We are a separate company

On 1 April the Electricity System Operator became a legally separate company within the National Grid Group. Find out more about what this change means.

Frequency response services

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.

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Future frequency response products

To improve and develop our balancing services products and markets, we are investigating what a new, faster-acting frequency response product suite may look like.

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​Mandatory response services

Mandatory Frequency Response is an automatic change in active power output in response to a frequency change and is a Grid Code requirement.

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Firm frequency response (FFR)

Firm Frequency Response (FFR) is the firm provision of dynamic or non-dynamic response to changes in frequency. Find out about tendering with us.

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​Enhanced frequency response (EFR)

EFR is a service to provide frequency response in one second or less.

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System frequency is a continuously changing variable that is determined and controlled by the second-by-second (real time) balance between system demand and total generation. If demand is greater than generation, the frequency falls while if generation is greater than demand, the frequency rises.

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.