Analysis of Complex Electrical Field on Valve Side Winding of Converter Transformer

Abstract

In order to analyze the electrical field distribution of the converter transformer,the simulation model of oil-paper combination is established,and the maximal field intensity positions of the insulation under different excited voltages such as DC field,AC field,superimposed AC-DC field and a polarity reversal voltage are emulated with FEM(Finite Element Method).The distinguishing features of the transient field are summarized,and the calculation results show that the characteristics of electric field at valve side winding of converter transformer are both regularity and complexity.The electric field's distribution under the DC voltage is depended on the resistivity,which leads to the higher electric-field intensity in the insulating carboard.And the electrical field distribution under AC voltages is depended on the dielectric constant,which leads to the higher electrical field intensity in the oil.Under the polarity reversal voltage,the oil will undertake a very high voltage caused by the space charge accumulation.