Natural Gas Pipeline Leak Detection Based On Adaptive Frequency Analysis

Pipeline leak detection technology is an important method to ensure the safety of pipeline. Since the 21 st Century, put forward some new requirements to ensure the production safety of pipeline, such as improve the positioning accuracy, detect small leakage and reduce false alarm rate, etc. But the infrasound generated by pipeline leak is a kind of non-stationary signal, it’s propagation in pipes will suffer serious interfe- reence by the external environment, resulting in high rate of false judged about pipeline leakage and the positioning is not accurate. Adaptive time-frequency analysis(TFA) is the important way to analyze the non-stationary signal, and it can achieve the time- frequency process of acoustic signals in pipeline and extract time-frequency characteristics, improve the pipeline leakage detection and leak point positioning precision, and combine with LabVIEW and MATLAB, constituted an natural gas pipeline leak detection system. The main work of this paper is as follows:1. Study several basic theories of TFA and compare the advantages and disadvantages of those theories. The results show that the AOK with high time and frequency resolution and time-frequency concentration, and it can effectively inhibit the cross-term-interference signal, so it is an ideal method for signal analysis of natural gas pipeline leakage.2. The propagation of infrasound in gas pipeline, infrasound pipeline leak detection and leak point positioning was studied in this paper. Finally, using AOK to handle the infrasound of natural gas pipeline leakage, then compared the processed result with several other time-frequency analysis algorithm, the compared results showed that AOK can accurately judge the infrasound of pipeline leakage, and can extract accurately leakage time, it has a great advantage on the pipeline leakage judgment and leak point positioning precision.3. According to the requirements of the work scene, design the natural gas pipeline leak detection system that include subordinate computer acquisition system, upper computer monitoring system and data transmission system with LabVIEW. The design of subordinate computer system include pipeline acoustic signal acquisition, data processing and feature extraction of the infrasound, time setting module. the design of data transmission system include two different kind of data transmission and reception module. Upper computer monitoring system mainly includes the design of pipeline leakage judgment, leak point positioning and warning, data display, storage and query, permissions management of the pipeline leak detection system.4. In the laboratory environment and actual operating environment to test the natural gas pipeline leak detection system. The test results show that, the system can achieve small leakage of natural gas pipeline detection and location, the positioning accuracy meet the actual requirements of the work scene.