The Influence of the Aging States on Characteristic Parameter of Frequency-domain Dielectric Spectroscopy

In order to get more effective and accuracy results of condition evaluation for transformer, a dielectric response function model for frequency-domain dielectric spectroscopy (FDS) is presented in this paper based on dielectric physics in depth study. Firstly, the FDS properties of oil-immersed paper (OIP) are measured in lab. And the effect of the aging states on FDS characteristics of OIP was investigated. Secondly, with the proposed model, the actual FDS curves with different aging degree were mathematically fitted with high accuracy and some characteristic parameters are extracted. Finally, the relationships between characteristic parameters and aging degree were studied. The results indicate that the reconstructed FDS curve was in good agreement with the measured curve. The aging of the OIP not only produces moisture, which causes the conductivity loss to increase, but also contributes to the dielectric polarization, which leads to an increased polarization loss at high frequency. The characteristic parameters alpha, beta, and tau can be used to quantitatively describe the aging status of OIP. There is a linear correlation relationship between. and the aging time t, and between tau and t. The relationship between beta and t is an exponential correlation.