Analysis On The Thermal Field And Moisture Diffusion Of Oil-immersed Transformer

Power transformer is the important equipment to guarantee the electrical power systems’ operation,its normal operation own important meaning for the stability and economy of power transmission.The damp of transformer is one important factor that impact the normal operation of transformers,the increasing moisture content in insulating paperboard will seriously reduce the mechanical strength and electrical strength of insulating paper,insulating paperboard moisture content doubled,its mechanical life by half,thermal aging rate is doubled.So it is important to dry the damp transformers.At present,traditional transformer drying methods exist a variety of defects,short-circuit drying method is the future development trend of dry transformers,In order to further explore the drying effect of short-circuit drying method,it is necessary to study the distribution of thermal field and the migration effect of moisture at different temperatures when the short circuit current is loaded into the transformer.According to the related theory of thermal field and flow field,as an example of SFSZ11-63000/220 power transformer,without affecting the simulation results under the premise of the structure of the transformer to a reasonable simplification,the solution model of thermal field is established by FLUENT software.By changing the size of the current density,the thermal field distribution of the transformer under different loads are obtained.Analyzing the the changing temperature trend,the location of the hottest point,the flow rate of the transformer oil and the effect of load change on hot spot temperature,which provide the theoretical basis for selecting the reasonable short circuit current for the transformer drying.According to the related theory of moisture diffusion,the model of diffusion of moisture in insulated paperboard is deduced,the change of moisture diffusion with time and thickness and the change of average moisture content in insulating paperboard were obtained under different temperature conditions,which provided some reference for the study of transformer drying effect.