The effect of the inclined lightning channel on electromagnetic fields and the induced voltages on overhead lines

Abstract

In this study, the effect of lightning channel inclination on above-ground lightning electromagnetic (LEM) fields and their induced voltages on the overhead lines at different distances from stroke location (SL) in the presence of lossy soil ground is investigated. To this end, the finite element method is used to solve the full-wave Maxwell’s equations. The results show that channel inclinations affect LEM fields significantly at all distances from the SL. At an equal distance from SL, the observation point position relative to the lightning channel is important, and LEM fields of the points located on the horizontal axis of the lightning channel are affected more than other points. If the ground is more conductive, increasing channel inclination affects the radial component of the electric field at a close distance to the SL more; if the ground is more resistive, increasing channel inclination angle affects the radial component of the electric field at a far distance to SL more significantly. The vertical electric fields and azimuthal magnetic fields are slightly affected by ground conductivity but significantly affected by the position and channel inclination angle. Seven different states are considered for the channel position relative to the overhead line, and the lightning-induced voltage along the line is calculated at three points. The obtained results show that position and soil electrical parameters significantly affect the peak and wave shape of the induced voltage. If the lightning channel passes above the overhead line, the induced voltage peak will increase at points near the SL. If the horizontal axis of the lightning channel is parallel to the overhead line, the induced voltage peak will increase for the ground with lower conductivity by increasing the channel inclination angle. In this case, at distances farther from the SL, the effect of increasing the channel angle is negligible for high-conductivity grounds, but the induced voltage peak for less conductive grounds will increase. If the lightning channel's horizontal axis is perpendicular to the overhead line and the lightning channel does not pass above the overhead line, close to the SL, the induced voltage peak will decrease by increasing channel angle. At points far from the SL, increasing the channel angle in the low-conductivity ground will increase the voltage peak, and grounds with larger conductivity will decrease the voltage peak.