基于电容换流的高压直流断路器研究

Research on HVDC Circuit Breaker Based on Capacitor Commutation

柔性直流电网技术面临快速隔离直流侧故障的巨大挑战,直流断路器被认为是直流故障隔离的有效解决方案。针对高压直流断路器普遍存在的直流故障隔离速度慢、换流站侧提供短路电流的水平高等问题,提出了一种新型高压直流断路器拓扑,利用基于电容的换流支路为断路器的可靠、快速分断创造条件,能够快速隔离直流故障,有效限制短路电流水平,降低直流故障对换流阀的冲击。描述了拓扑的结构及工作原理,对故障分断过程进行了理论分析;分析了两种分断策略与拓扑参数的影响关系。通过仿真平台搭建高压直流断路器仿真模型,仿真结果验证了所提直流断路器拓扑隔离直流故障的有效性。

The VSC-HVDC power grid faces a great challenge of rapidly isolating DC fault. DC circuit breaker is an effective solution for DC fault isolation. In view of the existing difficulties of the DC circuit breaker, such as low isolation speed of short-circuit fault, high-level injection of short-circuit current by converter station side, we proposed a novel topology of HVDC circuit breaker, which uses capacitor commutated branches to create reliable and fast breaking conditions for this topology. The topology can quickly isolate DC short-circuit fault, limit the level of short-circuit current effectively, and reduce the impact of short-circuit fault on converter valves. Moreover, we described the structure and working principle of the topology, and analyzed the breaking process theoretically. Meanwhile, we analyzed the influences of two different interrupting strategies on parameters design. Finally, the topology is modeled in MATLAB/Simulink, the simulation results verify the effectiveness of the proposed topology on isolating DC fault.