Who can participate?

Service Description

Mandatory Frequency Response is an automatic change in active power output in response to a frequency change. All generators caught by the requirements of the Grid Code are required to have the capability to provide Mandatory Frequency Response. The capability to provide this Service is a condition of connection for generators connecting to the GB Transmission System.

Why is it needed?

Mandatory Frequency Response helps to fulfil National Grid’s obligation to ensure that sufficient generation and/or demand is held in automatic readiness to manage all credible frequency change contingencies.

Major Technical Requirements

A Mandatory Frequency Response provider must:

• Have a 3-5% governor droop characteristic[1]
• Be capable to provide continuous modulation power responses to counter the frequency changes via synchronised generation through their automatic governing systems.

Procurement Process

Once a new generating unit is built (or modified), National Grid must test its response capabilities. Following successful assessment by National Grid that the generating unit meets the minimum requirements, a Mandatory Service Agreement is put in place (or amended), which allows National Grid to instruct the Service when it is needed.

Payment

When service provider delivers the service as instructed, they will be paid in accordance with the CUSC section 4.1.3.8 with two types of payment:
Holding Payment (£/h): Made for the capability of the unit to provide response when the unit has been instructed into responsive mode. Generators submit holding prices on a monthly basis through the Frequency Response Price Submission System.
Response Energy Payment (£/MWh): Remunerates the amount of energy delivered to and from the system when providing Frequency Response. The response energy payment for a settlement period is calculated based on the formula below:

                                        Response Energy MWhrs * the Market Index Price *Factor

Where;
If the response energy is Low Frequency response energy (Additional Energy), the factor is 1.25.
If the response energy is High Frequency response energy (Reduced Energy), the factor is 0.75.

BSAD: Not Applicable

ABSVD: For Mandatory Frequency Response, energy volumes will be determined in accordance with the CUSC section 4.1.3.9A.

Summary of Further Information
Grid Code CC6.3.7 (C) (ii)
CUSC Section 4.1.3.
CUSC section 4.1.3.9A

Mandatory Frequency Response Calendar

[1]Droop is defined in the Grid Code CC6.3.7 (C) (ii)) as “The ratio of the steady state change in speed in the case of a Generating Unit, or in Frequency in the case of a Power Park Module, to the steady state change in power output of the Generating Unit or Power Park Module