Methodology For The Method Of Images In Transient Analysis Of External Fault Electromagnetic Forces In Power Transformers [articol]

Abstract

In this paper, it is presented a methodology to apply the Method of Images in the determination of transient electromagnetic forces in windings of power transformers due to external faults. Correction factors are introduced in the process of calculus, avoiding the need for iterations. Only four images of the windings and one simulation with both the method of images and the finite element method with the rated current of the transformer are needed for the determination of the correction factors. The method proposed was implemented in C++ and the results were compared to those of the finite element method through simulations performed in the free software Femm 4.2. The simulations exhibit that the correction factors are valid for any value of current circulating through the windings, hence, they can be used for transient analysis of the forces, where the current is variable. The method of images, as described here, perform transient analysis in much less time than the finite element method.