Study On Leakage Magnetic And Thermal Field Distribution Of Dry Type Transformer

Epoxy resin casting foil type winding dry type transformer is widely used in the power system field because of its advantages of fire prevention, moistureproof, deeply to load center, ampere-turn evenly distribution and the ability to short-circuit resistance. But compared with oil-immersed transformer, Epoxy resin casting foil type winding dry type transformer has a poor thermal performance for its cooling medium is atmosphere which could make transformer internal temperature differential and service life shortened. So accurate calculation to temperature distribution of the transformer is very important for thermal design and life prolonging of it.In this paper the structure model of Epoxy resin casting foil type winding dry type transformer is established, based on which magnetic leakage field mathematical model combined with magnetic field theory is set up adopting method of finite element, then using this model leakage magnetic field distribution of the transformer is simulated in steady field, the horizontal and vertical leakage flux density of the transformer are figured out, and on the basis of the reckoning eddy-current loss of transformer winding is computed, finally eddy current distribution is got and excess and total loss of transformer winding are counted.After getting the overall loss of winding, finite element equations of Two-dimensional fluid field and temperature field are established based on heat transfer and hydromechanics theory. Then the loss is uploaded to transformer winding as heat source, and the fluid parameters are crossover operated with temperature parameters adopting the method of fluid structure interaction, at last the temperature distribution of transformer winding is got, meanwhile hot position and the hotest temperature are got either.The theory and test results are compared with analog computation in the aspects of leakage magnetic field, eddy-current loss and temperature distribution in this paper. And we proved that the calculated results showed in this paper are close to that of actual measurement, the method refered to is feasible, and it provide evidence for the future thermal design and hot prediction.