电流换相H桥型混合式直流故障限流器

A Current-Commutation-Based H-bridge Type Hybrid Fault Current Limiter

半桥型模块化多电平换流器构成的直流电网在发生故障时,存在成本与切断速度之间的矛盾。在不限制故障电流时,直流侧故障难以清除。该文提出一种新型适用于抑制直流侧故障电流的H桥型混合式故障限流器拓扑。正常运行时负载电流通过低损耗支路通流,故障后电流流过换相支路实现限流过程。换相支路由晶闸管、换相电容、限流电感和4组H桥型二极管所组成。文中对所提限流器的工作原理、控制模式、电气应力和工程设计进行详细研究,并在单端换流站和四端直流电网中进行仿真验证。研究表明,所提限流器能够有效抑制电流增长,并具有良好的经济性,验证了理论分析的正确性和限流方案的可行性。

The fault of the DC grid to be cleared exists challenges between cost and cutting speed by the half-bridge modular multilevel converter(MMC).The fault is difficult to be cleared without fault current limitation.A novel topology of H-bridge hybrid fault current limiter(FCL)was proposed to suppress DC side fault current.In this topology,the load current flows through the low-loss branch at steady state,and the current flows through the commutation branch after the fault to realize the current limiting process.The commutation branch consists of thyristor,commutation capacitance,current-limiting inductance and four groups of H-bridge diodes.The principle,control method,electrical stress and preferences of the proposed limiter have been studied,and the simulation verification was carried out in single-terminal converter station and four-terminal DC grid.It is shown that the proposed FCL is suitable for HVDC transmission with effective current limiting result and economic efficiency.The simulation results show the correctness of the theoretical analysis and the feasibility of the current limiting scheme.