Method for Contactless Power Harvesting from Medium and High Voltage Power lines (11kV and above) /

Abstract

Sensing and Monitoring is critical for the Medium Voltage Transmission Lines (MVTLs) and High Voltage Transmission Lines (HVTLs) because of gradual degradation of power lines due to severe weather conditions and environment. This degradation of power lines causes undesired variations. Sensors are deployed to monitor the condition and variations of power lines. These sensors are powered up by batteries which need to be continuously replaced due to constraint of discharging. This occasional replacement of batteries can cause safety and life hazards due to their placement near the induction zone. The initial aim of research was to investigate a method for contactless energy harvesting and recharge these batteries without occasional replacement and going near induction zone of power lines to avoid life hazard. Inductive coupling was realized the best method to harvest energy near power lines. Power lines generate a region of magnetic field when current is passed through conductors. Inductive coil, using inductive coupling method, concentrates the magnetic field and converts it into Electrical energy. For making of inductive coil, ferromagnetic materials i.e. Mu-Metal, Silicon-Steel and Ferrite were comparatively analyzed with geometries like Cylindrical, Rectangular and Cone in ANSYS Maxwell Electromagnetism. The visual results of magnetic flux concentration showed that core of Mu-Metal cone is suitable for making inductive coil. A Mu-Metal cone-shaped coil was physically designed and tested in Laboratory under the magnetic Field region generated by Helmholtz coil. The coil was placed at the magnetic field density of 10uT which induced voltages of 1.25V. It was further connected to the energy harvesting circuit that was consisted of Multiplier circuit and Buffer circuit. When fully recharged, the end terminals showed the DC output of 650mV. The total coil resistance under magnetic field region was 90ohms at 3950 copper turns. Total power and power density achieved by the coil was 6mW and 5.5uW/cm3 which is better than any previous designs using inductive coupling method.