RESEARCH ON APPLICATION OF DISTRIBUTED FBG IN ON-LINE TEMPERATURE SENSING OF POWER TRANSFORMER

Transformer undertakes the task of energy transmission and is widely used in power system. As one of the core state parameters, temperature determines the lifespan of transformer. Therefore, the realization of accurate on-line real-time temperature measurement is the assurance of a safe and stable power grid. Fiber Bragg grating (FBG) overcomes the defects of traditional temperature measuring methods, such as lack of measuring points and susceptibility to electromagnetic interference. FBG has the advantages of corrosion resistance, high sensitivity, small size and low cost, showing high research and application value. In this paper, the packaging of FBG is optimized firstly and a series of performance tests are carried out. Results show that FBG has good dynamic response characteristics and stability in the range of 30C~160C. Moreover, the linearity of the fitting function is measured to be 0.999 and temperature coefficient is 11.9pm/C, which meets the needs of temperature measuring. Secondly, a distributed FBG temperature sensing system based on Fabry-Perot demodulation is developed. The FBG system is successfully embedded in a 110kV power transformer to realize distributed online temperature monitoring of transformer oil and three-phase windings.