Research on Impact Mechanism of High-Frequency Interference from Power Electronic Equipment on PD Monitoring of High-Voltage Cables

The online monitoring system for high-voltage cable partial discharge (PD) observes real-time changes in PD during operation, offering timely alerts for insulation anomalies and abnormal discharges, thereby enhancing reliability and safety. However, with the widespread application of power electronic devices, high-frequency (HF) interference generated by power electronics may disrupt online PD monitoring. In addressing the issue of HF interference during online partial discharge monitoring of a 500kV cable tunnel in Shanghai, this paper begins by examining the current and frequency spectrum waveforms associated with four auxiliary control devices: the LED light, broadcasting system, fire alarm, and video terminal utilized within the tunnel. Next, the HF components in the leakage current of bolts are analyzed. Finally, the current of the online PD monitoring equipment is measured, and its frequency spectrum waveform is analyzed. The results indicate that interference generated by auxiliary control devices propagates along the ground wire to the PD equipment, thereby interfering with online monitoring. Analysis of HF interference characteristics and propagation paths will contribute to the research on strategies for suppressing HF interference signals.