Analysis of Lightning Current Using Electromagnetic Models and 3D-FDTD Method in Presence of a Tall Object

In this work, we are interested in the study of the lightning return stroke current distribution along a tall object namely a tower and along the lightning channel. The considered tower is that of Peissenberg in Germany. To carry out this study, we have developed a computer code based on the use of electromagnetic models and the three dimensions finite difference time domain (3D-FDTD) method. The latter is combined to UMPL boundary conditions and is based on Taflove formulation. The program was developed in MATLAB environment. So, in this study electromagnetic models have two configurations. The first one is that adopted for the Peissenberg tower, in which the latter is represented by a perfectly conducing wire and a cubic extension below the ground. The second one is the lightning channel configuration, which is represented by a vertical resistive wire coated by a fictitious material having a relative permittivity and a relative permeability values greater than that of the air. In the validation aim of the used approach and the developed calculating code, the simulation results are compared to those taken from the literature data recorded of the current waveforms at the top of the tower. According to this comparison, the approach proposed in this work yields reasonably accurate results. Thus, the effect of the variation of the ground conductivity values on the lightning current magnitudes and waveforms is examined. This investigation showed that the lightning current is affected by the variation of the ground conductivity values when it propagates along the tower and along the lightning channel.