A Multiple Sections Model of Stray Current of DC Metro Systems

In DC metro systems, the stray current may cause many challenges for the nearby metal structures and the AC power systems, such as the corrosion of the buried pipes and the grounding grids of substations. Therefore, calculating the stray current and analyzing the distribution characteristics of the stray current are necessary for the design of the buried pipelines and substations. To obtain the stray current, considering the through-type structure characteristics of the return current system and the traction power supply system, a multiple power supply sections simulation model (multiple-section model) of stray current is proposed. In the proposed model, the train is equivalent to two dc current sources, and the dynamic results can be completed. Through comparing the rail potentials of simulation results and the field test data of the Shenzhen metro line, the proposed model is verified. And based on the proposed model of the Shenzhen metro line, the stray current distributions are obtained and analyzed. The results indicate that the stray current distribution has a certain periodicity which is approximately equal to the headway time of the train.