Fault current suppression for MMC-MTDC with the resistive type superconducting fault current limiter

Abstract

With effective properties, a resistive-type superconducting fault current limit (R-SFCL) has become an effective device to restrain DC-side bipolar short fault currents in multilevel modular converter multiterminal DC systems (MMC-MTDCs). However, due to the resistance-energy accumulation-dependent characteristics of the R-SFCL device, the fault durations and different fault current values will produce various output resistances at each fault stage, and the related coordinated protection and control strategy needs to be adjusted accordingly. Therefore, in the first part of this paper, we analysed the DC side short circuit current mechanism and the fault current restraint characteristics of R-SFCLs. Subsequently, to verify the above analysis, the R-SFCL-based four-terminal MMC-MTDC with DC bipolar short fault modelling and simulation are presented in the next section. Finally, based on the above analysis and research, the advanced DC bipolar fault control and protection strategies of the R-SFCL-based MMC-MTDC system are discussed to promote further study of coordinated and protection control and the application of R-SFCLs in subsequent engineering applications.