Synergistic Effects of Excess Electrons and Water Molecules on Charge Trapping and Chemical Reactions in Oil/Paper Insulation Materials

Charge and water accumulation in oil/paper insulation systems are widely recognized as critical factors affecting their electrical and insulating properties. However, the molecular-level mechanisms underlying these phenomena remain poorly understood. In this study, we employ ab initio molecular dynamics simulations to investigate the effects of excess electrons and water molecules on charge trapping and structural degradation in mineral oil (MO), vegetable oil (VO), and insulating paper. Our results demonstrate that excess electrons enhance the trap depth in oil/paper insulation due to self-trapping behavior. The presence of water molecules further increases the trap depth, with the most pronounced effect observed in VO, which can be attributed to chemical reactions between water clusters and ester groups. Additionally, electron accumulation promotes the formation of water ion clusters during these reactions, a process that appears to play a pivotal role in the degradation of oil/paper insulation. These findings provide critical insights into how excess electrons and water molecules influence charge trapping and material degradation, offering valuable guidance for enhancing the insulating performance of oil/paper materials in power transformers.