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ESO
Frequency response services
Please note: Given the challenges posed by COVID-19 we will be constantly reviewing our plans and several projects may be impacted. Click here to find out more.
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.
Dynamic Containment
Dynamic Containment is the first of our new end-state services, in order to meet our most immediate need for faster-acting frequency response.
Dynamic Moderation (DM)
Dynamic Moderation (DM) rapidly delivers with the aim of assisting the ESO to keep frequency within operational limits.
Dynamic Regulation (DR)
Dynamic Regulation (DR) is a pre-fault service designed to slowly correct continuous but small deviations in frequency.
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.
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.
For historic frequency data, please visit the page Historic Frequency Data.