Harmonic Magnetic Field Energy Harvesting for Self-Powered Sensors in HVDC Transmission Lines

Due to the lack of abundant alternating electric and magnetic fields, there is no efficient and stable energy harvesting method for high-voltage direct current (HVDC) transmission lines, which hinders the deployment of self-powered sensors. The finite switching frequency of electronic devices results in the coexistence of dc and harmonic currents in HVDC transmission lines. In this article, a novel method for harvesting harmonic magnetic field energy is proposed for the first time utilizing a free-standing magnetic field energy harvester (FSMFEH). Compared with current transformer-based magnetic field energy harvesters with closed toroidal cores, the designed arc-shaped core effectively avoids saturation caused by high dc currents. The ac magnetic field generated by the harmonic current induces a voltage in the coil and transfers power to the load. The working principle, equivalent circuit, load power and reliability of the FSMFEH are analyzed and experimentally verified. By optimizing the core structure and selecting the core material, the FSMFEH achieves a load power of 25.79 mW and a power density of 0.279 mW/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> under the condition of 1000 A dc current superimposed with a 3A/60 0 Hz harmonic current. The designed FSMFEH is capable of meeting the power requirements for most sensors in HVDC transmission lines.