The Transformer Winding Temperature Monitoring System Based on Fiber Bragg Grating

High temperature is one of the important reasons causing the fire in power system. Therefore, the early warning could be told by monitoring the temperature and effective measures could be taken. The corresponding accidents will be reduced. The traditional transformer winding temperature monitoring methods are electrical signal measurement and infrared measurement. Such electrical signal sensors are vulnerable to the interference of electromagnetic field, so the result of measurement is bad. Multiplexing optical path is unable to be realized by fluorescence thermometry. The optical fiber Bragg grating technology is used on temperature monitoring of transformer winding in this paper. The transformer winding temperature monitoring system based on optical fiber Bragg grating includes three parts: Temperature monitoring program based on the LabVIEW programming language, a fiber Bragg grating wavelength demodulation system and FBG temperature sensor. When the temperature of the transformer windings changes, the central wavelength of the fiber Bragg grating changes accordingly. Broadband ASE light source emits light, which is transmitted from the optical circulator into the fiber Bragg grating. The reflected light gets into the wavelength demodulation module again through the optical circulator. Wavelength demodulation module could transmit the center wavelength of the spectral reflectance information, peak power information to the computer. The computer analyzes, processes the information and displays the data with XY graph by calling the LabVIEW program. The program can get center wavelength values at the same time then get temperature by fitting function and display temperature on the front panel of the program. The fitting line of linearity between center wavelength of optical fiber Bragg grating sensor and temperature is above 0.95. The function reveals a good linearity which fitting the wavelength changes of the optical fiber Bragg grating during this temperature range. The experimental results show that the system has high accurate measurement which meeting high precision requirements of transformer winding temperature.