适用于柔性直流电网的新型限流式直流断路器

New Current-limiting DC Circuit Breaker Suitable for Flexible DC Power Grid

混合型高压直流断路器凭借损耗低、速度快、高可靠性等优势,成为直流领域中的重要方向.而现有断路器在减少电力电子器件冗余方面的贡献有限,并且未充分挖掘断路器的故障限流潜力.为解决上述问题,文中提出一种兼备限流及开断功能的直流电网保护动作设备.利用晶闸管来替代传统断路器中IGBT的大规模使用;通过主动短路的方式进行引流,达到减小故障时线路开关的电压电流应力的效果;通过加入限流电感抑制故障电流的上升速率.最后,在PSCAD软件中将所提拓扑应用于四端柔性直流电网,并与传统直流断路器进行对比,验证了所提拓扑的有效性与经济性.

Hybrid high-voltage DC circuit breakers have become an important direction in the DC field with the advantages of low loss,fast speed,and high reliability.However,the existing circuit breakers have limited contributions in reducing the redundancy of power electronic devices,and have not fully exploited the fault current limiting potential of the circuit breakers.In order to solve the above problems,this paper proposes a DC grid protection action device with both current limiting and breaking functions.Use thyristors to replace the large-scale use of IGBTs in traditional circuit breakers;use active short-circuiting to divert current to reduce the voltage and current stress of line switches during faults;and add current-limiting inductors to suppress the rate of rise of fault current.Finally,the proposed topology is applied to a four-terminal flexible DC grid in PSCAD software,and compared with traditional DC circuit breakers,the effectiveness and economy of the proposed topology are verified.