Research On Hybrid Technology Of Distributed Raman Temperature And Discrete FBG Strain Sensing

The Raman Distributed Temperature Sensor(RDTS)technology based on the Raman effect has become a technology widely used in distributed temperature monitoring due to its inherent protection against electromagnetic interference,corrosion resistance and low cost.At the same time,it has the advantages of large measurement range and high temperature resolution.The related technology research is also one of the research hotspots in the field of fiber optic sensing.However,due to the current technology,it is difficult to further improve the accuracy of the sensor and maintain the cost of the system.There is a certain compromise between the measurement range and resolution,and the insensitivity to physical quantities other than temperature is difficult to meet the measurement of multiple physical quantities which makes further application of this technology more difficult.This research combines the distributed Raman temperature sensing technology with the quasi-distributed grating sensing technology,and systematically explores the structure of the Raman DTS system and the grating sensing fusion system,and experimentally verifies the performance of fusion system about multiple parameters' measurements,the main research contents and results completed are as follows:1.The research status of RDTS technology at home and abroad is analyzed,the development of distributed temperature sensing are introduced.The research done by domestic and foreign researchers in this technology field are analyzed to improve the performance of measurement range,temperature resolution,and spatial resolution.2.The temperature sensing theory and signal demodulation method based on Raman effect are studied,and the temperature sensing error caused by the difference of attenuation coefficient in traditional demodulation method is quantitatively described.3.A temperature sensitivity correction algorithm in distributed temperature sensing system is proposed,and the measurement error generated at the remote end during large-scale distributed temperature sensing is simulated.The error between the sensing signal and the actual temperature field distribution is analyzed.The reason for the cumulative effect of increasing the length of the sensing fiber.An algorithm for correcting the sensor signals is proposed,and experiments are designed and verified for the algorithm.The experimental results show that the temperature measurement error is reduced from 18.01 ° C(traditional demodulation algorithm)to 1.56 ° C at 10 km,which illustrates that the effectiveness and feasibility of the algorithm.4.Combining Raman distributed temperature measurement and grating sensing technology,an experimental system for simultaneous monitoring of distributed temperature and quasi-distributed stress is proposed,and a dual parameter sensing study of the system is carried out.5.The proposed system combines the above-mentioned signal correction algorithm,and at the same time compensates the cross sensitivity of the grating in stress measurement,and finally achieves a temperature measurement accuracy of 0.48 ° C and a stress measurement accuracy of 10.47 ??.The system does not need to add additional light sources.It also retains the advantages of single-ended measurement and has good stability.By designing an algorithm for the RDTS system to improve the temperature measurement performance,the distributed temperature and quasi-distributed stress measurement hybrid system proposed in this study has the ability to simultaneously monitor the above-mentioned physical quantities,which is very important in many applications that require multi-parameter monitoring.