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基于声发射技术的城市管道泄漏精确定位研究
论文作者:童鞋论文网  论文来源:www.txlunwenw.com  发布时间:2019/9/4 8:04:40  

摘要:我国城市埋地压力管道泄漏往往在出现初期得不到发现和修理,等到发展成为重大事故时才做应急处置,这时已造成巨额生命财产损失,因此管道初期泄漏是应该关注的一个重要问题。由于城市埋地管道年久失修,管道中不仅存在单个的泄漏,还存在多个点的泄漏情况,如何有效识别初期泄漏信号,尤其是混合的多点泄漏信号,并精确、快速定位是亟待解决的重要课题。声发射技术方法由于其灵敏性、实用性、经济性高的优点,被人们广泛应于城市管道泄漏检测与定位系统中。但采集的声发射泄漏检测信号中含有大量的噪声以及一些突发性的非泄漏有效信号,其检测定位精度上还存在误差较大的问题。为此需要对管道泄漏声发射信号进行分析与处理,以实现城市管道泄漏精确定位。本论文具体研究内容如下:

(1)通过对国内外声发射技术文献的研究分析,总结归纳管道单点泄漏与多点泄漏情况,以及定位精度不高的原因,尤其分析了多点泄漏定位以及影响定位的因素;深入了解管道泄漏声发射传播特点与现有管道声发射泄漏检测方法;研究模态声发射技术原理,为管道泄漏声发射信号的速度确定提供理论基础。

(2)基于变分模态分解的基本原理,结合相对熵分析方法,提出了一种基于变分模态分解与相对熵的管道泄漏信号提取方法;利用变分模态分解方法识别并分解泄漏信号与无泄漏信号,应用相对熵分析的自适应选择方法,获取最佳观测信号,通过信号仿真证明该方法的有效性。

(3)建立管道单点泄漏与多点泄漏定位模型。在管道单点泄漏定位模型中利用模态声发射理论与广义S变换互时频分析,获取准确信号声速与延时,得到的定位平均误差为2.31 %,最小相对定位误差为0.69 %。在管道多点泄漏定位模型中,为将管道多源泄漏信号分离,引入奇异值分解对多源信号进行源数目估计,结合盲源分离技术将多源泄漏信号进行分离。并分别利用直接互时频分析方法,得到平均相对定位误差为2.97 %,最小相对定位误差为1.00 %。

(4)为验证该方法的有效性,将文中方法与其他方法进行比较。在单点泄漏定位中,本文的到平均定位误差为2.31 %,互时频分析法的平均相对定位误差为5.56 %,基于相关系数分析法的平均相对定位误差为4.79 %;在多点泄漏定位中,本文平均相对定位误差为2.97 %,互时频分析方法无法实现定位,基于经验模态分解法的定位误差为7.36 %,且相较于国外目前基于模型法的多点泄漏平均相对定位误差3.4 %,泄漏相对定位误差下降了12.65 %。由此可见,所提出的方法能够有效减少管道泄漏定位误差,管道泄漏定位精度明显提高。

The leakage of buried pressure pipelines in urban areas is often not discovered and repaired at the beginning of the period in China. When the development of major accidents occurs, emergency disposal is carried out, which has caused huge loss of life and property. Therefore, the initial leakage of pipelines is an important issue that should be concerned. Due to the long-term disrepair of buried pipelines in China's cities, there are not only single leaks in the pipelines, but also leaks at multiple points. It is especially important to find an economical, high-precision, fast-reacting pipeline initial leak location method. The acoustic emission technology method has been widely used in urban pipeline leakage detection and positioning systems due to its advantages of sensitivity, practicability and high economy. However, the collected acoustic emission leakage detection signal contains a large amount of noise and some sudden non-leakage effective signals, and it is difficult to accurately locate the pipeline leakage. To this end, the collected pipeline leakage acoustic emission signals need to be analyzed and processed to achieve accurate positioning of urban pipeline leakage. The specific research contents of this paper are as follows:

(1) Through the research and analysis of domestic and foreign acoustic emission technology literature, summarize the single-point leakage and multi-point leakage of the pipeline, and the reasons for the low positioning accuracy, especially the multi-point leakage location and the factors affecting the positioning; The characteristics of pipeline acoustic emission propagation and existing pipeline acoustic emission leakage detection methods; study the principle of modal acoustic emission detection technology, and provide a theoretical basis for the speed determination of pipeline leakage acoustic emission signals.

(2) The basic principle of Variational Mode Decomposition (VMD) is studied. Combined with the Relative entropy analysis method, a pipeline leakage signal extraction method based on VMD and Relative entropy is proposed. The VMD is used to identify and decompose leakage. Signal and non-leakage signals are applied to the adaptive selection method of Relative entropy analysis to obtain the best observation signal. The effectiveness of the method is proved by signal simulation.

(3) Establish a single point leakage and multi-point leakage location model for pipelines. In the pipeline single point leakage location model, the pipeline Modal Acoustic Emission theory and the generalized S-transform mutual time-frequency analysis are used to obtain the accurate signal sound velocity and delay, and the obtained positioning average error is 2.31 %,and the minimum relative positioning error of the pipeline leakage is 0.69 %. In the multi-point leak location model of pipeline, in order to separate the multi-source leakage signal of the pipeline, the singular value decomposition is introduced to estimate the source number of the multi-source signal. On this basis, the blind source separation technique is used to separate the multi-source leakage signal. And using the direct mutual time-frequency analysis method. The average relative positioning error is 2.97 %, and minimum relative positioning error is 1.00 %.

(4) In order to verify the effectiveness of the method, the method in the paper is compared with other methods. In the single point leakage location, the average positioning error is 2.31 %, the average relative positioning error of the mutual time-frequency analysis method is 5.56 %, and the average relative positioning error based on the correlation coefficient analysis method is 4.79 %. In this paper, the average relative positioning error is 2.97 %, and the mutual time-frequency analysis method can’t achieve the positioning.

关键词:管道泄漏;变分模态分解;相对熵;多点泄漏;精确定位

Pipeline leakage; Variational mode decomposition; Relative entropy; Multi-point leakage; Precise positioning

上一篇:石墨烯基双金属(氢)氧化物/聚苯胺复合材料的制备及热稳定性     下一篇:基于卷积神经网络的城市燃气管道故障诊断技术研究
 
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