8 th Symposium on Power System Management Cavtat, November 9-12, 2008

1. WIDE AREA MEASUREMENTS FOR IMPROVED PROTECTION OF POWER SYSTEMS SISTEMSKA MJERENJA ZA POBOLJSANJE ZASTITE Arun Phadke Virginia Tech Blacksburg, VA Damir Novosel Quanta Technology Raleigh, NC 8th Symposium on Power System Management Cavtat, November 9-12, 2008

2. Topics covered: • Wide Area measurements ~ History • Modern WAMS and their architecture • WAMS based Protection ~ issues • Current applications of PMUs in the US/Canada • Ideas for WAMS based protection systems • System Integrity Protection Schemes • A road map for future 8th Symposium on Power System Management Cavtat, November 9-12, 2008

3. GPS receiver PMU Signal conditioning unit User Interface (b)

4. GPS receiver Analog Phase-locked Inputs Modems oscillator Phasor Anti-aliasing 16-bit micro- filters A/D conv processor Phasor Measurement Unit (PMU) This is the basic instrument of modern wide area measurements. 8th Symposium on Power System Management Cavtat, November 9-12, 2008

5. Phasor measurement process q PMU Xrms Filters Input wires Sampled Data Phasor Xr + j Xi = Xrmsejq Phasor Estimator Phasor time-tag (reporting instant) Positive sequence Voltages and Currents 8th Symposium on Power System Management Cavtat, November 9-12, 2008

6. Utility’s WAN Utility’s WAN WAMS Architecture ISO's PDC ISO’s WAN Utility's PDC Utility's PDC ... ... PMU PMU PMU PMU 8th Symposium on Power System Management Cavtat, November 9-12, 2008

7. Communications • Early installations: • Used available commercial communication media • Telephone lines, leased or dial-up • Company owned microwave system • Analog modems on analog channels • Direct digital where available • Recent trends: • Fiber-optic channels • Dedicated where available • Ethernet • TCP or UDP 8th Symposium on Power System Management Cavtat, November 9-12, 2008

8. Communications • Fiber-optic configurations Fiber bundle in ground wire Power line Fiber bundle on separate towers Fiber bundle wrapped around Phase conductor Transmission Tower Fiber bundle direct buried 8th Symposium on Power System Management Cavtat, November 9-12, 2008

9. Phasor Measurement Units in the US/Canada 8th Symposium on Power System Management Cavtat, November 9-12, 2008

10. Some Current Applications of WAMS in the US/Canada 8th Symposium on Power System Management Cavtat, November 9-12, 2008

11. Ideas for WAMS based protection systems • WAMS not to intervene directly in high speed protection • WAMS may alter protection group settings • Promising candidates belong to these classes: • Back-up • Stability related • System Protection • Back-up • Stability related • System Protection • Some examples and suggestions 8th Symposium on Power System Management Cavtat, November 9-12, 2008

12. System State Protection 1 No Or Logic To Circuit Breakers Protection Arbitration And 2 No Vote Protection 3 No Adaptive adjustment of Security and Dependability From System Control Center 8th Symposium on Power System Management Cavtat, November 9-12, 2008

13. Monitoring vulnerability of relay settings Critical Relay locations Dynamic: Swings Static: Load encroachment How close? Revise settings? How close? Revise settings? 8th Symposium on Power System Management Cavtat, November 9-12, 2008

14. Adaptive Out-Of-State Relaying Georgia S-PMU S-PMU Out of step condition Relay Relay 8th Symposium on Power System Management Cavtat, November 9-12, 2008

15. Pre-fault Adaptive Out-Of-State Relaying Post-fault Interval Prediction Interval Observation

16. Adaptive Out-Of-State Relaying for meshed networks Time-series of swing curves and prediction Two machine equivalent d1 - d2 PMU PMU Observation window PMU data Time Observation Interval Prediction Interval 8th Symposium on Power System Management Cavtat, November 9-12, 2008

17. Supervision of back-up zones B A B B B B B Zone 3 picks-up at A Then at B } Balanced Conditions? Any Zone-1 picked up? Yes. If not Block Zone-3 8th Symposium on Power System Management Cavtat, November 9-12, 2008

