Effects of pantograph arcing on railway systems with auto transformers

Conducted and radiated electromagnetic interferences on auto transformer (AT) caused by pantograph arcing in electrified railway system are investigated. The overhead lines of electrified railway system can be simplified by three parallel overhead conductor lines. The model of AT in this paper is situated at the end of lines. The propagation of electromagnetic waves along the three conductors is solved by using finite-difference time-domain (FDTD) method. The circuit model for AT is created by state variable equations, and the equations are discretized by backward Euler method. The pantograph arcing is represented by a trapezoidal voltage pulse which has a wide band of frequency just like an arcing has; the rise and fall time are determined by the main frequency. The voltages across the AT windings are computed by the final FDTD iterative equations when all factors are considered.