www.eirgrid.com renewables and system services ann scully
TRANSCRIPT
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Renewables and System Services
Ann Scully
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Existing Transmission System
400 kV - 440 km
220 kV - 1,830 km
110 kV - 4,000 km
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ContextWeekly Peaks 2006 & 2007
• Operational Generation Capacity = 6,618 MW
• Certified Generation Capacity = 6,325 MW
• Number of Generation Customers Certified Operational = 26
•Total Connected Renewable Generation Capacity = 1,071 MW
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Context
Electricity Consumption by Generation Source 2007
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ContextInstalled Renewable Capacity
Note: 2008 Figures are projected based on connection dates
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Context
• We need services which the TSO believes will enhance secure, reliable and economic operation of the transmission system
• With the introduction of large-scale wind generation additional variability arises.
– Increased dependence on wind forecasting.
– Forecasting errors
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Context• Under generation
– The additional reserve to meet these requirements will be needed in the range of minutes to hours.
• You can obtain the reserve in these time frames from the following sources:– Demand Side Units– Inter system exchanges.– Loading of already synchronised plant.– Off load available plant.– Open cycle gas turbines.
– Pump storage plant. – Others?
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Proposed New Services
• Off load Plant: Warming Contracts and Maintenance of Heat State
• Combined Cycle Gas Turbines (CCGT) Multimode Operation
• Some proposed services, others will be considered based on consultation with industry
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Off load Plant: Warming Contracts and Maintenance of Heat State
• Conventional steam plant that is not connected to the system but available to start becomes colder, takes longer to re-synchronise, and is slower to load up, the longer it is off load.
– The warmth state of a unit, which directly relates to its time to resynchronise, moves from hot to warm to cold after desynchronising.
– The plant becomes slower to react to system needs the longer it remains off load.
– Plant that can change to or maintain a hotter warmth state will reduce quick start plant running periods, Open Cycle Gas Turbine (OCGT) capacity requirements, and meet additional reserve requirements.
• We are proposing two new products:– The ability to change to and maintain a hotter warmth state– The ability to maintain hot warmth state after resynchronisation
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The Payment• Payment would be a fixed rate per hour to maintain warmth state.
• The service would be tested by the TSO: a test failure would incur a charge.
• Delivery or non-delivery of the service would be assessed by the TSO by reviewing the time to synchronise of the unit. Non delivery would incur a charge.
• There would be an interaction between warming contracts and the SEM which would need to be considered in developing the warming
contract arrangements.
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Combined Cycle Gas Turbines (CCGT) Multimode Operation
• CCGTs can operate in either open or closed cycle modes.
• If the steam turbine is bypassed using boiler gas side bypassing, the gas turbine will operate independently at efficiencies of approximately 30% and be fully available within relatively short timeframes (<20 mins) for full gas turbine output.
• Steam Turbine not started – steam not used
• Open cycle operation with boiler bypassing provides a fast run up ability similar to an OCGT
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Combined Cycle Gas Turbines (CCGT) Multimode Operation
The product required is:• Open Cycle Gas Turbine operation • Flexibility to continue to closed cycle operation
after dispatched on open cycle
OCGT operation would be paid on the basis of the difference between SEM income and an agreed income for operating in OCGT mode (determined on a costs plus basis in the procurement process).
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Other changes
• Wind grid code introduced
• Specific renewable integration cross functional group created
• Gate process introduced to handle incorporation of large amounts of wind
• Wind farms paid for the provision of Reactive Power were capable and in line with Grid code
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Reactive Power Payment for Wind• Commercial arrangements for the provision of Reactive Power Ancillary
Services– Required – Grid Code requirements met.
• Arrangements reflects those for thermal/ hydro.
• ‘utilisation’ payments (for production or consumption of Reactive Power) and, where appropriate, ‘capability’ payments (for being available to produce or consume Reactive Power).
• Reactive Power capability payments will only be made to WFs that can maintain Reactive Power capability that is not dependant on energy production.
• interim in nature pending all-island harmonisation of Ancillary Services.
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