The Study On The Influence Of Electric Aging On The Dielectric Characteristics Of Main Insulation Of Generator Stator

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.