Research On The Mechanism Of The Impacts Of Multiple Sulfur Corrosion On Transformer Oil-paper Insulation Degradation Properties

Power transformer is one of the most important equipment in power grid system,and its normal operation offers an important guarantee of safe,reliable and economic functioning of power system.Oil-immersed transformer is the most widely used one among power transmission and distribution equipment,which is one of the most important and core equipment to ensure the safe operation of the power grid.Active sulfide existing in the transformer oil react with copper wire to generate copper sulfide,which deposits on the surface of the insulating paper,reducing the electrical insulation properties and insulation fault.Today domestic and foreign research on corrosive sulfur mostly concentrated on the DBDS,considering DBDS in transformer oil is the most significant corrosive sulfide.Also transformer oil contains a variety of sulfur ingredients,such as mercaptans,sulfones,thioether compounds,various sulfur composition of interactions will also affect transformer oil-paper insulation,sulfur corrosion reaction may be related to this interaction.Therefore,the research on multiple sulfur corrosion of oil-paper insulation degradation mechanism has important academic value.To study the influence rule of multiple sulfur compounds on the degradation mechanism of oil-paper insulation,the accelerating thermal aging test at 140? on oil-paper insulation containing different concentration of DBDS,dibenzyl sulfide and dodecyl mercaptan was conducted,the samples were taken regularly and the characteristic parameters of oil-paper insulation such as degree of polymerization,acid value and moisture of oil and paper were measured and analyzed.As the result indicates,corrosive sulfur accelerates the degree of aging of oil-paper insulation.Besides,the amplitude of the acid value and micro-water content,pyrolysis rates of insulation paper,furfural content in the oil increase with the increasement of concentration of DBDS and dodecyl mercaptan.Apart from this,the combined influence of various multiple sulfur compounds on oil-paper insulation which involves interaction is not just the simple linear superposition of single sulfuret.To study the influence of external environment condition on multiple sulfur corrosion reactions,the accelerating thermal aging test on oil-paper insulation system under 130 ? containing different concentration of DBDS and 1-Hexadecanethiol and 1-Octadecanethiol was conducted with regular sampling test,setting temperature and oxygen control.Research shows that the oxygen concentration makes difference on oil-paper insulation aging characteristics under the influence of multiple sulfur corrosion.The sulfur corrosion effect on the degree of ageing overall increases with temperature.Among the samples containing two types of sulfide,sample with 1-Hexadecanethiol and 1-Octadecanethiol shows weak influence on the promotion of copper corrosion.Based on the combination technique of gas chromatograph and sulfide luminescence detector,a qualitative and quantitative analysis method of multiple sulfur compounds in transformer oil was established to research the kinds and contents of sulfur compounds in corrosive oil.By using the method,erosion effects to transformer oil of different mercaptans is studied.Test results show that when there is only one kind of mercaptan in transformer oil,the erosion will only product corresponding sulfoether;when there are multiple mercaptans in transformer oil,crosslinking reactions occur and producing new sulfoethers.