Modeling direct lightning attachment to electrified railway system in Sweden

Direct lightning attachment to a single-track electrified railway system in Sweden is modeled in this paper. Using this model the induced voltages in each of the nine conductors at heights varying from 0.5 m (tracks) to 10 m above the ground are estimated. The effect of the finitely conducting ground is included using a time domain expression for the transient ground impedance. The main interconnection between the conductors and the flashover strength of the supporting insulators are included in the simulations. A simple model for the arc channel during flashover of the insulators and the ionization of the soil around the pole foundations are also included in the model to assess the possible realistic surge voltage distribution in the system. It is shown in the paper that finite ground return parameters, interconnections between the conductors, and arcing phenomena like insulation flashover, and ionization at the pole footing decide the voltage/current distribution in the conductors.