Lightning-Induced Voltages Over Lossy Ground: The Effect of Frequency Dependence of Electrical Parameters of Soil

The impact of the frequency dependence of soil resistivity and permittivity on lightning overvoltages induced on overhead lines over lossy ground is investigated. The Visacro-Alipio expressions were implemented on the hybrid electromagnetic model to take this effect into account. Systematic simulations were performed considering representative current waveforms of first and subsequent strokes and different stroke locations near the simulated overhead line. In general, the results indicated that this effect is responsible for a reduction of the induced overvoltage. This reduction increases with increasing soil resistivity and becomes relevant for soil resistivity above 1000 Ω·m.