Online Monitoring Of Medium Voltage Electrical Apparatus Based On Wireless Power Transfer

With wide range supply, power distribution points and large capacity, medium voltage distribution networks are the backbone of the regional power supply. The online monitoring of its electrical apparatus, to ensure safety and stability of the power grid, will be of great significance for the build-up of strong and smart power grid. The primary side of electrical apparatus has high voltage and carries large currents. Strong electromagnetic environment makes it difficult to online monitoring, particularly in the supply of monitoring device at high voltage (HV) side, sensor data collection, data transfer between the HV side and low voltage (LV) side, and electrical insulation.Recently, wireless power transfer (WPT) is widely concerned and has been studied in many fields. Among several ways of WPT, Magnetic coupling resonance performs well in mid-range power transfer without any electrical connection. With the distance of WPT and adequate electrical space, WPT can transfer power from LV to HV side and supply monitoring device at HV side.The paper outlines the research status of medium voltage electrical equipment online monitoring technology. Then, the introduction to the mechanics of WPT is made and the principle of magnetic couple resonance is analyzed. Simulation and experiment are performed to determine the factor that affects the process of WPT. The author designs a WPT system suitable for power transfer between HV and LV side. With class E high frequency inverter, the LV side generate alternate magnetic field. The WPT increases transfer distance and acquire higher efficiency. At HV side, the receiver output stable power through high frequency rectifier and regulator. Moreover, methods for key parameters measurement at HV side are provided. And the paper states the principle of sensor detection. The real-time monitoring of temperature, current and voltage at HV side are measured at heavy current and high voltage environment. The wireless ANT has advantages of ultra low power consumption, which, in turn, may transmit sensor data from HV to LV side under proper operation. Experiments about supply balance and communication situation of the entire system are carried out. Finally, the author summarizes the research and propose further step to study.During the procedure of electrical apparatus online monitoring, both power supply and sensor data are transferred wireless between HV and LV side. With no physical connection, it’s reliable in electrical insulation and has flexible installation location. Sensors, installed at HV primary side, may achieve sensitive and accurate detection data with the advantage of reliable insulation. It’s a new method to achieve online monitoring of the medium voltage electrical apparatus.