Transcript Document

Managing a Power System with
40% Wind
Dr Alan Rogers
EirGrid
Outline
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Current Situation
Case study: August 26th 2009 > 40% Wind
Power System Stability
System Stability Tools
Conclusions
Current Status
• Oct 2009:
• End of 2009:
• End of 2010:
1119MW of wind generation connected
1250MW installed
1600MW installed
• Minimum Generation (August 2009): 1632MW exported
• Expected Winter Peak Load 2009: 4750MW
• Current Maximum Wind Generation: 999MW
• Rapidly moving towards:
– 50% instantaneous wind penetration
– 33% capacity penetration (Installed Wind MW / Peak MW)
Maximum Percentage Wind during 2009
Hourly Wind Variability
Increased Wind needs more flexible conventional plant
Maximum Hourly Change in Wind MW vs Maximum Wind
400.0
300.0
200.0
MW / hour
100.0
0.0
0.0
200.0
400.0
600.0
800.0
1000.0
1200.0
1400.0
-100.0
-200.0
-300.0
-400.0
-500.0
Wind / MW
On this day, wind
peaked at 750MW and
dropped by 370MW in
one hour
Case Study
August 26th 2009 3:45am > 40% Wind
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Wind generation now regularly exceeds 40% of demand
Highest wind penetration in the world on a synchronous system
Occurs during night valleys, when demand is at its lowest
Conventional Generation Dispatch must be carefully managed
– Geographical spread of generation for voltage control
– Certain amount of flexible plant to cope with sudden changes in wind
(e.g. hydro)
– Large machines to provide inertia, synchronizing torque, and shortcircuit power
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Approximate Dispatch on August 26th:
– 870MW Wind
– 850MW Large conventional machines at minimum load
– 200MW Peat / Hydro / Small-scale Gas
Change in Dispatch from Low to High Wind
Night Valley Dispatches: Aug 14th (Low Wind) vs Aug 26th (High Wind)
1 x MP min
2 x TB min
PBCCGT min
1400
1200
HNC min
HN2 min
3 x TH pumping
1000
800
MW
600
400
200
0
Large Conventional
Small Conventional
Wind Generation
Calm
Windy
Case Study – Control Issues
Wind generation peaked at 880MW on August 26th
30MW of non-firm wind was curtailed in South-West
NCC expected severe contingencies in North-West, so SONI agreed to
import 20MW at both Strabane and Enniskillen to alleviate contingencies
Night Valley Frequency Traces
Aug 26 & Sep 30
Wind MW
fluctuations make
jitter amplitude
larger  PQ issue
/ freq control issue
50.12
50.1
Frequency (Hz)
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50.08
50.06
High Wind
Low Wind
50.04
50.02
50
49.98
1
3601
Time (seconds)
Normal fluctuations
in demand cause
frequency jitter
Power System Stability
Power System Stability
Rotor-angle
Stability
Transient
Stability
Smallsignal
Stability
Voltage
Stability
MVAr
Balance
Tapchanger
Actions
Frequency
Stability
Shortterm
Longterm
System Stability Tools
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Online Wind Security Assessment Tool (WSAT) in development:
Real-time Analysis (every 30mins)
– Transient Stability Analysis – Full Dynamic Simulation
• Faults at every bus / Tripping of large machines / Relay Actions
• Does the system remain as one synchronous area?
• Do any machines trip unexpectedly?
– Voltage Stability Analysis (Margin to Voltage Collapse / N-1
Contingencies)
• Voltages in range / Overloads / Voltage Collapse
– Frequency Stability
• How low will frequency go / frequency recovery / system inertia ?
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Damping Monitor Relay
– Analyzing low frequency modes 0.001Hz – 99Hz
– Oscillatory Events / Magnitudes / Damping / Duration
– Any systemic change in behaviour with high wind penetration?
System Security: August 26th
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Voltage Security Assessment – extra 500MW wind could be
accomodated before voltage collapse / unsolved loadflow
– Yellow region means secure but with some overloads if certain lines trip
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Transient Security Assessment showed that a large generator trip
would cause a frequency drop to about 49.3 Hz
– This is normal. No other problems were flagged
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No stability problem with 40% instantaneous wind during SNV as far as
we can tell
– Key limitations: Thermal Limits / Conventional Plant Constraints
643.4 843.4 1043.4
1443.4
1843.4
Wind
2243.4
2643.4
Conclusions
• 40% instantaneous wind becoming more common
• Change in Dispatch / System Behaviour
– Flexible Generation Requirements
– Extensive dynamic simulations required
• Power System Stability Tools
– WSAT
– Damping Monitor
• 2020: 37% Average Wind Energy
– Very high instantaneous penetration in theory (70/80%)
– Careful study of stability limits will be required
Possible 2020 Fuel Mix
Fuel Mix 2020
37%
2%
1%
2%
1%
Coal
Peat
Oil
Gas
Wind
15%
Hydro
Pumped Hydro
Wave/Tidal
Biomass
5%
1%
36%