Transcript HECO Dynamics Seminar - Alaska Energy Authority Inc

NREL Wind Integration
Workshop
By Electric Power Systems, Inc.
June 28-29, 2010
Wind Integration in the Railbelt
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Challenges and Issues
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Islanded Electrical System
Power Regulation
Transmission Capacity
Wind Forecasting & Scheduling
Dispatch & Control Responsibility
Control Agreements & Implementation
Voltage Ride-Through Requirements
Frequency Ride-Through Requirements
Slide 2
Wind Integration in the Railbelt
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Challenges and Issues
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Curtailment Procedures & Authority
Fuel Impacts
Hydro-Thermal Inefficiency
Transient Stability, Short Circuit
Transmission Access
Slide 3
Islanded Power Systems
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Limited Inertia
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Unit Displacement
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Difficult to displace thermal units due to lack of
emergency support
Limited Voltage Stability
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Displaced hydro/thermal decreases frequency stability
Increased transient frequency excursions
Displacement of base load units can increase voltage
instability
Limited Regulating Units
Slide 4
Power Regulation
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Upward Regulation
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Downward Regulation
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Amount of unloaded capacity on other generation
units that can be used to make up for decreases in
wind power
Amount of loaded generation capacity that can be
unloaded to allow for increased wind energy
Regulation Expense
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Regulation costs vary with unit commitment, time of
day and type of unit.
Slide 5
Power Regulation
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Regulation Ramp Rate
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The rate at which generation can increase up or down
to meet changes in load or wind generation
Regulation ramp rates are generally limited to 4-5% of
the unit’s capacity/minute for long-term unit
maintenance
Typical ramp rates for thermal units in Railbelt range
from1.25 MW/ minute to 3.4 MW/minute
Typical ramp rates for hydros range from 5
MW/minute to 25 MW/minute
Hydros have time constants of 7-15 seconds for
upward regulation
Slide 6
Transmission Capacity
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Transmission Constraints
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Anchorage – Fairbanks Intertie
Anchorage – Kenai 115 kV line
Transmission today is scheduled energy
delivery
Following wind integration, transmission
must include regulation capacity
Transmission utilization will decrease
with regulation scheduling
Slide 7
Transmission Capacity
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Transmission capacity constraints
including regulation will reduce spill
energy available from Bradley
Transmission capacity including
regulation constraints will decrease
energy deliveries from Kenai
Slide 8
Wind Forecasting & Scheduling
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Forecast for daily/weekly wind energy
Interchange scheduling between utilities
Responsibility for forecast deviations
Wind modeling and development costs
Slide 9
Dispatch & Control
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Responsibility for wind monitoring &
control area interchange
Alarm and control responsibility
Curtailment control
Slide 10
Control Agreements
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Control agreements required for dynamic
scheduling
Hardware/software changes required for
dynamic scheduling
Coordination of regulation capacity
requirements
Slide 11
Voltage Ride-Through
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VRT is defined for both high and low
voltage conditions
Transmission, subtransmission and
distribution reclosing coordination
requirements
Consistency throughout Railbelt
Slide 12
Frequency Ride Through
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FRT is defined for both high and low
frequency conditions
Must coordinate with Railbelt generation
Cumulative wind capacity may represent
the largest contingency on the Railbelt
FRT must be consistent throughout
Railbelt
Slide 13
Curtailment Procedures/Authority
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Curtailment of wind for generation
requirements
Curtailment for transmission
Curtailment for system conditions
Curtailment between control areas
Curtailment by host control area
Unauthorized disconnects
Incident resolution
Slide 14
Fuel Impacts
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Off-schedule wind energy – off-schedule
gas requirements
Gas scheduling requirements by plant
Gas penalties applicable to over/under
utilization, 3,000 mcf/day
Gas penalties $30/mcf for variance
Gas delivery may not be capable of
sustaining generation ramp rates
Penalty allocation will be difficult
Slide 15
Hydro-Thermal Inefficiency
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Hydro currently utilized to:
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Mitigate gas constraints
Mitigate transmission constraints
Mitigate thermal generation costs
Hydro “value” is currently optimized to
result in least cost generation
Hydro not scheduled during off-peak or
shoulder load periods depending on
thermal unit commitments
Slide 16
Hydro-Thermal Inefficiency
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Hydro with wind integration:
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Provide regulation capacity on hydro & thermal units
Mitigate gas constraints
Mitigate transmission constraints
Mitigate thermal generation costs
Hydro optimized to provide regulation
Hydro scheduled during all load periods
with insufficient thermal regulation
Balance of regulating hydro energy vs
“ponded” wind energy difficult to forecast
Slide 17
Transient Stability, Power Flow,
Short Circuit Impacts
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Standardized procedures and
methodologies across Railbelt
Wind models for each important, but
difficult to obtain
Without unit de-commitment, not much
impact on stability, power flow or short
circuit
Slide 18
Transmission Access
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Transmission access costs and
methodologies must be developed
across Railbelt
WTG facilities on other circuits need
system specific transmission rates
Transmission interconnection studies
and requirements should be consistent
Slide 19