Research on Cable Defect Location Method Based on Joint Time-Frequency Analysis

To solve the single time-frequency resolution problem of time domain reflectometry (TDR) and frequency domain reflectometry (FDR) in the localization of cable defects, a cable location method based on joint time-frequency analysis is proposed. Firstly, the basic principles of the joint time-frequency location method are briefly explained in terms of time-frequency distribution, reference signal selection, time-frequency offset, and time-frequency cross-correlation function. Then, the method proposed in this paper is used to achieve high-precision location of local defects, and the feasibility of the method is tested by modeling and simulation of 10 kV long cables with local defects. The simulation results show that the method can effectively locate cable local defects in different locations and degrees, and the error of the location results is only about 0.02%. Compared with the traditional TDR and FDR methods, this method utilizes the time limit and band limit characteristics of reference signals and introduces the time-frequency cross-correlation function to achieve higher precision location, which combines the advantages of TDR and FDR.