Investigation on micro‐mechanism of palm oil as natural ester insulating oil for overheating thermal fault analysis of transformers

Abstract

In order to explore the pyrolysis mechanism of palm oil as the natural ester insulating liquid from the molecular aspect, the ReaxFF reactive force field was used to simulate the pyrolysis process of palm oil. Firstly, the molecular models of the four main molecules of palm oil—tripalmitin, trilinolein, triolein, and tristearin—are constructed via density functional theory (DFT). Secondly, the vibrational frequencies of the four molecules are calculated, so as to calculate the infrared (IR) spectra. Thirdly, molecular dynamics (MD) simulations employing the ReaxFF method are performed to simulate the pyrolysis reaction of the palm oil system under different temperatures, so as to observe the generation pathways of major products used in the dissolved gas analysis (DGA) in the transformer thermal fault analysis. Finally, hydrogen bonds in the pyrolysis process are counted. It is found that the number of hydrogen bonds gradually increased with the increase of pyrolysis time and pyrolysis temperature. It reveals why the life of the insulating paper immersed with natural esters is prolonged, and why the breakdown voltage is reduced slowly in the actual experiment from another perspective. This study can provide theoretical guidance and effective reference for the thermal fault analysis of an insulating liquid using palm oil as raw material.

Axial and radial electromagnetic‐vibration characteristics of converter transformer windings under current harmonics

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A review on a novel method for aging evaluation of transformer insulating paper based on methanol

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Microscopic Mechanism of Electrical Aging of PVDF Cable Insulation Material

“…The theory of quantum mechanics means that molecular simulation technology is not only limited to the study of chemistry, but also extended to electrical, physical, biological and material science and other disciplines, promoting the development of interdisciplinary research and providing a new means for people to understand the material world, in addition to experimental methods and theoretical methods [15]. Many scholars have applied molecular simulation methods to the field of high-voltage insulation, such as the synergistic effect of electric fields and temperature on insulating oil [16,17], the microscopic mechanism of the overheating of insulating oil [18,19], the aging and degradation of insulating materials [20,21], and the diffusion of gas molecules in oil paper insulation systems [22,23]. Meanwhile, molecular simulation has been successfully used in the study of PVDF, the static and dynamical mechanical properties of PVDF [24], elastic properties of PVDF crystals [25], and the effect of the addition of ionic liquids to PVDF [26].…”