混合式直流故障限流器改进拓扑及其参数设计方法

故障限流器可以有效保障设备安全和柔性直流电网的可靠故障穿越，是柔性直流电网故障处理的核心技术之一。为消除传统限流电感对系统暂态响应速度及运行稳定性的不利影响，提出一种基于电感电阻混合拓扑结构的新型混合式直流故障限流器，在系统发生故障后以电感与电阻并联的方式实现故障限流。与现有的直流故障限流器相比，所提混合式直流故障限流器有效减少了拓扑中的晶闸管数量，造价成本大幅降低。同时小信号模型分析表明，电感两端并联的电阻能够有效消除限流电感对系统暂态响应和稳定运行的不利影响。最后，在PSCAD/EMTDC仿真平台上搭建了四端环状柔性直流电网，充分验证了所提方法在保障限流效果的基础上能够有效改善系统的运行稳定性。

Improved topology of hybrid DC fault current limiter and its parameter design method

Fault current limiter can ensure the safety of equipment and reliable fault ride-through of flexible DC grid, which is one of the core technologies of flexible DC grid fault handling. A new type of hybrid DC fault current limiter based on inductor-resistor hybrid topology structure is proposed to eliminate the adverse effects on the transient response speed and operation stability of the system caused by traditional current limiting inductor, which can limit the fault current with the parallel connection of inductance and resistance after fault happened in system. Compared with the existing DC fault current limiter, the number of thyristors in the topology is reduced effectively in the proposed hybrid DC fault current. Consequently the construction cost is greatly reduced. Meanwhile, the small-signal model analysis shows that the adverse effects on the transient response and operation stability of the system caused by the current-limiting inductor can be eliminated effectively by the resistance connected in parallel at both ends of the inductor. Finally, a four-terminal ring-shaped flexible DC power grid is established on PSCAD/EMTDC simulation platform, which fully verifies that the operation stability of the system is improved effectively by the proposed method on the basis of guaranteeing the effect of current limiting.