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摘要
Thermal stress of gas-insulated metal-enclosed switchgear (GIS) basin-type insulators weaken its mechanical properties, which will threaten the safe and stable operation of GIS. In this article, the simulation and experiment of thermal stress in a 252-kV GIS basin-type insulator were carried out. An acoustic-distance difference method based on the ultrasonic critical refraction longitudinal wave (ultrasonic) and a measuring method for propagation depth of ultrasonic were proposed respectively: the variation of propagation depth in epoxy composites was measured by ultrasonic probes of different frequencies, and a mapping function between the propagation depth and detection frequency was established. The 2-MHz variable-angle ultrasonic probes were used to test the circumferential thermal stress below the surface of the 252-kV basin-type insulator, and the thermal stress simulation of the insulator was performed. The circumferential thermal stress at different positions of the insulator was obtained and then a contour plot of the stress was established by the cubic spline interpolation. The results showed that the propagation depth of ultrasonicin the subsurface of epoxy composites decreased exponentially with the frequency, the mapping relationship of depth-frequency had a good goodness of fit, and the coefficient of determination was as high as 0.988. The circumferential thermal stress at 9 mm below the surface of the insulator was tensile stress, which decreased first and then increased along the radial direction, showing as a V-shaped distribution. The experimental values were in good agreement with the simulation values, which verified the effectiveness of the proposed methods.
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单位y; 南方电网技术研究中心
