Short circuit current calculation and grounding design both are the important parts of engineering design

which is of great significance to the safe and stable operation of the converter station. In this paper

based on ±1100kV Guquan UHVDC converter station with hierarchical connection

different levels of short-circuit current have been calculated. After considering the shunting effect of short-circuit current via lightning shield wires and the transformer neutral point

the grounding fault current of converter station is calculated. According to the grounding fault current

design scheme of grounding grid for the UHVDC converter station and safety evaluation have been proposed. For converter stations with hierarchical access

the asymmetric short-circuit current should be calculated for different AC buses based on variant operating situations

and the maximum value of short-circuit current should be used to verify the ground grid design indicators.