Analysis of Methods Eddy Current Loss Estimation in Power Transformer Windings with Multiphysical Consideration (Electromagnetic and Fluid Dynamic)

Abstract

The temperature rise in the transformers is caused by the dissipation of internal losses. The main sources of heat in the power transformers are those generated at full load, caused mainly by the applied current and those originated by the magnetic field. The consideration of the magnetic field in the loss estimate is necessary, as it can reach high values depending on the design and make the calculation of the internal temperature imprecise. To reduce the imprecision in the results, in this work the losses are calculated using the Finite Element Method (FEM) considering the temperature of the conductor, coupled with the dynamic analysis of fluids. 2D and 3D approximations with simple and sectioned cables were used to make comparisons with the calculation modes, analyzing the influence of the temperature effect on the additional losses created by eddy current and compared with the analytical form presented in the specialized literature. The methodology was applied to a 470 MVA power rate autotransformer with ODAF cooling mode. The results show that Foucault losses can reach high values, depending on the project, and the use of sectioned cables that allow the reduction of losses and the increase of the winding temperature must be considered.