Download Power System Restoration Methodologies & Implementation

Power System Restoration
(Black Start)
Black Start Panel Session
IEEE PES Summer Meeting
Chicago, Illinois
July 23, 2002
M. M. Adibi
IRD Corp., P.O. Box 34901
Bethesda, MD 20827
[email protected]
(c) IRD 2002
Pre-disturbance Conditions
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•
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Peak load, low voltage, large network loads
Light load, high voltage, no cycling units
Long weekends (Labor Day)
Scheduled maintenance
(c) IRD 2002
Post-disturbance Status
• Complete collapse with no interconnection
assistance
• Partial collapse with interconnection
assistance
• Power system beak-up (System Islands)
(c) IRD 2002
The Three Restoration Stages
• Preparation stage, actions are time critical
(1-2 hours)
• System integration, achieving postrestoration target system (3-4 hours)
• Load restoration, minimizing MWH (8-10
hours)
(c) IRD 2002
Initial Sources of Power
• Combustion Turbines, Start-up in 5-15 min.,
probability of success 30 –50%, limited
under-excitation, use low voltage links
• Run-of-the-River Hydro, Pumped- Storage,
Start-up 5-10 min., probability of success is
high, can use HV links
(c) IRD 2002
Initial Sources of Power
(cont.)
• Once-through Units with full-load rejection,
probability of success 20-80%, maximum
elapsed time to min. loading 30 minutes,
coordinated loading problem to min. gen.
• Low Frequency Isolation Scheme (LFIS)
and Controlled Islanding, probability of
success is low.
(c) IRD 2002
Initial Critical Loads
• Cranking drum-type units, high priority
• Pipe-type cable pumping plants, high
priority
• Transmission and distribution stations, high
to medium priority depending on locations
• Industrial load, medium to low priority
(c) IRD 2002
Black Start Steam Electric Units
(Drum Type Boilers)
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•
•
•
•
Are base load units, supply large portions of demand
Max. elapsed time for hot re-start is 30-45 minutes
Min. elapsed time for cold start-up is 3-4 hours
Are remote from the load centers
Need cranking power 5-7% of their ratings
• Min. generation 25 to 30 %
(c) IRD 2002
One-Line diagram of a SE Unit
System Bus (345 kV)
GSU Taps
(5 no-load)
GSU
XFMR
Generator Bus
(18.0 kV)
Generator:
Max 185 MW
Min 90 MW
AUX Taps
(5 no-load)
SE
Gen.
AUX
XFMR
Standby Taps
(5 on-load)
Standby
XFMR
Normally Open
AUX Load Bus
(4.16 V)
AUX Load Bus
(4.16 kV)
Large Induction Motors
(350 to 6000 Horse Power)
(c) IRD 2002
Combustion Turbine Units
(cranking source)
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•
•
•
•
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Are peaking units, supply daily peak load
Cold start up within 5 – 10 minutes
Possibility of successful start up is 1 in 3
Are close to the load centers
Need small local cranking for start ups
Hot restart within 2 – 3 hours
(c) IRD 2002
One-Line diagram of the CT Unit
System Bus (115 kV)
GSU Taps
(6 no-load)
GSU
XFMR
Generator Bus
(13.8 kV)
Twin Generators
(42 MVA, 85% PF)
AUX Taps
(5 no-load)
CT
Gen
AUX
XFMR
Local
XFMR
XFMR Taps
(5 on-load)
AUX Load Bus
(480 V)
Local Load Bus
(34.5 kV)
AUX Load
(150 kW)
Local Load
(7.5 MW)
(c) IRD 2002
A Typical Black Start System
(c) IRD 2002
Cumulative Starting & Running Auxiliaries
50
MVAR Generation
40
Start-up
MVAR Required
30
20
10
0
-10
Running
MVAR Required
-20
0
1
2
3
4
5
6
7
8
Motor Start-up Sequence
(c) IRD 2002
9
10 11 12 13 14
Conclusions
• Characteristics of steam units dictate
parallel start ups (45 to 60 minutes)
• SE units should be individually matched
with black start CT units
• Systems are sectionalized into subsystems,
each at least having one SES & one CTS
• Cranking operation uses generation,
transmission and distribution facilities
(c) IRD 2002
Recommendations
• CT units should be able to absorb line &
cable charging currents
• CT units should be able to supply reactive
power required for the start ups of large
induction motors
• Each black start operation should be
planned, analyzed/simulated, field tested
and then operators trained and exercised in
its implementations
(c) IRD 2002