基于桥臂电抗器耦合的MMC-HVDC系统故障过流抑制方法

直流侧双极性短路故障作为模块化多电平换流器高压直流输电系统最严重的故障之一，会导致换流器桥臂发生严重的过流，威胁系统的安全。为了抑制该过流，文中提出了一种利用桥臂电抗器耦合抑制故障过电流的方法，将模块化多电平变流器同一相中上臂和下臂的电抗器耦合在一起来抑制短路电流。通过仿真从三个方面客观的评价了该仰制方法。结果表明，该方法可以有效降低损耗，双极故障时有效抑制故障电流的增加，为保护赢得时间。

based on bridge arm reactor coupling MMC-HVDC system fault over current suppression method

As one of the most serious faults of the modular multilevel converter HVDC system, the dc side bipolar short circuit will lead to serious overcurrent of the converter bridge arm and threaten the safety of the system.In order to suppress the overcurrent, a method of using bridge arm reactor coupling to suppress the fault overcurrent is proposed.Suppress short-circuit current by coupling the reactors of the upper arm and lower arm in the same phase of the modular multilevel converter.The method is evaluated objectively from three aspects through simulation.The results show that the proposed method can effectively reduce the loss and inhibit the increase of fault current in bipolar fault, thus gaining time for protection.