Modeling and Analysis of Short-Circuit Fault Current for MMC-HVDC Grid with DC Circuit Breaker

DC line fault is one of the important factors restricting the development of flexible DC system. DC circuit breaker is an effective means to realize the short circuit fault isolation on DC side of flexible DC system. Therefore, it is necessary to add DCCB into the short-circuit current calculation and modeling of MMC-HVDC power grid for comprehensive analysis. Firstly, the external characteristics of the hybrid HVDC circuit breaker and the modular multilevel converter (MMC) are modelled. Then, the modeling of short-circuit fault current in different stages was analysed. The analysis method of short circuit fault current of four-terminal MMC system with DC circuit breaker is obtained. Finally, the simulation results and the calculation results are compared and results show the effectiveness of the short-circuit calculation method proposed by this paper.