Characteristics of Earth Electrodes Under High Frequency Conditions: Numerical Modelling

Abstract

The earthing segments of electrical power systems play an important role in ensuring human safety. A core function of these earthing systems is to maintain reliable operation and ensure safety for personnel and apparatus during fault conditions. Earthing electrodes can be buried in the soil to dissipate lightning and fault currents into the earth and limit the effect of any magnitude of voltage and current generated between different contact points to earth structures that may be occupied by people or sensitive electrical equipment. In order to obtain the best design of an electrical system to protect power system installations and ensure human safety against abnormal conditions, it is useful to clarify the behaviour of earthing systems subjected to variable frequency currents. In this paper, a numerical study is thus implemented to investigate the behaviour of earthing electrodes subjected to variable frequency current using the computational software program HIFREQ/FFTSESCDEGS with a uniform equivalent soil model. The effect of soil resistivity and permittivity on the behaviour of earthing electrodes is thus obtained, and the relationship between the length of earthing electrodes and their earthing responses over a wide range of frequencies from DC up to 1MHz is identified.