Abstract：During the operation of high-voltage DC power grid，due to factors such as load characteristics and

voltage fluctuations，the instantaneous power characteristics such as capacitor current and harmonics are more

complex，which increases the difficulty of identifying faults in the power grid system. Therefore，a bipolar short

circuit fault identification technology for high-voltage DC power grids considering instantaneous power

characteristics was proposed. By establishing a topology model of the high-voltage DC power grid，the bipolar

short circuit fault of the high-voltage DC power grid was anlyzed. Based on the instantaneous power characteristics

of the endpoints of the high-voltage DC power grid，the area where the bipolar short circuit fault occurs

was determined. Using the maximum value positioning method of dual terminal fault current to obtain bipolar short

circuit fault location，the fault identification of bipolar short circuit in high-voltage DC power grid was completed.

The experimental results show that the proposed method has high accuracy in locating and identifying bipolar short

circuit faults in high-voltage DC power grids，and the efficiency of fault identification is improved.

      Key words：high-voltage DC power grid；instantaneous power；bipolar short circuit；maximum current positioning method；modular multilevel converter （MMC）；fault identification