A Self-Sustained Current Sensor for Smart Grid Application

Abstract

Along with the ever-increasing attraction of the internet of things, self-sustainable smart sensor is receiving more and more attention. However, in some industrial sensing applications, such as the monitoring system of the transmission line in power grid, there are still a lot of critical technical issues that remain to be addressed. On the one hand, the power issue has long been an obstacle of the sensors in power grid because the routine maintenance in this case is almost impossible considering its high cost. On the other hand, highly integrated current sensing techniques with large linear range for measuring the transmission current in power line are still limited. To date, in the power grid, autonomous current sensor nodes with free-standing designs are in great demand. In this article, a complete solution for addressing these two issues has been proposed. First, a magnetic energy harvester that can scavenge the ambient power-frequency magnetic field around the transmission line is proposed. The proposed electrodynamic design is based on nonlinear resonance, which is demonstrated to have a higher power density. The power density of the prototype can be as high as 3.42 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (tested at merely 3 Oe applied magnetic field). Second, a power management circuit is specially designed for the energy harvester. The minimum input voltage of the circuit can be as low as 0.33 V. Finally, an anisotropic magnetoresistance (AMR) sensor head with large linear range is customized for sensing the current in power grid. The largest linear range of the AMR sensor can be as large as ±170 Oe. The specially designed sensing system can be a promising solution to realize the new generation of self-sustainable current sensor network in power grid.