【作者】 封皓；

【导师】 靳世久；

【作者基本信息】 天津大学 ， 精密仪器及机械， 2011， 博士

【摘要】 油气长输管道作为油气资源重要的输送手段,其总里程数随着石油消费和油气工业的发展快速增长,其安全问题也越来越受到人们的重视。课题组研究的分布式光纤油气管道安全预警系统可在管道发生泄漏前预判威胁管道安全的入侵事件,并对其进行准确定位,及时通知工作人员采取措施加以制止,可防患于未然,避免油气泄漏所带来的环境污染和经济损失,具有巨大的社会和经济效益。该系统在实验过程中发现,用于事件定位的两路信号的相关性呈随机变化状态,如果相关性恶化,则会导致定位误差突然增大,严重影响系统的稳定运行。本文对分布式光纤油气管道安全预警系统的琼斯矩阵模型和定位过程进行了深入的研究,主要的研究内容如下:(1)分析了单模光纤的偏振特性,建立了单模光纤的等效琼斯矩阵模型。利用单模光纤的等效琼斯矩阵,建立了分布式光纤油气管道安全预警系统的模型,并对该模型进行了仿真分析,找到了影响相位偏移和幅度衰落的因素,指出相位偏移(简称相移)是导致定位误差增大的原因。(2)根据系统模型,提出了基于双臂检测信号相关系数的偏振控制方法,用于检测信号的有源相移补偿。详细研究了采用全局搜索算法和模拟退火算法控制双臂检测信号相关系数的工作原理,通过实验确定了全局搜索算法的搜索步长和模拟退火算法的初始温度、最大搜索步长、温度更新常数等关键参数。经现场实验验证,两种偏振控制算法均可以将双臂检测信号的相关系数稳定在1附近,且模拟退火算法比全局搜索算法具有更快的收敛速度和更高的控制效率。(3)根据系统的琼斯矩阵模型,提出了一种采用333耦合器的相位软解调解决方法,将正、反两个光路相移前的信号解调出来用于时延估计,可消除双臂检测信号的相位偏移。现场实验证明,该方法可以有效地提高定位精度,维持系统长期稳定运行。(4)提出了基于三阶累积量和自适应滤波器的时延估计方法用于管道入侵事件的定位。研究了三阶累积量和自适应滤波器用于时延估计的原理和算法,利用三阶累积量抑制高斯相干噪声,再通过自适应滤波器抑制非高斯相干噪声并获得时延估计,可明显的提高定位精度和定位一致性。(5)研制了两种分布式光纤油气管道安全预警系统,并安装于实际成品油和天然气长输管道。现场实验及长期运行结果表明,上述方法能保证系统长期、稳定、有效运行。更多还原

【Abstract】 As an important means of transporting oil and gas resources, the length of pipeline is growthing rapidly due to the development of oil and gas industry and consumption. And people pay more and more attention to pipleline’s security issues. The distributed optical fiber oil and gas pipeline security pre-warning system studied by our research group, can perform pre-warning monitoring and locating the abnormal dangerous events that happens nearby the oil and gas pipeline.so that the pipeline administrative staff could take preventive measures to stop threatening events to avoid safe accidents. This will bring great social and economic benefits.In the system experitments, the correlation of the two signals, which are used in location process, is often in the state of random variation. This will lead large location error, and affect the stability of the system operating. In this paper, the system’s Jones matrix model and the location process are deeply studied. The main contents are as follows:(1) The polarization properties of single-mode optical fiber are studied, and then the single-mode fiber Jones Matrix model is established. The model of the system is established using the single mode fiber model, and then the model simulation is analyzed to find the reasons of phase shift and polarization fading. Phase shift is the the mainly cause of large location error.(2) Based on the Jones Matrix model, an active phase shift compensation method, which uses a polarization controller to control polarization states of output light, is proposed. The global search algorithm and simulated annealing algorithm based on the correlation coefficient of two signals are studied, and then some key parameters, such as the initial temperature, the maximum step length, the temperature update constant, are determined through the experiment. The on-site experiment shows that the two polarization control algorithms can stabilize the correlation between the two detection signals. But the simulated annealing method has faster response speed and greater control efficiency than global search method.(3) Based on the Jones Matrix model, a phase passive soft demodulation solution using 3×3 couplers is proposed. By this soft demodulation, both clockwise and counterclockwise signals are demodulated to estimate the time delay. The on-site experiments show that this method can improve location accuracy, maintain long-term stable operation of the system.(4) A time delay estimation method for locating the pipelines invasionevents, based on third-order cumulant and adaptive filter is proposed. The third-order cumulants and adaptive filters algorithm for time delay estimation are studied.In order to improve the events locating accuracy and consistency, the third-order cumulant is used to abate Gaussian coherent noise, and the adaptive filter is used to abate non-Gaussian coherent noise and get time delay estimation.(5) Two kinds of distributed fiber oil and gas pipeline safety pre-warning system are developed and installed on the actual long-distance pipeline. The on-site experiments and long-term operation results show that the methods proposed in this paper can ensure the system operating with long-term stable and effective.更多还原