Research on Evaluation Method of Composite Insulator Shed Aging State Based on Terahertz Time Domain Spectroscopy

Silicone rubber composite insulators are widely used in modern power system due to its excellent performance, but with the increase of operation time, the aging problem of composite insulator is increasingly prominent. In this paper, the molecular simulation method is used to analyze the structure of methyl vinyl silicone rubber (MVQ) molecules with a degree of polymerization of 10 under an applied electric field. It is found that the chemical properties of the short chain are unstable, and condensation polymerization may occur, which makes the internal cross-linking of molecules produce traps, resulting in polarization charges on the surface of the material. At the same time, this paper selects insulators to conduct partial discharge experiments to classify the aging degree, and then uses the terahertz time-domain spectrum (THz-TDS) to obtain the absorption coefficient spectrum of these samples. The number of absorption peaks between 0.50.8 THz increases, which is considered to be caused by the increase of alcohol groups and hydroxyl groups in the composite insulator with the growth of the operating years. Finally, an evaluation model of insulator aging degree based on support vector machine (SVM) is established, the classification accuracy rate is 91.6667%.