分布式光纤传感技术及其铁路安全监测应用研究
文献类型：学位论文
| 作者 | 曹玉龙 |
| 学位类别 | 博士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 蔡海文 |
| 关键词 | 分布式光纤传感 BOTDR φ-OTDR 铁路安全监测 工程应用 |
| 其他题名 | Studies on Distributed Fiber Sensing Technique and its Applications in Railway Safty Monitoring |
| 中文摘要 | 分布式光纤传感技术，不仅具有普通光纤传感器抗电磁干扰能力强、体积小重量轻、绝缘、耐高温耐腐蚀等，而且能够在整个传感范围内对光纤沿线每一处的多种物理量进行分布式检测，在大型建筑健康检测、周界安防诸多领域具有广泛的应用前景，近年来成为光纤传感领域的研究热点。光纤中的布里渊散射光相对于入射的本地激光，有11GHz左右的频移，这种布里渊散射光的频移和强度与光纤所处环境的温度和应变之间成线性函数关系。基于此原理的分布式光纤传感系统，能够实现对光纤沿线温度和应变的分布式传感。基于瑞利散射的分布式光纤传感系统，能够对光纤沿线的振动、应变等动态信息进行探测。本文针对具有广泛应用前景的几种分布式光纤传感技术进行了深入的实验研究，包括基于布里渊散射的布里渊光时域反射计（BOTDR）技术和基于瑞利散射的相位敏感光时域反射计（φ-OTDR）技术，并在此基础上搭建和集成了传感系统样机。 铁路安全监测对用于其中的监测设备具有长距离、多参量测量、寿命长等诸多要求，而分布式光纤传感技术均能满足这些需求。我们在铁路沿线安全监测领域进行了工程应用的实验研究，根据铁路实际工程应用中的问题和需求为出发点，对分布式光纤传感器的稳定性和一致性进行改善，对实际应用过程中出现的一些问题，如双峰布里渊散射谱现象、温度和应变交叉敏感等问题进行探讨和解决。本文的主要研究内容如下： 1. 针对分布式光纤温度和应变传感，基于宽带移频技术和相干检测技术对微弱的自发布里渊散射光进行探测采集，搭建了布里渊光时域反射计（BOTDR）系统样机；基于数字相干检测技术，利用MATLAB编写了数据采集和处理程序，对采集得到的自发布里渊散射光信号进行分析并解调得到强度和频移信息，并将这些信息转换为具有位置信息的温度、应变分布。BOTDR样机能够对40km的光缆进行监测，温度精度为±2℃，应变精度40με，定位精度5m。 2. 基于120°相差干涉仪搭建自外差相位敏感型光时域反射计，并提出了基于干涉仪传输矩阵的相位解调方案，实现了对10km光纤的振动传感。该技术基于3×3干涉仪对光纤中的瑞利散射光相位进行分布式解调，使用自外差相干检测技术，有效地消除衰落效应的影响，且能够准确快速地解调得到相位分布，对于光纤的振动进行有效地感知。 3. 针对工程应用中存在的双峰甚至多峰布里渊散射谱，利用洛伦兹曲线拟合的算法难以准确地解调出中心频率，提出双峰洛仑兹拟合和权重算法解调布里渊散射谱的中心，结果表明对于存在双布里渊散射峰的光纤能够准确地进行传感解调。 4. 针对工程应用中的温度应变交叉敏感问题，通过线路中光缆不同区域的温度补偿来解决温度和应变的难以分离的问题。在应力检测区域，将夹具之间的应力感测光缆拉紧，同时在其附近预留足够的松弛光缆进行温度补偿，通过该光缆进行温度检测，应力感测光缆所得频移值减去温度变化之后即可得到应变变化数值，其中涉及到线路中的详细定标，对于温度和应变感测区域需要进行准确的定位。 5. 将我们自主研制的传感样机应用于铁路沿线的光电缆温度、应变等方面的监测，应用范围包括：(1) 光缆断线，针对铁路沿线非授权作业、电缆燃烧、塌方等导致的通信光缆断线进行定位监测；(2)光电缆异常温度变化监控，针对铁路沿线的烧荒、同槽电缆老化导致的烧伤、高压牵引电缆的异常温升等进行感知；(3)结构应变测量，针对铁路沿线的边坡、隧道等复杂地形可能存在的滑移、形变和塌方等现象进行监测。工程应用实验表明BOTDR技术在铁路安全监测领域具有很高的应用价值。 |
| 英文摘要 | The distributed fiber sensor based on scattering, not only has all advantages of single fiber sensor, such as electromagnetic-free, small size, light weight, insulation, high temperature resistance, anti-corrosive and so on, but also could measure the related physical characters continuously along the long distance fiber. This technique has extensive application prospects in numerous fields, such as huge building health monitoring, boundary security and protection. The distributed sensing technique has been the focus of sending field for years. The frequency shift and intensity of the Brillouin scattering are linear to the temperature change and strain variation, while the Brillouin frequency shift (BFS) is about 11GHz. Based on these principles, the distributed fibre sensor, called as Brillouin optical time domain reflectometry (BOTDR), can be used to detecting temperature change and strain variation along the fiber. And the distributed fibre sensor based on Rayleigh scattering, called as phase sensitive optical time domain reflectometry (φ-OTDR), can be used to explore the dynamic signal such as vibration and strain along the fiber. The distributed fiber sensors are applicable to railway safty monitoring,which requested long