Equivalent Circuit Modelling of Transformer Oil-Paper Insulation from Frequency Domain Spectroscopy Measurements

Abstract

This paper puts forward a novel approach to evaluate an equivalent circuit of oil paper insulation used in transformers from frequency domain spectroscopy measurements. In recent years, there has been considerable attention on the development of diagnostic tools for condition monitoring of power transformer insulation. Frequency Domain Spectroscopy is one such tool. A proper modelling will ensure that the parameters are influenced by insulation deterioration. Hence, if FDS data can be used for such modelling, it may lead to better interpretation of FDS data from the perspective of insulation monitoring. Considering the above-mentioned facts, a method has been proposed in this work that can model the FDS data through an equivalent circuit comprising of resistances and capacitances. The influence of moisture content on the circuit parameters have been investigated. From the investigation, a relation between the DC conductivity and moisture content of the insulation has also been proposed.