高压直流断路器快速限流控制

Fast Current Limiting Control of High Voltage DC Breakers

高压直流断路器能够隔离系统故障,使得直流电网在一条线路发生故障时无需闭锁所有换流站,不影响其他线路的正常运行,是构建直流电网的关键设备。一种具有限流控制功能的混合式高压直流断路器,能够在系统故障时将故障端电流维持在固定值周围,为系统其他控制策略的进行争取时间。该文首先分析了高压直流断路器的无弧分断和限流控制原理,随后提出一种快速限流控制方法,加快了高压直流断路器的分断以及避雷器的投入,降低了故障电流峰值大小,减少了限流过程中避雷器吸收总能量。最后,通过PSCAD/EMTDC仿真分析,验证了该控制方法的有效性。

The high voltage DC circuit breaker could isolate healthy sections in DC grids from sections with faults, which avoids the blocking of all converters and has the healthy sections unaffected during the fault, and therefore it is the key equipment of the DC power grid. A hybrid high voltage DC breaker with current limiting function could keep the fault current fluctuating around a reference value, and then an additional time is provided for the grid-wide protections to select the appropriate protection actions. The arcless breaking and current limiting control was analyzed first, and then a fast current limiting control was proposed. It accelerates the breaking of the high voltage DC breaker and operating of arrestors, so the fault current spike and energy absorbed by arrestors is lowered. Finally, the simulation results in PSCAD/EMTDC show that the proposed fast current limiting control is effective.