Distribution and Propagation Characteristics of Mechanical Vibration Signals in GIS Enclosure

Mechanical defects constitute a significant proportion of failures in gas insulated switchgear (GIS) systems, thereby posing a substantial threat to the operational safety and stability of power grids. Vibration signals serve as key indicators of such mechanical defects, highlighting the significance of analyzing the distribution and propagation characteristics of mechanical vibration signals within the GIS enclosure. In this paper, a horizontal GIS busbar model, excited by a three-phase power frequency current source, is developed to perform steady-state electromagnetic field analysis, yielding the electromagnetic forces exerted on the enclosure. The results reveal that the metallic enclosure is subjected to periodically varying electromagnetic forces at a frequency twice that of the excitation source. These forces induce mechanical vibrations in the enclosure, and the vibration acceleration is most prominent at the midline nodes on both sides of the enclosure. A structural mechanics model of the metallic enclosure is then developed, and the sequential coupling method is applied to compute the vibration acceleration response to electromagnetic force excitation. Experimental investigations on an actual GIS system demonstrate that the amplitude at 200 Hz is the most prominent in the vibration signal spectrum at the disconnector location, while the abnormal components of the vibration signal undergo significant attenuation as they propagate. Furthermore, the vibration signals at the midline positions on both sides of the horizontal GIS surface are found to be the most distinct.