| Fiber Bragg Grating (FBG) sensor, which uses the property that the Bragg wavelength is sensitive to temperature and strain, is a new kind of fiber optic sensor. In addition to having the same functions as the traditional electric sensors, the FBG sensor also has some special characteristics such as distributed sensing, immune to electromagnetic interference, high precision and long-term stability. Temperature measuring is one of the most important applications of FBG sensors.According to the existing researches, FBG has stable sensing properties, and thus is an ideal kind of temperature sensing material. The aim of the research task is that on the basis of probing into the characteristics of FBG, to research the encapsulating method of fiber grating temperature sensors, to develop production technology of fiber grating temperature sensors which is suitable to practice engineering application, and probe into fiber grating temperature sensing system applied in temperature measuring of electric power system.After deeply study on the FBG sensing technology, the design requirements of FBG temperature sensor is analyzed, according the practical needs in engineering. On the basis of research on the current status of FBG temperature sensor encapsulation, and the characteristics of existed encapsulation structures, a new encapsulating method using thin steel tube is designed. Then we study the effects of this encapsulating method on the FBG temperature properties by experiments. We also perform some theoretical analyses on the experimental results.The main work of this thesis includes:(1) Introduces and analyzes the structure, sensing principle, manufacturing technology, sensing model of fiber grating, and basic structure of fiber grating sensing system and sensing network.(2) Introduces and analyzes various demodulating methods of fiber grating, concludes characteristics of every demodulating methods, and does comparison of each demodulating methods. Emphatically researches the fiber grating demodulating solution based on Fabry-Perot cavity, and improves demodulating precision by using polynomial fitting algorithm.(3) Analyzes effects of characteristics of fiber grating temperature sensor by various encapsulating methods. Researches on fiber grating temperature sensing measuring system applied in industrial application. Discusses the application of the system in electric power system. |
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