State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University), Beijing 102206, China

A general design method is proposed for the optimization of current limiting reactor in the multi-terminal DC(MTDC)power grid. The minimization of the total current limiting reactors installed in the system is determined as the design objective, and the constraints of DC circuit breaker, converter blocking and protection requirements are considered. The optimization algorithm is used to determine the optimal allocation of current limiting reactors. The proposed design method can reduce the adverse impacts of large reactors, and enables the continuous and reliable operation during fault ride-through. Furthermore, since the approximate model of fault currents calculation for MTDC is used, the calculation efficiency is improved greatly. At last, a three-terminal modular multi-level converter(MMC)based DC power grid is modeled based on PSCAD/EMTDC simulation platform, and the simulation results verify the effectiveness of the proposed method.