Natural Gas Pipeline Leak Automatic Detection And Location Method

Transport The Natural Gas From The West To The East" is one of the four symbolic projects in "West Development". Along with this project is being carried on, the number of laid natural gas pipeline will be increased. Besides normal corrosion, now gas pipeline leakage is often made by human destruction such as stealing gas and so on, which makes pipeline leakage more and more frequently. Therefore, the leak of those pipelines will cause many people hurt, large area pollution and huge national fortune damaged. To reduce the loss, and lighten danger of accident, we need detect and locate the leakage point immediately. So, the detection and location of leakage have received the high concern in the academia. The accuracy and the instant of pipeline leakage detection and location have been the focus in this field.Seeing that the math model of natural gas is limited to model of pipeline fluid characteristic, terrain state, and pipeline characteristic and a great deal of complicated restriction of oneself, it is difficult to establish the accurate mathematics model. However, the SCADA systems are installed in these new laid nature gas pipelines, so we have lots of data. This paper combines with pipeline delivery of our country's actual conditions and other methods of detection and location. To the leakage characteristic of the fault to the long-distance natural gas pipeline, a method is raised, which is on the basis of wavelet and negative-pressure-wave to detect the leakage and locate. Jobs in this paper are as follows:Multi-resolution decomposition and reconstruction of wavelet transform is utilized to filter the noises, which the leakage brings the noises of negative-pressure-wave. The research is worked in the wavelet and wavelet packet filter. The wavelet transform have a fast and accurate recognition capability to signal singularity. This paper chooses wavelet technology to catch the break point of pressure signal. Accordingly, whether or not the leakage happened.If the leakage happened, the paper utilizes the locating principle ofnegative-pressure-wave to calculate the leakage position. That is X = Therefore, the accuracy of location is decided by the accuracy of velocity v and time difference Δt. Time difference (Δt) is gotten by wavelet technology to catch the pressure signal. The spread velocity of negative-pressure-wave was revised, and replaced the sound speed in the old formula. Considering the sound wave is influenced by the velocity of natural gas, the velocity of fluid in the pipeline was defined in this paper, by which the position of negative-pressure-wave formula was revised. It can improve the accuracy and dependability of location.Furthermore, it is proved by simulation experiments that the accuracy of Δt is increased through utilizing the wavelet packet to filter the noise, and the break point of negative-pressure-wave is identified by wavelet. Moreover, the accuracy of v is raised because of revised position formula and the revised velocity of negative-pressure-wave. So, the conclusion can be drew, that the precision of leakage location is improved greatly. At the same time, it is showed by simulation experiments that the theory is correct.Finally, a plan, which bases on SCADA system for inspection and detection ofnature gas leakage, is proposed in this article.