Analysis of Electric Field, Ion Flow Density, and Corona Loss of Same-Tower Double-Circuit HVDC Lines Using Improved FEM

This letter analyzes the ion flow field of the emerging same-tower double-circuit HVDC lines using an improved method. The improved method is based on SUPG FEM, which is more accurate than the widely applied upwind FEM. It is shown that the SUPG FEM results agree better with the measured data than the upwind FEM results. Reason for the upwind FEM´s inaccuracy is given. Using the SUPG FEM, the influences of same-tower double-circuit HVDC lines´ parameters on corona loss, ground-level maximum electric field, and ion flow density are analyzed.