【作者】 梁帅伟；

【导师】 廖瑞金；

【作者基本信息】 重庆大学 ， 电气工程， 2009， 博士

【摘要】 变压器是电网安全运行中最关键设备,变压器的严重事故不但会导致自身损坏,还会中断电力供应。由内绝缘问题引发的变压器故障占变压器事故重要部分。改革开放以来,运行20年以上的大型油浸变压器数量增长很快,其内绝缘材料(主要是绝缘油和绝缘纸)的老化决定变压器运行寿命,并极易因材料老化引起设备故障并造成事故。抑制变压器内绝缘老化,延长运行寿命和提高安全运行水平已成为现实的迫切需要。目前,国内外所报道的传统变压器油抗老化研究,只局限于油本身的抗老化,未涉及对变压器油-纸绝缘老化的影响,尚存在很多技术难题和学术问题需要解决。因此,研究抗老化变压器油和油对提高绝缘纸抗老化能力的影响具有重要学术价值和实际意义。该文①首先通过399天加速老化试验研究了天然酯-纸绝缘和矿物油-纸绝缘的热老化特性,为进一步研究矿物油和酯混合式抗老化油奠定了试验和理论基础,也为研究抗老化油对油-纸绝缘抗老化的影响夯实基础。接着,开展了矿物油和酯混合式抗老化变压器油的研制,探索了其中添加的复合抗氧化剂的协同抗氧化作用机理,研究了该油各项理化参数,参数均满足标准要求,并研究分析了该油的击穿电压、介电频率谱和介电温度谱。然后,通过264天加速老化试验研究了所研制抗老化变压器油的老化特性,实验检验了其优良的抗老化性能,成功实现油和油-纸绝缘双重抗老化目的,并深入探讨了它对油-纸绝缘抗老化的机制。论文取得主要创新性成果有:研究了天然酯-纸绝缘的热老化特性,结果表明酯能抑制绝缘纸老化,为研究混合式抗老化油奠定基础。成功研制了高性能抗老化变压器油,并提出了酯的最佳萃取条件,提出了采用0.3%T501+0.3%L06来提高抗老化变压器油的抗老化性能。将分子模拟、红外光谱技术和压力差式扫描法相结合,得到了复合抗氧化剂T501和L06的抗氧化协同增效作用机制。研究得到了所研制的抗老化变压器油的参数值:透明度、气味、密度、凝点、闪点、运动粘度、酸值及水溶性酸或碱等,均满足变压器油技术标准GB 2536-90的要求;20℃～90℃之间该油运动粘度和矿物油几乎相等;在30～106Hz频率范围内,该油相对介电常数基本维持恒定,且比矿物油相对介电常数略大;其工频击穿电压远高于矿物油。这些初步研究结果表明,该油可作为电力变压器绝缘用油。研究了所研制的抗老化油和纸组成的油-纸绝缘热老化特性,包括油的颜色、酸值、糠醛浓度、微水含量、运动粘度以及绝缘纸聚合度、纸中酸值、纸中微水含量等重要参数的变化规律,结果表明该油既能提高变压器油本身的抗老化性能,又能明显抑制绝缘纸老化,即所研制的变压器油和由其浸制的绝缘纸具有双重抗老化能力。首次提出了混合式抗老化油-纸绝缘的抗老化机制:在分子层面上提出混合式抗老化油具有束缚水分子的作用;用红外光谱证明了高分子酸与绝缘纸产生酯交换反应,抑制纤维素热应力下的水解作用;提出了高分子酸与纤维素之间的酯交换反应和酯中羰基氧原子与水分子形成氢键具有联合抗老化能力。建议IEC制定相关标准将油-纸绝缘老化过程中低分子酸和高分子酸分别测量。更多还原

【Abstract】 Transformer is the most critical equipment insuring the safe operation of power grids, because its serious incidents will not only damage itself, but also interrupt the electricity supply. The transformer failure caused by inner insulation problems accounts for an important part of the transformer accidents. The number of oil-immersed transformers running more than 20 years has increased rapidly since Chinese Reform and Open-up. The aging of insulation materials (mainly parts are the insulation oil and paper) decides their operational life. And for the aging, materials are vulnerable which could cause equipment fail and other accidents. It is urgent to inhibit the transformer insulation aging, extend the operational life and improve the safe operation level. Nowadays, the antioxidation research of insulation oil is only focused on the oil antioxidation itself, but not on the oil and paper. Therefore, in order to improve insulation ability, the research about antioxidation transformer oil and①paper has important academic value and practical significance.The properties of natural ester paper insulation and mineral oil paper insulation were studied through 399 days’aging experiment, which not only built the experimental and theoretical foundation of further study on mixture antioxidation oil, but also tamp the foundation of research on influence of antioxidation oil to insulation paper. Then the mixture antioxidation oil is developed. The cooperation antioxidation mechanism of the antioxidants was studied, and the physical and chemical parameters of mixture oil were measured, all of them were according to the standard. The relative permittivity of the oil and breakdown voltage were studied as well. After that, the properties of mixture oil paper insulation were studied by 264 days’aging experiment. The excellent property of the oil has been studied so that we could gain the goal of antioxidation for oil and paper. The excellent properties and mechanisms of oil have been studied. The main results of this paper are as following.After the properties of natural ester paper insulation were studied. We could find that the natural ester can restrain the aging of paper.The antioxidation oil was developed successfully. The best extraction condition was advanced. The compound antioxidants 0.3%T501+0.3%L06 was brought forward. And the cooperation mechanisms of the compound anti-oxidant were studied by molecule simulation, infrared analysis and Pressure Differetial Scanning Calorimetry (PDSC).Most parameters for the mixture antioxidation oil were studied and they were consistent with GB 2536-90, including transparence, smell, density, solidifying point, flash point, viscosity, acids and water-solubility acids;The viscosity of the antioxidation oil at 20℃～90℃was as same as mineral;And the relative permittivity at 30～106Hz was invariable and it was higher than mineral oil so that the electric field of the antioxidation oil paper insulation was more equilibrious. The break down voltage of the oil was higher than mineral oil. It can be used in transformer by these research results.Properties of antioxidation oil paper insulation were studied, including the oil colour, acids in the oil, furfural concentration in the oil, water content in the oil, viscosity, degree of polymerization (DP) of the paper, acids in the paper, water content in the paper. And the results showed that the antioxidation oil can not only restrain the oil oxidation itself, but also can restrain the aging of the paper immersed in the oil.The DP-Value of the paper immersed in the antioxidation oil is more higher than the mineral oil’s. Namely, the developed transformer oil and insulation paper dissolved from this kind oil have double anti-aging ability.Mechanisms of antioxidation oil paper insulation were studied. At the molecule level, this paper showed anti-aging oil mixed has bounding water molecules ability. The esterification between the high molecule acids and cellulose was prove by infrared spectrum analysis. It can restrain the hydrolysis under the thermal stress. The esterification between the high molecule acids and cellulose, and the hydrogen bond between oxygen atom in the ester has combination antioxidation ability. We suggested that IEC should develop some standards for measuring the low molecule acids and high molecule acids.更多还原