Damage to the metro rail ground insulation will lead to the reduction of the transition resistance, resulting in the surge of leakage current and the rise of the ground potential gradient. First, considering the continuous distribution of the transition resistance along the track under the local insulation damage of the track, a distribution model of the rail to ground transition resistance is proposed and established. Then, the train fast traction strategy is introduced, and the dynamic distribution model of stray ground current and the gradient model of ground potential for the complete traction cycle are constructed. Based on the distributed parameter theory, the continuous distributed current is equivalent to several discrete distributed point current sources. Finally, a complex image method is used to solve the Green's function to calculate and analyze the dynamic stray current distribution and dynamic ground potential gradient distribution of the whole line. The accuracy and superiority of the model are verified by CDEGS software comparison. The results show that keeping high insulation performance in acceleration and deceleration areas is the key to reduce the influence of DC traction power supply system on nearby ground potential gradient and DC interference in a soil environment.

This work is supported by the Youth Fund of National Natural Science Foundation of China (No. 51607110).