Computation And Analysis Of Power Transformer On Eddy Current Field And Hot Question

Computation and analysis of power transformer on eddy current field and hot question is key problem in the power transformer design and computational process. Power transformer's capacity is bigger and the leakage magnetic field is stronger, so the winding and the structures eddy current density which induces by the leakage magnetic field is much bigger. It not only causes the eddy current loss and stray losses enlargement but also causes the winding and the structures overheated, therefore, studies on power transformer's eddy current field and the hot question thoroughly accurately has the vital practical significance.Based on the power transformer eddy current field and thermal problems at home and abroad, a power transformer model DFP1-240MVA/500kV has been researched. Through the reasonable simplification for the complex model and the application of power transformer electromagnetic field theory and finite element analysis basic theory ,the power transformers eddy current field and thermal problem has been analyzed in this paper. First, the finite element analysis software ANSYS has been used to establish three-dimensional model of power transformers, through the accurate calculation and analysis of the power transformer on three-dimensional leakage magnetic field, the eddy current distribution and loss of the structures in power transformer can be obtained. The calculating the results is similar to the experimental data, which demonstrate to apply ANSYS software for simulating power transformer leakage magnetic field is feasible ,and the results is also correct; Secondly, based on the accurately calculate the eddy current loss of power transformer and the analysis and calculation on several structures which contains installing electromagnetic shielding on tank wall, installing electromagnetic shielding pieces on clamping part and slotting on the pulling plate of, this thesis gives a methods on how to reduce the eddy current loss on structures; Finally, based on fluid dynamics and heat transfer theory, by using AutoCAD, GAMBIT and FLUENT such as these common software tools, the temperature rising and flow velocity distribution of oil-immersed power transformer winding and oil flow under cooling medium in different conditions on power transformer has been given. As the same time this paper put in use relevant theories to analysis the results and propose methods to reduce the temperature rise ,and the method has been demonstrated practicality and effectiveness through the examples.Through the analysis on power transformer leakage magnetic field, eddy current and temperature fields, the method to reduce eddy current loss and temperature rise of the oil flow has been given in the paper; meanwhile the method of calculation and analysis has been proved correctly which can direct how to design accurately on large-scale power transformer.