Research on Coordination and Optimal Configuration of Current Limiting Devices in HVDC Grids

This paper proposes a collaborative optimal configuration method of current limiting reactors (CLRs) and fault current limiters (FCLs) in the modular multilevel converter (MMC)-based high voltage direct current (HVDC) grids. The calculation methods of dc line fault currents and bridge arm fault currents considering the collaboration of CLRs and FCLs have high accuracy. The multi-objective optimization configuration model is established, in which the fault current limiting effect, the total inductances of CLRs and the number of FCLs are used as objective functions while the DCCBs current breaking capacity, the converter valves overcurrent protection, the boundary of the dc line protection area, the dynamic performance of the dc system and the converter station outlet dc voltage are used as constraints. In this paper, the multi-objective optimization algorithm is used to solve multi-objective optimal configuration problem for the CLRs and FCLs. Finally, the proposed method is tested with a symmetrical monopole four-terminal MMC-HVDC grid in PSCAD/EMTDC. The simulation results verify that the proposed optimal configuration method can ensure the continuous and reliable operation of the dc grid under dc faults.