Research and design of multi‐stage multi‐load wireless power supply system for high voltage online monitoring equipment

Many online monitoring devices in substations are placed at high potential differences from the ground, and it is not possible to supply power to these devices directly from the ground through wires. Placing magnetically coupled structures inside the substation pillar insulators for inductive power transfer is considered a feasible solution, and at this stage of research, systems that add multi‐stage repeating coil structures are mostly used to achieve stable power supply for individual online monitoring devices. However, the monitoring point generally requires multiple devices to monitor together, and the power requirements of different devices are different, so adding multiple repeating coils at the same time will increase the complexity of the system design, which is not conducive to engineering applications. Therefore, this paper designs and optimizes a multi‐stage multi‐load wireless power supply system magnetic coupling structure, using a three‐dimensional hollow solenoid combined with a ferrite core as the system repeating coil structure and an embedded magnetic coupling structure as the receiver end structure to reduce the number of system repeating coils while supplying power to devices with different power requirements. A prototype with a transmission distance of 1.02 m was built in the experiment, and the experimental results showed that the highest transmission efficiency of the system was 44.3% and 39.2% under single load and double load conditions, respectively. As the load resistance increases, the system can achieve constant voltage output under both single‐load and dual‐load operating conditions. Adjusting the number of turns of the receiving coil can change the output characteristics of the system and achieve constant voltage output of different voltage levels or constant current output of different current levels, which can meet the power supply needs of different loads.