Impact of electric field on the moisture diffusion properties of insulation paper: a molecular dynamics simulation study

Kraft paper is widely used in oil-paper insulation of power transformer. This type of cellulose insulation paper degrades under the combined influence of a number of interrelated factors, including moisture and electric field, during the long-term running process of power transformer. And researchers have conducted a lot of researches in the field of moisture and electric field influence on the ageing process of insulation paper. Current researches are still confined to studies of moisture on the aging of insulation paper by means of macrostructure testing. And the influence of electric is carried out only by adopting Ansoft, Ansys and Matlab and other common simulation software in electrical engineering. While microcosmic process and mechanism of moisture and electric field influence on insulation paper could not be reflected by these approaches. The Material Studio software for material simulation was adopted in this article to study the electric field influence on moisture diffusion in insulation paper. Different simulation models, such as crystalline and amorphous cellulose with multiple electric fields, were established respectively, and relevant simulation results were as follows: the polarization of electric field on the surface of crystalline cellulose has obvious implication on water diffusion, which restricts the movement of water molecules on the crystalline surface. The diffusion coefficient was reduced with significant differences in different directions X, Y and Z. In comparison, the electric field influence on water diffusion in amorphous cellulose model was lack in regularity.