Research On Key Technologies Of Distributed Optical Fiber Raman Scattering Temperature Sensing

Temperature sensing measurement has a wide range of applications in fields such as oil and gas well logging,monitoring of the operation status of oil and gas pipelines,fire warning,and power grids.The research on the theory and technology of fiber optic temperature sensing based on Raman scattering has always been a research hotspot in distributed temperature sensing measurement.Based on the theoretical and systematic research of fiber Raman temperature sensing,this article focuses on the key technologies of signal processing to improve temperature and spatial resolution.The main research content is as follows:(1)The theory of Raman scattering sensing technology was elaborated,the temperature effect of fiber Raman scattering and the methods of demodulation in distributed fiber Raman temperature sensing was discussed.The advantages and disadvantages of various demodulation methods was compared.Moreover,the optical time domain reflection positioning technology was described.(2)A distributed fiber Raman temperature sensing system was designed and constructed,and experimental testing was conducted.Analyze the key performance indicators of the system,select parameters from various hardware modules,and complete the system hardware design scheme.Introduce the working principle of the system,and analyze the noise contained in the system,providing a basis for subsequent signal processing methods.Designed a data acquisition interface,wrote a signal processing program,and achieved the integration of data acquisition and processing;Conduct systematic temperature calibration experiments to provide a reference for temperature measurement.(3)Research on the key technologies of signal processing methods in the system has solved the problems of low measurement accuracy and spatial resolution.In response to the problem of low measurement accuracy in the system,an improved wavelet modulus maximum algorithm is proposed by combining the rules in error processing methods.The improved algorithm changes the traditional experiential method in selecting the threshold of the highest decomposition layer.Simulation and experimental verification have shown that this algorithm can effectively improve the temperature measurement accuracy of the system,reducing temperature measurement fluctuations from 3.55 ℃ to 1.30 ℃;To address the issue of low spatial resolution in the system,a deconvolution correction algorithm is adopted to increase the spatial resolution of the system to 1m without replacing hardware.The distributed fiber Raman temperature sensing system built in this article provides methods and approaches for temperature sensing over a wide range and long distance.