Nonlinear Adaptive Magneto-Thermal Analysis at Bushing Regions of a Transformers Cover Using Finite Difference Method

Abstract

In this study, losses analysis at bushing regions of a transformer covers is done using finite difference method (FDM), considering that FDM being more flexible to deal with the nonlinear constitutive law and easier to be implemented than finite element (FE) and analytical methods. The analysis is performed based on a 2-level adaptive mesh solution of Maxwell equations and Ohm law at the cross section area in the axial symmetry page of a steel disk, taking account the nonlinear magnetic permeability of the steel. The losses density obtained, as a heat source, is imported into an alternating direction implicit (ADI) approach of heat conduction equation. Therefore, a finite difference (FD) solution algorithm for magneto-thermal analysis on cover plate is obtained by combination of adaptive mesh refinement and ADI-FDM, which improves the accuracy and decreases the computational time without losing accuracy. The reliability of the proposed technique is confirmed by experimental and FE method (FEM) results, considering the temperature distribution of the cover. The comparison of the results with those obtained from FEM and experiments shows the efficiency and capability of the method.