Aerial and grounding system analysis by the shifting complex images method

This paper introduces a novel computer method for the analysis of both aerial and grounding systems of conductors. The computer method based on an hybrid approach, allows to incorporate into a single linear system both lumped and distributed circuit parameters, evaluated by a rigorous electromagnetic field analysis. The conductor system is replaced by a suitable set of elementary current sources. These may be plain or hollow, bare or insulated, freely oriented and interconnected in the three dimensional space, which is considered formed by two half spaces each one homogeneous, linear and isotropic (e.g., air and soil). Therefore the method does not pose geometric and topological limitations and enables to compute voltages and currents at the source (boundary) elements as well as vector potentials, electric and magnetic fields anywhere in the surrounding medium. The range of application of this method is sufficiently wide including any practical electric power system application. The method may be applied for frequencies up to 1 MHz, thus covering the frequency spectrum of a typical full lightning too. Results which are derived first in the frequency domain can be converted to the time domain by Fourier transform algorithms. In this way it is also possible to analyze the response to transient signals of both aerial and grounding systems having complex geometry.