Optimization Study of Breaker Failure and Dead zone Protection in Two-thirds Wiring Mode

Aiming at the problem that 450ms is needed to isolate the AC system breaker failure and dead zone fault in the extra-high voltage AC/DC hybrid system, which may lead to the multiple consecutive commutation failure in the multi-circuit DC system and thus seriously threaten the stability of the system, the composition of the isolation time of the AC system breaker failure and dead zone fault in the existing 3/2 breaker is analyzed, and the distributed fast breaker failure and dead zone protection system integrated by string is proposed. By optimizing the breaker failure and dead zone protection logic, simplifying the circuit, shortening the transmission time of the remote trip command and improving the logic of the remote trip protection, and reasonably reducing the redundancy delay of multiple links, the resection time of breaker failure and dead zone faults is shortened from 450ms to 200ms under the premise of guaranteeing the reliability. The simulation and test results show the correctness of the theoretical analysis and the effectiveness of the optimization strategy.