Transcript Generator Model Validation Using Monitoring Data

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Review of BPA Voltage Control
Conference
Steve Enyeart, Dmitry Kosterev, Terry Oliver,
Eric Heredia, Bart McManus and Steve Hitchens
Bonneville Power Administration
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BPA Voltage Control Conference
 Held on August 23, 2011 in Portland OR
 About 100 participants from Western, Eastern
Interconnection and ERCOT
 Presentations and Next Steps are posted at
 www.bpa.gov/ti
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Presentation Subject
 The presentation focus is on control needs for “stability” time
frame – i.e. making sure that the power system survives and
performs during the power system disturbances
 Specifically, the presentation will focus on:
– Voltage stability and controls
– Monitoring and modeling
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Many of BPA Paths are Stability-Limited
Cross-Cascades North
Montana - Northwest
Cross-Cascades
South
Wind
Pacific HVDC Intertie
California – Oregon Intertie
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August 10 1996 Outage
“Those who forget the past are condemned to repeat it”
Slatt Voltage
575
COI sepration
550
Keeler-Allston outage
Voltage [kV]
525
McNary tripping begins
500
475
Oscillations
450
425
15:41:00.00 15:42:00.00 15:43:00.00 15:44:00.00 15:45:00.00 15:46:00.00 15:47:00.00 15:48:00.00 15:49:00.00 15:50:00.00 15:51:00.00
Time
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August 10 1996 Outage
 Outage
– A combination of voltage collapse and unstable oscillations resulted in
COI separation and PDCI shutdown
– 28,000 MW of load lost, 7.5 million customers
 Lessons learned:
– There are interactions among several transmission paths in Pacific
Northwest, on-line generation and load levels
– Dynamic reactive reserves in lower Columbia are critical to support
the high power transfers and this is where much of the wind is
located
– Operating in POWER FACTOR instead of VOLTAGE control is highly
detrimental
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Impact of August 10 1996 Outage
 Interties were de-rated:
– COI and PDCI was de-rated by 33%
 Significant investments were made by BPA to improve voltage
stability in the Pacific Northwest
–
–
–
–
Synchronous condenser capabilities at two Lower Columbia plants
Shunt capacitor additions
AC Reactive RAS and Fast AC Reactive Insertion
PDCI control modification
 Operating procedures
– COI / PDCI Operating Nomogram
– Dynamic reserve monitoring for generators in Lower Columbia
– Equivalent unit monitoring for voltage swing support
 Bakeoven series capacitors are added in 2011 to increase COI
utilization
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Voltage Control
 Voltage control goes beyond maintaining plant
voltages during power ramps
– This is given
 Voltage control helps the system to survive
“macro” disturbances
– the system ability to survive disturbance sets the
System Operating Limits
– at times wind will be the predominant generation
line, and we depend on them for voltage control
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Early Wind Generation (pre-2006)
 Voltage control was not required because
amount of wind generation was small
 Wind turbine technology was induction
generators (type 1 or type 2)
 Unfortunately, several events of voltage
instability were observed with these generators
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Voltage Control Problem
220
200
Power
180
160
140
120
100
11:00
11:15
11:30
11:45
12:00
12:15
12:30
12:45
13:00
13:15
13:30
11:15
11:30
11:45
12:00
12:15
12:30
12:45
13:00
13:15
13:30
250
245
Voltage
240
235
230
225
220
215
210
11:00
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Wind Ramp Event
Voltages
244
This is actual data, not
simulations
Voltage (kV)
242
240
All lines in service
238
236
234
0
50
100
150
Time (min)
200
250
300
Wind power plants are in
power factor control mode
Wiind Total Power
500
Power (MW)
400
300
200
100
0
0
50
100
150
Time (min)
Wind ramping up event
200
250
300
200
250
300
Wiind Total Reactive Power
Power goes up
Voltage goes down
Recipe for disaster
Reactive (MVAR)
20
10
0
-10
-20
0
50
100
150
Time (min)
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Wind Ramp Event
PV-Curve for same event
PV Plot - Voltage versus Wind Total
243
242
241
The edge
240
Voltage (kV)
B
239
238
237
236
235
234
233
0
50
100
150
200
250
Power (MW)
300
350
400
450
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2006 Study…
 How integrating 3,000 MW of wind generation will
impact the system “macro” stability
 Conclusion 1:
 The Interties will be de-rated if the wind power
plants do not provide dynamic voltage control
– Voltage stability
– Damping of inter-area oscillations
– Transient stability
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…2006 Study
 Conclusion 2:
 To integrate reliably 3,000 MW of wind
– Wind power plants have adequate reactive
capabilities
– Wind power plants are operated in voltage control
mode
 New wind generation technologies are capable of
voltage control, and can offer performance better
than synchronous machines. But they must be
set and remain in proper control mode.
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Voltage Control Requirements
 BPA requires wind power plants to provide voltage
control and reactive power to support the grid – just like
other large generation projects
 How much reactive is needed:
– Dynamic reactive sized to provide continuous +/- 0.95 power
factor at 34.5-kV bus
– Switched shunts to compensate for reactive power losses
between WTGs and Point Of Interconnection, high switching
duty
 How to control reactive resources:
– Operate in continuous (no dead-band !) voltage control mode,
control POI voltage to BPA schedule with reactive droop
– Shunt switching to maximize the availability of dynamic
capabilities at the plant
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Observed Challenges
 A plant is commissioned in high side voltage control
 Plant experiences large MVAR swings for small
voltage fluctuations
 Power plant operator turns plant into MVAR control
 BPA is working with large wind power plant operators
on correcting their voltage control responses
 How to test the voltage control response ?
– Trust but verify
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Performance Monitoring
 BPA installs Phasor Measurement Units (PMUs) at plant POIs
– PMUs provide time-synchronized measurements 60 times per
second versus 2-second SCADA – often compared to MRI vs. X-ray
technology
 WECC is investing more than $108 M in the PMU technology
 Applications include:
– Performance monitoring, including voltage response verification
– Model Validation
– Detection of operational issues (e.g. voltage flicker)
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2011 Study
 How integrating 8,000 MW of wind generation
will impact the system “macro” stability
 Studies done up to now has not shown “macro”
stability issues with 8,000 MW of wind in Pacific
Northwest - as long as wind power plants follow
BPA voltage control requirements and study
models are correct
 … Will reality agree with the studies ?
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BPA Voltage Control Conference
 Wind generation technologies (type 3 and 4) are
certainly capable of delivering the required voltage
control performance
 BPA is working with the wind power plant operators
on settings wind plant controls
 BPA is following up on the Next Steps
 www.bpa.gov/ti
Slide 19
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