Research Based On Pipe Line Leakage Signal Extraction With Piezoelectric Sensor

Nowadays, pipeline is one of the most important tools in industrial transportations and has been playing a more important role on national economy growth.Due to the erosion of pipeline, human-intended damage, the safety of pipeline transportation is in danger. So it is most urgent and important to keep pipeline in a well working state.The techniques for pipeline leak detection are the key to protect the industrial transportations from damages. Many ideas and ways have been developed to detect pipeline leakage, while the key to leakage signal detection is leakage signal feature extraction. As the difference of pipeline size and local natural condition, pipeline leakage signal has different spectrum features, and this leakage signal feature is also affected by dynamic working condition of pipeline transportation, besides that, non-linear errors of sensors and quantization error of AD converter also introduce the difficulty to extract leakage signal features. The difficulty of leakage signal feature extraction has draw great attention of many researchers. In this paper, piezoelectric dynamic pressure based leak signal transient is chosen as research object, differences between leak signals of upstream and downstream under different operational conditions are analyzed, leakage signal enhancement using wavelet decomposition is introduced. A method of positive and negative interval divisions of dynamic pressure signal is proposed, differences of weighted signal sums, signal mean values, signal peaks of every two consecutive intervals are selected as three features of leak signal, Feasibility criteria for lengthwise and breadth wise evaluation of leak signal features are present, evaluation is done with features extracted from field data and feasibility is verified. At last, neural network based leak diagnose model with both features from upstream and downstream and its training, testing results are delivered.In addition, with the novel pipeline leakage signal extraction method introduced above, a pipeline leakage detection system based on Linux operating system is developed. The front-end of this system is programmed by Qt, a well-developed open-source graphic user interface tool. Pipeline signal is received using TCP/IP network from remote terminal unit. Powered with great SQLITE database, all the pipeline signal data can be stored easily and is convenient to use for future analysis. This pipeline leakage detection system has the following functional blocks: live signal receiving, wavelet analysis, historical signal search and database storage for pipeline signal.