Calculation And Analysis Of The Temperature Rise And Eddy Current Loss In Power Transformer

The eddy current loss and the local overheating problem in the power transformer is very important problem. The larger transformer capability is, the greater leakage magnetic is, the greater the eddy loss is, the more distinct calculation of local overheating caused by the eddy loss is. So how to solve this problem has became very vital and practical.The significance and purpose of the current loss and temperature rise field calculationare introduced in the beginning of the thesis, and then the development of the leakage magnetic field and temperature rise field of the transformer are discussed. By using the theory the finite element methd and power transformer, the large universal finite element software-Ansys is used to analyze and calculate accurately the 3-D leakage magnetic field in the of transformer with building the 3-D leakage magnetic model, then the distribution of magnetic flux density along radial and axial direction of the high voltage winding and low voltage winding is concluded. On the base of the conclusion, the eddy current loss caused by the leakage magnetic field is calculated. The result is similar to the experimental one, so the accuracy of result and the feasibility of Ansys simulation is demonstrated. According to the result, leakage-magnetic and eddy loss has been given. As the same time, the paper has analized the influence of the electric-magnetic shield on oil tank wall and the slotted pulling plate on the leakage-magnetic filed and eddy loss.On the base of the result of eddy loss calculation in the windings and the structure parts, the magnet-fluent-temperature rise coupled field in the power transformer is analyzed. This paper considers the Joule loss as the load of fluent analysis by using the method of direct coupled field. Then, the distribution of temperature rise field in the winding and structure parts can be obtained by solving fluent field and temperature rise field. The paper not only analyze the result with relative theory but also provides the method of reducing temperature. By using Visual Basic program to compile simulation software of the mag-netic field and temperature rise field calculation in the transformer, the parameterized model and load are created,and the result data can be acquired from the database.