The ion flow formed by UHVDC lines migrates under the influence of wind force

which makes the quantitative assessment of the the ion flow density

ρ

j

and the total electric field

E

difficult due to the territoriality and stochasticity. Presently

the assessment of

E

considering wind force doesn’t take into account the correlation between wind speed and direction

and lacks the simulation of the ion flow under different wind directions. Therefore

in this paper the ±800 kV line is taken as an example

the total field finite element model of the traditional 2D line is expanded to 3D

the va

riation of

E

and

ρ

j

under the influence is obtained. Moreover

the probability model is construct-ed by the Copula function to propose a kind of safety assessment technology. The results show that the wind speed determines diffusion degree of space charge and the wind direction determines its diffusion trajectory. The increase of wind speed makes

ρ

j

and

E

increase firstly and then decrease

and the reduction of the included angle between the wind direction and the line orientation causes the wind force to weaken. The wind speed-wind direction distribution shall be fully considered to control the design margin of the line. The set up height of the±800 kV line can be reduced down to 22 m and

at this time

95.08%of the

E

statistical values are still within the

E

95

limit.