Design of Commutation Circuit for DC Vacuum Circuit Breaker Based on NSPSO

For a mechanical direct current vacuum circuit breaker,in order to successfully break the fault current,it is necessary to introduce commutation circuit to make artificial current zero point.The operation of DC vacuum circuit breaker,equipped with the self-designed 30 kV/8 kA commutation circuit,was empirically approximated,mathematically modeled,theoretically analyzed and numerically simulated in non-dominated sorting particle swarm optimization algorithm.The influence of the multi-variables involved inductance,capacitance and pre charging voltage of capacitance,at the same time,the competition between the thickness of the sheath and the vacuum gap is considered,on the simultaneous minimization of the capacitance and pre charging voltage was investigated for design optimization.In addition,the dependence of the commutation circuit characteristics,including the commutation frequency,changing rates of current and voltage at current zero,on the topology design and variable selection of the commutation circuit was evaluated.The results show that compared with the traditional particle swarm optimization single objective optimization,the multi-objective design is beneficial to balance the contradiction between breaking performance and design cost of DC VCB.