Insulation structure optimization of 1100kV UHV oil-gas bushing under all working conditions

In this paper, the physical dimensions of UHV oil-air bushing and UHV Oil-SF6 bushing are analyzed in detail. UHV Oil-SF6 bushing adopts epoxy impregnated paper solid insulation structure, UHV oil-air bushing adopts outer porcelain sleeve structure and built-in oil impregnated paper composite insulation structure. UHV bushing prototypes are developed. At the same time, the UHV bushing and its aging test platform are comprehensively considered, and the three-dimensional model is further established. The model also considers the structural size of the bushing body and the pressure equalizing device at the tail of the bushing. The electric field on the surface of the bushing voltage equalizing cover is simulated and calculated, and the maximum electric field intensity on surface is 11kV/mm. Taking the electric field distribution at the tail of UHV bushing as the optimization object, the structural size is optimized in four schemes, and finally the optimal structural design method is obtained. Finally, according to the planning and requirements of 1000kV AC UHV project, the design parameters of UHV aging test platform are: the maximum nominal rated current of the equipment is 6.3kA, and the current can reach 7.56kA when considering the expansion factor of 1.2. The design parameters of the equipment are based on 8kA, and the maximum working current can reach 8kA. On the other hand, at present, the rated current of UHV AC bushing is mainly 2500A and 3150A. Selecting 8kA current can meet current required for accelerated aging test of bushing insulation.