Abstract
The overall life of oil-immersed power transformers depends on the long-term life of the oil–paper insulation system throughout continuous operation. Studying the reliability assessment methods for oil–paper insulation can help determine the reliability level of power transformers accurately, and ensure their safe and stable operation. In the present paper, the life of oil–paper insulation is proven to obey the Weibull distribution under eight different temperatures set by the Weibull reliability probability paper; the failure mechanisms of the different temperatures are highly consistent. The Weibull distribution reliability curve cluster of oil–paper insulation is plotted under different temperatures by which an oil–paper insulation reliability assessment method is proposed. Lastly, the statistical validation experiment of the proposed method is conducted, which proves its theoretical validity. Thus, the present study puts forward a simple and effective method for the oil–paper insulation reliability assessment of power transformers under different temperatures at different life stages.
Highlights
Large oil-immersed power transformers perform the important task of power transmission for power systems
Studies on oil–paper insulation of oil-immersed power transformers are mainly focused on the aging test, the extraction of aging characteristic parameters, and the assessment of residual life, among others
According to the distribution of oil–paper insulation life under different temperatures, the current work proposes an oil–paper reliability assessment method in which time and temperature are used as variable factors
Summary
Large oil-immersed power transformers perform the important task of power transmission for power systems. Studies on oil–paper insulation of oil-immersed power transformers are mainly focused on the aging test, the extraction of aging characteristic parameters, and the assessment of residual life, among others. Kachler et al [9,10] carried out a thermal aging test under normal operating temperatures of power transformers They obtained the trend of the characteristic resultant in the process of oil–paper insulation aging, analyzed the main influencing factors of aging such as moisture and temperature, and completed a preliminary study of the aging mechanism. According to the distribution of oil–paper insulation life under different temperatures, the current work proposes an oil–paper reliability assessment method in which time and temperature are used as variable factors.
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