Design of SF6 Insulation Structure for ±500kV Converter Transformer Bushing Performance and Verification with Image Processing Method

±500kV converter transformer bushing belongs to the typical power equipment of the medium and high voltage converter valve hall. It is a transitional equipment between the ±800kV ultra-high voltage level converter bushing and the ±400kV converter transformer bushing. Moreover, the ±500kV converter transformer bushing is widely used in the ultra-high voltage DC projects. Therefore, the focus is on studying the high-altitude operating environment analysis of the ±500kV converter transformer bushing, Based on this, further research is needed to quantitatively design the insulation structure inside the core of the converter sleeve. The design results show that the typical design of the ±500kV converter transformer bushing is that the number of pole layers is 63, the length of the zero layer pole plate is 6762mm, the diameter of the conductive rod is 100mm, the length of the N-layer pole plate is 1730mm, and the diameter of N-layer plate is 385mm. Typical ±500kV converter transformer has a carrying capacity of the 3800A on the central conductive rod of the bushing. Under full wave lightning impulse voltage of 1950kV, the maximum electric field strength of the SF6 gas atmosphere equalization device in bushing is 9921V/mm, and the maximum electric field strength on surface of the equalization ball in transformer oil is 14810V/mm; At rated operating voltage of 515kV, the radial field strength of the converter bushing core is 5.8kV/mm, and the axial field strength is 0.45kV/mm, both of which meet design requirements of valve side converter bushing. The calculation results of article can provide parameter values for the typical converter bushing power equipment, and conduct correlation analysis with actual equipment insulation faults, providing theoretical and practical basis for design and operation maintenance of the internal and external insulation structures of high-voltage converter bushing.