3D Modelling of an Integrated Grounding System for High-Speed Trains Considering Rail-Train Current Reflux

Abstract

The integrated grounding system for high-speed trains consists of two parts: on-board dynamic and fixed terrestrial grounding sub-systems. The on-board grounding sub-system contains working and protective grounding modes, both of which share the rails as the common path for discharging current. Current reflux occurs frequently, which can contribute to the circumflux in the ‘train body – grounding wheel set – rail’ circle, due to the dynamic coupling effects between grounding points. The path and value of the circumflux vary transiently because of the changing impedance between the grounding wheels and rail under the dynamic conditions. In our previous work, a 2D grounding model was built to evaluate the impact from the current reflux, but the lateral and vertical impedances of train bodies and rails were ignored. In practice – when the protective and working grounding is applied independently to rails on the left- and right-hand side separately – the current reflux can be restricted by benefitting from the impedance existing in train bodies and rails. It therefore becomes essential to build a 3D ‘train–rail’ coupling grounding model accounting for the full-dimension impedances, while different grounding distribution protocols is considered to improve the grounding performance.