Overvoltage Simulation of Circuit Breaker Switching off Shunt Capacitor Banks

The vacuum circuit breakers are used to switch shunt capacitors which are used as a reactive compensator. Due to capacitors' energy storage characteristic and asynchronous closing of vacuum circuit breakers, system will produce high overvoltage during switching off the shunt capacitors especially when a beaker is restriked. It's harmful to the insulation and lifecircle of the equipments and even threatens power system safe and stabile operation. This paper theoretically deduces the variation trends of both recovery voltage between the contacts and the capacitors voltage. It is given simulation of three cases that the circuit breakers are seriously restriked in one or two phases with EMTP model of a 220kV typical substation of Guangdong grid. According to the theoretical analysis, the simulation result is valid.