Study On Sulfide Diffusion In Transformer Oil And Suppression Of Sulfide Corrosion By Modified Mesoporous SiO₂ With Copper Oxide

As the core equipment of power transmission and distribution,the safe and stable operation of transformer determines the key of power transmission.Transformer insulation is mainly composed of insulating oil and insulating winding.The corrosive sulfide contained in insulating oil will react with copper winding,resulting in sulfur corrosion.Sulfur corrosion in transformer seriously damages the mechanical and electrical properties of insulated windings,and then leads to transformer failure.Therefore,how to effectively inhibit the occurrence of sulfur corrosion in transformer is of great significance to ensure the normal operation of transformer.Based on this,the inhibition effect of metal oxide supported mesoporous silica on sulfur corrosion in transformer was studied by molecular simulation and experiment.The influence factors of sulfide diffusion in oil paper insulation system were analyzed by the motion trajectory,diffusion motion,free volume and interaction energy of sulfide.The solid adsorbent with relatively good adsorption energy was selected to adsorb sulfide in insulating oil.By comparing the interaction between CuO,MgO,ZnO and DBDS interface by molecular simulation,the CuO with better adsorption performance for DBDS was selected to support on mesoporous silica.The aging test was carried out by adding SiO₂ loaded with CuO to insulating oil.The change rule of copper and sulfur on insulating paper with aging time,the change rule of sulfur on copper winding with aging time,the change rule of copper and acid value content in insulating oil with aging time were studied.The main conclusions are as follows:（1）The binding ability of different sulfides to oil paper is different,which leads to the different distribution of sulfides in oil paper system.The diffusion ability of sulfide in insulating oil or paper has a negative correlation with the interaction energy,because the binding energy of sulfide with insulating oil or cellulose inhibits the movement of sulfide and reduces its diffusion ability.Through the calculation of free volume,it is found that the free volume fraction of hydrogen sulfide is the largest in both oil and cellulose.This means that hydrogen sulfide molecules can better move holes in insulating oil or cellulose,indicating that free volume fraction determines the diffusion ability of small molecules.（2）Copper oxide,magnesium oxide and zinc oxide can adsorb DBDS,and the adsorption can be spontaneous.Compared with MgO and ZnO,CuO has stronger adsorption capacity for DBDS.By analyzing the interaction energy between the three metal oxides and DBDS,it is found that the interaction energy between copper oxide and DBDS is the largest,which well explains that the thickness of the interface between copper oxide and DBDS is the largest,and the diffusion motion of DBDS is inhibited by the interface between copper oxide and DBDS.（3）Based on the analysis of the change of sulfur content on the surface of insulating paper with time,the change of sulfur content on copper winding,and the change of copper and acid value in oil,the results show that the mesoporous silica loaded copper oxide can inhibit the sulfur corrosion in transformer.It has a good inhibition effect on the sulfur corrosion of low concentration sulfide in insulating oil,but not on the sulfur corrosion of high concentration sulfide.At the same time,the water and acids will be adsorbed on the mesoporous silica,reducing the adsorption sites of DBDS.