engleski

Improved numerical calculations of grounding system parameters in non-equipotential AC substation grounding grids

This paper presents a more accurate mathematical modeling of the nonequipotential large grounding system at power frequency, which includes transversal mutual conductances between grounding segments as well as longitudinal mutual inductances. Numerical calculation of the grounding current field is based on the point collocation method with current density approximation by the second-degree polynomials and two-layer soil model. The method of images is used for solving the boundary value problem. . Using the direct solution of a system of linear equations (matrix inversion), unknown coefficients of the current density approximation along all grounding elements and unknown potential values at nodal and collocation points are obtained. Such accurate modeling enables more accurate computation of the grounding impedance, too. This procedure is applied in determining the inductance of the rectangular grids with uniform square meshes. The calculation is applied to rectangular grids usually used in high voltage substations. The results calculated by the proposed model have been compared with other authors' models and with the results of the analysis performed on the similar cases

grounding grid; grounding impedance; mutual inductance; non-equipotential

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