Transient characteristics of grounding systems

This paper presents dynamic behaviors of grounding system in power systems. The limitation of a conventional method based on a circuit approach is described. The numerical electromagnetic analysis method is employed as a simulation tool for analyzing the transient characteristic of grounding systems. The simulation results composing potential rise caused by a lightning current and magnitude and phase angle of impedance of a grounding electrode in the frequency domain, show that in a case of a low resistivity of soil the grounding resistance is the most significant effect to the characteristic of the grounding electrode in a low frequency range (below 100 kHz) but in a high frequency range (over 100 kHz) inductance and capacitance effects have to be taken into account in grounding analysis. In a case of low resistivity (below 1000 Ωm) of soil, the input impedance of a grounding electrode is influenced by the inductance effect. In a case of high resistivity (over 1000 Ωm), the input impedance of a grounding electrode is influenced by the capacitive effect. The analyzed results can be adapted for being the methods of development and design of the grounding system in power systems in an effective way.