Predictive analysis of ion flow field at the ground level under HVAC and HVDC hybrid transmission lines

Running HVAC and HVDC transmission lines in same corridor is an effective way to minimize land use of transmission lines. The control of ion flow field at the ground is one of major obstacles in the construction of such projects. In this paper, a 1000kV HVAC and ±800kV HVDC hybrid transmission lines was chosen as an example. Based on finite element method (FEM) and finite volume method (FVM), the electric field and ion current density at the ground level with different separation distances and heights of the transmission lines were analyzed. Calculation results show that the dc electric component is mainly concentrated under dc transmission lines, vice versa for the ac electric field component. With the change of separation distance the magnitude of ac and dc electric field components do not change a lot, but the horizontal displacement of the peak values of ac and dc electric field components would appear. The heights of dc transmission lines almost have no effect on the distribution of ground level ac electric field.