A Novel Method for Identifying Cable Defect and Improving Location Accuracy Based on Frequency Domain Reflectometry

Power cables in the urban power supply system are laid in cable trenches or directly buried underground, and the insulation is susceptible to corrosion and penetration, causing local insulation aging or abrasion. Early detection of soft faults helps prevent power system faults from occurring. This paper proposes a method that can detect cable multi-point soft faults and distinguish fault types based on Frequency Domain Reflectometry (FDR). Firstly, we establish a numerical calculation model of distributed parameters to analyze the impedance spectroscopy characteristics of different types of defects and the positioning methods and errors. Next, a simulation study was carried out for different characteristics of aging and damage, which means different types of soft faults were successfully distinguished. Then, based on the results of the simulation, experiments are carried out to verify the effectiveness of the positioning algorithm and the feasibility of distinguishing defect types. Simulation and experiment show that the positioning error is within 0.5% and 1% simultaneously. Compared with traditional location methods, the defect location method proposed in this paper can determine the type and severity of the defect while locating multiple defects. The experimental results show that the defect identification method proposed in this paper has great potential for field application.