​Enhanced frequency response (EFR)

​Enhanced frequency response (EFR) is a dynamic service where the active power changes proportionally in response to changes in system frequency. This service was aimed at improving the management of system frequency pre-fault to maintain system frequency closer to 50Hz.


EFR providers are required to have the following technical capabilities:

  1. be capable of delivering a minimum of 1 MW of response. This may be from a single unit or aggregated from several smaller units. Maximum response of 50MW; and
  2. be capable of responding within one second to frequency deviations and operate in frequency sensitive mode within the operational envelope and associated restrictions set out in the invitation to tender.
Service dispatch

When providers need to be available to deliver EFR service

There is a requirement for dynamic frequency response all year round, although the exact requirement will vary, depending on the demand profile and the generating plant on the system at a particular time.

Typically, greater levels of response are required in the summer than in the winter. EFR providers are required to deliver according to their tendered windows.

How will providers be dispatched?

  • The EFR service is dispatched automatically
  • Units providing dynamic response must be in frequency sensitive mode at the start of each EFR window so they can be automatically dispatched.

How often will providers be dispatched?

EFR providers will dispatch themselves automatically, as per their tendered windows.

Testing and guidance documents