The assessment of the interaction effect of a lightning strike with a grounding system in a dissipative half-space

This paper presents a method for modeling the interaction between lightning strokes and grounding grid in semi-infinite dissipative medium. We treat the two cases of direct and indirect effects of lightning strike. In the first case, we inject in the impact point of grounding grid a lightning current of Heidler´s form, and we calculate the potential distribution, currents on the grid and the electromagnetic field it will emit. For the second case, we treat a problem of electromagnetic coupling to calculate the induced currents which are developed on the grounding grid illuminated by a lightning channel located in its vicinity. The lightning channel is modeled as monopole antenna energized by current source at its base. The assessment of the induced current distribution is obtained by solving the Pocklington´s equation of using the method of the moments. The transient electromagnetic field components are evaluated using a new method based on the concept of the hertzian dipoles and the asymptotic expansion of a single dipole.