Utility Implements Communications- Assisted Special Protection and Control Schemes for Distribution Substations

Transcription

1 Utility Implements Communications- Assisted Special Protection and Control Schemes for Distribution Substations Michael. Duff City of College Station Payal Gupta, Dharmendra Prajapati, and Alex Langseth Schweitzer Engineering Laboratories, Inc City of College Station and SEL

2 Provides electric power to residential and commercial customers Is composed of City of College Station (COCS) College Station Utilities (CSU) ~20 miles of transmission lines ~458 miles of distribution lines 7 substations OpenStreetMap contributors

3 Traditional 13.2 kv Distribution Substation 138 Electromechanical kv ring bus relays Two No bus 138 differential kv / 13.8 kv power protection transformers Two No breaker buses electrically failure backup connected via normally No automatic source open tie breaker transfer Four feeders per bus Challenge coordinating supplied from main breaker for simultaneous fault conditions

4 13.2 kv Distribution Substation for Special Protection and Control Scheme (SPCS)

5 Information Flow Diagram

6 Communications Link Supervision for High-Speed Data Bits Transmit eceive TB1 TB2... TB8 B1 B2... B TB1 TB2... TB8 B1 B2... B8 Transmit eceive IEDs OK = 1 OK = 0 Status Description Communications channel good Communications channel bad Inverse (NOT) of OK is used to create digital alarm bit to alert operations of communications failure

7 Communications Link Supervision for High-Speed Data Bits IED-B IED-COM B-IED Logic Processors COM = 1 COM = 0 Status Description Communications channel good Communications channel bad Communications link supervision in logic processors only allows received data bits of good quality to be considered in algorithms

8 Different Schemes Implemented Fast bus tripping scheme for significantly reduced bus fault-clearing time Breaker failure protection scheme for shorter breaker failure clearing time Double-circuit feeder trip scheme for faster clearing of simultaneous faults without causing substation outage, and stall reclose logic for system availability Automatic source transfer scheme (ASTS) for higher power system availability

9 SCPS Six Major Design Criteria Dependability Security Selectivity esilience Speed Cost

10 Fast Bus Tripping Scheme Limitation of traditional bus protection philosophy Bus fault is cleared with time-delayed transformer backup protection Typical fault-clearing time is between 0.6 and 1.0 seconds Solution Bus differential protection is fast and secure, but has added cost Fast bus tripping scheme is fast and cost-effective

11 Fast Bus Tripping Scheme Fault on Bus 1

12 Fast Bus Tripping Scheme Fault on F1 Feeder Circuit

13 Limitation of traditional breaker failure protection philosophy Fault is cleared with upstream inverse-time overcurrent protection Long fault-clearing times lead to equipment damage or reduced equipment lifespan Solution Breaker Failure Protection Scheme Dedicated, fast breaker failure protection scheme using existing IEDs and communications backbone Low implementation cost with minimal wiring

14 B-BF T1 Breaker Failure Protection Scheme Fault on Bus 1 Breaker Fails Bus 1 M1 TB-BF TIE F1 F2 F3 F4 B-BF B-BF B-BF B-BF B-BF Logic Processor T1

15 Limitation of traditional system Simultaneous faults may cause coordination issues Main breaker 51 element may misoperate IED overcurrent pickup and time-dial settings must be adjusted (resulting in slower tripping) Solution Double Circuit Feeder Trip Scheme and Stall eclose Logic Double-circuit feeder trip scheme with low implementation cost Fast 51 element setting and improved service reliability

16 Double Circuit Feeder Trip Simultaneous Fault M1 M2 Bus 1 TIE Bus 2 F1 F2 F3 F4 F5 F6 F7 F8 TB-PU B-PU TB-PU B-PU B-PU B-PU B-PU B-PU B-PU B-PU Logic Processor T1 B-PU Logic Processor T2

17 Stall eclose Logic M1 M2 Bus 1 TIE Bus 2 F1 F2 F3 F4 F5 F6 F7 F8 TB-S B-S Logic Processor T1 Logic Processor T2

18 ASTS Limitation of traditional system Less power system availability with more disruption Long restoration times Solution ASTS that automatically switches from primary source to alternate source Short restoration times to improve power system availability

19 11 22 T1 T2 ASTS Transformer Fault TB-FAULT M1 Bus 1 TB-52A Bus 2 TIE TB-52A B-CLOSE M2 F1 F2 F3 F4 F5 F6 F7 F8 TB-52A TB-NO FAULT SCADA ASTS ENABLE Logic Processor T1 Logic Processor T2

20 Other Schemes Multiple SPCSs run in parallel and coordinate with each other as complete, integrated solution Other control logic is implemented to improve system availability and dependability Hot-line mode IED health alarm

21 Questions?