A quantitative characterization method of oil-paper insulation aging condition based on multi-characteristic parameters

Due to the long-term operation, the transformer oil-paper insulation system will gradually experience aging and degrading, resulting in the insulation failure. And the insufficient research about the accurate diagnosing method of aging condition will severely threaten the security and stability of the transformer. At present, the diagnostic criteria for the aging of transformer insulation is only limited to the degree of polymerization of the insulating paper/pressboard and furfural in the oil without a comprehensive diagnostic scheme. Based on the existing theory, for the oil-paper insulation system after undergoing the accelerated thermal aging test, the degree of polymerization of the insulation paper, frequency domain dielectric properties, furfural, CO, CO₂ were firstly tested in the laboratory. Then, principal component analysis (PCA) was used to integrate the measured multiple parameters and obtain a comprehensive evaluating index of the insulation aging condition, and the establishment of the degree of polymerization and the evaluating index was conducted, which was in good linear relationship. According to the evaluating index and the quantitative relationship with the degree of polymerization, a diagnostic method that can be applied to the aging assessment of transformer insulation in the field is put forward, which makes up for the deficiency of the current diagnosis method only including single assessment factor and is of certain practical significance.