Reducing the power system restoration time has always been an important topic in power system research. For AC/DC hybrid systems, if the rapid regulation ability of HVDC is utilized in the early stage of black start, the restoration time can be reduced. This paper proposes a HVDC startup strategy while considering HVDC lines and explores their control flexibility in the black start process. The requirement on the minimum short-circuit ratio (SCR) is presented based on the concept of critical short-circuit ratio (CSCR) under non-rated state. The maximum transmittable power of HVDC is obtained using the short-circuit ratio of the system. The feasibility of the proposed HVDC startup strategy is proved through numerical simulation on the IEEE 24-bus test system and the black-start scheme that including HVDC startup can significantly reduce the system restoration time.

HVDC,power system restoration,restoration time,black start