Simulation Study on Distributed Parameter Changes and Impedance Spectrum Response Under Typical Cable Defects

In this paper, the influence law of typical defects (local breakage and aging) on the distribution parameters and impedance spectrum of the cable is investigated by building a COMSOL finite element simulation model. The model of YJLV 8.7/15 kV single-core cable is established, and the frequency range of 100 kHz-100 MHz is set to analyze the change characteristics of the distribution parameters (resistance, inductance, capacitance and conductance) under different degrees of defects. The results show that: localized damage leads to a significant increase in distributed resistance and inductance, and a decrease in distributed capacitance and conductance, and the deeper the degree of damage, the more obvious the changes; local aging mainly causes an increase in distributed conductance. Further analysis of the impedance spectrum reveals that the damage defects increase the impedance amplitude and shift the resonance point to the right, and the resonance point of the phase spectrum is shifted, while the aging only causes a small increase in amplitude, and the phase spectrum is basically unchanged. The simulation results show that the impedance spectral characteristics can effectively identify the defect type, providing a theoretical basis for cable defect diagnosis.