地铁轨道局部绝缘损坏下动态杂散电流及地电位梯度建模与分析

地铁轨地绝缘损坏会导致过渡电阻降低，造成泄露地电流激增、地电位梯度升高等问题。首先，针对轨道局部绝缘损坏下沿轨过渡电阻呈连续分布的特性，提出并建立了轨地过渡电阻区段分布模型。然后引入列车快速牵引策略，构建了完整牵引周期的杂散地电流动态分布模型及地电位梯度模型，并基于分布参数理论将连续分布的电流等效为若干离散分布的点电流源。最后利用复镜像法求解格林函数的方法，计算分析全线动态杂散电流分布和动态地电位梯度分布。通过CDEGS软件对比验证了模型的准确性与优越性。算例结果表明，保持加速、减速区域较高的绝缘性能是降低直流牵引供电系统对附近地电位梯度影响以及减小土壤环境直流干扰的关键。

Modeling and analysis of dynamic stray current and ground potential gradient under partial insulation damage of a metro track

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).