基于分布式光纤传感的水下输气管道泄漏检测与定位分析

介绍了一种基于Sagnac/Mach-Zehnder混合干涉仪原理的分布式光纤传感水下输气管道泄漏检测及定位系统。在强干扰微小泄漏情况下，通过分布式光纤传感器获取由管道泄漏引起的光干涉信号，采用小波包方法对信号进行多层分解，提取小波包能量特征，用欧式距离法对管道泄漏与否进行聚类分析；对泄漏系统利用零点频率进行精确定位，并将基于零点频率的传统检测定位、经小波去噪和最小二乘曲线拟合处理后的检测定位及本文提出的检测定位三种方法进行对比分析，统计了系统虚警率（FAR）。实验结果表明，该系统能准确识别管道泄漏，本文提出的泄漏检测定位法虚警率最低，与经小波去噪和最小二乘曲线拟合处理后的检测定位法相比，虚警率降低了6.6%，提高了系统泄漏检测定位的可靠性。

Leak Detection and Localization Analysis of Underwater Gas Pipeline Based on Distributed Fiber Optic Sensing

For underwater gas pipeline leakage point detection and localization,a distributed optical fiber sensor system was proposed based on a hybrid configuration of Sagnac/Mach-Zehnder interferometer. Tiny leakage signals were covered by strong interferences,and optical interferometric signals caused by pipeline leakage can be obtained by the distributed optical fiber system. Wavelet packet is used to deal with interferometric signals,and signals were decomposed into different frequency bands to extract energy features. Those features were clustered with Euclidean distance to discriminate pipeline leakage. The leakage point can be captured from null frequency spectrum. Three leakage localization methods (the traditional detection based on null frequency,the detection of wavelet de-noising and least squares curve fitting process,the proposed method) performances were compared,and the false alarm rate (FAR) is calculated. The experimental results show that the system can identify leakage point accurately. The pro?posed method owns the lowest FAR in three methods. Compare to the wavelet de-noising and least squares curve fit?ting method,the FAR of proposed method is reduced about 6.6%,and it improves the reliability of leakage detec?tion and localization system.