oscillation monitoring of large-scale power systems€¦ · monitoring hundreds of pmus...
TRANSCRIPT
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Mani V. Venkatasubramanian Washington State University
Oscillation Monitoring
of Large-Scale
Power Systems
© Washington State University
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
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Real-time security monitors @ WSU
Oscillation
Monitoring
System
Voltage
Stability
Monitor
Angle
Stability
Monitor
PMU
Real-time
data
PMUs
&
PDC
System
Security
Status
Real-time
Display &
Control
Entergy, IPC
Entergy, IPC
Small-Signal Stability
Negative damping
Growing oscillations
Positive damping
Oscillations damp out
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2
4 3
1 2
3 4
© Washington State University
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Small-signal Stability
Well-damped Poorly damped
time
Position
time
Position
© Washington State University
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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
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© Washington State University
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Small-signal Instability in WECC
Northwest
California
COI
lines
August 10, 1996 WECC blackout
Negative damping
Growing oscillations Unstable 0.25 Hz
Inter-area mode
300 350 400 450 500 550 600 650 700 750 800
1100
1200
1300
1400
1500
1600
1700
Time (s)
M
W
Malin to Round_Mountain 1_Line MW flow vs time
Keeler-Allston line trips
Ross-Lexington line trips
© Washington State University
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Small-Signal Local Event
Plant
System
1.2 Hz local mode
Negative damping:
Growing
oscillations
Positive
damping:
Oscillations
damp out
Oscillation Monitoring System
OpenPDC
OMS
OMS action adapters built into OpenPDC 64 bit version 2.
IEEE C37.118
BPA PDCstream
Real-time PMU
data stream OMS results
OMS
openPDC
SQL server
Open PDC
historian
Architecture
OMS
openPDC
PMU 1
PMU 2
PMU 3
PMU 4
PMU 5
PMU N OMS custom action adapters built into openPDC version 2.
Historian
SQL Database
Published
Results from Two Engines
820 840 860 880 900 920 940
5.09
5.1
5.11
5.12
5.13
5.14
5.15
x 105
Time (s)
Vol
tage
(V)
Bus Voltage Magnitude at Cumberland
Event Analysis
1.2 Hz at +1.5% damping. Local Mode.
Ambient Noise Analysis
1.2 Hz at +1.8% damping. Local Mode.
Nov. 29th 2007 TVA event
FDD
analysis for
ambient data
Event?
Prony analysis
for post-
disturbance data
Start
Read data
from PDC
Moving window
crosscheck
Yes
No
Moving window
crosscheck
Alarm
Controller triggerPoorly damped
mode detected?
Yes
No
OMS Flowchart
Event
Analysis
Engine
Damping
Monitor
Engine
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)
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
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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
0.22 Hz WECC mode (well-damped)
0.38 Hz WECC mode (poorly damped)
June 13 2013 IPC Results
June 13th PSD Singular Values from WECC data
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)
June 13th 0.37 Hz oscillations at Generator
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
0.6 Hz Eastern system mode
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
OMS Mode Shape
TVA
SSAT Sunday, October 13, 2013, 20:10:13
SSAT 10.0 Testing_1.bin Powertech Labs Inc.
Copyright 2010 All rights reserved
Mode Shape Scatter
Real = -0.1515 1/s Imaginary = 3.7147 rad/s Frequency = 0.5912 Hz Damping = 4.08 %
Case: Testing_1.ssa Scenario: Inter Area Oscillations Contingency: No fault
Dominant State: 527161 : MUSTANG_13.8 : 0 : : Z : GENCLS : : Angle
Mode Shape Reference: 335075 : 1DYNEGY_18.0 : 0 : : 1 : GENROU : : Speed
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 ]
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.-0.8
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-0.6
0.6
-0.4
0.4
-0.2
0.2
0.2
-0.2
0.4
-0.4
0.6
-0.6
0.8
-0.8
TVA Entergy
SOCO
Entergy 5.5 Hz oscillations
Pattern different
on different
days
5.5 Hz oscillations
Actual Current Magnitude
seen in PMU
(From openHistorian)
OMS FDD 5 Hz mode
energy level captures the
change.
Entergy 5 Hz oscillations
Mode frequency changes during some days
5.45 Hz mode shape
5 Hz mode shape – different mode
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2.5
Event
Analysis
Damping
Estimate
PMU
Bus
Voltage
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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.