New Approaches to Represent the Frequency Dependence of Soil Parameters on the Time-Domain Hybrid Electromagnetic Model (HEM-TD)

This paper presents two new approaches to consider the frequency dependence of electrical parameters of soil in the hybrid electromagnetic model in the time domain (HEM-TD). According to these approaches, the frequency dependence of soil resistivity and permittivity was considered using specific rational functions. The quality of their results was assessed, in terms of the calculated grounding potential rise and impulse impedance. A significant improvement was achieved in relation to the results of the first approach adopted in HEM-TD.