The Electricity Capacity Regulations 2014

PART 2 Reliability standard

Reliability standard

6.—(1) The reliability standard is 3 hours of expected loss of load per capacity year.

(2) In paragraph (1), “the reliability standard” means the cumulative duration of periods in a capacity year in which it is to be presumed—

(a) by the Secretary of State in—

(i) making any decision about whether a capacity auction (other than a DSR transitional auction) is to be held; and

(ii) setting auction parameters for such a capacity auction; and

(b) by the Delivery Body in making any recommendation in an electricity capacity report,

that, on average over the long term, loss of load should occur.

(3) For the purposes of this regulation, “loss of load” occurs if—

(a) the national system operator instructs one or more distribution network operators to disconnect customers, or to reduce the voltage on all or part of their network;

(b) the national system operator takes emergency action to avoid disconnections or voltage reductions; or

(c) automatic low frequency demand disconnection takes place,

but not if the action referred to in sub-paragraph (a), (b) or (c) takes place solely because of one or more faults in the GB transmission system or a distribution network.

(4) In paragraph (3)(b), “emergency action” means—

(a) instructing a generator to increase the generation of electricity by a generating unit to its maximum output, otherwise than in accordance with a bilateral contract between the national system operator and that generator; or

(b) securing the transmission of electricity to Great Britain through an electricity interconnector, where—

(i) the electricity would not have been so transmitted without the national system operator’s action; and

(ii) the primary purpose of the action is to avoid disconnections or voltage reductions.

(5) Where an event referred to in paragraph (3) occurs, the period of loss of load is the time—

(a) from the national system operator issuing an instruction under paragraph (3)(a) or (4)(a) it until it withdraws that instruction (or, if the national system operator issues two or more such instructions for overlapping periods, from it issuing the first of those instructions until it withdraws the last of them);

(b) during which electricity is transmitted through an interconnector as mentioned in paragraph (4)(b); or

(c) where automatic low frequency demand disconnection takes place, from demand being disconnected until the national system operator issues an instruction to reconnect that demand.

(6) In this regulation, “automatic low frequency demand disconnection” has the meaning given in the Grid Code as it was in force on 1st April 2014 (see section OC6.6 of that code).