Interferences mitigation in partial discharge continuous monitoring

Continuous Partial Discharge (PD) monitoring is essential for assessing the condition of electrical insulation in medium voltage (MV) switchgears, transformers, and other equipment. Early detection of abnormal PD activity minimizes unplanned downtimes and optimizes maintenance costs. However, the increasing deployment of high-frequency (HF) power electronics, driven by the electrification of renewable energy sources and electric vehicle charging stations, introduces potential interferences that can mask genuine PD events and lead to false alarms. This paper identifies and characterizes interference sources affecting online PD monitoring systems from both MV and low voltage (LV) sides of power substations. A thorough state-of-the-art review of HF interference sources is conducted, followed by simulations and tests on representative network components to illustrate the propagation of HF signals, particularly at the MV/LV transformer interface. We propose a novel interference detection procedure applied to full Phase-Resolved PD patterns, along with filtering and mitigation strategies for unwanted contributions. The findings demonstrate that the reliability of online PD monitoring systems can be significantly enhanced by addressing HF interference. Our proposed filtering approach requires minimal processing capabilities, making it suitable for integration in to cost-effective and compact electronic devices, thus facilitating broader deployment in diverse applications.