Find out about the different types of existing frequency response services and how to get involved.

We have a licence obligation to control system frequency at 50Hz plus or minus 1%. We make sure there is sufficient generation and demand held in readiness to manage all credible circumstances that might result in frequency variations. On this page you can find out more about the different types of frequency response that we procure to enable us to do this. 

There are two categories of frequency response:

Dynamic frequency response is a continuously provided service used to manage the normal second by second changes on the system

Non-dynamic response is usually a discrete service triggered at a defined frequency deviation.

Firm Frequency Response (FFR)

Firm Frequency Response (FFR) is our traditional frequency response suite used for balancing grid frequency in real time.

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New Dynamic Services (DC/DM/DR)

Dynamic Containment (DC), Dynamic Moderation (DM) and Dynamic Regulation (DR) make up our new suite of Dynamic Response Services.
​Mandatory Frequency Response (MFR)

Mandatory frequency response (MFR) is an automatic change in active power output in response to a frequency change. The service helps us to keep frequency within statutory and operational limits.
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Future of response services

We are investigating what a new, faster-acting frequency response product may look like, and how it could form part of a new suite of frequency response products.

Frequency data

You can find real-time data, such as demand data and frequency data over the last 60 minutes, on our Realtime Extranet site.

The Historic Frequency Data page holds data for Great Britain at a 1 second resolution up to and including 2020.  For historic frequency data after 2020 this is now published on the ESO Data Portal.