Optimal breaker failure protection for potential over-limit short-circuit current

摘要

In this paper, an optimal breaker failure protection (OBFP) is proposed to deal with the risk of potential breaker failure which is caused by unpredictable over-limit short-circuit current (SCC). First of all, to avoid the severe consequence caused by directly opening the circuit breaker (CB) with unpredictable over-limit SCC, an ultrafast SCC forecasting method is adopted to detect the unpredictable over-limit SCC event. Once an over-limit SCC event is detected, any tripping signal corresponding to the CB will be temporarily blocked. The blocking signal will be kept until the SCC is reduced under the rated breaking capacity of the CB. Then the Thevenin equivalent model of the backside system interconnected to the bus is generated on-line to evaluate the effects of various potential current-limiting measures. Finally, a comprehensive strategy of OBFP consisting of multiple current limiting measures is put forward, which can reliably remove the above-mentioned extreme fault with an acceptable time delay and consequences. The effectiveness of OBFP is validated through various simulation test results.