Lightning induced voltages on overhead lines above an inhomogeneous ground

In this paper the lightning induced voltages on an overhead single-phase lines are calculated for an inhomogeneous ground with a mixed-path structure. This ground configuration is frequently found in rural distribution networks installed in several regions of Colombia. The simulations were carried out using the finite-difference time-domain (FDTD) method for a three dimensional space in which a lightning channel model and a single-phase line model of constant height were included; both elements were modeled using a thin-wire approximation. The results show that there could be representative differences on the lightning induced overvoltages when considering the variations of the ground conductivity along the path of the overhead line; this could result on an inadequate selection of surge protective devices and of the line insulation level.