长距离Φ-OTDR关键技术研究
文献类型：学位论文
| 作者 | 王照勇 |
| 文献子类 | 博士 |
| 导师 | 瞿荣辉 |
| 关键词 | 相位敏感光时域反射计 Φ-OTDR 分布式光纤传感 distributed fiber sensing technology 定量化 quantitative measurement 长距离检测 long-haul monitoring 超高响应带宽 ultra-broad response bandwidth. |
| 其他题名 | Study on Key Technologies of Long-haul Φ-OTDR |
| 英文摘要 | 分布式光纤传感技术不仅具有普通光纤传感技术的优势，如抗电磁干扰、隐蔽性好、耐腐蚀、绝缘等，而且可以实现整条光纤链路上各类物理量（温度、振动、应变等）的连续检测。相位敏感光时域反射计（Φ-OTDR）作为一种高灵敏度的分布式光纤传感技术，可实现光纤沿线振动信息的实时检测，满足了大型结构健康监测、周界安防、长距离管线状况监测等领域对长距离振动检测的迫切需求，得到了广泛关注。本文针对Φ-OTDR在长距离振动检测中面临的传感距离受限、系统响应带宽较低等诸多关键技术问题，开展了分布式光放大、时间序列多频率光源技术等理论和实验技术研究，构建了原型样机，验证了系统的性能；针对Φ-OTDR在实际应用中面临的技术难题，开展了快速模式识别技术、车辆跟踪技术、多维度综合分析技术等方面的理论和技术研究，测试了相关技术的应用性能，并在周界安防、铁路运输等领域获得了很好的工程示范性应用。 本论文的主要研究内容如下： 1、研制了一套定量化Φ-OTDR传感系统样机，详细介绍了系统的结构、器件选取与相位解调方案。利用此平台进行了分布式振动和声音传感的定量化实验。 理论分析了光源线宽、频率漂移、脉冲宽度、脉冲消光比等参数对系统性能的影响；介绍了定量化Φ-OTDR传感系统样机的结构，设计了基于现场可编程门阵列（FPGA）的同步控制板；介绍了基于数字相干相位解调的数据处理流程，并设计了程序软件和显示界面，提出了数据回放功能；最后利用系统样机进行了分布式振动和声音的传感实验，实现了正弦波、三角波和方波的线性重建，利用自制光纤声音传感头有效地重建了环境语音，实验结果令人满意。 2、提出了基于时间序列多频率源的超高响应带宽技术，实现了9.6 km传感范围&500 kHz响应带宽的定量化检测，将长度带宽积提升了100倍。 建立了超高响应带宽技术的理论模型，探讨了该技术的理论可行性，分析了调制参数对光源性能的影响，为光源的优化设计提供依据；设计了时间序列多频率光源，搭建了实验系统，采用多种扰动信号对系统响应带宽进行了验证。实验结果表明，超高响应带宽技术在不牺牲传感范围的前提下，可以有效提升系统的响应带宽。此外，论文还深入研究了该技术的性能极限。 3、提出了基于布里渊散射的分布式光纤放大技术，将Φ-OTDR系统的传感范围提升至89.9 km，尾端信噪比提升10 dB。 从理论上研究了自发布里渊散射与布里渊分布放大的基本机理；分析了相关参数对放大效果的影响，利用电光调制和注入锁定产生泵浦光源；设计了前向泵浦和后向泵浦结构的Φ-OTDR系统，并分别进行了实验验证。实验结果表明，该技术可以实现Φ-OTDR光信号的有效放大和传感范围的拓展。针对该技术在工程应用中所面临的困难进行了详细分析和讨论。 4、深入研究了Φ-OTDR的模式识别技术，针对不同应用场景，提出了多种基于Φ-OTDR的模式识别技术，包括快速模式识别技术、车辆跟踪技术和铁路安全综合检测技术。 初步研究了用于周界安防的车辆定位跟踪技术，提出了动态频率空间图像分析方法实现了车辆行驶信号与无关信号的分离，并通过外场测试对这一技术的效果进行了验证。提出了用于铁路安全综合检测的多维度综合分析技术，实现了铁路沿线堑坡落石、人员入侵、非法施工、列车行驶等振动信号的全天候、实时检测，并建立了应用示范工程。提出了用于周界安防的频谱欧氏距离分析算法，实现了快速、高效的信号识别，有效地降低了系统误报率。这些针对性的模式识别技术开拓了Φ-OTDR在周界安防、铁路运输等领域的应用，为分布式光纤振动传感的发展提供了技术支持和理论依据。; Distributed fiber sensing technologies could detect the physical changes along the whole fiber continuously, except the superiority of conventional fiber sensoring technologies, such as, anti-electromagnetic, anti-corrosion, insulation, etc. Phase-sensitive optical time domain reflectometry (Φ-OTDR) is a kind of distributed fiber sensing technology with high sensitivity, and it can monitor the ambient vibration conditions along the whole fiber. In consequence, Φ-OTDR satisfies the requirement of long haul vibration monitoring for many fields, such as, large structure health monitoring, perimeter security, pipeline condition monitoring, and so on. In this paper, some key technologies for long haul vibration monitoring were proposed and researched to improve the limited sensing range, response bandwidth, etc. The distributed fiber amplification technology and temporally sequenced multi-frequency source were theoretically analyzed and experimentally researched. The prototype has been constructed and the system performance was verified. With regard to the technical issues in engineering applications, many researches were carried out, including fast pattern recognition, vehicle tracking technology, and multiple dimension comprehensive analysis. The performance of related technologies were tested and these technologies have been applied in perimeter security, railway transportation and other correlative fields. The main research contents in this paper are shown as follows, 1) A prototype of quantitative Φ-OTDR system was developed. Meanwhile, the system structure, component selection, and the phase demodulating scheme were also introduced. The quantitative experiments of distributed vibration and voice were carried out. The influence of relevant parameters on system performance was theoretically analyzed, including the linewidth of laser source, the frequency shift, the pulse width, pulse