根据直流输电线路线下地面合成电场、地面离子流密度、无线电干扰场强、电晕可听噪声等控制指标，对3 000～5 300 m特高海拔地区直流输电线路采用不同分裂导线进行相关计算，建议特高海拔地区±400 kV直流输电线路极导线采用4×LGJ-400/35钢芯铝绞线。

According to control indexes for DC transmission line, such as the composite electric field under the wires, ion current density of the ground, field intensity induced by radio interference and corona audible noise et al, the corresponding calculations are carried out for various bundle conductors of DC transmission line in 3 000~5 300 m ultra-high altitude regions. It is concluded that 4×LGJ-400/35 aluminium conductor steel reinforced (ACSR) is applicable for ±400 kV DC transmission line in ultra-high altitude region.