China's normal speed electrified railway mainly adopts the double-track direct power supply mode. The feeder protection devices of major domestic manufacturers adopt the reactance method to locate the fault point based on the reactance-distance table in case of single-track fault. Due to the influence of mutual inductance between the up-line and down-line, the reactance values detected at the feeder port of the substation under single-track fault and double-track fault are not equal. When the fault occurs on double-track traction network, the reactance-distance table in case of single-track fault will cause large fault location error, and the up-line and down-line current ratio method will also be affected by the non-uniformity of electrical parameters of the traction network. The circuit model of the double-track direct power supply traction network with station yard is analyzed in this paper. The reasons for the inaccuracy of the up-line and down-line current ratio fault location method are analyzed and an improved application scheme of the up-line and down-line current ratio fault location method is proposed. The accuracy of the scheme is verified based on Matlab/Simulink simulation model.

double-track power supply traction network;fault location;reactance method;up-line and down-line current ratio method