EVALUATION OF ELECTROMAGNETIC FIELDS ASSOCIATED WITH INCLINED LIGHTNING CHANNEL USING SECOND ORDER FDTD-HYBRID METHODS

Abstract

Evaluation of electromagnetic flelds caused by the lightning channel is an appealing topic in order to consider the indirect efiects of lightning on the power lines. A common assumption for the calculation of electromagnetic flelds at the observation point is a vertical lightning channel, but the fact is that in reality the lightning channel is seldom vertical on the ground surface. In this study, the electromagnetic flelds due to inclined lightning channel at various observation points with difierent angles and with respect to the image of lightning channel on the ground surface were explored. This study also proposes general equations that can estimate the electric flelds due to inclined lightning channel through the 2nd FDTD method. The proposed method supports the notion of vertical lightning channel while the channel angle with respect to z-axis is assumed to be zero. This method was validated through the data gathered from flve flelds: three at a close distance from inclined lightning channel and two at intermediate distances from vertical lightning channel. Similarly, due to inclined lightning channel, the efiects of geometrical and current parameters on the electromagnetic flelds are considered. This study substantiates difierent coupling models with FDTD structure directly at the time domain without a need for extra converters.