Oscillation Monitoring of Large-Scale Power Systems

Transcription

1 Washington State University Oscillation Monitoring of Large-Scale Power Systems Mani V. Venkatasubramanian Washington State University 1

2 Stability Requirements Voltage Stability Sufficient reactive power reserves? Voltage collapse Small-Signal Stability Can damp out small disturbances? Oscillatory instability Transient Stability Can withstand large disturbances? Loss of synchronism and islanding Operational Reliability Washington State University 2

3 Real-time security WSU PMUs & PDC PMU Real-time data Oscillation Monitoring System Entergy, IPC Voltage Stability Monitor Entergy, IPC Angle Stability Monitor System Security Status Real-time Display & Control 3

4 Small-Signal Stability Positive damping Oscillations damp out Washington State University Negative damping Growing oscillations 4

5 Small-signal Stability Well-damped Poorly damped Position Position Washington State University time time 5

6 Small-Signal Stability Issues Poorly damped oscillations Causes rotor fatigue Rotor life-span shortened Power quality issues Sustained oscillations Coupled oscillations and forced oscillations Rotor fatigue Can lead to tripping of generators Growing oscillations Can lead to tripping of generators and lines May lead to cascading blackouts Washington State University 6

7 Small-signal Instability in WECC August 10, 1996 WECC blackout Malin to Round_Mountain 1_Line MW flow vs time COI lines Northwest California M W Ross-Lexington line trips Keeler-Allston line trips Time (s) Unstable 0.25 Hz Inter-area mode Washington State University Negative damping Growing oscillations 7

8 Small-Signal Local Event Plant Positive damping: Oscillations damp out System 1.2 Hz local mode Negative damping: Growing oscillations Washington State University 8 8

9 Oscillation Monitoring System IEEE C Real-time PMU data stream BPA PDCstream OpenPDC OMS openpdc OMS SQL server OMS results Open PDC historian OMS action adapters built into OpenPDC 64 bit version 2.

10 Architecture PMU 1 PMU 2 PMU 3 PMU 4 PMU 5 OMS openpdc Historian SQL Database Published PMU N OMS custom action adapters built into openpdc version 2.

11 Voltage (V) Results from Two Engines 5.15 x 10 5 Bus Voltage Magnitude at Cumberland Event Analysis Ambient Noise Analysis 1.2 Hz at +1.8% damping. Local Mode Hz at +1.5% damping. Local Mode Time (s) Nov. 29th 2007 TVA event

12 OMS Flowchart Start Read data from PDC Event? Yes Damping Monitor Engine No FDD analysis for ambient data Moving window crosscheck Prony analysis for postdisturbance data Moving window crosscheck Event Analysis Engine Poorly damped mode detected? Yes Alarm Controller trigger No

13 Complementary Engines Event Analysis Engine (EAE) Multiple algorithms Prony, Matrix Pencil, HTLS, ERA, and Multidimensional Fourier Ringdown Algorithm (MFRA). Aimed at events resulting in sudden changes in damping Damping Monitor Engine (DME) Ambient noise based. Continuous. Provides early warning on poorly damped modes. Several algorithms Fast Frequency Domain Decomposition (FFDD), Distributed Frequency Domain Optimization (DFDO), and Recursive Adaptive Stochastic Subspace Identification (RASSI)

14 WSU Research Objectives Oscillation Monitoring System for large power systems Monitoring hundreds of PMUs simultaneously System modes are changing adaptive engines Interactions with power electronics Damping Monitor Engine ambient data analysis Event Analysis Engine detection and analysis of ringdowns and oscillations Real-time engines and off-line engines

15 Estimation Results Dominant modes are analyzed for each data set For each mode: Mode frequency Mode damping ratio Mode energy Mode shape Estimation confidence level 15

16 0.22 Hz WECC mode (well-damped)

17 0.38 Hz WECC mode (poorly damped)

18 June IPC Results

19 June 13th PSD Singular Values from WECC data

20 Mode Shape points to one generator 0.37 Hz at Near Zero Damping Ratio (7.30 am to 8.00 am) 0.4 Hz at Near 8% Damping Ratio (10 am to 11 am)

