Diagnosis and Location of Defects in a Cross-Bonding Cable System Based on Multi-Phase High-Voltage High-Frequency Collaborative Excitation

In the industrial field, a cross-bonding (CB) connection is adopted in long-distance multiphase transmission cables to reduce the induced voltage of metal sheath. Due to the mutual coupling of signals in the three-phase cable sheath, it is difficult to diagnose and locate the defects of CB cables. Therefore, this article proposes a location method for CB cable defects based on multiphase high-frequency high-voltage collaborative excitation. A novel high-frequency high-voltage cascade topology circuit is proposed, which breaks the gain–bandwidth product limit of traditional amplifiers and solves the severe attenuation problem that the signal amplitude is too low for long-distance CB cables. A multiphase differential frequency collaborative excitation testing system was constructed based on this topology, achieving synchronous triggering and injection of three-phase isolated differential frequency sinusoidal excitations into the initial terminals of the CB cables. The three-phase impedance spectrum under different defect location is synchronously obtained based on the proposed CB cables transmission line decoupling model and impedance spectrum difference-frequency decoupling algorithm. The experiment shows that the location error rate is no higher than 0.127% through the synchronous transformation location algorithm, which demonstrates the extremely high location accuracy and testing efficiency.