Quantitative Diagnosis of Micro-water in Oil-paper Insulation Transformer Based on Integral Function

The micro-water content of insulation transformer is one of the important factors affecting its serving life. Based on the theory of depolarization electric quantity and dielectric response, the beginning depolarization electric quantity S
oil
and the terminal depolarization electric quantity S
paper
of depolarization current are extracted to evaluate the micro-water content of oil-paper insulation transformer. Firstly, the depolarization current curves of insulating oil and insulating paper under different moisture content were compared; Then, the two characteristic vectors S
oil
and S
paper
are extracted according to the identification results of dielectric response parameters of depolarization current curve. The analysis results show that both S
oil
and S
paper
increase exponentially with the increase of micro-water content in oil-paper insulation. Finally, an example is given to verify that the proposed characteristic vectors can better evaluate the micro-water content of oil-paper insulation transformer.