Search

Oil-immersed insulation paper (OIP) bushing is one of the most important equipment in power transmission and distribution systems. Moisture is one of the most serious factors that affect the insulation status of OIP bushing. In this paper, the OIP bushing was assumed to be in a stable and simplicity condition, and then the transient moisture distribution of capacitor core and its effects on the electric field were studied. First, by dissecting a 110 kV OIP bushing, the specific sizes for modelling were obtained. Afterwards, a moisture diffusion model for OIP bushing was established based on COMSOL Multiphysics software, and it was also verified by moisture diffusion experiment. Then, the moisture distribution for different conditions were obtained and analyzed. Finally, a model for the electric field of OIP bushing was established, and then the effects of moisture on the electric field were studied.

Because the temperature and load of transformer are variable, the moisture is usually inhomogeneous in oil-paper, especially for the traction transformer. In order to research the dielectric relaxation behavior of the oil-paper composite insulation with an inhomogeneous moisture distribution, it was proposed that a theoretical model for dielectric medium with an arbitrary distribution of conductivity and dielectric constant. The dielectric frequency response of oil-paper with transient moisture distribution was simulated by using the proposed model. The results show that transient moisture distribution caused the concentration polarization(CP), which enhanced the low-frequency relaxation. The model is validated against experimental data. [ABSTRACT FROM AUTHOR]