Control of the central sectionaliser in a wide area back-up protection expert system

The concept of tripping control of the central sectionaliser to achieve selectivity in the wide area backup protection expert system [J.C. Tan et al. (2000), J.C. Tan et al. (2000), J.C. Tan et al. (2001)] (BPES) is described in the paper. The BPES is an innovative intelligent system designed to provide back-up protection to a region of a transmission network using decisions derived from an action factor based expert decision system. The paper will illustrate how the central sectionaliser is identified and how the opening of the central sectionaliser leads to current redistribution when a fault exists on the network. This redistribution of current contributes to the identification of the faulted component. A busbar sectionaliser will be identified as the central sectionaliser if it involves the most number of lines most likely to be affected by the fault. An example will be included to demonstrate how control of the central sectionaliser was integrated into the BPES system. This is used to achieve selectivity of fault clearance for a fault only detected by a number of zone 3 distance elements on the south-western part of the UK national grid system.