Abstract When a fault occurs on the line equipped with Unified Power Flow Controller (UPFC) based on Modular Multilevel Converter (MMC), it may cause the blocking of MMCs and then make UPFC out of operation. To avoid the non-function of UPFC under the condition of external fault, a UPFC fault ride-through (FRT) strategy is proposed based on the analysis of fault characteristic. The FRT strategy is realized by adding virtual impedance (VI) loop in the Shunt Side MMC control process and connecting a Current Limiting Reactor (CLR) on the DC bus to limit the valve-side current of shunt side and the fault current fed through the DC bus from the Series Side MMC. Furthermore, the evaluating indicators and the value selected method for VI and CLR are provided, and the values of VI and CLR are discussed. Finally, simulation results based on PSCAD/EMTDC verify the fault characteristic and the effect of proposed FRT strategy.

中文翻译：

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基于虚拟阻抗和限流电抗器的UPFC故障穿越策略

摘要 当装有基于模块化多电平转换器（MMC）的统一潮流控制器（UPFC）的线路发生故障时，可能会导致MMC闭锁，进而导致UPFC停止运行。为避免UPFC在外部故障条件下失效，在分析故障特征的基础上，提出了UPFC故障穿越（FRT）策略。FRT策略是通过在并联侧MMC控制过程中加入虚拟阻抗（VI）回路，并在直流母线上连接限流电抗器（CLR）来限制并联侧阀侧电流和馈入的故障电流来实现的。来自串联侧 MMC 的直流总线。进一步给出了VI和CLR的评价指标和取值方法，并对VI和CLR的取值进行了讨论。最后，