Estimation of Insulation Condition Sensitive Parameters from Polarization Current using DFA

Polarization and Depolarization Current measurement technique is a popular technique used for the condition assessment of Power Transformer insulation system. The assessment is usually done by identifying Debye model parameters from the measured polarization current data. However, obtaining the Debye model parameters involves complex computation and the model parameters are also dependent upon the number of branches in the model. Hence, in the present work, a Detrended Fluctuation Analysis (DFA) based method is proposed for the estimation of insulation condition sensitive parameters of the oil-paper insulation system. It was observed that one of the DFA coefficients maintain well-defined relationships with the Insulation condition sensitive parameters: dissipation factor, paper moisture content, polarization index and dielectric absorption ratio, which shows the applicability of the proposed technique.