Molecular ionization potentials of triglycerides and mechanism analysis of streamer discharge in vegetable insulating oil

With the enhancement of social awareness of environmental protection, scholars have gradually began to focus their research on vegetable-oil-based insulating fluid. In this work, we calculated the ionization potential of triglyceride molecules in vegetable oil (VO), analyzed the mechanism of charge generation, and explained the cause of fast streamer discharge in VO based on the distribution characteristics of ionization potential. Some interesting results were obtained. The position of C--C on the triglyceride branch chain can affect the ionization potential of triglycerides. Specially, the C--C at the Sn-2 position can significantly reduce the ionization potential of glycerol molecules. The ionization of unsaturated triglycerides is mainly caused by the electron loss of carbon atoms in the C--C double bond; the formation of negative ions mainly rely on ester groups and their nearby atoms to capture electrons. In VO, low ionization potential molecules are predominantly present, and their presence results in a lower breakdown voltage and easy formation of the fast streamer discharge. We anticipate that our research can provide theoretical support for the application research of vegetable insulating fluid.