A non-linear phenomenon in dielectric response used for insulation diagnosis of oil-immersed paper

The insulation diagnosis method based on frequency domain dielectric spectrum is widely used in field test because of its nondestructive testing, rich insulation information and so on. FDS measurement results are easy to be affected by many factors. However, interpretation on the dielectric properties of oil paper insulation with moisture content, impurity ion concentration influence mechanism of the current research is not very ideal, so it is necessary to determine more appropriate and effective dielectric response simulation and experimental analysis of characteristics. In addition, moisture content (m.c.) is an extremely important factor which can determine the insulation state of Oil-immersed paper. Therefore, the evaluation of moisture content of oil-immersed paper has obvious significance. In this paper, based on the experimental results, the extended Debye model parameters of the field transformer are obtained. Then, the influence of the insulation resistance value in the Debye model on the FDS curve is simulated by MATLAB modeling. The simulation and experimental verification show that the regularity of the change of the FDS conductance process is obviously different from the moisture content influenced by the impurity ions. The impurity ions mainly affect the low frequency section of the imaginary part of the complex capacitor. A non-linear phenomenon in dielectric response with different moisture contents under different is observed. We found that the non-linear phenomenon has relationship with the hindrance effect of cellulose (m.c.<;5%), which is modeled and testified with experimental results.