The delay optimization of circuit breaker failure protection based on the CT current tail truncation algorithm

Circuit breaker failure protection (CBFP) is a widely used back-up protection in electrical power system. To avoid maloperation, the CBFP needs a long delay to confirm the status of the circuit breaker, which means the cut off time will be long, sometimes too long to keep the stability of the power system. Therefore, it is very important to propose an optimized method to calculate the CBFP delay time for improving the stability of the system. A CT current tail truncation algorithm based on a CT tailing current-short circuit current criterion plane has been shown in this paper, which can truncate CT tailing current quickly and thereby shorten the delay of CBFP. Without special configuration of P level CT, this algorithm ensures the reliability and rapidity of CBFP, significantly reduces the risk of system operation, and has good economic benefits.