Insulation coordination study for a 50 kV traction feeder station

The heavy haul rail network in Queensland Australia generally adopts a lightning impulse withstand voltage rating of 250 kV for the switchgear and autotransformers within its 50 kV ac traction feeder stations. The aging switchgear across a number of feeder stations in this network are undergoing upgrade and the rail network operator is considering the possibility of using 200 kV rating for the upgraded switchgear. This paper investigates the lightning over-voltages that could occur at the feeder stations under review. Fast front transient models of the feeder stations and the associated traction corridors are developed in PSCAD/EMTDC software. Simulations are conducted to evaluate the likely over-voltages under various scenarios and the results are presented. Finally, the required lightning impulse withstand voltage rating for the switchgear is determined based on the simulation results.