Study On A Nondestructive Technique To Detect The Polymerization Degree Of Transformer Insulation Paper

The viscosity method has disadvantages of procedure-complex,time-consuming and damaging to insulation paper on detecting the polymerization degree of insulation paper,the paper presents a rapid,non-destructive,high accuracy of near infrared spectrum measurement method to solve the problems.The paper design two insulation paper aging schemes,which one is aged in the transformer oil without oxygen,another is aged in the oven with oxygen,and to build the corresponding curve between the polymerization degree of insulation paper and the aging time.It is found that the aging rate of insulation paper aged in the oven with oxygen is faster than the one without oxygen;and the higher the temperature,the lower the polymerization degree of insulation paper;the existence of oxygen can faster the aging procedure.Design portable spectrometer and transformer insulation paper aging system,determine the best spectral acquisition parameters and the pretreatment method: scanning distance: 0mm,integration time: 120ms;average frequency of spectrum: 5,pretreatment method: 8 point smoothing,wavelength range: 1300~1650 nm,1850~2250 nm.To compare principal component regression and partial least-squares regression mathematical model of a layer of insulation paper aged in the oven,partial least-squares regression has a better effect on detecting the polymerization degree of insulation paper.The best model is as follows: principal component: 5,correlation coefficient of calibration of Rc: 0.9756,correlation coefficient of validation of Rp: 0.9778,the root mean square error of correction RMSEC is 56.5,the root mean square error of prediction RMSEP is 33.5.Measurement error is 1.56%~19.42%.Model for different layers of insulation paper aged in the oven by partial least-squares regression,single insulation paper have a better effect than multi-layer insulation paper.The best model of one layer insulation paper aged in the transformer oil is as follows: principal component: 7,Rc: 0.8853,Rp: 0.8738,RMSEC: 102,RMSEP: 118.Its correction and prediction ability are not as good as insulation paper aged in the oven.By the research above,we use the best model for the field experiments,and the measurement error is less than 20%,basically fulfill the requirements of engineering application.