Online Monitoring of the Cable Insulation State Based on the Impulse Impedance Spectrum

The rapid development of power systems has raised the requirements of the online monitoring of cable insulation performance. Considering that a signal extracted using traditional online monitoring technology is weak and vulnerable to environmental electromagnetic interference, this article proposes using the impulse impedance spectrum to monitor the insulation aging degree of a cable online. First, the amplitude–frequency characteristics of the impulse voltage are calculated, and the feasibility of using the impulse voltage for online monitoring is analyzed. Then, adopting the two-port circuit model of a cable, the impulse impedance spectrum of a cable is derived to characterize the insulation performance, and the process of monitoring of a cable online is proposed. Finally, the change law of the impulse impedance spectrum is analyzed in an experiment and simulation, and the feasibility of the impulse impedance spectrum for online monitoring is verified. The impulse signal is parasitic in the power system, has a wide frequency range, contains abundant information, has a large amplitude, and has a strong anti-interference ability. The utilization of the impulse voltage makes full use of the inherent information of the power system, and the proposed use of the impulse impedance spectrum is expected to promote the development of online monitoring technology and improve the operational stability of power systems.