Microscopic mechanism analysis of the effect of ester insulating oil components on its power frequency breakdown characteristics

Ester insulating oil is a green and environmentally friendly insulating oil and is currently a hot topic in research. The power frequency breakdown characteristics of ester insulating oil are critical for ensuring the safe operation of ester insulating oil transformers. In this study, four models of saturated and unsaturated triglycerides were constructed based on the fatty acid composition of common ester insulating oils. Using molecular dynamics simulation, the molecular mechanisms by which ester insulating oil components affect its power frequency breakdown performance were investigated and analyzed. The simulation results show that the number of molecules per unit volume in unsaturated triglycerides is higher than that in saturated triglycerides, and glyceryl tristearate exhibits the strongest intermolecular forces. The radii of gyration for the four triglyceride-water models are similar, primarily due to their comparable molecular structures. Tripalmitin has the largest free volume, which facilitates stronger acceleration during electron redischarge. Trilinoleylglycerol, with the weakest binding ability to water molecules, is more prone to bridging reactions with small molecular impurities. This paper provides theoretical insights for the molecular design and structural development of high-performance ester insulating oils and offers valuable support for the safe and stable operation of ester insulating oil transformers.