Phasor Measurements in the Western Electric Power System

Transcription

1 Phasor Measurements in the Western Electric Power System Kenneth Martin Principal Engineer The Bonneville Power Administration

2 Presentation Phasor measurement systems Deployments Typical system Data exchanges Applications Analysis Stability probing Displays State estimation Control (WACS)

3 WECC deployments First PMUs tested at BPA in 1988 PMUs produced at Virginia Tech Field tests showed improved measurement Lab tests showed high quality measurement EPRI-WECC controls project PMUs installed at several utilities WECC blackout in 1996 Measurement showed potential Current development 1996 to present NERC disturbance monitoring requirements

4 WECC Plan - NERC Requirements NERC planning standard 1.F. Implemented by Disturbance Monitor Workgroup Plan includes WAMS monitors at: Key Interconnections and Hubs Generating Plants > 1500 MW Other Information Rich Sites Such as RAS sites, DC lines, controller sites Plan also includes data retention, posting & exchange Phasor measurement not required but encouraged Most utilities use real-time phasor measurement systems

5 Phasor Measurement System Real-time, continuous data flow Typical real-time system V - I - F Measurement - substations PMU PMU PMU Data input & management - control center Phasor Data Concentrator (PDC) Correlates data, feeds selected applications, monitors system Operations monitors display & alarms SCADA, database (PI), state estimation, etc Displays RTDMS, Power World, etc. StreamReader Display & recording System Controls Real-time controls: Voltage & reactive stability; inter-area angle limits Direct exchange with other utilities PDC Data storage

6 Phasor Systems in WECC PMU Real Time to PDC BPA - 22 in NW, 1 in CA SCE - 16 in S. CAL & NEV PG&E - 6 in N. CAL PNM - 2 in NM WAPA - 4 in WY,CO & NM BC Hydro - 6 in BC APS/SRP - 7 in AZ & NM Not real time, stored files Alberta ISO - 6 in Alberta Pacific Power 2 in WY & UT

7 Inter-utility WAMS Development BPA < > SCE 2 PMUs, since 1998 BPA > CAISO BPA > CAISO All PMUs (14), T1, 2002 WAPA > BPA WAPA > BPA 4 PMUs, T1, 2004 SCE > CAISO SCE > CAISO All PMUs (14), T1, 2004 PG&E > CAISO & BPA PG&E > CAISO & BPA All PMUs (5), T1, 2005 BPA: 33 PMUs CAISO: 48 PMUs BPA PG&E CAISO SCE WAPA Future more direct utility links

8 Phasor System Applications Event and system analysis Improved operational observability Dynamic System Probe State estimation Measurement based controls Voltage stability Angle stability

9 Data Analysis applications PhasorFile - user selected displays for system response comparison with scaling & printing options PSM Utilities Matlab based utility and analysis tools for system dynamic analysis including Prony & Fourier ringdown tools

10 Display applications RTDMS multi- Function graphic Stream Reader strip chart w/file recording Phangle EMS phase angle Power World geographic phase angle w/ bus voltages

11 Angle monitoring Special displays for unique situations Cut-plane (flow gate) limits and alarms Monitoring of critical re-closer situations Inadvertent system separation detection Example: Generation located on transmission corridor Line open in heavy loading creates large phase angle at breaker Reclose if angle < 19 deg; otherwise ramp down generation From distant generation To distant loads PDC Phase angle display To distant loads ~ ~ PMU ~ PMU ~ From distant generation

12 Dynamic System Probe Injects stimulus - measures natural system response Detects changes in system damping Probing Signal Generator DC Converter or SVC Controller Power System Display - Analysis Stimulus Phasor Data Concentrator PMU PMU Ringdown Response PMU

13 Probe Signal & Response Summary Plot For ModeProbes_Ringdown_BPAPDC ModeProbes_Ringdown_BPAPDC MALN 06/21/00_08:15:51 Round Mountain 1 Current MW Response Signal - S. Oregon SCE1 Palo_Verde 500 kv Line Current MW Response Signal - S. California BE23 Celilo 3 Current MW Probe Signal Time in Seconds +/- 125 MW probe signal applied to DC transmission line

14 State Estimation with Phasor Data Improve speed, topology error detection, solutions Several projects under way (BPA, BC Hydro) Ve -j φ Ve -j φ Ve -j φ Ve -j φ

