Grounding Behavior and Optimization Analysis of Electric Multiple Units in High-Speed Railways

Abstract

In high-speed railways (HSRs), the overvoltages and overcurrents of train body (TB) are two critical issues for the grounding safety and reliable operation of the electric multiple units (EMUs). Running of EMUs inevitably encounters all kinds of electromagnetic transient scenarios, resulting in unfavorable surges on the TB. To restrain the surges, some grounding optimization countermeasures, such as adding groundings, have been proved to be effective for some scenarios but easily bring more rail currents into TB. Besides, only one or two operational scenarios are focused on the previous optimization design. Therefore, this article implements the grounding behavior and optimization analysis stemming from more comprehensive consideration. Typical EMUs are taken as an instance for establishing the accurate vehicle-grid models of all kinds of scenarios. Using EMTP simulations, both the TB voltages and TB currents in different grounding layouts and grounding resistances are analyzed and compared, focusing on each scenario. An optimization scheme is designed according to the comparison results. Finally, the Gini coefficient approach and entropy weight method are first applied to demonstrate the validity of optimization design, with the aim to suppress both the electromagnetic transient surges on TB and the return currents of entering TB to the maximum degree.