Mandatory response services
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.
Primary response
Response provided within 10 seconds of an event, which can be sustained for a further 20 seconds.
Secondary response
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.
Providing MFR
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.