DC Side Main Circuit Parameter Selection of MMC-MTDC Systems with HVDC CBs and SFCLs

The modular multilevel converter (MMC) had shown great value in HVDC systems. One of the major obstacle that limited the usage of MMC in multi-terminal HVDC systems (MTDC) is the DC fault handling method. To minimize the impact of DC faults in MTDC, HVDC circuit breakers (HVDC CBs) was a preferred choice. Due to the limited dc current breaking capability, HVDC CBs combined with superconducting fault current limiters (SFCLs) was a potential solution. For MMC-MTDC with HVDC CBs and SFCLs, this paper proposed a DC side main circuit parameters selection method. This method included the method for selecting the parameters of the smoothing reactor and the SFCLs. This method is easy to realize and could avoid time-domain simulation. The case studies are performed on a ± 200 kV 5-ternimal MMC-MTDC system. The time-domain simulation results showed a good consistency with the calculated results. Therefore, the validity of the proposed method was proved by simulation results.