A Discussion of Two New Types of Time‐Domain Greens Functions for Simulating Lightning Transient Grounding Using the Galerkin's Moment Method

ABSTRACT

This paper innovatively proposes a new type of time‐domain closed‐form Green's functions for simulating lightning impulse grounding problems in substation grounding grids within multi‐layer horizontally stratified soils using the Galerkin's moment method (MM). This closed‐form time‐domain Greens functions can simultaneously account for the contributions of both conductive and capacitive leakage currents generated by a point current source in a multi‐layered, horizontally stratified soil. The contributions of conductive and capacitive leakage currents are explicitly represented in the matrix of equations derived for the Galerkin's MM, thereby elucidating the physical significance of the leakage currents obtained through this Galerkin's MM. The two‐dimensional time‐domain quasi‐static complex‐image method adopted in this paper efficiently derives the closed‐form Green's function for point current sources in multi‐layer horizontally stratified soil, thereby improving the efficiency and accuracy of this numerical method. The novel Galerkin's MM developed in this paper is capable of simulating transient surge grounding problems caused by soil ionization effects induced by large lightning currents.