Lightning Surge Propagation Analysis in OHGW of Electrified High Speed Railway

This paper proposes the analysis of the lightning surge propagation along overhead ground wires based on the telegraph equations which describe the voltage and current on a power transmission line and the finite difference time-domain (FDTD) method. The proposed FDTD method was tested with the 25-kV power transmission system of a high-speed railway in comparison with the solution obtained by using the Bewley method. From the results, after the travelling surge reaches the contact point between the overhead ground wire and the transmission pole, the surge is partially reflected and partially passes through. If the grounding resistance at a transmission pole is small, the peak of the reflected voltage surge is greater than that of the surge passing through. However, the higher value of grounding resistance causes the higher peak of the surge that passes through than the peak of the reflected surge. The computations show that the FDTD method is one of the most accurate methods to analyze lightning surge propagation in power transmission lines.