ESO launches constraint management service for East Anglia

The Electricity System Operator (ESO) has launched a new enduring intertrip service to manage network constraints across the EC5 transmission boundary in East Anglia.

The body is already tendering for an interim service which will commence in December this year.

The Constraint Management Intertrip Service (CMIS) will allow the ESO to maximise its use of existing network capacity by giving it the ability to rapidly disconnect or reduce the output of generators in the area in the event of a fault. This will avoid the need to pre-emptively curtail generation when the expected flows across the boundary would exceed the capacity of the network if a fault occurred.

The new CMIS will be based on the blueprint developed as part of the Constraint Management Pathfinder, which established an intertrip service to manage network constraints across the B6 boundary between Scotland and England.

The pathfinder programme awarded contracts to a number of wind farms and battery storage systems across two tenders. The service went fully live in October but the ESO announced in February that it had already saved £80 million in constraint costs since April last year by allowing six units to begin providing the service early.

The ESO is looking to contract 2.4GW of generation to participate in the enduring CMIS for the EC5 local boundary for a four-year period beginning in April 2025.

The boundary encloses large parts of East Anglia and multiple offshore wind farms, including Dudgeon, Sheringham Shoal and part of the multi-phase East Anglia mega-project.

To participate in the service, generators must be already connected to, or contracted to connect to, the transmission or distribution networks in the area before April 2028 to ensure they are able provide at least one full year or service.

Generators will be paid arming fees (£/MWh) for periods in which they are armed as well as intertrip fees for each occasion on which the ESO pulls the trigger. The latter include tripping fees for being disconnected from the power grid, and de-loading fees for reducing their exports to zero.

As part of their bids, generators must submit an arming fee cap and a tripping fee for their first 12 months of service. They can also submit a de-loading fee if they wish.

Those that are awarded agreements will be able to resubmit arming fees on a monthly basis, provided they are below the cap submitted as part of their bid. They will also be able to re-submit their arming fee cap and intertrip fees in April of each year.

The ESO is planning to invite expressions of interest in providing the service in January 2024 and award the first contracts in October 2024.