A Frequency-Based Fault Location Method for Overhead Metallic Return Conductors in HVDC Transmission System

In HVDC transmission systems, the metallic return conductor of overhead lines plays a crucial role in ensuring operational continuity and system flexibility. Unlike conventional pole conductors, the metallic return operates at ground potential and is normally not energized. This characteristic makes the application of traditional fault detection and protection techniques commonly used for overhead lines largely ineffective. As a result, faults occurring on the metallic return conductor may prevent the safe execution of switching operations at converter stations and potentially compromise the overall availability of the HVDC system.