Underground Ground Wires for Transmission Lines: Electrical Behavior and Feasibility

Icing of overhead ground wires on transmission lines may result in faults and widespread power outages. This paper investigates the feasibility of an unconventional overhead line structure that is equipped with underground rather than overhead ground wires to prevent faults caused by icing. The underground ground wire is a buried bare conductor connected to the grounding of each transmission-line tower. To analyze the ground fault of the overhead line structure, this paper derives analytical equations to evaluate the current and potential distribution in the underground ground wire, earth surface potential around the wire, and grounding impedance of the faulted tower. The validity of the presented equations is verified by measurements. Based on the ground fault analysis, this paper evaluates the electrical safety of the discussed overhead line structure. Lightning shielding of overhead lines is not considered in this paper.