Defect diagnosis of distributed power cable terminal based on electromagnetic coupling characteristics

Abstract

At present, the defect of the cable terminations is caused by the manual installation. Such defects cause local distortion of the electric field and cause degradation of the insulation, so the research of the types of faults in the cable is an important problem that needs to be studied. This paper takes 35 kV cross-linked polyethylene (XLPE) cable terminations as the research object and conducts simulation and intelligent identification studies on the transient electromagnetic response of typical defects. Based on the structural parameters of an actual Raychem 35 kV three-core medium-voltage cable termination model, a three-dimensional model was established using SolidWorks modeling software, and three insulation damage models were established: main insulation scratches, air gaps, and metal particles. Transient electromagnetic wave simulation analysis was performed using COMSOL simulation software. The results show that among the three typical defects, metal particle defects produce the highest peak electric field intensity (5200 V/m), followed by air gap defects (315 V/m), and scratch defects (135 V/m) produce the lowest. Regarding waveform characteristics, the observation point measurement results show significant differences in pulse width, oscillation number, dominant frequency, and attenuation characteristics. Among them, metal particle defects have the richest high-frequency components, with a dominant frequency of approximately 3.0 GHz. Features were extracted and a support vector machine (SVM) model was used to analyze the defect types. Using five-fold cross-validation, the overall classification accuracy of various defects reached 99.67%. Among them, the recognition rate of scratch defects was 100%, and the recognition rates of air gap defects and metal particle defects both reached 99.5%. This paper establishes an intelligent classification method based on defect geometry and electromagnetic propagation characteristics, providing theoretical support for online monitoring and condition assessment of cable terminals.