Energy harvesting is a process of capturing, storing and conditioning ambient and residual energies for future use. The amount of residual energy captured is very small and can be used for low power load such as wireless sensor nodes. Wireless sensor nodes are used to monitor physical parameters at diverse locations. They find extensive applications in military, health care industries, environmental monitoring and smart grids. One of the major constraints of Wireless sensor node is battery lifetime as battery gets depleted over a period of time. Energy harvesting techniques can be used to overcome this constraint and has the ability to make wireless sensor node self sustainable. This paper provides an overview of energy harvesting techniques used for wireless sensor nodes in smart grid application.

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Real time monitoring of high voltage devices in smart grid is implemented using wireless sensors. They ensure reliable power transfer and avoid cascading power failures. Powering these sensors remotely is a challenge. This paper presents a novel method of powering sensors remotely using magnetic field harvester. A dumbbell shaped magnetic core is designed and optimized to harvest magnetic field near high voltage bus bars/transformers in electrical substation. The harvested power is rectified and boosted. Impedance matching circuit is designed to obtain maximum power transfer to the wireless sensor. The energy thus harvested is used to power wireless sensors and make them self sustainable. The experimental results show that the proposed core with 40,000 turns can harvest 17.6 mW of output power when placed in magnetic flux density of 9 µTrms.