A numerical simulation of transient electromagnetic fields for obtaining the step response of a transmission tower using the FDTD method

This letter presents a numerical simulation of transient electromagnetic fields using the finite-difference time-domain (FDTD) method for obtaining the step response of a 500-kV transmission tower. The purpose of this simulation is to reproduce the result of a field test which has been carried out for obtaining the step response of the tower as fundamental data for lightning overvoltage studies. From the comparison between the calculated and measured results, the accuracy of the FDTD method, when applied to lightning overvoltage studies, is examined. The simulation carried out in this letter takes into account the following items that have been ignored or oversimplified in the existing simulations. One is the resistivity of the ground soil, and the other is the detailed structures of the arms, the lattice elements, and the foundations. The calculated result obtained closely reproduces the field-test result.