A Novel Fiber-Optically Powered Partial Discharge Monitoring System for Cable Joints Based on Acoustic Emission

This article proposes a low-power, fiber-powered acoustic emission (AE)-sensing system for partial discharge (PD) monitoring in cable joints. First, finite-element simulations are conducted to model the internal discharge process within cable joints. The results show that sharp structural defects inside the joint can lead to local electric field enhancement, which, in turn, induces AE signals. These acoustic waves are capable of propagating through multilayer insulation structures and can be effectively detected at the outer surface using AE sensors. Second, a system incorporating a photovoltaic energy-harvesting module tailored for optical fiber delivery is proposed, which enables long-term, autonomous monitoring without reliance on local power infrastructure. Taking advantage of the relatively low-frequency nature of PD-induced ultrasonic signals (20–60 kHz as specified in national standards), the system adopts a low sampling rate acquisition scheme while maintaining an average power consumption below 200 mW. To further reduce complexity and energy requirements, a weak phase-resolved PD (W-PRPD) algorithm is introduced. The algorithm removes the dependence on a power-frequency phase synchronization sensor by randomly initializing the initial phase; multicycle aggregation is, then, applied to extract phase-related discharge features. Finally, the system is experimentally validated in an indoor substation environment, where actual PD events from a GIS cable terminal are successfully detected. These results confirm the physical feasibility of AE-based PD sensing and demonstrate the proposed system’s robustness, low power consumption, and practical value in harsh or energy-constrained field applications.