21 June 13th 0.37 Hz oscillations at Generator

22 Generator MW Forced Oscillations Operated in rough zone when wind power output high. Vortex effect in Francis turbine when water flow level is low Air compressor to keep oscillations low to nil 5 to 25 MW oscillations observed at 0.37 Hz Tricky for ambient mode monitoring engines Mode shape analysis critical Multi-dimensional analysis crucial

23 Mode Identified using WSU OMS in Sept 2013 by Entergy PMU team led by Floyd Mode seen in data from April 2013 and possibly in 2012 Mode damping averages around 4% and goes as low as 2%. Has been reproduced by Entergy via SSAT Mode not well observed Study in early stages 0.6 Hz Eastern system mode

24 0.6 Hz Eastern system mode SSAT Sunday, October 13, 2013, 20:10:13 Mode Shape Scatter Real = /s Imaginary = rad/s Frequency = Hz Damping = 4.08 % Case: Testing_1.ssa Scenario: Inter Area Oscillations Contingency: No fault Dominant State: : MUSTANG_13.8 : 0 : : Z : GENCLS : : Angle Mode Shape Reference: : 1DYNEGY_18.0 : 0 : : 1 : GENROU : : Speed TVA SOCO Entergy OMS Mode Shape Area 101 [ISO-NE ] Area 102 [NYISO ] Area 103 [IESO ] Area 104 [TE ] Area 105 [NB ] Area 106 [NS ] Area 201 [AP ] Area 202 [ATSI ] Area 205 [AEP ] Area 206 [OVEC ] Area 207 [HE ] Area 208 [DEI ] Area 209 [DAY ] Area 210 [SIGE ] Area 212 [DEO&K ] Area 215 [DLCO ] Area 216 [IPL ] Area 217 [NIPS ] Area 218 [METC ] Area 219 [ITC ] Area 220 [IPRV ] Area 222 [CE ] Area 225 [PJM ] Area 226 [PENELEC ] Area 227 [METED ] Area 228 [JCP&L ] Area 229 [PPL ] Area 230 [PECO ] Area 231 [PSE&G ] Area 232 [BGE ] Area 233 [PEPCO ] Area 234 [AE ] Area 235 [DP&L ] Area 236 [UGI ] Area 295 [WEC ] Area 314 [BREC ] Area 320 [EKPC ] Area 328 [PLUM ] TVA Area 330 [AECI ] Area 331 [BCA ] Area 332 [LAGN ] Area 333 [CWLD ] Area 339 [NLR ] Area 340 [CPLE ] Area 341 [CPLW ] Area 342 [DUK ] Area 343 [SCEG ] Area 344 [SC ] Area 345 [DVP ] Area 346 [SOCO ] Area 347 [TVA ] Area 349 [SMEPA ] Area 350 [PS ] Area 351 [EES ] Area 352 [YAD ] Area 353 [SEHA ] Area 354 [SERU ] Area 355 [SETH ] Area 356 [AMMO ] Area 357 [AMIL ] Area 360 [CWLP ] Area 361 [SIPC ] Area 362 [EEI ] Area 363 [LGEE ] Area 364 [OMUA ] Area 366 [TAP ] Area 401 [FPL ] Area 402 [PEF ] Area 404 [GVL ] Area 406 [JEA ] Area 407 [KEY ] Area 410 [NSB ] Area 411 [FMPP ] Area 412 [SEC ] Area 415 [TAL ] Area 416 [TECO ] Area 417 [VER ] Area 418 [NUG ] Additional areas are not printed due to lack of space. Testing_1.bin SSAT 10.0 Powertech Labs Inc. Copyright 2010 All rights reserved

25 Entergy 5.5 Hz oscillations Pattern different on different days

26 5.5 Hz oscillations Actual Current Magnitude seen in PMU (From openhistorian) OMS FDD 5 Hz mode energy level captures the change.

27 Entergy 5 Hz oscillations Mode frequency changes during some days

28 5.45 Hz mode shape

29 5 Hz mode shape different mode

30 PMU Bus Voltage Event Analysis Damping Estimate -2

31 Summary PMUs enabling technology for online oscillation analysis Self-diagnosis: important to assess estimation quality System changing: fast and adaptive engines needed. Oscillation modes: analyze full bandwidth of signals. Mode shape crucial for analysis: simultaneous processing of all available PMUs recommended. Distributed algorithms needed.