Influence of space charge distribution around the conductor surface on ionized field computation

Space charge density around the conductor surface is a boundary condition in the ionized field computation of HVDC transmission lines. Upstream finite element method is a common method to study ionized field problem. In this method, the distribution regularity of space charges around the conductor surface needs to be determined before computation. The difference of distribution assumptions will cause different results. In this paper, three distribution assumptions of space charges around conductor surface in ionized field computation are summed up. The effect of these assumptions is evaluated by a reduced-scale experiment in the laboratory. Finally, computation results of -800kV unipolar and ±800kV bipolar equivalent single transmission lines are discussed, and the percentage of relative error is given.