Magnetic Shunts Geometry Effects on the Axial Forces and Leakage Flux in Power Transformers Based on FEM Method

Abstract

The influence of arrangement, dimensions, and magnetic permeability of the magnetic flux shunts on the flux distribution, leakage reactance as well as axial electromagnetic forces acting on the transformer yokes, is studied in this paper using finite elements method and a simple modeling. By using magneto-static analysis and finite element method, the flux distribution in the 2D model of a core-type three phase power transformer was calculated, and then the leakage reactance of the transformer windings is calculated using the magnetic stored energy method. By calculating the leakage reactance, the short circuit current amplitude and therefore the flux distribution in short circuit conditions and axial electromagnetic forces on the transformer windings were obtained. By studying the different models including magnetic flux shunts, the effect of the arrangement, geometric dimensions as well as the magnetic permeability of the magnetic flux shunt on the leakage reactance and the net axial forces acting on the transformer yokes were studied and some interesting results were obtained. It is shown that the variation of these parameters in the transformer model has the significant effect on the leakage reactance and net axial force acting upon the transformer yoke, for instant, for certain value of the magnetic shunt length, the net axial force acting upon yoke has its maximum value.