Overvoltage management of SF6 circuit breaker switching for 66kV parallel capacitor bank based on ATP-EMTP

The purpose of this study is to investigate the overvoltage management methods during the process of shunt capacitor bank throwing at 66kV by SF₆ circuit breakers and to compare different schemes. First, the background and objectives of the study, i.e., the overvoltage problems that may be caused during the shunt capacitor bank throwing, are introduced. Then, the principles of phase-controlled circuit breaker and series resistance schemes are elaborated. A capacitor throwing simulation model was constructed by ATP-EMTP, and numerical simulations were performed. The comparative analysis results show that the phase selection operation of circuit breaker throwing can meet the inrush current limiting effect when closing, but cannot limit the overvoltage after reignition of breaking, and there are problems of high technical requirements and high cost in practical application. Compared with this, series resistance program in the cost and simplicity of implementation is more advantageous. Taking into account the technical and economic aspects, it is concluded that the series resistance scheme is more desirable at this stage.