Scheme of failure protection for HVDC circuit breakers in MMC HVDC grid
PENG Fa xi1, DENG Yin qiu1, WANG Zhen1, ZHENG Chao2, SONG Yun ting2
(1.College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China;
2.China Electric Power Research Institute, Beijing 100192, China)

Abstract: Aiming at solving the problem of fast DC fault clearing in HVDC grid based on MMC (MMC HVDC), the principle of MMC HVDC and three main isolation techniques of DC faults were studied. By comparing three technical routes of HVDC circuit breaker (DCCB), the hybrid DCCB was used to interrupt DC faults. The topology and DC fault isolation process of a hybrid DCCB were studied. Referring to the failure protection strategy in AC grid, a scheme of failure protection for HVDC circuit breaker in MMC HVDC grid was proposed. A four terminal MMC HVDC grid was used to verify the feasibility of the proposed strategy in PSCAD/EMTDC platform. The results indicate that the proposed scheme can order adjacent DCCBS to interrupt DC faults completely and clear fault current if a DCCB fails to act.

Key words: MMC HVDC grid; modular multilevel converter (MMC); hybrid DCCB; DC fault; failure protection