Controlled Breaking Strategy of Shunt Reactor Based on Fast Vacuum Switch

At present, it is all three-phase simultaneous breaking when conventional vacuum circuit breaker breaks a 35KV shunt reactor. The traditional breaking method often produces serious switching overvoltage phenomena, which in turn causes equipment fault. All research experiments have shown that the main factor generating overvoltage is the continuous reignition of the first opening phase and the equivalent chopping current of the last two clearing poles during the breaking period, that is, the simultaneously breaking overvoltage of three phases. In the paper, the electromagnetic transient model for breaking 35 k V shunt reactor is set up by the use of PSCAD/EMTDC, and the overvoltage mechanism was simulated and analyzed. For the overvoltage caused by three-phase simultaneous breaking, phase-controlled switching strategy based on fast vacuum switch was proposed in the paper, which uses the fast vacuum switch and phase-controlled switching technology. The last two clearing phases are opened until the first opening phase is successfully broken. It is hoped that the probability of reignition of the first opening phase and equivalent chopping current of the latter two clearing phases are reduced fundamentally, which makes it possible to eliminate the switching overvoltage to the utmost extent.