration: 2014-2019 30.0% 25.0% 20.0% 15.0% 10.0% 5.0% 0.0% 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 # of Days Calendar days from date of misoperation to Corrective Action Complete
Definitions Protection System Protective relays which respond to electrical quantities, Communications systems necessary for correct operation of protective functions Voltage and current sensing devices providing inputs to protective relays, Station dc supply associated with protective functions (including station batteries, battery chargers, and non-battery- based dc supply), and Control circuitry associated with protective functions through the trip coil(s) of the circuit breakers or other interrupting devices
Definitions Composite Protection System - The total complement of Protection System(s) that function collectively to protect an Element. Backup protection provided by a different Element s Protection System(s) is excluded. Misoperation The failure a Composite Protection System to operate as intended for protection purposes. Any of the following is a Misoperation: 1. Failure to Trip During Fault A failure of a Composite Protection system to operate for a Fault condition for which it is designed. 2. Failure to Trip Other than Fault - A failure of a Composite Protection system to operate for a non-Fault condition for which it is designed, such as a power swing, undervoltage, overexcitation, or loss of excitation.
Definitions Misoperation The failure a Composite Protection System to operate as intended for protection purposes. Any of the following is a Misoperation: 3. Slow Trip During Fault A Composite Protection system that is slower than required for a Fault condition if the duration of its operating time resulted in the operation of at least one other Element s Composite Protection System. 4. Slow Trip Other than Fault - A Composite Protection system that is slower than required for a non-Fault condition, such as a power swing, undervoltage, overexcitation, or loss of excitation, if the duration of its operating time resulted in the operation of at least one other Element s Composite Protection System.
Definitions Misoperation The failure a Composite Protection System to operate as intended for protection purposes. Any of the following is a Misoperation: 5. Unnecessary Trip During Fault An unnecessary Composite Protection system operation for a Fault condition on another Element. 6. Unnecessary Trip Other than Fault - An unnecessary Composite Protection system operation for a non-Fault condition. A Composite Protection System operation that is caused by personnel during on-site maintenance, testing, inspection, construction, or commissioning activities is not a Misoperation.
