DC fault management for VSC MTDC system using delayed-auto-re-configuration scheme

With the growing maturity of power electronic devices, the applications of the voltage source converter (VSC) technique on the high-voltage direct current (HVDC) transmissions have attracted great attention. Due to the inherent control characteristics of the VSC, the realization of multi-terminal HVDC (MTDC) grids becomes less complicated. However, one significant issue that restrains the development of VSC MTDC grids is the proper management against DC faults. This paper proposes a DC fault management scheme, delayed-auto-re-configuration (DARC), for VSC MTDC systems. This scheme does not require additional component to be added to the existing system. With appropriate protection and control, the MTDC system can be well protected and after the isolation of the faulted line section, the unfaulted terminals will be controlled and recovered to form a new MTDC configuration. The effectiveness of the proposed scheme is validated by simulations using the real-time digital simulator (RTDS).