Finite Element Analysis Of The Transformer Leakage Field And Its Oil-Tank Eddy Current Losses

The distribution of eddy current loss is non-uniform due to the complexity and scrambling of the metal structures in transformer.Local over-temperature arises easily and operation reliability of transformer decreases with the improper design.Most eddy current losses in transformer structures come from the oil tank,therefore,the accurate and further investigation of transformer leakage field and eddy current losses in the oil tank is significant to engineering practice.The problem of quasi-static alternating electromagnetic field is investigated in this paper.So the theories of quasi-static alternating electromagnetic field and finite element method applied to analyzing the electromagnetic field are especially introduced,the reason and its effects generating transformer leakage field are analyzed as well.Based on the actual power transformer model,through being simplified reasonably,the computing model of eddy current loss in transformer the oil tank is created applying the Ansofl/Maxwell3D software,defined model 1.Contraposeing the problem of reasonable mesh generation in ferromagnetic material is not solved in the case of low depth of penetration.Based on the analysis of structure and eddy current characteristics,using surface impedance method,the problem is solved.Based on the analysis of 3D eddy current field of the transformer oil tank.Eddy current loss in transformer oil tank is calculated,the conclusion is analyzed and validated as well.Further more,the numerical calculation conclusion meets the precision need of application in engineering.The tank-wall electromagnetic shielding model and the magnetic shielding model are created to reduce eddy current loss based on the calculation of eddy current loss,defined model 2 and model 3.The eddy current loss of the tank-wall is reduced on shielding. Shielding efficiency of two shielding is contrasted and analyzed,and some suggestion is proposed for application.3D eddy current field model is created For preventing local overheating being consequent on the convergence of eddy current loss when three-phase Transformer Lead passes the tank lid,defined model 4.The 3D eddy current field distributing,eddy current loss and local overheating are calculated and analyzed,and some advice able to guide engineering practice are obtained.