Discrete modeling and calculation of traction return-current network for 400 km/h high-speed railway

The planned 400 km/h high-speed train capable of cross-border intermodal transportation will inevitably cause a greater return-current and bring more challenges to signaling infrastructure and integrated grounding while achieving stronger traction. Based on the existing AC autotransformer power supply mode, this paper proposes a discrete modeling and calculation method of the traction return-current network concerning impedance equivalent, realizing the simulation and quantitative analysis of the return-current distribution of multiple current-carrying conductors in the block section and station yard under the double-track condition. Then, the dynamic distribution is analyzed comprehensively considering traction power supply, signaling, and integrated grounding systems. Also, the method is verified with field test data. Finally, the simulation of the return-current proportion of multiple conductors is carried out under the dynamic operating conditions of high speed, and the distribution characteristics are compared and analyzed under different ballast resistances. In the most unfavorable case, the maximum return-current in the rails, grounding wire, and protective wire can reach 1046 A, 180 A, and 126 A, respectively. This work helps evaluate the electromagnetic compatibility between signaling and strong currents in engineering practice, further optimize the capacity configuration of equipment along the railway lines, and improve the signaling immunity design.