【作者】 许强；

【导师】 李胜利； 黄茂；

【作者基本信息】 华中科技大学 ， 环境工程， 2017， 硕士

【摘要】 变压器是电力系统的核心部分,与整个电网正常运行紧密相关,因此,及时有效监测变压器的运行状况十分关键。目前,国内外多采用聚合度、糠醛等作为变压器的检测指标,但仍存在实际操作困难、检测不精确等缺点,而甲醇是纤维素分解的第一产物且具有良好的热稳定性,同时在老化初期就有较高含量,可作为老化特征产物。基于此,本文尝试以甲醇作为变压器新的检测指标,与聚合度和糠醛的检测效果进行对比,验证甲醇作为变压器检测指标的可行性和创新性。模拟实际变压器运行环境,在130℃条件下探究绝缘纸老化过程中聚合度的渐变过程,用乌氏粘度计分别测定不同时间点下的聚合度,得出结论:老化前期绝缘纸聚合度下降速度很快,当老化时间大于50天时,聚合度随着时间的增长,降速变慢,180天时老化基本结束。用萃取浓缩的方法对油中糠醛进行预处理,借助光谱仪检测油中糠醛的含量,得到:甲醇萃取液和油样体积比为1:1,离心静置30分钟为最佳预处理条件。理想变压器油中糠醛在波长270 nm有较好的出峰,但实际情况下由于添加BHT(二丁基羟基甲苯)使其出峰受到严重干扰。研究发现加入TBA(2-硫代巴比妥酸)可与糠醛反应得到黄色化合物,此化合物在波长为392 nm处稳定出峰。设计了一种检测水中甲醇含量的光谱法,并以此为基础推广至油相检测中,最佳实验条件为:0.5 mL高锰酸钾、2.5 mL稀硫酸同甲醇反应并保持10 min,用亚硫酸钠中和至无色后,再加入变色酸(与甲醇摩尔比3.2:1),并添加6 mL浓硫酸。最佳实验条件下,可在波长554.55 nm处,得到反应最终生成物的最佳吸光度,且标准曲线相关性较好。克拉玛依25号油中使用甲醇含量作为变压器的检测指标,验证效果比较理想,甲醇回收率为94.7~96.0%,精密度为0.8~2.9%,此手段具备检测实际变压器老化油中甲醇含量的可行性。更多还原

【Abstract】 As an important component of the power system,transformer is closely related to the normal operation of the whole power grid.It is crucial to monitor the operation condition of the transformer in time.At present,degree of polymerization and furfural are usually used as detection index of the transformer,but it is also difficult to detect and the accuracy is low in practice.Methanol is the first product of decomposition of cellulose and has good thermal stability,at the same time,it have higher content in the early aging,in that case it can be used as the aging characteristics of products.At that point,we attempted to use methanol content as a new index of transformer aging,compared with the degree of polymerization and furfural detection,to verify the feasibility and innovation of methanol as a transformer testing indicators.Actual operating environment of transformer is simulated to explore the gradual process of polymerization degree of insulation paper aging under the condition of 130℃.Degree of polymerization is measured by ubbelohde viscometer at different time points.It is concluded that the polymerization degree of insulation paper drop quickly at the beginning of aging.When the aging time is more than 50 days,the degree of polymerization slow down as time goes on,and the aging basically end at 180 day.Furfural in oil is detected by multichannel ultraviolet–visible spectroscopy,with extraction pretreatment.Methanol extract and oil volume ratio is 1:1,centrifugation and set aside for 30 minutes are the best pretreatment conditions.In the ideal transformer oil,we can find a highest absorption peak at 270 nm for furfural,but the peak is seriously disturbed due to the addition of BHT(butylated hydroxytoluene).It is found that the addition of TBA(2-thiobarbituric acid)can react with furfural to form a yellow compound,and a obvious absorption peak can be found at 392 nm.A spectrum detection method is designed to measure the methanol content in water,then it is used in the oil phase.The optimum experimental conditions are as follows: keep 2.5 mL sulfuric acid and 0.5 mL potassium permanganate with methanol for 10 min.then sodium carbonate is added to neutralize solution;add the chromotropic acid(with molar ratio of methanol to 3.2:1),then add 6 mL concentrated sulfuric acid.Under the optimum experimental conditions,the optimum absorbance of the final product can be detected at the wavelength of 554.55 nm,and the correlation of the standard curve is fine.The use of methanol content as the indexes of the Karamay No.25 transformer oil,is verified ideally,and the methanol recovery percentage is 98-102%,the precision is 4-5.5%.There is the feasibility of this method in actual detection of methanol content in oil of aged transformer.更多还原