Diagnosis of Multiple Impedance Mismatch Segments in Power Cables Based on Frequency Domain Reflection Method

Cross linked polyethylene (XLPE) cable has been widely used in urban power transmission and distribution system. The accurate location of cable partial defect is of great significance to maintain the safe operation of the cable. In this research, a method of cable partial defect diagnosis based on frequency domain reflectometry (FDR) is proposed. Firstly, the mathematical model of cable transmission line is established, and the basic principle of this method is described. Then, the Dolph-Chebyshev window function is selected to eliminate the inaccuracy of positioning results caused by signal spectrum leakage. And through the feasibility of this method is explored by establishing a simulation model. Finally, several experiments were carried out on 10kV XLPE cables in Chengdu. The results show that the diagnosis conclusions of cable intermediate joints and local defects location are basically consistent with the cable account information and the actual situation. Which indicate that the method is feasible for locating and diagnosing local defects and intermediate joints.