15 WACS Wide Area Control System Phasor measurement sensing Output via existing RAS control circuits Digital outputs to RAS controller RAS Controller Access to trip circuits WACS Controller Calculations, sanity checks, outputs Wideband data output by Ethernet Control outputs for Gen drop, reactive insertion PDC (Data Concentrator) Inputs & correlates Phasor data ~ PMU PMU PMU SVC )(

16 WACS Control Functions First swing protection NW-SW swing around.25 Hz Need response < 1 sec, before first peak Recovery-stability after first swing Maintain voltage stability with sufficient reactive, support transmission Seconds to minutes, stability before human reaction Transient stability control First swing, sense intertie voltages Voltage control First swing or other condition, intertie voltage & var support Control actions include capacitor insertion, AGC off, generation trip

17 WECC Grid Tie lines from the Pacific NW to: Canada Montana Idaho California Loss of generation in California Overloads tie lines Overloads alternate path though Idaho Loss is not immediately detected in NW OLINDA VACA- DIXON SAN FRANCI SCO AREA PORTLAND AREA MEDFORD ROUND MT. TABLE MT. TESLA SAN LUIS LOS ANGELES AREA SEATTLE/ TACOMA AREA GATES DIABLO CANYON SUMMERLAKE MALIN MIDWAY MIDWAY HARTFORD TRACY MIGUEL DEVERS NANEUM GRIZZLY BROADMAN VALMY HARRYALLEN MARKETPL ACE CHIEF JOESPH N.GILA GRAND COULEE LOWER MONUMENTAL MIDPOINT DWORSHAK PALO VERDE TAFT BEN LOMOND CAMP WILLIAMS INTER- MOUNTAIN REDBUTTE BORAH BRADY GLEN CANYON PHOENIX AREA GARRISON CHOLLA VAIL SIGURD HUNTER/ EMERY NAVAJO PINTO SPRING- ERVILLE TOWNSEND BONANZA CORONADO GREENLEE FOUR CORNERS RIFLE SAN JUAN DIABLO BROADVIEW JIM BRIDGER CRAIG WEST MESA LARMIE RIVER STA. AMRAD CALIENTE COLSTRIP DENVER AREA BLACKWATER ARTESIA

18 Swing from large generation loss Limits power transfer on intertie With WACS detection, transfer can be increased Guards against unanticipated events 575 kv 550 kv 525 kv 500 kv 475 kv 450 kv Malin (worst case) 425 kv

19 Palo Verde Loss Voltage at Malin swings to 450 kv COI swings from 2750 to 5500 MW (2 500 kv lines) Frequency to Coulee-Devers phase angle: 60 to 138 degrees

20 Comparison with model Actual flows lighter (2750 MW compared with model 5000 MW) but only 2 lines Similar first swing Quicker damping with lighter loading Comparable stations shown in plot 450 kv 575 kv 525 kv 450 kv 425 kv

21 Future controls Wide area phasor measurement Measurement and data collection can be done in a fraction of the time required for a decision Measurement & communications faster than system response (electro-mechanical wave) Example of wide area disturbance Loss of generator in NW causes reaction in SW Detectable indicators faster than electrical response Suitable detection levels can select real events

22 Comparison of Frequency & Phase Angle - Power Flow Grand Coulee frequency - blue, Coulee - Vincent phase angle - red, San Onofre power - green Power Compensation (southern Cal) Initial fault ~0.4 sec GC frequency N. Washington

23 IEEE Standard C Completed 1995, published March 1996 Standard includes: Measurement definitions Steady-state accuracy requirements A real-time data communication protocol Total Vector Error: Difference between the theoretical and estimated phasors, calculated as the RMS difference using the rectangular component representation. Phasor defined at t = 0. X = X r + jx i X r X X i Waveform matches phasor definition at t = 0. UTC Time (GPS) Phasor Measurement Unit (PMU) PMU estimates phasor equivalent from an interval of the waveform. X(n) = X r (n) + jx i (n) X(n) X r (n) X i (n) The estimate is compared with the defined phasor to determine error (TVE). TVE = [((X r (n) - X r ) 2 + (X i (n) - X i ) 2 ) / (X r 2 + X i 2 )]

24 Summary Phasor measurements Time synchronized, accurate system measurement System-wide, match models Standard C now available Serve multiple applications Disturbance analysis Monitors for operations Model verification State estimation Real-time monitor and control