Analysis On Magnetic Leakage And Eddy Current Loss Of Metal Structure Of Power Transformer

With the development of economic, the demand of electric power is moreand more big, the grid capacity will be increasingly high. As an indispensablyimportant equipment of power grid, greater capacity power transformer will besurely needed. However, leakage magnetic field strength will increase in thegreater capacity transformer. With the leakage magnetic field strength increasing,the stray loss in the metal structure of transformer will be larger. As a result, thelower efficiency of transformer will be caused. At the same time, because sometransformer metal components have irregular shape and are relatively close to thewinding, so large eddy current density will be produced in local region. When thecooling condition is not ideal, it is easily produced local overheating which willaffect the normal run of transformer. So the analysis and calculation of leakagemagnetic field and eddy current field of metal structure of power transformer isvery necessary.An actual large power transformer is simulated and calculated by a widelyused ANSYS finite element software in the paper. The magnetic flux leakagemagnitude and distribution of the windings and metal structures which arecomprises a transformer tank, clamps and the tie-plate are got, what is more, theexhaustive analysis is carried on. On the basis of that, the eddy current field ofthe transformer metal structure are calculated and analyzed and the eddy currentloss density distribution and eddy current loss of the metal structure are got.Based on the value and the distribution regulation of eddy current loss of thetransformer metal structure, the measures that can correspondingly reduce theeddy current loss and eddy current loss density of transformer metal structure aretaken. The transformer oil tank is added magnetic shielding and the effect toreduce the oil tank eddy current loss by different shield sizes is given, likewise, itis also taken additional magnetic shielding to reduce the eddy current loss and eddy current loss density of the clamps. The tie-plate is slotted to reduce the eddycurrent loss and the maximum eddy current loss density, at the same time, theinfluence on the effect to reduce the eddy current loss is given under differentsize and number of the slot. Meanwhile, mechanical strength check is made tothe tie-plate with different slots.Through the analysis of transformer leakage magnetic field and eddy currentloss and measures to reduce the eddy current loss of the metal structure, it canprovide an evidence for transformer metal structure design and more reasonablemeasures to reduce the eddy current loss.