Thermal Simulation And Structure Optimization Of Oil-Immersed Transformer

As low loss,large capacity,good heat dissipation characteristics,the oil-immersed transformer is still the main product in the power grid. The natural oil circulation of transformer has both of the above characters,but also has low noise,can avoid"oil flow electrification,"etc,it is more and more applications and concerns. The direct consequence of adopting oil natural oil circulation cooling is increase of temperature between copper and oil,so transformer cooling problems become more and more prominent. At the same time as the increasing electricity demand and the continuous improvement of reliability,the greater losses generated by the transformer,how to effectively distribute out the heat generated by the transformer and avoid failure,it is a serious problem. With the depth study of thermal fault of transformer found that the most sensitive part of transformer materials is winding insulation paper,which life affected temperature,and the ageing of insulation paper begins from the hot spot. Therefore,it has great significance to study temperature field and hot spot temperature of natural circulation transformer and optimized cooling structure.In this paper,based on theoretical analysis of thermal performance of natural oil circulation oil immersed transformer, a simplified model of natural oil circulation oil immersed transformer is established using AUTOCAD and GAMBIT software . Model takes the transformer as a whole,the temperature and the flow field are simulated using flow calculation software FLUENT, taking into account physical properties of transformer oil with temperature changes. The transformer winding hot spot rise and hot spot position are determined through the analysis of the temperature field,to provide a basis for measuring the transformer's hot spot. Then the model geometry is changed,the oriented structure,non-oriented structure ,the impact of the size of horizontal oil duct,the vertical oil duct width,the location of the radiator and the load on the hot spot temperature rise is analyzed , proposing a method to improve the cooling conditions.Using the experimental values provided by the manufacturer, the FLUENT simulation results are verified, the former result agree well with the FLUENT simulation result,within the allowable error range. It proves that FLUENT software can simulate the flow field of complex models, while it is helpful for the actual running transformer.