Design and Application of a CT-Based High-Reliability Energy Harvesting Circuit for Monitoring Sensors in Power System

This paper presents a current transformer (CT)-based high-reliability energy harvesting circuit (EHC) for an electromagnetic energy extractor, which powers monitoring sensors in power system. Differing from the previous studies on EHC, this study employs only analog electronic components, which makes the EHC both simple and low-cost. Effectively, the EHC accomplishes the integration of surge current protection, power balance adjustment, and auto-sensing controllable startup-running-stop management. Respectively, 1) The EHC bypasses the secondary strong current coupled by primary surge current to protect the load sensor and the EHC itself. 2) The EHC only extracts the needed power by regulating the switching duty cycle in real time so that the harvested power can synchronize with the consumed power. 3) Adopting a segmented voltage control strategy, the EHC could sense the starting condition automatically and start up rapidly. After the starting condition is triggered, the EHC keeps working continuously until it receives the command to stop. Based on theoretical analysis and simulation of the above-mentioned functions, the circuit scheme diagram and the implementation of the EHC are finished. The experimental results indicate that the EHC is reliable and meets the design requirements. In terms of applications, the EHC has been used in the ultra-high voltage shunt compensating capacitor bank (UHV-SCCB) state monitoring sensor units, which reveals that the EHC can operate steadily in any working stage of the monitoring sensor.