Application of the Three-Dimentional FDTD method to the Analysis of Lightning-Induced Surges in Secondary Circuits of a Substation owing to a Lightning Impulse Current

In case of a direct lightning strike to a substation and transmission line, some parts of the lightning current flow into the grounding structure of the substation, and they may induce overvoltages in the secondary circuit of the substation owing to the effect of the transient ground potential rises of the grounding structure and electromagnetic coupling. In this study, we applied the three-dimensional flnite-difference time-domain (FDTD) method, which is one of the numerical electromagnetic computation methods, to the analysis of the transient response of grounding grids and surges induced on the shielded control cable of a test platform of the primary and secondary circuits of a substation, and confirmed the applicability of the FDTD method by comparing the simulated results with measured waveforms.