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AEP’s Experience with WAMS
By AEP Transmission Operations
October 3-4, 2017
AEP’s Service Territory
• AEP operates in 11 states constituting parts of ERCOT, SPP and PJM’s footprints
• AEP has by far deployed 266 PMUs across three footprints (PJM, ERCOT, SPP)
• The PMUs has been used to detect oscillations and identify power quality issues
• Architecture1. Field units sending data to ePDC, which feeds AEP PMU data to RTOS
2. ePDC sends data to e-PhasorPoint, which feeds alarms to AEP’s EMS
3. e-PhasorPoint configured for all three footprints of AEP with redundancy servers set up
• Functionality1. Real-time monitoring and grid stability assessment
2. Oscillation detection and power quality issue identification
3. Data archive for post event analysis
AEP’s Wide Area Management System
AEP PMU System Architecture
PMU
PMU
PMU
ePDCPhasorPoint
(SPP)EMS (SPP)
PhasorPoint(PJM)
PhasorPoint(ERCOT)
EMS (ERCOT)
EMS (PJM)
PJM RTO
SPP RTO
ERCOT RTO
AEP’s PMU Statistics
• 120 PMU deployed in PJM, 123 PMU in ERCOT, 23 PMU in SPP
• Customized oscillation alarm configured for active power and frequency
• Probability based event detection developed, awaits testing and deployment
• Automatic daily report available to review oscillatory events
• E-PP events streamed to EMS as alarms and alerts.
• Architecture1. Field units sending data to ePDC, which feeds AEP PMU data to RTOS
2. ePDC sends data to e-PhasorPoint, which feeds alarms to AEP’s EMS
3. e-PhasorPoint configured for all three footprints of AEP with redundancy servers set up
• Functionality1. Oscillation detection and power quality issue identification
2. Data archive for post event analysis
3. Real-time monitoring and grid stability assessment
AEP’s Wide Area Management System
How AEP is using WAMS ?
• System Oscillation Detection
1. Oscillation Baselining for high voltage devices
2. Heuristic based alarm configuration
3. Oscillation event detection and archiving in daily report
• Post-Event Analysis
1. Decouple oscillation components in frequency domain
2. Detect oscillation source
3. Probability based event detection and alarm reconfiguration
• Real Time Monitoring
1. E-PhasorPoint customized views created for wall display
2. Grid Stability Assessment (GSA) alarm interpretation
Oscillation Monitoring
• What is important for the operators?
– How big is the oscillation? (Oscillation Amplitude)
– How quick the oscillation can settle down? (Oscillation Damping Ratio or Decay Time)
– Is this a system glitch or persistent? (Oscillation Hysteresis)
• How to set these alarm threshold?
– Challenges• No hard limit
• System always changing
• How to separate the true oscillation from noise and switching?
– Baseline Analysis
Alarm Parameters for Oscillation Detection
Amplitude Exclusion: Alarm will not be triggered despite damping if amplitude below the exclusion level
Damping Threshold: Maximum damping ratio to trigger low damping oscillation alarm
Amplitude Threshold: Minimum amplitude to trigger high amplitude oscillation alarm
Damping Exclusion: Alarm will not be triggered despite amplitude if damping above the exclusion level
Oscillation mode captured in past 15 min
Oscillation Baselining and Alarm Configuration
Export 1 month of Oscillatory data
Y axis as Magnitude, X axis as time
Y axis as magnitude, X
axis as Damping
Eyeball the outliers with Higher Amplitude
Locate the outliers on Locus
Plot
Amplitude Threshold
Damping Exclusion Level
Damping Threshold
Amplitude Exclusion Level
Investigate
Event Typ
e
Plo
t Lo
cus
Plo
t Ti
me
Do
mai
n
Alarm Major Oscillation, Alert minor Oscillation
Let go power swing , switching
Baselining Example 1#
Line Switching
Power Swing
True Oscillation
Active Power Oscillation Data Captured by PMU 11025 at RIO HONDO
Baselining Example 1#
Line Switching
Power Swing
True Oscillation
Oscillation Outliers Located on Locus Plot with Alarm ConfigurationDamping Exclusion Damping Threshold Amplitude Exclusion Amplitude Threshold
Alarm 20% 2% 2.0MW 3.2MW
Baselining Example 2#
Minor Oscillation low amplitude and Sufficiently damped
Major Oscillation 1
Major Oscillation 2
Active Power Oscillation Data Captured by PMU 11015 at Magic Valley
Baselining Example 2#
Short lasted Minor Oscillation
Major Oscillation 1 and 2
Oscillation Outliers Located on Locus Plot with Alarm ConfigurationDamping Exclusion Damping Threshold Amplitude Exclusion Amplitude Threshold
Alert 30% 5% 1.5MW 3MWAlarm 20% 3% 2 MW 4MW
15
Alarm Configuration Results
• Active Power✓ PJM and SPP:
500kV and Above: Customized alarm settings for every line345KV and Below: Customized alarm settings for every substation
✓ ERCOT: 345kV: Customized alarm settings for every line138kV and Below: Customized alarm settings for every substation
• Frequency: ✓ PJM and ERCOT:
Without known event: One set of alarm configuration for all PMUsWith known event: Customized alarms for specified PMUs
Oscillation Event Detection-ePhasorPoint
How AEP is using WAMS ?
