Long Distance Natural Gas Pipeline Leak Detection And Location Research

As one of the five main transport industries, long pipeline delivery system and its safe operation are of great significant importance due to the serious consequences that may result from different reasons. Leaks from the pipelines can not only lead to a great deal of product losses and environment pollution, but also cause many people hurt, even to die. In recently, with some artificial destruction such as stealing natural gas and so on, leakage cases became more and more seriously. So it's very important and very necessary to find the leak and locate it on time in order to reduce the losses and keep the system operate normally.With the "West Development" project carried on. the natural gas pipeline in our country will get into another high tide. Plenty of pipelines will be launched into building and running. In order to reduce the harm caused by leakage to the least and to get to higher leak sensitivity and location accuracy, it's very necessary to research the leak detection and location technique.Seeing that the math model of natural gas pipeline is limited to the fluid character, terrain status, pipeline itself character as well as some complicated restriction, it's difficult to establish the accurate mathematic model. On the other hand, the SCADA systems have been installed in the new laid natural gas pipeline. Lots of local date can be easily obtained. At the same time, combining with the actual condition of delivery pipeline of our country and some prevalent leak detection and location methods, this paper raised a method, which is based on wavelet analysis and negative- pressure-wave to detect and locate the leakage. Jobs in the paper are as follows:As affected by gas density, pressure, specific heat and pipe material, the velocity of negative-pressure-wave improved depending on the energy conservation. At one time, taking the affection of velocity of gas flow, the location formula was modified in some degree.When locating the leaks with location formula, the iterative approach algorithm was adopted as a new method to increase the location accuracy level of system.Multi-scale decomposition and reconstruction of wavelet transform is utilized to filter the noise of negative-pressure-wave, which was brought by leakage. With the capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the break point of pressure signal. The work improved the accuracy of At in location formula, accordingly improved the location accuracy.Wavelet is a suitable tool for signal analysis. The distinct character is that the mother-wavelet is of optional. That means choosing different mother-wavelet will get different analysis result. So we studied how to choose mother-wavelet and its scale for signal singularity detection. The method is to choose a wavelet by regularities of the wavelet and the signal.Finally, a plan, which bases on SCADA system for inspection and detection of natural gas leakage, is proposed in the article.