交流系统故障时多端柔性直流系统的控制策略

Control Strategy of Multi-terminal VSC-HVDC System for AC System failure

介绍了柔性直流的控制方式,搭建了一个三端柔性直流输电系统模型,给出了各个换流站的控制方式,并对定直流电压控制端交流系统故障时直流过电压的原因进行了仿真分析,提出了一种基于交流电压检测的控制模式转换策略,同时对模式转换逻辑控制电路进行了设计,在PSCAD/EMTDC上进行了不同故障类型的仿真验证,结果表明该方法能够有效地抑制直流过电压,促使系统成功穿越故障,为多端柔性直流输电系统定直流电压控制端交流系统故障提供了一种参考控制方法。

This paper introduces the control mode of VSC-HVDC,constructs a VSC-MTDC system with three terminals,defines the control modes of various converters,and simulates for the reason of DC over-voltages under AC system fault of DC voltage control side.Then a mode switching control based on AC voltage detection is presented and the logic control circuit of mode conversion is designed.Finally,simulations in PSCAD / EMTDC are conducted to verify various faults,and the results show that the method can effectively inhibit DC over-voltage and help the system ride through fault successfully,providing a reference for multi-terminal VSC-HVDC under AC system fault of DC voltage control side.