distance, multi-parameter, long operating life and so on. Our sensing system prototypes have been constructed and used in engineering application in railway system. In allusion to problems and requirement in practical application, such as the cross sensitivity of temperature and strain, doublet Brillouin spectrum and so on, solutions have been proposed to solve them. The main contents in this paper are as followed: ? For the distributed optical fiber temperature and strain sensing, the BOTDR fiber sensing system prototype with two channels is constructed based on broadband frequency shift and coherent detection technology. Data acquisition and processing program is compiled and used to demodulating the temperature and strain along the fiber. ? A phase sensitive optical time domain reflectometer (φ-OTDR) based on 120° phase difference Michelson interferometer is proposed. Michelson interferometer with arm difference of 4m is used to test the phase difference between Rayleigh scattering from two sections of fibre. A new demodulation method called inverse transmission matrix demodulation scheme is utilized to demodulate the distributed phase from the backward scattering along the long fiber. The experimental results show that the 120° phase difference interferometer φ-OTDR can detect the phase along 10km fiber, and acoustic signal within the whole human hearing range 20Hz~20kHz is reproduced accurately and fast. ? In order to obtaining accurate information from double-peak even multi-peak Brillouin spectrum in engineering application, doublet Lorentz fitting demodulation is propoed and used to achieving accurate peak frequencies of the spectrum. Accurate Brillouin frequency shift could be demodulated by using these method synthetically. ? Against the cross sensitivity of temperature and strain in BOTDR, the method by temperature compensation is used to solve the problem. Loose fiber cable are reserved beside the strain sensing fiber cable to measure temperaure of that area, which would be subtracted and strain parameter will be obtained. Accurate location of each sensing fiber cable is necessary for the solution. ? Our BOTDR prototype is used to temperature and strain monitoring in the railway system. Some engineering applications are verified：(1) optical cable break line: location the break line position along the optical cable. (2)abnormal temperature changing of optical and power cable: for detecting the moorburn and fire burn due to cable maturing; (3) structure health monitoring：for detecting the slippage and overbreak of side slope and tunnel along the railway. BOTDR can be useful to engineering applications for long distance and high accuracy health monitoring. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15970]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 曹玉龙. 分布式光纤传感技术及其铁路安全监测应用研究[D]. 中国科学院上海光学精密机械研究所. 2016. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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