SWITCH-ON FAULT DETECTION IN RELAY BASED ON TRAVELLING WAVES

Travelling waves are generated when circuit breaker operates. Reliability of protective relaying based on travelling waves is disturbed by this kind of operation. To resolve this problem, properties of switch-on induced travelling waves under different conditions are analyzed in detail in this paper. New method is proposed and implemented by wavelet transform to discriminate whether circuit breaker is closed to fault transmission line or not. The scheme can not only distinguish switch-on fault on transmission line, but also indicate fault location if permanent fault occurs. Various EMTP simulations proved the correction and feasibility of this new method.