提出基于Sagnac/Mach-Zehnder混合干涉原理的水下天然气管道泄漏检测系统,采用基于时域统计特征的信号提取方法,通过光纤干涉信号时域分析,提取信号幅值在均值上下特定范围内波动的概率特征,建立天然气管道泄漏工况下的主成分模型。根据平方预测误差（SPE）统计量判别管道泄漏状况,并与传统零点频率法的分布式光纤管道泄漏检测进行对比分析,统计了系统漏警率(MAR)。结果表明,提出的时域统计特征向量能够描述管道泄漏特征,采用SPE统计量泄漏诊断法能够准确判别天然气管道是否泄漏,漏警率降低至传统零点频率法的1/10左右。

To detect the natural gas leakage of the pipeline underwater, a distributed optical fiber sensor system is introduced based on hybrid configuration of Sagnac/Mach-Zehnder interferometers. Based on time domain statistic features, the probability features of amplitude values distributed near the average can be extracted with time domain analysis of optical fiber interferometric signals. A principal components analysis model based on statistic features is established to monitor gas pipeline leakage condition. The squared prediction errors (SPE) statistics is used to discriminate pipeline condition, and compared to the traditional method of distributed optical fiber pipeline leakage detection which just depends on whether null frequency existing or not. The missing alarm rate (MAR) is calculated. The results show that the proposed time-domain statistical feature vector can describe the characteristics of pipeline condition, the SPE statistics in leakage condition can discriminate pipeline leakage accurately, and MAR decreases to about 1/10 of that with the traditional method based on null frequency.