Using circuit elements to represent the distributed parameters of a grounding system under lightning strokes

Abstract

This work presents a proposal to represent electrical grounding systems directly in the time domain. The advantage in using this type of representation is that voltage and current are better understood in this domain, and the model can easily be inserted into conventional software such as the Alternative Transient Program (ATP). The proposed method is applied to horizontal electrodes, vertical rods and grounding grids. The grounding is initially modelled in the frequency domain to obtain harmonic impedance, which is then represented by means of an approximation in the time domain, by passive elements (resistors, inductors and capacitors) associated in series and/or parallel. Validation was achieved by comparing the results with those obtained using the TLM (transmission line model), the HEM (hybrid electromagnetic model) and technical literature. The TLM and HEM were used to obtain the harmonic impedance of the grounding systems, but any other model could have been used, since this process has no effect on the proposed method, making the proposed method very versatile and attractive.