Ancillary services are those services that are necessary to maintain the system security and reliability, and ensure appropriate quality of electricity supply. These services include:
- Load Rejection and System Restart
- Spinning Reserve
- Dispatch Support
- Load Following Ancillary Services (LFAS) Plan and Audit
LFAS allows for supply and demand to be continuously balanced in real-time. It compensates for variations between load and intermittent generation, and forecast, as well as normal generation deviations. It is provided by generators that are capable of being regulated under automatic generation control to maintain system frequency.
Apart from LFAS, all other services are contracted by the System Manager. LFAS is bought and sold in a specifically-designed market.
The ERA is required to determine regulated prices for load rejection, system restart and spinning reserve services. In addition, System Management must obtain the ERA's approval before entering into a contract for dispatch support. The ERA must determine whether the contract would achieve the lowest cost to market.