Research On The Aging Mechanism Of Oil-paper Insulation Based On Dielectric Response Theory

Oil-paper insulation is the main insulation system of the oil-paper insulation equipment.The aging of oil-paper insulation is the main cause of the oil-paper insulation equipmentfault. The dielectric response method is an effectively non-destructive testing method fordiagnosis oil-paper insulation aging status. The research of oil-paper insulation’s agingmechanism is done from the identification of the extended Debye model and the rule ofdielectric response curve with the oil-paper insulation aging status, to providing theoreticalbasis to the use of dielectric response method.Firstly, the step-by-step fitting method based on depolarization current is proposed byanalysis the principle of dielectric response and extended Debye model. This method canidentify different number of RC series connection according to different Oil-paperinsulation, improving the correct of the identification of extended Debye model.Secondly, the oil-paper and oil-paperboard insulation sample is made in this paper.Accelerated thermal aging is implied to the oil-paper and oil-paperboard insulation samplebased on time-temperature superposition and accelerated electrical aging is implied to theoil-paper insulation sample based on step-voltage method. The insulation sample ismeasured by depolarization method in the process of accelerated aging. The extendedDebye model is identified using the step-by-step fitting recognition method. Recoveryvoltage curve and frequency domain spectroscopy also the cole-cole curve are calculated.The dielectric response curve overall trend and parameters of the different dielectricresponse: the initial value and the final value of depolarization current curve, the peak andU500svalue of recovery voltage curve, the tan1Hzof frequency domain spectroscopy andthe value of of the cole-cole curve is analysis. Oil-paper insulation aging rules ofdielectric response is summarized to support the application of dielectric response test onOil-paper insulation aging.Finally, the content of furfural in the old Oil-paper insulation istested and compared with the rules of dielectric response in the process of Oil-paperinsulation’s aging. The rules of the furfural and the rules of depolarization current andfrequency domain spectroscopy have consistency.