Black Start

Who can participate?

Service Description

Black Start is the procedure to recover from a total or partial shutdown of the transmission system which has caused an extensive loss of supplies. This entails isolated power stations being started individually and gradually being reconnected to each other in order to form an interconnected system again.

In general, all power stations need an electrical supply to start up: under normal operation this supply would come from the transmission or distribution system; under emergency conditions Black Start stations receive this electrical supply from small auxiliary generating plant located on-site. Not all power stations have, or are required to have, this Black Start capability. Black Start capability is usually a consideration when the plant is being built.

Why is it needed?

The likelihood of a total or partial system shut-down occurring is considered remote.. However, it is the case should a total or partial shut-down occur anywhere on the transmission system that arrangements must be in place to enable a timely and orderly restoration of supplies.

The need to contract for black start at an individual location will largely be driven by current arrangements at other nearby power stations, the expected longevity of such contracts and the implications involved in improving system restoration.

Major Technical Requirements

Irrespective of the type of plant installed to provide a Black Start service, the following technical capabilities are required:

• The ability to start up the main generating plant (at least one unit / module) of the power station from shutdown in agreed timescales without the use of external power supplies;
• The capability to energise part of the National Grid Transmission System or, if appropriate, the host Distribution System within two hours of instruction from National Grid;
• The capability to accept instantaneous loading of demand blocks, ideally in the range 35 to 50 MW, and controlling frequency and voltage levels within acceptable limits during the block loading process (under these conditions, frequency will be within the range 47 to 52 Hz);
• The ability to provide at least three sequential Black Starts, within two hours, to allow for possible tripping of the Transmission / Distribution System(s) during the re instatement period;
• Back-up fuel supplies (e.g. distillate fuel) to enable the power station to run for a minimum duration, ideally in the range 3 to 7 days, following a Black Start instruction;
• Mains independent barring and jacking facilities on all generating units. This facility needs to be independent of the Black Start auxiliary units and must be able to operate for a minimum period of 20 minutes after the loss of external supplies;
• The ability to maintain a high service availability on both the main and auxiliary generating plant (typically 90 - 95%); and
• The reactive capability to charge the immediate Transmission / Distribution System(s). This capability will depend on the local system configuration, but generating plant connected at 400kV or 275kV with a capability of at least 100Mvar leading (as measured at the commercial interface) should almost invariably meet this requirement.

Procurement Process

Generally, National Grid expresses interest in procuring the black start service from new power stations during the Connection Agreement process. However National Grid may also express interest in determining the feasibility of retro-fitting black start capability to existing power stations.

Regular inspection and testing of all the associated station plant on both the main and auxiliary generating units is required. Testing is carried out in accordance with the Grid Code and the specific Commercial Services Agreement.

Payment

Payment Structure:
Black Start providers are paid an agreed fee per settlement period for their availability and an Utilisation payment both for testing purposes and in the event of a Black Start. The payments will depend on a number of factors including what plant has been instructed, whether all the plant is registered as BMU and what type of fuel was required. In a Black Start situation, payments for energy provided are dealt with under the BSC.

BSAD: Not Applicable

ABSVD: Not Applicable

Summary of Further Information
Grid Code Operating Code OC5.5.4 – Black Start Testing