应用附加电容的柔性直流输电线路自适应重合闸策略

针对柔性直流输电线路在故障跳闸后线路健全极与故障极不存在耦合关系和基于感应电气量变化特征的重合闸判据难以适用的问题,提出一种基于附加电容放电电压变化特征的柔性直流输电线路自适应重合闸策略。在直流线路跳闸后投入附加电容器,构建附加电容放电的数学模型,分析故障消失前后附加电容放电电压特征的差异。结合该差异设计出能有效识别永久性故障和瞬时性故障的柔性直流线路故障性质识别新判据,基于此故障性质识别判据实现对线路的重合闸。最后利用PSCAD/EMTDC平台搭建了线路模型,仿真验证了所提柔性直流输电线路自适应重合闸策略的有效性与可靠性。

Adaptive reclosure scheme of MMC-HVDC transmission lines using additional capacitors

For the MMC-HVDC transmission line after the faulty trip, there is no coupling relationship between the line integrity pole and the fault pole, which makes the reclosing criterion based on characteristics of induced electrical quantities are difficult to apply. Thus an adaptive reclosing strategy for MMC-HVDC transmission lines based on the characteristics of additional capacitor discharge voltage variation is proposed. The additional capacitor is switched on after the DC line trips to construct the mathematical model of the additional capacitor discharge and then analyze the difference of the characteristics of the additional capacitor discharge voltage when there is fault and the fault disappears. Combined with the difference, a new criterion for fault property identification of the flexible DC line is designed to determine the permanent fault or the transient fault. Based on the fault characteristic identification method, the reclosing of the line is realized. Finally, the circuit model is built based on PSCAD/EMTDC to verify the validity and reliability of the adaptive reclosing strategy of the MMC-HVDC transmission line. This work is supported by National Natural Science Foundation of China (No. 51877185).