Calculation and Analysis of Induced Voltage in Overhead Ground Lines of UHVDC Transmission Lines After Ground Insulation Modification

The insulated ground wire of ultra-high voltage direct current (UHVDC) transmission lines may produce induced voltage due to proximity to operating lines after insulation modification, which can affect the safety of the equipment and operators in the deicing circuit. In this paper, a calculation model for induced voltage after the insulation modification of UHVDC transmission line ground wire was established. The influence of model symmetry, grounding switch status, and soil resistivity on induced voltage was quantitatively studied, and field tests were conducted on ±800 kV transmission lines for verification. The results show that the asymmetry of the ground wire and optical cable in UHVDC transmission lines is an important factor affecting calculation accuracy. When there is a grounding point in the deicing circuit, the main influencing factor of induced voltage changes from the electrostatic induction component generated by the DC voltage to the electromagnetic induction component generated by the ripple current, with an effective value of 783 V in this project. The calculation and measurement results in this paper can provide reference and basis for the design and construction of ground deicing devices and deicing circuits in UHVDC transmission projects.