Corona onset field strength is one of the important parameters for corona control of fittings in converter station valve hall

considering the over-adequacy problem of anti-corona design of fittings in ±800 kV UHV DC valve hall

the corona onset voltage tests of tube bus and shielding balls are carried out in labs with altitude of 50 m and 4 300 m.Based on the results of corona onset voltage tests

Peek formula and Ansys 3D electric field simulation calculation

the minimum anti-corona design sizes of different fittings are obtained

the suggestions for the surface electric field control principles of valve hall fittings are proposed.It is recommended that the equivalent pipe diameter of tubular fittings shall not be less than 150 mm

the equivalent ball diameter of the shielding ball fittings shall not be less than 800 mm

and the radius of chamfered edge curvature shall not be less than 30 mm.In accordance with the field strength control principle of no more than 12 kV/cm when the equivalent diameter of valve hall fitting is greater than 200 mm and no more than 18 kV/cm when the equivalent diameter is less than 200 mm.The research results provide a reference for anti-corona optimization design in ±800 kV valve hall of electric power fittings

and also provide technical support for developing the surface field strength control standard.