Research on the characteristic impedance model and breakage detection method of high-voltage cable outer sheath

Abstract The outer sheath of high voltage cables is the “first line of defence”, preventing the internal structure of the cable from being damaged in the first place. However, during cable operation, the outer sheath can break due to termite erosion, external stress, and other factors. In order to detect the broken state of the outer sheath of high-voltage cables and to improve the stability and reliability of the power grid operation, this paper proposes the detection method for the identification and localization of the fault point of cables. First, it establishes a model of the characteristic impedance of high-voltage cables’ outer sheath and the distribution parameters calculation method. Then, it builds the experimental platform consisting of two parallel-laid 110kV single-core XLPE cables as the experimental object to carry out the experimental verification of single-side breakage and bilateral breakage. Finally, it uses the time-frequency domain reflection (TFDR) method to detect and localize the two cables’ fault points with localization relative errors of 0.39% and 1.09%. The model’s accuracy as a high-voltage cable detection model is verified.