Optimal configuration of Current-Limiting Devices in the Multi-Terminal MMC-HVDC Grid

With the rapid development of modular multilevel converter based high voltage direct current (MMC-HVDC) grid, the structure of the dc grid is becoming more and more complex and the optimal calculation quantity of current limiting devices is greatly increased. So achieving the optimal configuration of current-limiting devices in the complex multi-terminal MMC-HVDC grid and improve the overall optimal calculation efficiency of the complex multi-terminal MMC-HVDC grid are urgent problems to be solved. Firstly, this paper proposes a principle of area division, dividing the complex dc grid into lower coupled area II and higher coupled area I to improve the optimal calculation efficiency of current-limiting devices parameters in the multi-terminal dc grid. On this basis, corresponding methods of fault current calculation for different areas and different optimal configuration methods of current-limiting devices in each area are proposed. Finally, the validity of the proposed methods of fault current calculation and optimal configuration of current-limiting devices are verified through a two -terminal and zhangbei four-terminal MMC-HVDC grid on PSCAD/EMTDC.