Ancillary services

Those services necessary to support the transmission of electric power from seller to purchaser, given the obligations of control areas and transmitting utilities within those control areas, to maintain reliable operations of the interconnected transmission system. Ancillary services supplied with generation include load following, reactive power-voltage regulation, system protective services, loss compensation service, system control, load dispatch services, and energy imbalance services.

Other energy-related services that are required to control system frequency, to meet changing scheduling requirements, to react to changing loads and unexpected contingencies, and to ensure system stability (i.e. preventing blackouts).