A New Approach to Compute Transient Behavior of Grounding Electrodes in Time-Domain

In this paper, based on the electromagnetic field theory in frequency domain and by using the full set of Maxwell´s equations, an exact numerical method is presented to calculate the high frequency characteristics of electrodes excited by high frequency sources such as lightning, faults etc. In this method, the effect of ground-reflected waves which exist due to the boundary between earth (lossy medium) and air have been considered according to the modified image theory that includes a modified reflection coefficient (RC) instead of solving the Sommerfeld integral in the high frequency formulation of the Green function. In addition, the transient voltages in time domain are calculated applying fast inverse-Laplace transform technique (FILT) to the frequency response of the grounding electrode.