Research On Oil-immersed Transformer Winding Hot Spot Temperature Simulation

The winding hot spot temperature of oil-immersed power transformer refers to the highest winding temperature in the design and operation of transformer,which is an important factor affecting the load capacity and service life of transformer.If the temperature of winding temperature point is too high,it will accelerate the aging of insulation between windings,reduce the service life of the transformer,and even cause insulation defects,resulting in transformer winding turns short circuit and other accidents.Therefore,it is of great significance for the design and operation of transformer products to accurately analyze the distribution law of internal temperature of oil-immersed transformer and calculate its hot spot location and temperature.In this paper,a 200kVA,20kV transformer is taken as an example to establish a three-dimensional simulation model of transformer which takes the oil channel structure between winding layers into consideration.The model fully considers the non-uniform distribution of losses in the core,winding and metal structural parts during transformer operation,the temperature effect of winding materials,and the natural convection heat transfer between the oil tank ripples and air and other factors.The coupling calculation of electromagnetic field,temperature field and fluid field is completed,and finally the winding temperature distribution and hot spot temperature of the transformer are obtained.The rationality and accuracy of the improved simulation model are verified by comparing with the test results of the same type of transformer.The model is also applied to the temperature simulation of the three-dimensional coil oil immersed transformer.The influence of the transformer leakage magnetic field on the low-voltage foil winding is considered in the model,and the temperature distribution of each component and the winding hot spot temperature are simulated during the rated operation of the transformer.Finally,an effective method for temperature field simulation of oil-immersed transformer is summarized.The simulation model applies the multi-physical field coupling analysis method,which can provide more accurate data for the design and calculation of oil-immersed transformer products,and has certain guiding significance for the optimization of winding structure and the installation of optical fiber temperature measuring points,and can improve the operating efficiency of equipment.