具备故障限流功能的新型线间直流潮流控制器

直流电网在发生故障时，电流会迅速增大，危及整个系统安全运行。而用于切断故障电流的直流断路器开断能力有限，需要与故障限流器配合使用。随着直流电网结构的日益复杂，潮流控制问题也日益突出。在直流潮流控制器原有的潮流控制能力上，探索其故障限流能力并提出一种具备故障限流能力的新型线间直流潮流控制器拓扑。潮流控制部分采用线间直流潮流控制器，故障限流部分采用晶闸管控制电感投入实现限流。对所提控制器的工作原理、动作过程及理论分析进行了研究，并在单端等效系统及四端柔性直流电网中进行了仿真验证。仿真结果表明，该控制器可在正常运行时控制2条线路的潮流，在某一线路单极接地故障时进行故障限流并通过与直流断路器配合完成故障电流的切除，该装置及控制策略的可行性与有效性得到验证。

Interline DC Power Flow Controller with Fault Current Limiting Function

When a fault occurs in the DC power grid, the current increases rapidly, which endangers the safe operation of the entire system. The DC breaker used to cut off the fault current has a limited breaking capacity, which needs to work with the fault current limiter. With the increasing complexity of the DC power grid structure, the problem of power flow control is increasingly prominent. Based on the original power flow control capability of the DC power flow controller, this paper explores its fault current limiting capability and proposes a novel topology of the interline DC power flow controller with fault current limiting capability. The power flow control part adopts the interline DC power flow controller, and the fault current limiting part adopts thyristors to control the inductor into service, which realizes the current limiting. The working principle, operation process and theoretical analysis of the proposed controller are investigated, and simulation verification is performed in the single-terminal equivalent system and the four-terminal flexible DC power grid. The simulation results show that the controller can control the power flow of two lines during the normal operation, limit the fault current when a pole-to-ground fault occurs on the line, and complete the clearance of the fault current by cooperating with DC circuit breaker. The feasibility and effectiveness of the device and the control strategy are verified.