Transient Analyses of Grounding Systems Subjected by Lightning Surge Currents through Fuzzy-Based Models of Input Impedance in the Frequency Domain

In this paper, fuzzy-based models which is special for electromagnetic problems are applied to model the input impedance of the grounding systems such as vertical and horizontal electrodes. In each model, the behavior of the electrode is first extracted by if-then rules, and then the effects of different parameters for instance soil resistivity and electrode radius are separately extracted as simple curves. Then using spatial membership functions, these effects are combined so as to create simultaneous effects of all parameters on the input impedance. As a result, the input impedance is efficiently predicted for arbitrary resistivity of soil, radius, and normalized length of electrodes. Finally through fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT), the transient voltage for each electrode is efficiently computed