extinction ratio, etc. The prototype structure was introduced and a synchronous controlling circuit was developed. The data processing scheme was briefly introduced； The program software and graphical user interface were developed. The data playback was designed to help analyzing the raw data. Finally, the sensing experiments of vibration, voice and temperature were carried out. Three kind of vibration signals, including sinusoidal wave, triangular wave, and square wave, were linearly rebuilt; the ambient voice was obtained by the Φ-OTDR prototype and a self-made fiber sound sensing head. The results were satisfying. 2) The temporally sequenced multi-frequency source technology (TSMF) was proposed and the quantitative measurement was realized with 500 kHz response bandwidth over 10 km sensing range. The result of system distance and bandwidth was improved as 100 times as before. The theoretical model of TSMF was set up, the theoretical probability was discussed. The influence of related property parameter on laser property was analyzed, which is the basis of laser source design. The temporally sequenced multi-frequency source was designed, the experimental system was set up and the system bandwidth was experimentally verified. The experiment results show that DFSI can improve the system bandwidth without sacrificing the sensing range. In addition, the performance linmitation of DFSI was studied. 3) The distributed fiber Brillouin amplification technology was proposed, and the sensing range has been extended to 89.9 km. The system signal-noise ratio was improved by 10 dB. The principles of spontaneous Brillouin scattering and distributed fiber Brillouin amplification was theoretically studied. The influence of relevant parameters was analyzed, and the Brillouin pump was designed by EOM modulation technology and injection locking technology. The forward pumping and backward pumping Φ-OTDR was designed, and both were verified experimentally. It showed that the Brillouin amplification was effective to amplify the light signal and to improve system sensing range. The difficulties and problems in Φ-OTDR-based Brillouin amplification were discussed in details. 4) With regard to different applications, we proposed several pattern recognition technologies, including fast pattern recognition technology, vehicle tracking, and railway safety comprehensive monitoring technology. Firstly, the vehicle positioning and tracking technology was developed for perimeter security, the dynamic frequency-space image analysis (DFSI) method was proposed to extract vehicle-vibration signal from extraneous signals, and this technology was verified in field test. Then, the multiple dimension comprehensive analyzing (MDCA) method was studied for railway safety comprehensive monitoring. The MDCA has been applied in many fields of all-time railway safety monitoring, including rock fall detection, personnel invasion, illegal constructions, train tracking, etc. Some demonstration projects are also set up. Finally, the Euclidean-distance-of-Fourier-spectrum (EDFS) algorithm was proposed, the pattern recognition was achieved, and the false alarm rate was effectively reduced. These specific recognition technologies exploit a wide application prospect for Φ-OTDR in perimeter security and railway transportation. Meanwhile, these technologies provide technological support and theoretical foundation for the development of distributed fiber sensing. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31003]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 王照勇. 长距离Φ-OTDR关键技术研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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