A New Evaluation Method of Operation State for Hybrid AC/DC Double-ended MMC System

For hybrid AC-DC system based on flexible HVDC technology, how to evaluate the operation state of MMC station using the phase identified electrical information of MMC is a new problem. So the influence of transient disturbance of AC/DC transmission line on the voltage and current on each bridge arm of MMC station is analyzed. It is pointed that the energy distribution of each phase bridge arm in the converter station when transient faults occur on AC/DC transmission line is different from that in normal status. Based on this phenomenon, a novel evaluation method is proposed based on exponential entropy and gray relational analysis theory, and is used to evaluate the operation state of MMC station, which realizes comprehensive assessment on the impact of different faults on the operation state of MMC station.