The corona space charge distribution of Changji-Guquan ±1100kV UHVDC transmission line within the Thundercloud Electric Field

For a long time in the lightning protection design of DC lines, the effect of corona space charge has not been considered. The DC operation voltage of Changji-Guquan project is up to ±1100kV, and the impact of corona space charge may be significant. In this paper, the corona space charge distribution characteristics of this line within thundercloud electric field are studied. A mathematical model for this case is established and to improve the calculation accuracy of electric field and reduce the time and memory cost, a hybrid method of simulation charge method, finite element method (FEM) and the boundary electric field constraint equation is used to solve the Poisson equation. The upstream FEM is used to solve the continuity equations. Using the model and calculation method, the influences of the protection angle and terrain on the space charge distribution are studied. The results show that the protection angle has little effect on the surface charge density of the polar conductors, but a great one on that of ground wire and so does the slope angle. The surface charge density of the negative pole conductor increases as the increase of the slope angle and it is by about 3.8 times when slope angle is 40 degrees.