Ancillary services

About ancillary services

We procure ancillary services to support the reliable operation of the power system and assist us to meet our Principal Performance Obligations

Black start

Black start is the first step in the process of system restoration in the unlikely event of an island-wide black-out.

Frequency keeping

Frequency keeping services are required to manage short term supply and demand imbalances to ensure that the system frequency is maintained at or near 50 Hz.

Instantaneous reserve

Instantaneous reserve is generating capacity, or interruptible load, available to operate automatically in the event of a sudden failure of a large generating plant or the HVDC link.

Over frequency reserve

Over-frequency reserve is provided by generating units that can be armed when required and automatically disconnected from the power system due to a sudden rise in system frequency.