Lightning flashover characteristics of metro viaduct section with contact rail power supply system

Abstract

A flashover of the insulation guardrail will lead to a ground fault of the contact rail, which will cause metro traffic interruption. In this paper, we study the lightning flashover characteristics of a metro viaduct section with a contact rail power supply system. The lightning protection zones of different lightning overvoltage types on metro viaducts are divided according to the rolling ball method, and it is found that it is very unlikely that lightning will strike the contact rails directly. The damage caused by lightning to the contact rail is induced overvoltage and back flashover. A simulation model of a metro viaduct was formulated using electromagnetic transient simulation software. Based on those models, a series of simulations are performed to study the lightning flashover characteristics of the contact rail power supply system. The study found that the lightning protection belt and trains are vulnerable lightning strikes. When lightning strikes a train, the lightning current required to cause the insulation guardrail to flashover is 118 kA. When lightning strikes the lightning protection belt, only 53 kA is sufficient to cause an insulation fence flashover. In addition, the influence of the pier grounding resistance is also analyzed. The result indicates that reducing the pier grounding resistance could improve the lightning withstand level of the contact rail power supply system.