Research on the method of air gap clearance selection for bushing at high-altitude areas

Abstract

Abstract As an important component of the core equipment of the UHV substation, the operation reliability of the bushing is directly related to the safe operation of the main equipment. There are some technical problems in the development of casing in the Sichuan-Chongqing project, such as technical problems at high altitudes and a lack of relevant experience in the correction of air gap and equipment external insulation altitude. Therefore, there is an urgent need to research the selection of gap distance for UHV AC substation bushing electrical characteristics test in high altitude areas. In this paper, based on the standard meteorological conditions and the rod-plate gap switching impulse discharge test data at an altitude of 4300 m, the minimum gap distance of UHV AC substation bushing withstanding 1800 kV and 1950 kV under different methods is obtained. The results show that by comparing the two calculation methods, the minimum distance calculation method of the true test combined with the gap coefficient method avoids the error of altitude correction, and the minimum gap distance is reduced by 7.84%-14.17% compared with the former. The research content can provide a reference for selecting the dry arc distance of the casing. The next step should be to carry out the discharge characteristic test of the true-size electrode at a high altitude, so as to simulate the field situation more realistically and provide more powerful technical support for the project.