Spatial Distribution of Ion Current Around HVDC Bundle Conductors

The ion flow from the bundle conductors of HVDC transmission lines is different from that of a single conductor. This paper presents systematic research on the spatial distribution of ion current due to corona around bundle conductors. A corona cage capable of fitting different bundle conductors is designed for the experiments. Extensive measurements are carried out in different voltages and polarities for four kinds of bundle conductors. To determine the roughness factor of the wires, the experiment with a single conductor is also included. The numerical methods, based on computation along the electric flux lines or based on triangle meshes, are used to calculate the ion current distribution around bundle conductors. Charge density distributions on different bundles are compared. To improve the accuracy of the mesh-based method, a new scheme of surface charge density distribution on the bundle is proposed. The characteristics of the ion current distribution and the total ion current of the bundle are also analyzed in this paper.