Lightning Electromagnetic Fields and Their Induced Voltages on Overhead Lines: the Effect of a Non-flat Lossy Ground

This paper presents an accurate representation of a non-flat lossy ground to study its effect on the lightning electromagnetic fields as well as the associated induced voltages on overhead lines. The simulations are carried out for above-and under-ground lightning electromagnetic fields as well as for the induced voltages on a single conductor overhead line. It is shown that all components of the lightning electromagnetic fields are affected by a non-flat ground configuration. The radial component of the electric field increases as the steepness angle theta increases from 0 to a certain value beyond which it starts decreasing. Also the vertical component of the electric field decreases as the steepness angle of the non-flat surface increases. The azimuthal magnetic field shows a behavior similar to the horizontal electric field. As for the lightning induced voltages, it is shown that, the peak value and the rise time of the induced voltages are markedly affected by the non-flat lossy ground.