Influence of Placement of Overhead Ground Wires on Steady State Induction in AC-DC Hybrid Transmission Corridor

To meet the growing power demand of the future, utilities and researchers have considered the addition of dc circuits in existing transmission corridors. The previous research has focused on analyzing the field environment, steady state induction and the negative effects of induction in the hybrid transmission lines. The overhead ground wires (OHGWs) have been used only for improving the lightning performance of overhead lines (OHL). In this paper, the spatial position of OHGWs has been studied with the objective of minimizing the steady state induction between power conductors as well as poorly grounded metallic objects like railroads and fences present near the ac-dc OHL. Candidate space for placement of OHGWs having shielding failure rate of less than four is identified using the conventional electro-geometric model. The steady state induction in the power conductors and nearby metallic objects is studied as a function of position of OHGWs using electro-magnetic transient simulation. The results indicate a strong correlation between the height of OHGWs and magnitude of induced voltage in power conductors, and metallic objects underneath the transmission line. The conscious effort in placement of OHGWs can reduce the magnitude of induced voltages while ensuring adequate lightning performance.