Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
CFD EVALUATION OF THE OIL COOLING SYSTEM IN A MOBILE POWER TRANSFORMER
Submission Author:
Luciene Martins Moura Rodrigues , MG , Brazil
Co-Authors:
Luciene Martins Moura Rodrigues, Rudolf Huebner, Paulo Vinicius Trevizoli
doi://10.26678/ABCM.COBEM2021.COB2021-1647
Abstract
Power transformers represent an important part of the capital investment in transmission and distribution substations. Interruptions with a power transformer have a major technical and economic impact on the operation of the electrical system. The cooling of the windings (electrical coil) depends on the convection of heat, enhanced by the forced circulation of oil in the windings, as well in heat exchangers. The latter may either by natural or forced convection of air. Forced circulation of oil combined with forced circulation of air in the heat exchanger is usually found in mobile transformers, whose compact structure is a challenge in terms of heat transfer rates. An improper design or fabrication problems associated with the assembling of the cooling system may result in an inefficient exchange of heat, consequently, in the burning of the transformer due to overheating. The overheating is one of the main causes of “hot spots”, which can appear in the windings and in the magnetic core. This way, the present work proposes a CFD study of the winding cooling system in a 138X69-13.8kV 25MVA power transformer, with the objective of evaluating the thermal performance of the transformer operating under nominal conditions. It is considered nominal inputs of flow rates of oil, temperatures, power dissipated. In a second evaluation, some constraints are artificially imposed to the transformer, which may impact the velocity and temperature fields, in order to understand the formation of “hot spots” and the potential for failure of the transformer.
Keywords
Power Transformer, oil cooling system, overheating, CFD
