Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Wind turbine wikipedia , lookup
Alternating current wikipedia , lookup
Amtrak's 25 Hz traction power system wikipedia , lookup
Life-cycle greenhouse-gas emissions of energy sources wikipedia , lookup
Power engineering wikipedia , lookup
Electrical grid wikipedia , lookup
Electrical substation wikipedia , lookup
Electric power transmission wikipedia , lookup
NREL Wind Integration Workshop By Electric Power Systems, Inc. June 28-29, 2010 Wind Integration in the Railbelt • Challenges and Issues - - 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 • Challenges and Issues - - Curtailment Procedures & Authority Fuel Impacts Hydro-Thermal Inefficiency Transient Stability, Short Circuit Transmission Access Slide 3 Islanded Power Systems • Limited Inertia - • Unit Displacement - • Difficult to displace thermal units due to lack of emergency support Limited Voltage Stability - • 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 • Upward Regulation - • Downward Regulation - • 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 - Regulation costs vary with unit commitment, time of day and type of unit. Slide 5 Power Regulation • Regulation Ramp Rate - - - - - 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 • Transmission Constraints - • • • 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 • • 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 • • • • Forecast for daily/weekly wind energy Interchange scheduling between utilities Responsibility for forecast deviations Wind modeling and development costs Slide 9 Dispatch & Control • • • Responsibility for wind monitoring & control area interchange Alarm and control responsibility Curtailment control Slide 10 Control Agreements • • • Control agreements required for dynamic scheduling Hardware/software changes required for dynamic scheduling Coordination of regulation capacity requirements Slide 11 Voltage Ride-Through • • • 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 • • • • 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 • • • • • • • 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 • • • • • • 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 • Hydro currently utilized to: - • • 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 • Hydro with wind integration: - • • • 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 • • • 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 • • • 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