1.State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University), Beijing 102206, China;2.University of Electronic Science and Technology of China, Zhongshan 528400, China
This work is supported by National Key R&D Program of China (No. 2018YFB0904600) and National Natural Science Foundation of China (No. 51777072).
With the increase of voltage and capacity of high voltage direct current (HVDC) system, the requirement for rapid clearance and isolation of DC faults is getting higher and higher. As the most effective solution, hybrid DC circuit breaker is not mature enough, which restricts its engineering application. Accordingly, this paper proposes a low-cost DC fault clearance scheme suitable for clearing fault in DC grid. In this scheme, the traditional half-bridge modular multilevel converter (MMC) is partially innovated to have the ability of auxiliary breaking operation. With the effect of the MMC auxiliary breaking operation at both ends of the fault line, the DC fault current can be quickly interrupted and isolated by low-cost circuit breaker unit installed in the DC transmission line. The equivalent circuit in the fault isolation process is modelled and analyzed, and the fault isolation sequence is designed. Furthermore, the comparative analysis of devices usage among typical schemes is performed. Finally, a simulation model with the proposed scheme is built, and an MMC prototype is developed. The simulation and experimental results validate the effectiveness of the proposed scheme.
ZHAO Chengyong,LI Shuai,ZHANG Jiyuan,et al.An Augmented Modular Multilevel Converter for Clearing Fault in DC Grid[J].Automation of Electric Power Systems,2020,44(5):60-67.DOI:10.7500/AEPS20190128005Copy