To meet the demands of construction for ultra high voltage direct current（UHVDC） convertor station connecting to AC grid by way of hierarchical connection

we comprehensively researched and compared the concept design schemes of the main AC/DC conversion equipments

such as convertor valve

transformer etc.

which were designed for ±800 k V/8 000 MW and ±800 k V/10 000 MW UHVDC projects based on all kinds of technology routes. Moreover

we generalized the shape parameters of main DC equipment

and summarized the general requirements of valve hall’s concept design scheme

the key factors of controlling the firewall spacing and restricting valve hall internal electrical layouts

and the layout principles of the main and auxiliary equipment. After optimization of AC 1 000 k V air clearance values under typical electrode shapes

we presented the conceptual design sizes of high voltage（HV） and low voltage（LV） valve halls considering functional and economical principle of convertor station preliminary design

when DC 800 k V was connected to AC 500 k V/1 000 k V power grid hierarchically for 10 000 MW UHVDC transmission projects. In combination with the actual site circumstance and all technical route of the equipment

it is suggested that convertor area of Taizhou station is designed by "line-styled" scheme. The conceptual design sizes（length×width×height） of HV and LV valve hall are recommended to use 83 m×35 m×28.5 m and 89 m×24 m×18.7 m

respectively. It is suggested that convertor area of Linyi station is designed by "back-to-back" scheme. The conceptual design sizes of HV and LV valve hall are recommended to use 89.2 m×35 m×28.5 m and 99 m×23.1 m×18.7 m

respectively.