Analysis Of Stray Losses Induced By Heavy Current Of Lead Wire In Power Transformer

With the fast development of national economy, power transformer is becoming more and more important. People care much more about safe operation and service life of the power transformer. Therefore, stray losses and local overheating should be given due attention. Reducing and unforming the stray losses are beneficial to decreasing overheating and preventing aging of insulation. The research on these problems is of profound practical significance for the safe operation and service life promoting of the transformer.In this thesis, a single phase transformer,380000kVA/500kV, with its heavy current of 14074.1A in low-voltage lead wire is taken as an example. Based on the commercial software ANSYS, the harmony analysis module is used to carry on the simulation and computation for magnetic field and eddy current field. Through the establishment of reasonable computation model and the specification of appropriate boundary condition, the result data are obtained. The research of this thesis focus on the analysis of the magnetic field and eddy current losses in the structure parts surrounding the heavy current lead wire of the power transformer, including the enclosure, high and low flange, cover of oil tank and its electric shield, screws along the oil tank cover and so on. The purpose is to discover the spot where the eddy current density maximum value occurs, obtain the possible local overheating positions. The research has an actual value of reference to the designer.At the same time, this thesis also analyzes the factors which affect the magnetic and eddy current distribution of the enclosure and other parts. The simulations are carried out in different cases of lead wire current, material properties, and thickness of the oil tank electric shield respectively. The calculated results are demonstrated by figures and tables to show the distribution of magnetic field and eddy current. which is advantageous in the careful understanding power transformer enclosure and around. Besides, a numerical model is designed to verity the computation precision. The results and some conclusions of practical significance can provide a useful reference for engineering design.