Aging evaluation for transformer oil-immersed cellulose insulation by using frequency dependent dielectric modulus technique

Abstract

Frequency domain spectroscopy (FDS) technique is widely used for the aging evaluation of the transformer oil-paper insulation system. However, the typical ‘relaxation information’ of FDS data in low-frequency regions is seriously affected by both the electrode polarization effect and conductance effect, which often leads to an unsatisfactory aging condition evaluation result. Existing researches reveal that the Frequency Dependent Dielectric Modulus M*(ω) technique can be utilized for solving this issue. Since the relevant parameters, that aims to represent the aging condition of transformer oil-immersed cellulose insulation, extracted from M*(ω) has been rarely reported, and the feasibility demonstration of the field testing by exploiting the relevant parameters extracted from M*(ω) is also rare. Therefore, the novel attempt for obtaining the relevant parameters of M*(ω) were reported in this paper. Moreover, the accuracy and feasibility of the extracted parameters were later verified with the evaluation test in the lab and field conditions. In that respect, the present contribution demonstrated that the extracted parameters could be used as an available tool for the aging evaluation of transformer oil-immersed cellulose insulation.