FDTD analysis of distribution line voltages induced by non-vertical lightning

•Lightning induced overvoltages in single-phase and three-phase overhead lines are investigated by a finite-difference time-domain (FDTD) method with considering “bent” and “computationally-generated” non-vertical lightning channels.•In the bent lightning study, the channel is represented by combinations of vertical and inclined paths with different connecting (bent) heights.•It is made clear by the bent lightning study that the lightning channel geometry under 100-m altitude is significant for the peak voltage when severe conditions of a 1/200-μs current and a lightning distance of 50 m are assumed. The dominant channel height for the peak voltage becomes higher when the distance d becomes longer and rise time td10–90 becomes slower.•A lightning-like (zig-zag) channel is computationally generated by a probabilistic calculation based on an electric potential distribution in a three-dimensional space, and its induced voltage is compared with that by a simply-inclined channel.•When the inclined angles in the simply-inclined channel are set to the average inclined angles under 100 m in the computed channel, the induced voltages show good agreement. A realistic non-vertical lightning channel can be represented by a simply-inclined lightning path with average inclined angles under 100-m altitude.•The difference of the peak voltages between the generated and inclined channels is less than 10%, and it decreases as the earth resistivity increases. This paper investigates lightning induced over-voltages on overhead lines considering “bent” and “computationally-generated” non-vertical lightning channels by using a finite-difference time-domain (FDTD) method. In the former case, combinations of vertical and inclined channels with different connecting heights are modeled to represent “bent” lightning. It is made clear that the peak voltage is significantly influenced by the lightning channel geometry under 100-m altitude when severe conditions of a 1/200-μs current and a lightning distance of 50 m are assumed. Induced voltages on the three-phase line show similar characteristics to those on the single conductor line. In the latter case, a lightning-like (zig-zag) channel is computationally generated by a probabilistic calculation based on an electric potential distribution in a three-dimensional space, and its induced voltage is compared with that by a simply-inclined channel. When average inclined angles under 100-m altitude in the computed channel are set to the ang