【作者】 宋扬；

【导师】 陈庆国； 付强；

【作者基本信息】 哈尔滨理工大学 ， 高电压与绝缘技术， 2020， 硕士

【摘要】 定子线棒主绝缘是大型发电机绝缘结构中的重要组成部分,主绝缘的老化状态直接影响发电机的稳定运行,为了研究电老化作用对主绝缘介电特性的影响,本文基于介电响应理论利用介电弛豫谱法（Dielectric Relaxation Spectroscopy,DRS）和热刺激电流法（Thermally Stimulated Current,TSC）研究大型发电机多胶主绝缘的介电特性,并分析其介电参数在电老化过程中的变化规律。应用电介质极化理论分析不同电老化时间多胶主绝缘的介电温谱和介电频谱（Frequency Domain Spectroscopy,FDS）特性,利用带直流电导修正的双弛豫Havriliak-Negami模型拟合不同电老化时间主绝缘FDS试验复介电常数测试结果,研究电老化作用对主绝缘松弛极化弛豫参数的影响,利用TSC法分析电老化过程中主绝缘内部粒子活化能（或陷阱能级）和陷阱与缺陷数量的变化规律。试验研究发现:工频介电温谱试验中主绝缘介质损耗因数和介电常数极值点随电老化时间的增加逐渐增大;变温FDS试验中主绝缘介质损耗因数和介电常数随试验温度和电老化时间的增加在10^-2Hz～10⁰Hz频段升高明显,80℃的FDS试验中出现了由转向极化主导的弛豫峰,峰值位置随电老化时间的增加向高频区移动;双弛豫Havriliak-Negami拟合结果表明,环氧粘合剂玻璃化转变前后主绝缘转向极化的弛豫过程发生改变,转向极化弛豫时间和弛豫强度明显提高,随着电老化时间的增加,主绝缘体系松弛极化弛豫时间逐渐减小,转向极化弛豫强度略有提高,电导率和界面极化弛豫强度显著上升;主绝缘TSC试验中的电流峰主要由界面极化和陷阱电荷引起,随着电老化时间的增加,界面极化峰的活化能略有降低,释放电荷量明显上升,陷阱电荷峰的陷阱能级明显降低,释放电荷量略有上升,可以表征主绝缘电导增加的过程。更多还原

【Abstract】 The main insulation of stator bar is an important part of the insulation structure of large generators,the aging state of the main insulation affects the stable operation of the generator directly,in order to study the effect of electrical aging on the dielectric properties of the main insulation,this paper uses dielectric relaxation spectroscopy（DRS）and thermally stimulated current（TSC）based on the dielectric response theory to study the dielectric characteristics of resin rich molding insulation of large motors,and analyze the change law of the dielectric parameters during electrical aging.Dielectric polarization theory was used to analyze the characteristics of the dielectric temperature specctroscopy and the frequency domain specctroscopy（FDS）characteristics of the resin rich insulation at different electrical aging times,the double relaxation Havriliak-Negami model with DC conductance correction was used to fit the complex dielectric constant test results of the main insulation FDS test with different electrical aging times,to study the effect of electrical aging on relaxation polarization relaxation parameters of main insulation,the TSC method was used to analyze the change law of the particle activation energy（or trap energy level）and the number of traps and defects in the main insulation during the electrical aging process.The test results show that:the extreme point of the dielectric loss factor and the dielectric constant of the main insulation in the power frequency dielectric temperature spectrum test gradually increases with the increase of the electrical aging time,the maximum and minimum values of the dielectric loss factor of the main insulation and the maximum value of the dielectric constant appear;in the FDS test of different temperature,the dielectric loss factor and dielectric constant of the main insulation increase significantly with the increase of the test temperature and electrical aging time in the 10^-2Hz～10⁰Hz;in the FDS test at 80℃,a loss peak dominated by steering polarization appeared,and the peak position shifted to the high frequency region with the increase of electrical aging time,the double relaxation Havriliak-Negami fitting results show that the relaxation process of the main insulation turning polarization changes before and after the glass transition of the epoxy adhesive,and the turning polarization strength significantly increases,with increasing of electrical aging time,the relaxation time and relaxation intensity of main insulation system gradually decreases,the turning polarization strength is slightly increased,the electrical conductivity and interfacial polarization intensity increase significantly;the current peak in the main insulation TSC test is mainly caused by interface polarization and trap charge,with increasing of electrical aging time,the activation energy of the surface polarization peak is slightly reduced,and the amount of discharged charges is significantly increased,the trap energy level of the trap charge peak is significantly reduced,and the amount of released charge is slightly increased,which can characterize the increase in the conductance of the main insulation.更多还原