Environmentally Friendly Generator Circuit Breaker Based on Vacuum Switch and Air Circuit Breaker

Different from the fault current fed by system, the fault current fed by large synchronous generator presents severe delayed current zero phenomenon, requiring generator circuit breaker (GCB) to damp the fault current to cross zero and withstanding high transient recovery voltage (TRV). At present, SF6 interrupters are commonly used in GCB with large capacity, using SF6 arc resistance to damp the current and withstand TRV. However, SF6 gas can severely exacerbate the greenhouse effect, and SF6 type GCB has long been monopolized by companies such as ABB and Alstom. To avoid the use of SF6 gas in GCB, considering the high arc voltage of air circuit breaker (ACB) and fast dielectric recovery speed of vacuum switch (VS), topology and working strategy of an environmentally friendly GCB with ACB and VS connected in series are proposed. The use of ACB is expected to damp the fault current to cross zero swiftly, and VS to withstand the high TRV. Simulation verifications have been carried out in PSCAD/EMTDC. Research shows that the use of 24kV VS and 1.5kV ACB in series can enable the GCB to be a feasible alternative to SF6 type GCB.