Optimal design of gas circuit breaker for increasing the small current interruption capacity

This paper describes the optimal shape design of gas circuit breaker to improve the small current interruption capability. The objective function is the minimal difference between the withstanding voltage and the applied voltage. To obtain the dynamic gas properties, the axisymmetric Euler equations are solved using the finite volume fluid-in-cell method and the withstanding voltage is calculated from the gas density and electric field intensity. The (1+1) evolution strategy is employed as the optimization tool. The optimization procedure is applied to the 170-kV gas circuit breaker model and an optimized model has considerably improved interrupting performance.