Analysis of the Influence of Cable Coupling on the Distribution Ratio of Rail Transit Backflow under AC Power Supply System*

With the development of AC power supply system in rail transit, it has been found in actual operation that poor traction return channels can cause power frequency and harmonic interference in track circuits, damage to track insulation, and pose a threat to train safety. Among them, the electromagnetic coupling generated by cables in the electric traction environment can affect the traction return of trains, resulting in poor return flow. At present, there is limited research on the impact of return cable coupling on the return distribution of rail transit under AC power supply system, therefore it is necessary to study it. This article takes the actual parameters of a subway project in Guangzhou as a template, uses EMTP simulation software to establish a two-layer subway tunnel model, and studies its impact on the traction return system of rail transit under AC mode by changing the parameters of the return system. Research has found that changing the reflux system parameters before the equalization point has little effect on the reflux distribution ratio; The spatial distance between the return cable and the power supply cable within 2 meters has a significant impact on the return distribution ratio, but it is not related to the contact points of the return cable at the station or the number of return cables. The distribution of current shows a skin effect.