Research On Eddy Loss And Hot Spot Temperature In Large Transformer Windings

With the increase gradually of the single transformer capacity, heating and coolingproblems of the transformer become more and more prominent. If the temperature of thetransformer winding exceeds the prescribed limit, it may cause insulation damage, make thetransformer can not work normally, and causes huge economic losses. In order to make thewinding hot spot temperature for transformer below the prescribed limit, winding hot spottemperature need to be analyzed. Therefore, it has important engineering application valueand practical significance for applied research of transformer winding hot spot temperature.Based on the finite element method, a two-dimensional simplified model is establishedby using special software MF2D, and the distribution of winding leakage magnetic field isobtained. On this basis, the eddy current loss for each partition of all windings is calculated,which provides the basic data to calculate the heat source density of transformer.On the basis of considering heat source and cooling structure, a two-dimensionalmodel and a three-dimensional model are established by using the fluid dynamics softwareFluent, and the model parameters such as material properties, boundary conditions are set.Eventually, the internal temperature distribution and hot spot location of transformerwinding are obtained by using finite volume method. The calculated results are comparedwith the optical fiber temperature measurement data, which verifies the rationality of the2d and3d calculation method, and an effective feasible method for calculating transformerthermal performance is provided.Finally, influences of the guide region number, the oil flow direction, the horizontal oilduct size and the vertical oil duct width in the winding hot spot temperature are researched,which provide applied conclusion for the design of product.