Abstract: Aiming at the problems of high cost and poor voltage quality in the conventional power distribution

scheme of long-distance electrical equipment of rail transit，a technical scheme of DC power distribution for longdistance electrical equipment was proposed to achieve the purpose of improving voltage quality and reducing project cost. First of all，combining with the characteristics of long-distance electrical equipment of rail transit，such as many types，wide distribution and high reliability requirements，the key technologies such as voltage level，power supply capacity and topology structure of DC power distribution system were deeply analyzed. Then，the design principles and calculation methods were given for the key parameters of the converter suitable for low-voltage power distribution. On this basis，a voltage coordination control strategy was proposed to ensure the stability of the voltage.Finally，the effectiveness of the proposed technical scheme was verified based on PSCAD/EMTDC simulation. Iaddition，considering the different distribution distances of electrical equipment，the engineering cost of the conventional scheme and the DC scheme was compared. The research results show that the economic advantage of DC power distribution is obvious. In the future，the technical scheme has certain guiding value for the planning and design of long-distance power distribution of rail transit.

      Key words: rail transit；long-distance power distribution；DC power distribution scheme；modular multilevel

converter （MMC）；voltage control strategy