Market mechanisms for power reserve services

NGC derives its quality criteria for system frequency from section 30(2) of the Electricity Supply Regulations which state that variations in the supply frequency shall not exceed 1% above or below the system standard of 50 Hz, save in exceptional circumstances. The interpretation of this rather simple statement follows the CEGB practice which was applied to an integrated system of generation and transmission in common ownership. The author discusses the shortcomings of the existing provisions including: natural plant response to falling frequency, service sophistication, interaction with the energy market, and criteria for a frequency responsive reserve. Two mechanisms are needed to introduce market processes into the provision of a frequency responsive reserve. The first should enable the despatcher to correctly identify when it is most economic for CCGT plant to de-load to meet a particular standard of response. The second should enable generators to offer prices for frequency reserve in the same timescale as their bids to the electricity Pool, and tailor the service more closely to specific plant performance