Online identification of protection element failure using wide area measurements

Fault in a power system is cleared by a protection scheme which comprises of different components such as relay, circuit breaker and accessories. Collective action of all elements in a protection scheme is necessary to correctly identify and isolate a fault selectively. Failure of any element in such a protection arrangement may lead to unwanted line trip risking further outages in the network. This work proposes a wide area measurement system (WAMS) data-based technique for online identification of failure of protection element for a transmission line. Synchronised voltage-current phasors along with relay decision and circuit breaker status signals are used to calculate indices which identify the failed component. The proposed method is tested for 39-bus New-England system and found to be accurate.