Study on The Aging characteristics of Transformer Oil-paper Insulation Based on Improved Time Domain Dielectric Spectroscopy

In order to study the aging characteristics of oil-paper insulation, and thus providing reliable basis for condition assessment of transformer insulation, in this paper, we carried out accelerated thermal aging test in Laboratory environment and researched the polarization/depolarization current of samples by using time domain dielectric spectroscopy. Then, we proposed an algorithm for improving time domain dielectric spectroscopy by wavelet transform theory. The results show that time domain dielectric spectroscopy can reflect the overall polarization processes of oil-paper insulation and as the aging time increases, the peak value of the dielectric spectroscopy increases. The improved wavelet transform algorithm can effectively improve the time domain dielectric spectrum, thus the main polarization processes of oil-paper insulation is clearly shown in the time domain dielectric spectroscopy. Peaks' value and time of improved time domain dielectric spectroscopy correspond to the intensity and responding speed of different polarization processes, and peaks value has a good linear relationship with aging times which can be used to quantitatively assess the aging condition of different part of oil-paper insulation.