温度和水分对大型发电机主绝缘FDS特性影响的试验研究  

Effects of Temperature and Moisture on Characteristics of Frequency Domain Spectroscopy of Generator Stator Insulation

作　　者：王兵[1] 高波[1] 郝长金 尹小兵[1] 陈奎[1] 范建斌[2] 吴广宁[1] 

机构地区：[1]西南交通大学电气工程学院,四川省成都市610031 [2]国家电网公司,北京市西城区100031

出　　处：《电网技术》2016年第2期626-633,共8页Power System Technology

摘　　要：为实现将频域介电谱技术用于发电机主绝缘状态的无损诊断,在实验室条件下系统的研究了测试温度对20 k V定子线棒绝缘在10-3~103 Hz范围内频域谱变化规律的影响因素,运用电介质极化理论对频域介电现象进行机理分析,建立Debye模型并基于过渡态理论提出求取定子线棒绝缘活化能DG1和活化熵DS1的新方法。此外,由于定子线棒运行存在吸湿情况,简要分析了不同水分含量线棒绝缘的介电特性。结果表明：随温度和水分含量的升高,介损和复介电常数虚部呈规律性增大且弛豫峰向高频区域移动;建立的3支路Debye弛豫模型拟合值与实验测量值相符,弛豫参数电阻值随温度升高而减小,电容值基本不受影响;选取特征参数活化能和活化熵可表征主绝缘随温度变化的特性,界面极化弛豫时间常数t1与绝对温度T满足Arrhenius方程,利用Debye模型拟合参数t1求解出的活化能DG10（30℃）为74.26 kJ/mol,运用过渡态理论能够阐释发电机主绝缘频谱介电性能的温度依存性;采用＂频温平移因子＂可实现将已知温度下的频域介电特征量折算到未知温度,消除测试温度对频域介电谱的影响。In order to apply frequency domain spectroscopy（FDS） in non-destructive diagnosis of generator bar insulation condition, FDS change rule of 20 k V stator bar insulation under different temperatures in frequency range of 10-3~103 Hz was investigated. FDS phenomenon was analyzed with dielectric polarization theory. Debye model is established and a new method to calculate activation energy and activation entropy of bar insulation is proposed based on transition state theory. In addition, because the bar is exposed in moistureabsorbing environment, its dielectric properties under different moisture content were analyzed. Research results show that tanδ and ε″ raised regularly with increase of temperature and moisture content, and relaxation peaks are moved to high frequency area. The established Debye relaxation model of 3 branches can well reflect experimental data, and R decreases with increase of temperature, but C is not affected. Characteristic parameters of activation energy and activation entropy were selected to show dielectric property changes with temperature. Interfacial polarization relaxation time and absolute temperature met Arrhenius equation. Activation energy calculated with Debye model was 74.26 k J/mol. So temperature-dependency of dielectric properties of bar insulation could be interpreted with transition state theory. Temperature impact on FDS results could be solved using ＂frequency temperature shift factor＂ to calculate FDS results at different temperatures.

关 键 词：发电机 频域介电谱 Debye模型 温度 活化能 过渡态理论 

分 类 号：TM85[电气工程—高电压与绝缘技术]