Research on influences to reduce the commutation failure of different topology structures of STATCOM

In the unbalanced condition, theoretical derivation of STATCOM circulating current with MMC topology is presented. The current of cascade STATCOM using separate phase control is calculated. The research analyzes influence factors of commutation failure in multi-in feed HVDC system, and studies the influence of STATCOM to the running function of the HVDC system. Different topology structures of STATCOM have different influences to reduce the commutation failure, which provides the technical support of the design of the main circuit of STATCOM equipment. Finally, the paper chooses a main circuit topology of STATCOM providing a rapid response to the danger of commutation failure.