Renewables and System Services

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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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(No Transcript)
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Context
Weekly 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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Context
Installed 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 (lt20 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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