Abstract
For a good understanding of EHV GIS external induced currents in multipoint grounding systems, generation mechanism, distribution characteristics and influence factors analysis of the induced currents have been proposed in this paper. According to the structural characteristics of the multipoint grounding system, self and mutual inductances in GIS were calculated by using Biot-Savart Law. Based on Lenz's law, external flux balance equation of GIS was proposed, which can be used to calculate the induced circuiting currents. And the composition of induced currents in different locations of EHV GIS has been analyzed. Furthermore, 3-D analytical models of GIS were established. And the finite element method(FEM) was used to analyze the influence factors and the distribution characteristics of induced currents. Not only the amplitude but also the phase angles of the induced currents were analyzed in this paper.