Dynamic Diffusion Model of Stray Current in DC Traction Power Supply System

The dynamic fluctuation of stray current is the main characteristic of the metro causing harm to surrounding buried metal structures. While establishing the equivalent circuit model of the return system, not only mainline but also metro depot should be considered. The diffusion models of the dynamic stray current of the DC traction power supply system (DTS) in multi-layer soil medium and massive texture soil medium are established. They are co-simulated with the DC traction power supply return system. The massive texture model (MTSM) is verified by an on-site experiment of ground potential distribution. In the case study, the direct grounding of the rail in the depot will deteriorate the ground potential gradient and stray current. When considering the impact of the river or lake, the stray current easily flows to the low resistivity texture soil, the maximum ground potential gradient increases.