To study the effect of fog-haze on the ionized field of high voltage direct current（HVDC） transmission lines

we proposed a computation method for the effects of fog-haze on the ionized field of HVDC transmission lines. Taking both the charging effects of haze particles and the influence of humidity on corona inception into account

we computed the field strengths and ion current densities in the vicinity of the ±800 k V ultra HVDC transmission lines under different haze pollution degrees using a finite element method. The results show that

in comparison to the values in fine condition

the total field strengths and ion current densities near ground increase with the pollution degree of hazy weather

and the growth rates of the respective maximum values for them are in a behavior of linearly increasing with respect to the pollution level at high pollution concentrations. Furthermore

the change of the ionized field with the pollution degree of hazy weather is more obvious for high humidity than that for the low one or for dry haze situation. The study suggests that the effect of humidity on corona inception and the charging of haze particles are the main reasons for the change of electrical field strengths and the ion flow densities near ground

and the decrease in ion mobility restricts the growth of ion flow densities under hazy weather. The study provides a method for analyzing the corona effect on HVDC transmission lines.