A Wireless and Passive Online Temperature Monitoring System for GIS Based on Surface-Acoustic-Wave Sensor

A novel temperature monitoring system for gas-insulated switchgears (GISs) based on surface-acoustic-wave (SAW) sensing is proposed in this paper. Compared with the existing systems, this system has several unique advantages, such as being wireless, passive, and at a proper cost with continuous monitoring. First, an accurate SAW temperature sensor is designed for the GIS conductor, where epoxy encapsulating and loop antennas are adopted in the SAW sensor to prohibit the potential partial discharge of the sensor itself. After that, a multifunctional reader antenna is developed, which can measure the conductor temperature and partial discharge by the time-division multiplexing technique. Experiments are carried out to examine the accuracy and response speed of the SAW sensors, and the results indicate that the uncertainty of the contact temperature measurement is smaller than 10 degrees C. Moreover, the insulation level and anti-interference ability are demonstrated based on experiments carried out on a 126-kV GIS. At last, temperature monitoring performance of the developed system is investigated by changing the current in the 126-kV GIS conductor. The experiment results prove that the developed system can meet the requirement of temperature monitoring in GIS.