Calculation of the ion flow field of AC-DC hybrid transmission lines

A simulation method to calculate the ion flow field of AC-DC hybrid lines is proposed. The charge simulation method (CSM) and the finite element method (FEM) are applied to calculate the electric field, while a time-dependent upwind differential algorithm is applied to calculate the migration of space charges. Furthermore, a variable time-step discretisation method is introduced to accelerate the computational process. The calculation results of ground level electric field and ion current density of a reduced-scale AC-DC hybrid line model are compared with previous experimental and calculating works. Satisfactory agreement is obtained between our calculation results and the experimental ones. As an application, the ion flow field of a hybrid 1000 kV AC/800 kV DC transmission line is simulated and analysed.