Frequency Regulation

Frequency regulation is a grid service in which a battery follows a signal from the grid operator every few seconds, charging and discharging to hold system frequency at nominal.

The grid operator sends an automatic generation control signal to each participating resource. A battery is well suited because it can swing from full charge to full discharge in under a second. The energy management system follows the signal while managing state of charge so the battery can keep responding. Frequency regulation is the fastest paid ancillary service and is distinct from frequency droop, which is an automatic local response to measured frequency.

Also called: Regulation service, Secondary frequency control, AGC following