A DOUBLE BUS CONFIGURATION WITH MULTI-PORT DC CIRCUIT BREAKERS FOR DC SWITCHING STATIONS

DC circuit breakers (DCCB) are recently applied to the protection of multi-terminal HVDC transmission systems. It is also possible to construct a DC switching station using multiple DCCBs. Double bus system has been used in AC switching stations to improve the reliability. Although the double bus system can also improve the reliability of DC switching stations, it increases the number of required DCCBs, causing the increase of costs. This paper proposes a double bus configuration for DC switching stations to improve the reliability. The proposed double bus system consists of two multi-port DC circuit breakers (MP-DCCB), which can reduce the number of DCCBs compared to the conventional double bus configuration. Simulation results verify that the system can continuously transfer 75 % of the initial power even after a bus fault and recover the power to the pre-fault value after operating the disconnecting switches.