Study On Oxidation Resistance And Dielectric Performances Of Polysilsesquioxane Modified Natural Ester Insulating Oil

Natural ester insulating oil is a kind of renewable environmental frendly liquid dielectric,which has the performances of high burning point and anti-aging of insulating paper,and has been widely used in distribution transformers.The weakness of oxidation stability and low breakdown performance of natural ester insulation oil limit its application in large power transformers.The problems of particles agglomeration and impurity bridge are easy to be produced in the nanoparticles modified insulating oil,which limits the practical application of nanoparticles modified insulating oil.Therefore,based on the grafting modification of polysesquioxane and epoxidized soybean oil,a kind of nanoparticles modified natural ester insulating oil with good dispersion stability,high oxidation stability and excellent lightning breakdown performance was developed.It has important academic significance and engineering value for the design and application of environmental protection nanoparticles modified natural ester insulating oil transformer.The main research contents of the paper are as follows:(1)The molecular dynamics simulation of polysesquioxane modified natural ester insulating oil was carried out.The antioxidant performance of polysesquioxane modified natural ester insulating oil under high temperature and oxygen atmosphere was studied.Based on Arrhenius model,the influence of polysesquioxane on the activation energy of natural ester insulating oil at different temperatures was calculated.The diffusion characteristics of oxygen molecules in polysesquioxane modified natural ester insulating oil were obtained.The mechanism of enhancing the oxygen performance of polysesquioxane modified natural ester insulating oil was revealed.The ionization energy and electronic affinity of polysesquioxane were calculated.it was proved that polybisilicoxane was a kind of nano material with antioxidant and high insulation performances.(2)The grafting modification of polysesquioxane with epoxidized soybean oil was proposed to prepare the polysesquioxane nanoparticle additive with excellent dispersion in natural ester insulating oil.The influence of the new additive content on the dispersion stability and oxidation stability of natural ester insulating oil were studied.The results show that the polysesquioxane modified natural ester insulating oil has excellent dispersion stability after accelerated precipitation tested by high speed centrifugal,and the initial oxidation temperature of polysesquioxane modified natural ester insulating oil was tested.It was found that polysesquioxane can significantly improve the oxidation stability of natural ester insulating oil.(3)Dielectric and lightning breakdown performances of polysesquioxane modified natural ester insulating oil were studied.The results show that polysesquioxane does not affect the dielectric constant and resistivity of natural ester insulating oil,and the power frequency breakdown voltage increases by 10 %.The lightning breakdown and discharge characteristics of polysesquioxane modified natural ester insulating oil were studied.The results show that the streamer of polysesquioxane modified natural ester insulating oil is similar to that of traditional nanoparticles modified oil,and its maximum positive lightning breakdown voltage increases by 17 %.The mechanism of improving the lightning breakdown performance of polysesquioxane modified natural ester insulating oil was analyzed.In this paper,a new grafting modification method of polysesquioxane was proposed to improve the oxidation stability and lightning breakdown voltage of natural ester insulating oil.A kind of nano particles modified natural ester insulating oil with good oxidation stability and insulation performance was prepared.The mechanism of improving the performance of natural ester insulation oil by polybissiloxane was analyzed.It is of great significance to the engineering application and academic research of nano particles modified natural ester insulating oil.