The Research Of Preparation And Properties Of Novel Thermal-Resistant Insulating Paper Based On Amine Compounds And Nano-Alumina

As the voltage level of the transformer increases and the capacity increases,the reliability of the transformer operation faces enormous challenges.At present,the main factor affecting the reliability of transformer operation is the deterioration of oil-paper insulation performance caused by thermal aging.The deterioration of the insulating oil can be improved by oil filtering or oil change,but the insulating paper must be replaced by hanging cover or disintegration of transformer.Therefore,the insulating paper is a key factor determining the life of the transformer,and the thermal aging resistance of the insulating paper is gradually becoming research hotspots.At present,in actual engineering,the position of the transformer is improved by the use of amine-based modified insulating paper(commonly known as thermally upgraded paper).However,related research shows that although the thermally upgraded paper has good thermal aging resistance,it will lead to accelerated deterioration of the insulating oil during the aging process.Therefore,how to slow down the degradation of the insulating oil by the amine compound while improving the thermal aging resistance of the insulating paper has become an urgent problem to be solved.Firstly,this paper uses the existing laboratory insulation paper copying platform to add different kinds of amine compounds to the insulating paper to prepare heat-resistant aging insulation paper.By accelerating thermal aging experiments,different amine compounds modified papers are made to investigate the influence on the thermal resistance and its compatibility with insulating oil,physical and chemical properties and molecular simulation were combined to explore its influence mechanism.Then,by studying the thermal aging resistance of paper modified with different ratio of amine compounds and its compatibility with insulating oil,the optimal formulation of the composite amine compound is obtained.Further,the nano-alumina is doped to improve the thermal aging resistance of the insulating paper and the insulating oil,and the related mechanism is investigated.Finally,the composite amine compound was added together with nano-alumina to prepare a novel thermal aging resistant insulating paper,and its compatibility with insulating oil was studied.The innovative research results of this paper are:(1)The insulation paper formulation with improved thermal aging resistance and insulating oil compatibility of insulating paper was obtained: 0.75 wt% dicyandiamide + 2.25 wt% melamine + 0.2 wt% polyacrylamide + 2 wt% nano-alumina.After 56 days of aging,the retention of tensile strength of this modified paper is higher than that of ordinary paper by 53%,and the polymerization degree is 160% higher than that of plain paper.In addition,the color,acid value,moisture and breakdown voltage of insulating oil with this modified paper are superior to the insulating oil corresponding to other formula insulating paper;(2)Combined with the physicochemical properties and molecular simulation of amine compounds,the mechanism of the influence of amine compounds on the performance of insulating oils is obtained.The amine compounds are hydrolyzed to produce ammonia during the aging process,and the complex reaction of ammonia and copper added to analog the copper windings of the transformers ammonia occur.The reaction will causes an increase in the concentration of the copper compound in the oil,thereby accelerating the deterioration of the insulating oil;(3)Combined with the analysis of physical and chemical properties of influence of nano-alumina modified paper during heat aging,it reveals the mechanism that nano-alumina will improve the heat aging resistance of insulating paper and insulating oil simultaneously.For insulating oil,copper compounds accelerate the degradation of insulating oil,while nano-alumina in insulating paper can adsorb copper compounds in insulating oil,and the reduction of the copper compounds concentration in insulating oil will slow down the aging of insulating oil.For insulating paper,due to the decrease of the aging rate of the insulating oil,the aging products such as peroxy radicals,which accelerate the aging of the insulating paper in the insulating oil,are reduced.At the same time,the nano-alumina reduces the participation of small molecules of acid and water in aging process to inhibit the aging rate of the insulating paper by physical adsorption and chemical reaction.