Power Capacitor Temperature Measurement System Using FBG Sensors and Its Validation

It is difficult to accurately measure internal temperature of power capacitor. To accurately measure internal and external temperatures of an operating capacitor, a capacitor temperature measurement system based on fiber Bragg grating (FBG) temperature sensors is developed. First, technical parameters of the sensors and the optical sensing interrogator are determined according to the practical situations. Second, the sensors are calibrated using a highly accurate thermostatic bath, and their reproducibility is checked. Third, in combination with ENLIGHT software, the temperature measurement system based on FBG sensors is set up. Finally, three BAM6.56-556-1W high-voltage film capacitors are manufactured, and the FBG sensors are put into a high-voltage film capacitor and placed on its shell, the temperature distribution of the capacitor in the thermal stability test is measured. The corresponding temperature field model of the capacitor under the same conditions is created and solved in Fluent. The simulation results are consistent with the measured results, which validates the temperature measurement system. This paper fixes the problem of internal temperature measurement for high-voltage film capacitor which can be taken as a reference to online monitoring of power capacitor temperature.