Characteristic impedance modeling and damage detection method for high-voltage cable sheath

High-voltage cables are the main transmission channels in urban power grids. Damage to their sheath can lead to a reduction in transmission capacity， as well as cable short circuits and breakdowns. Therefore， it is necessary to explore methods for detecting and locating damage to high-voltage cable sheath. Addressing the issues of low efficiency and environmental constraints of traditional methods， a detection and location method based on TFDR （time-frequency domain reflectometry） is proposed. A characteristic impedance model for the sheath of directly buried high-voltage cables laid in parallel is established， incorporating the sheath structure into the transmission line model. TFDR is utilized to detect and locate characteristic impedance changes caused by damage to the sheath. Simulation verification initially demonstrates the reliability of this method. Two parallel-laid XLPE （cross-linked polyethylene） cables， each approximately 40 meters long， are selected for sheath damage experiments. The experimental results indicate that the proposed method can accurately detect damage to the sheath of high-voltage cables.