Design of Draw-out Power Supply for On-line Monitoring System of Three-core Power Cables

The research described in this paper focuses on online power supply applied in the three-core cable by using the draw-out coil to acquire energy with the aim to find a technical solution to guarantee the on-line monitoring electronic devices operate at rated voltage chronically when the cable current changing in a large dynamic range. Based on electromagnetic induction, the energy is draw out directly from the cables by the draw-out power coil. The relationship between the output voltage of the draw-out coil and the structure of magnetic core has been analyzed by CST software. To ensure the device can provide a stable output power, a three-port converter is applied to the device. The three-port converter is connected with the draw-out power coil output, battery and load respectively. By charging and discharging the battery, the power imbalance between the draw-out power coil and the load can be compensated, so the device realized continuous and stable power supply to the load when the cable current changes in a wide range. Finally, simulation and experimental prototype have been carried out to verify the performance of the proposed device. The test results show that the device could achieve a stable output voltage for on-line monitoring sensors in a wide range of the three-core cable current.