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.
Providers can offer one of these or a combination of different response times.
Response provided within 10 seconds of an event, which can be sustained for a further 20 seconds.
Response provided within 30 seconds of an event, which can be sustained for a further 30 minutes.
High frequency response
Response provided within 10 seconds of an event, which can be sustained indefinitely.
Depending on their size and location, a power station may be obliged to have the capability to provide MFR. This requirement will be set out in their connection agreement and is summarised in the table below.
|National Grid||Scottish Power||Scottish Hydro Electricity Transmission|
|Small||< 50 MW||< 30 MW||< 10 MW|
|Medium||50 MW =< 100 MW||N/A||N/A|
|Large||=> 100 MW||=> 30 MW||=> 10 MW|
Offering MFR alongside other balancing services
You may provide other balancing services, as long as doing so does not interfere with your ability to deliver MFR.