Analysis of electrical field on valve side winding of converter transformer

This article analyzes the different types of voltage applied on the valve side winding of the converter transformer. The oil-paper insulation model is established in laboratory in order to analyze the distribution characteristics of electrical field caused by the voltage applied on the insulation. The distribution of the fields caused by DC voltage, AC voltage, DC superimposed voltage and polarity reversal voltage is emulated with FEM (finite element method). It can be concluded from the results that the resistive distributed electrical field caused by DC voltage will lead to high field intensity in the pressboard. The capacitive distributed electrical field caused by AC voltage will lead to high field intensity in the oil. Influenced by the space charge field, the oil withstands most of the applied voltage in the stage of polarity reversal. The results can provide evidence for the insulation design of the converter transformer.