A Novel Fault Ride Through Strategy based on Multidimensional Information for MMC-VSC HVDC System

The large-scale development and utilization of long-distance offshore wind power is one of the most mature renewable energy technologies. More and more offshore wind farms are integrated into the onshore utility network by MMC-VSC HVDC system. Moreover, the electrochemical energy storage system is increasingly involved in power assistance services and MMC-VSC HVDC system is a better system accessing mode. The HVDC system with small capacity is mostly connected to the grid through a single AC outgoing line. And, the MMC-VSC HVDC system will work in the open-phase condition during the AC line reclosing period. The conventional AC fault ride through strategy may fail and result in outage of the MMC-VSC HVDC system. In this paper, open-phase running of MMC-VSC HVDC system is analysed and the converter control process is researched in detail. A novel fault ride through strategy based on multi-dimensional information is proposed. Simulation model is built based on PSCAD/EMTDC. Several cases are studied to verify the feasibility and validity of the proposed strategy.