• System Oscillation Detection
1. Baselining oscillation characteristics for high voltage devices
2. Configure oscillation alarms
3. Oscillation event detection and data viewing\archiving
• Post-Event Analysis
1. Decouple oscillation components in frequency domain
2. Detect oscillation source
3. Probability based event detection and alarm reconfiguration
• Real Time Monitoring
1. E-PhasorPoint customized views created for wall display
2. Grid Stability Assessment (GSA) alarm interpretation
Event Summary
Event Number #2 (No e-PP Alarm/Alerts, notified by RTO)
Event Type AEP-West System Wide frequency Oscillation
Start Time 02/14/19 15:18 EST
End Time 02/14/19 16:20 EST
Event Number #1 (e-PP Alarm Triggered)
Event Type EI local power oscillation @ Jackson Ferry
Start Time 01/11/19 03:40 EST
End Time 01/11/19 04:05 EST
Event #1 Active Power Oscillation @ Jackson Ferry
1919
Damping Ratio @ Broadfor to JFerry
New alarm settings
Low damping, high magnitude
Event #1 Frequency Domain Analysis
Major Oscillation Mode Frequency Produced by e-PhasorAnalyticsMatches with FNET analysis results
Post event analysis based on FNET recordings
Event #2 AEP-WEST System Wide Oscillation
2121
Frequency oscillation observed by PMUs from both AEP and SPP
Oscillation Source Location
For two major modes, frequency oscillation @LAWTON EASTSIDE has the
most leading phase
AEP Analysis Result: The source of the oscillation identified as OKLU@LAWTON EASTSIDE
SPP Confirmation: Natural oscillation caused by switchgear operation at LAWTON EASTSIDE
Probability based Event Detection
Currently enhancing event detection mechanism to avoid overlooking oscillation events:
Oscillation Mode and
Decay Time
Probability Estimation
Find Outliers Where P(A>A0, D>D0)<P0
Event List
Validation
Daily ReportAdjustment
Alarm Setting
Future Actions
P0 Decides how many events we notify operators
Baselining Example 2# Continued
Missing Event 1 at March 10 10:40
Decay Time Exclusion Decay Time Threshold Amplitude Exclusion Amplitude ThresholdOld Alert Around 60 seconds Around 20 seconds 1.5MW 3MWNew Alert 64 seconds 22 seconds 0.7MW 3MW
Missing Event 2 at April 8 16:53
How AEP is using WAMS ?
• System Oscillation Detection1. Baselining oscillation characteristics for high voltage devices
2. Configure oscillation alarms
3. Oscillation event detection and data viewing\archiving
• Post-Event Analysis1. Decouple oscillation components in frequency domain
2. Detect oscillation source
3. Probability based event detection and alarm reconfiguration
• Real Time Monitoring1. E-PhasorPoint customized views created for control room
display
2. Grid Stability Assessment (GSA) alarm interpretation
Real-Time Monitoring-Customized View Display
26
• Customized frequency and voltage view for all three footprints with average frequency displayed on SCADA wallboard
Alarming power oscillation amplitude in MW
Detected oscillation mode frequency
Detected oscillation mode damping
Alarming power oscillation damping
Active power oscillation
Real-Time Monitoring-GSA Alarm Interpretation
Real-Time Monitoring-Alarm
Summary
Detected oscillation mode frequency 0.05Hz and damping 46.13%
• Reconfigure alarms using probability based mechanism to avoid false alarm or overlooking oscillation event.
• More profound use of daily oscillation event report---Creating feedback loop to modify alarm settings and enhance oscillation detection.
• Include various types of events (oscillation, power quality, magnitude…) in daily report
• More intuitive GSA oscillation alarm/alert description…
Future Work
Oscillation Event Detection-Daily Report
Index Date Time Location Type Measure
1 4/8/2020 15:57:55 Magic Valley Alarm Active Power
2 4/8/2020 15:58:53 Magic Valley Alert Active Power
3 4/8/2020 16:03:48 Magic Valley Alarm Active Power
4 4/8/2020 16:04:25 Magic Valley Alert Active Power
5 4/8/2020 16:31:18 Magic Valley Alert Active Power
6 4/8/2020 16:47:18 Magic Valley Alert Active Power
7 4/8/2020 16:48:33 Magic Valley Alert Active Power
Alarms passed from event archive to daily report
Oscillation characteristics plotted in daily report
AEP’s PMU Statistics-PJM
• 120 PMU located in 32 substations configured in e-PhasorPoint
• Two angle pairs defined for real-time monitoring of angle differences
• Alarm based on engineering calculation enforced for angle differences
• Individual oscillation alarm customized for active power on every line with higher than 500kV voltage
AEP’s PMU Statistics-SPP
• 23 PMU located in 16 substations configured in e-PhasorPoint
• Generic oscillation alarm set for frequency system widely
• Individual oscillation alarm customized for active power on every 500kV lines
AEP’s PMU Statistics-ERCOT
• 123 PMU located in 46 substations configured in e-PhasorPoint
• Individual oscillation alarm customized for active power one every 345kV line
• Daily event report enabled to display event captured in the past 24 hours
• Probability based event detection in progress
Real-time Monitoring-GSA Alarm Interpretation
• E-PhasorPoint events are streamed in real-time to GSA application in EMS as alarms and alerts
• Information about alarming/alerting value and limits are available in GSA main display and EMS alarm summary
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