Study On Deterioration Effect And Micro-Mechanism Influence Of Transition Metals On Vegetable Insulating Oil

With global warming,green and low-carbon environmental protection has become the theme of this era,and there is a greater need for environmentally friendly insulating oil products in the future.Vegetable insulating oil is considered a suitable alternative to mineral oil in the future development of low carbon networks and smart grids due to its renewable,biodegradable,high availability,and high ignition point properties.Compared to mineral oils,vegetable oils have higher flash and ignition points,but vegetable oils have high viscosity,high pour points and poor oxidation stability.The insulating oil in operating transformers is directly exposed to solid materials in the transformer,resulting in increased metal particle content in the oil and accelerated degradation of the insulating oil.Therefore,it is instructive to study the deterioration effect of transition metals on vegetable insulating oil to extend the service life of vegetable insulating oil and improve transformer operation and maintenance.In this paper,an experimental study on the degradation effect of transition metals on vegetable insulating oil was firstly conducted.Different kinds of transition metals and metal ions were used to perform thermal aging experiments on the vegetable insulating oil,and the physical and chemical properties and electrical performance indexes of the vegetable insulating oil were tested after aging.The results show that both iron and copper transition metals accelerate the deterioration of vegetable insulating oil,resulting in the reduction of its physicochemical properties,electrical properties,and oxidation resistance.Compared with iron,copper degrades vegetable insulating oil slightly more than iron.Compared with metals,metal ions have stronger oxidizing properties and degrade vegetable insulating oils to a much greater extent than metals.Next,experiments on the degradation effect of transition metals on vegetable insulating oil at different temperatures were conducted.Aging experiments were carried out using vegetable insulating oil at different temperatures with iron and copper,and the physicochemical and electrical performance indexes of vegetable insulating oil after aging were tested.The experimental results show that the higher the temperature is,the greater the decrease in the physicochemical and electrical performance indexes of the vegetable insulating oil and the deeper the degradation is.Compared with iron,copper has stronger degradation catalytic effect,resulting in lower physicochemical and electrical performance indexes than the oil after aging by iron,and the degradation rate of the oil is faster.Based on the above experimental results,to study the mechanism and microscopic mechanism of the deterioration effect of transition metals on vegetable insulating oil,a copper oil model was established in this paper,and the effects of temperature,contact area and oxygen on the catalytic effect of copper were investigated at the microscopic level by using a molecular dynamics simulation method based on ReaxFF reaction force field.The results show that copper accelerates the decomposition of insulating oil through the attraction of H and O atoms in vegetable insulating oil;the increase of temperature can accelerate the process of reaction,and the catalytic effect is enhanced with the increase of copper area.The above study reveals the microscopic mechanism of copper-catalyzed vegetable oil insulation degradation,which can provide theoretical reference for further exploration of effective insulation oil degradation protection technology.In conclusion,transition metals play a catalytic and facilitating role in the degradation of vegetable insulating oil.