Research on Isolation Scheme of A Distribution Power Network With MVDC- Flexible Interconnection Based on MMC

To solve the problem of low reliability of the traditional AC distribution network, the use of DC technology can be used to realize the flexible interconnection and closed loop operation. Especially, MVDC-flexible system based on multi-module converter (MMC) can significantly improve the power supply reliability and the ability to accept distributed energy and energy storage. However, the influence of fault condition and imbalance of three phase voltage can transfer to further system if interconnection with MVDC-flexible system can not isolate them. Thus, in the research, the different technical isolation schemes of A MVAC distribution network with MVDC-flexible interconnection was compared and studied. The use of DC transformer solutions and its future development potential was focused on.