A novel wind energy harvesting system with hybrid mechanism for self-powered applications in subway tunnels

With the rapid development of urban rail transit, the safety maintenance of subway tunnels has attracted attention in various countries. Tunnel safety monitoring systems are used to ensure the safety of subway operation. This paper presents a new type of self-powered system for WSN nodes in tunnels to solve the power supply problem in subway tunnel safety monitoring systems. This new self-powered system collects wind energy in subway tunnels and converts it into electrical energy for storage and utilization. The system is composed of three parts: electromagnetic wind energy acquisition module, piezoelectric wind energy acquisition module, and power generation energy storage module. The electromagnetic wind energy acquisition module uses the principle of electromagnetic induction to convert wind energy into electrical energy. The piezoelectric wind energy acquisition module uses piezoelectric patches to convert wind energy into electrical energy. The power generation energy storage module converts the collected AC power into DC power, stores it in the supercapacitor, and supplies power to the WSN nodes. Experimental data shows that the energy output power of the system at a wind speed of 7 m/s is 59.31 mW. The Chengdu subway line 2 was selected for case study; the energy consumed by WSN nodes accounts for 49.4%–59.8% of the energy collected by the system. The proposed system can provide continuous and stable power for WSN node systems in subway tunnels.