National Grid Electricity System Operator (ESO) has launched a pilot for a new flexibility service that will initially be used to manage transmission constraints at the border between Scotland and England.
The constraint management pathfinder will introduce a new generation turn-down service which will be used to ease congestion on the transmission network following a fault.
The ESO said this will reduce the amount of renewable generation which needs to be curtailed in anticipation of a fault when the network is heavily congested, even though the likelihood of one occurring is very low.
Generation units connected to either the onshore or offshore transmission network in Scotland above the B6 boundary with England have been invited to express their interest in participating in the service.
The ESO said it intends to turn down up to 800MW of capacity at any one time but said this could be made up of different generators depending on the system conditions and what is already running, meaning it is looking to procure than that amount in the tender.
When a constraint is identified, generators will be armed, with the amount depending on the level of constraint and other technical consideration. They will need to be capable of disconnecting within 150 milliseconds when subsequently tripped.
Compensation for the service will include both arming payments (per MWh per settlement period) and a tripping fee for each time a generator is disconnected.
The ESO said it is aiming to procure the service annually, with the initial tender being held in the first quarter of the 2021/22 financial year for delivery between 1 October 2022 to 30 September 2023, subject to the intertrip link being operational by the beginning of the period. If the connection to the generator is delivered earlier, they will be able to start delivering the service and being paid sooner.
It noted the possibility that it may not procure any flexibility in tender if none of the solutions offer economic benefits when compared to the forecast alternative cost of managing constraints through the Balancing Mechanism.
The constraint management pathfinder is one of three pathfinder projects being undertaken by the ESO, with the others covering stability, including inertia, and voltage control.