Analysis Of The Calculation Of Translating The Dielectric Spectroscopy Of Major Insulation Of Transformer To Oil-Impregnated Paper Using Xy Model

Frequency Dielectric Spectroscopy (FDS) Analysis has good application prospects in transformer insulation detection due to its non-destructive measurement and robustness against noise. Two steps are needed when analyzing transformer insulation using this method. The first step is to translate the dielectric spectroscopy of the major insulation of transformer to that of the oil-impregnated paper. Then based on dielectric spectroscopy, the aging degree and moisture content of the oil-impregnated paper are analyzed. Using a commonly used model named XY model, the complex permittivity of paper can be calculated by solving a quadratic equation. The equation has two solutions named solution1 and solution2 respectively. In this paper, the characteristics and distribution of the two solutions are studied. Firstly, the calculation process of translating dielectric spectroscopy of major insulation of transformer to oil-impregnated paper is introduced. For the cases of measured complex permittivity of oil-impregnated paper with different moisture content, the results show that the correct solution of most conditions is solution1. With the decline of moisture content of the paper, the range of frequency where solution2 is correct reduces. The calculated complex permittivity of oil-impregnated paper is decided by five variables. For universal cases, the variables' influences on the distribution of the two solutions are studied. The results show that for all the situations, one and only one solution is in the first quadrant of the complex plane. Thus, the part of the two solutions in the first quadrant of the complex plane is the correct solution. Only when omega < 0.01 rad/s, part of the correct solutions become solution2 and enlarge with the decrease of x. The increase of X and Y shrinks the outlines of the area which solution2 is correct and moves the outlines in the positive direction of X-axis.