Power Transformer Thermal Analysis by using an Advanced Coupled 3 D Heat Transfer and Fluid Flow FEM Model

Marina A. Tsili, Eleftherios I. Amoiralis, Antonios G. Kladas and Athanassios T. Souflaris 1 Faculty of Electrical & Computer Engineering, National Technical University of Athens, GR-15780, Athens, Greece (e-mail: [email protected], [email protected]) 2 Department of Production Engineering and Management, Technical University of Crete, 73100, Greece, (email: [email protected]) 3 Schneider Electric AE, Elvim Plant, 32011, Inofyta, Greece (e-mail: [email protected]) Abstract Thermal performance in oil-immersed power transformers is governed by the flow of oil, acting both as an electrical insulator and a medium for the transfer of heat generated in the core and windings towards the tank and the surrounding air. This paper presents the development of an advanced three-dimensional (3D) finite element model for the coupled solution of heat transfer and fluid flow equations governing transformer thermal performance. The main advantages of the proposed method are: (i) no need to predefine the convection coefficients at the interfaces between the active part/tank walls and the circulating oil, (ii) detailed representation of specific transformer parts that play an important role in the accurate representation of oil flow and heat dissipation (such as winding cooling ducts and corrugated tank panels) through an automated design process, enhancing the model accuracy with the least possible computational effort and (iii) accurate definition of the transformer heat sources (core and windings loss). The proposed methodology provides an integrated tool for thermal simulation, able to predict detailed thermal distribution in a specific transformer,