Investigation on Induced Energy Extraction from High-Voltage Transmission Lines Based on Three-Coil WPT Systems

Abstract

In order to realize an online power supply, this article develops an explicit design of induction power extraction technology combined with wireless power transmission (WPT) technology. Unlike the power supply mode of traditional batteries of online monitoring devices of high-voltage transmission lines, this technology solves the short battery life cycle problems. First, the principle of induction power extraction is analyzed. Based on the equivalent circuit of the mutual inductance model, expressions of induction power extraction without and with core saturation are derived, respectively. According to the current transformer (CT) magnetic coupling diagram, the open-circuit voltage of the secondary side of the CT is deduced. Therefore, the CT material and size could be selected. The CT coupling model is used to equivalent the current transformer to the ideal voltage source. Then, the four basic topological spaces of the magnetic coupling resonant WPT system are analyzed and calculated, and the efficiency of the SS topology WPT system is analyzed. Furthermore, aiming at long-distance power transmission, this article described the building of a three-coil WPT system and the analysis of the corresponding transmission efficiency and output power expression. With the aid of Maxwell, the technology proposed is simulated based on a 110 kV high-voltage transmission line with 1.2 m as the transmission distance of the system. Finally, the influence of a coupling coefficient and load resistance on the transmission characteristics of the multicoil system is obtained. Consequently, the simulation results with a system output power of 14.4 W verify the effectiveness of the technology.