Natural Gas Pipeline Leak Detection And Location Method

Because of long pipeline delivery system's safe operation and economical character and environmentalism, it has become one of the five main transport industries, which are railway, highroad, navigation and water carriage. But due to the reasons of inevitable too long using period ,erodibility and damage by persons and so on, the leaks of pipeline take place frequently, so the economic loss and environmental pollution are very serious. The real-time pipeline leak detection has become important study problem in the world. Because the methods based on hardware can not detect leak continuously, and the synthesizing capabilities of the software system based on single detection method like real-time trait> accuracy, leak sensitivity and so on, can not satisfy the need of us. With the development of SCADA and its use in pipelines in recent years, the synthesized software skills based on information disposal has been turned into the hotspot and tide of academe in the world. Based on the former work, the thesis elaborates some problems.In the first place, because the negative-pressure information including noise is collected when pipeline leaks, a method of adaptive filtering algorithm based on wavelet transform technology is presented. Through verification of white noise layer upon layer and a rule of selecting an effective threshold, the decomposing layer and each layer threshold are determined, and then the method is used to filter adaptively. In the end, emulation results demonstrate that this method not only has better filtering effect, but also can quicken response speed.In the second place, wavelet transform technology is too sensitive to negative-pressure signal singularity, and easy to produce false alarm, so the thesis brings forward to SPRT based on principle of dynamic mass balance principle. In the condition of settled false alarm and missing alarm, the stylebook is least; Aiming at the delay question of SPRT, compensation algorithm method is used, as a result, the speed of leak detection is improved and response time is shortened; When leak quantity is unknown or is estimated enough inaccurate, the thesis brings forward to a method that many SPRT are used to detect leak at one time, and the emulation result proves its probability and validity.Finally, in the negative-pressure location formula the velocity of medium in pipeline was looked as average, so the location accuracy was affected. A method is put forward to in this thesis, which is circulation iterative approach algorithm based upon uncertain state medium, the emulation result indicates that the location accuracy is better than the former method.