18. Loss-of-Field Relaying System Control Center determines Thévénin X Strong system Loss of field trajectory R Weak system 8th Symposium on Power System Management Cavtat, November 9-12, 2008

19. Dynamic ACE for intelligent load shedding 8th Symposium on Power System Management Cavtat, November 9-12, 2008

20. System Integrity Protection Schemes (SIPS) • Goal to prevent propagation of disturbances for severe system emergencies caused by un-planned operating conditions and ensure system security • Last line of defense to improve system security and prevent disturbance propagation - Could help better utilize system margins • Stabilize System for Equipment Outages, N-2 or beyond • Prevent overloading of the lines • Arrest voltage decline • Initiate pre-planned separation of the power system, etc. 8th Symposium on Power System Management Cavtat, November 9-12, 2008

21. SIPS Purpose • Initiate pre-planned, automatic, and corrective actions • Arms for pre-defined outages • Activates pre-defined actions • SIPS design is based on studies of pre-defined system contingencies for variety of conditions 8th Symposium on Power System Management Cavtat, November 9-12, 2008

22. 500kV Main Grid Communication; Measured 500kV voltages MJ MJ MJ MJ Communication; Voltage collapse detection result 27kV,154kV radial network Sub-Station 275,154/66 LS Sub-Station 275,154/66 LS MJ: Monitoring and Judging Unit LS: Load shedding Unit SIPS Design • Scheme types • Event-based • Parameter-based • Response-based • Combination of the above • Distributed vs. central schemes • Combined, scalable, multi-layer approach recommended • Cost of different measures • Switching of shunt/FACTS devices, start of gas turbines, etc. preferable to system separation and load shedding • Requires coordination of SIPS in the grid 8th Symposium on Power System Management Cavtat, November 9-12, 2008

23. System Frequency In Northern California August 10, 1996 Beginning At 15:46:41 PST 61.5 61 60.5 60 59.5 Frequency (Hz) FREQ. 59 58.5 58 57.5 57 56.5 -10 218 131 910 304 391 737 823 996 477 650 564 7.33 24.6 44.6 1169 1256 1342 1429 1083 Time (Seconds) SIPS Ingredients • Not intended to compensate for lack of other investments • Clear understanding of the requirements and consequences • Coordination with neighboring systems • High performance equipment • Emphasis on security vs. dependability • Real-time measurements and reliable communications • Designed for future expansions • System testing Source: Vahid Madani, PG&E 8th Symposium on Power System Management Cavtat, November 9-12, 2008

24. British Columbia Alberta Washington Montana Oregon Idaho Wyoming Colorado Nevada Utah Arizona New Mexico PACI RAS Islanding - Intertie Separation • Automatically separates WECC Electrical Grid into two islands: N&S • Separation by: • Tripping all intertie lines at California-Oregon border • Initiating the NE/SE separation scheme when transfer is above 600 MW N-S • RAS has provisions for: • Generator tripping in Pacific Northwest and California • Tripping pump and/or firm load in northern and southern California • Coordinated with other actions based on outage type and loading PACI – AC Corridor, 500kV PDCI – DC Link, 1000kV Source: Vahid Madani, PG&E 8th Symposium on Power System Management Cavtat, November 9-12, 2008

25. Summary of SIPS schemes • SIPS/RAS can minimize system impacts when systems are operated outside of reliability criteria • Fast changing operating conditions in power systems (ever smaller security margins and capacity, aging infrastructure, etc.) • Quickly changing enabling technologies for power system control and protection, e.g. communications, controllers, PMUs • Advanced analytical techniques are available for various types of SIPS applications 8th Symposium on Power System Management Cavtat, November 9-12, 2008

26. A road map for future • Identifying critical relay elements affecting security • Creating a future-proof plan WAMS architecture • Matching communications to applications • Phased Optimal placement of PMUs • Determining critical system state at Control Center • Implementation of pilot projects • Gaining some experience from field installations 8th Symposium on Power System Management Cavtat, November 9-12, 2008