The valve-side bushing of UHV converter transformer is the throat of DC transmission system

and its reliability is crucial for the safe operation of the DC transmission system. In this paper

the ±800 kV converter transformer valve-side bushing is studied on the basis of the measured anisotropic body conductivity of epoxy-impregnated paper. Moreover

the influence of bushing core temperature gradient on the conductivity of epoxy- impregnated paper under actual working conditions is taken into consideration

and an electric-thermal-flow coupling simulation analysis model of DC bushing is established. The transient process of charge accumulation and electric field change of the bushing is analyzed. It is found that

after considering the anisotropic body conductivity

at the voltage of +800 kV

most of the outer surface of the epoxy core at the SF6 end of the bushing accumulates positive charge

and there is a maximum positive charge density of 24.66 pC/mm2 near the outer inflection point of the arc corner surface. There is a large amount of negative charge accumulation on the gap surface and the arc corner surface near the shielding cover

and the maximum negative charge density is −14.82 pC/mm2. There is a maximum positive/negative charge density in a small local area. Under the action of accumulated charge

the field strength between the epoxy core at the bushing end and the shielding cover increases

which increases the risk of surface flashover of bushing caused by gap discharge.