Study On The Distributed Optical Fiber Pipeline Safe Detection Technology

Aiming at solving problems existed in present oil and natural gas pipeline detection technology and exploring safe pipeline detection technology which is independent of parameter variation of transmitted fluid, a new distributed optical fiber pipeline safe detection technology based on Mach-Zehnder optical fiber interferometer is brought forward in this dissertation. Main focus of the research is to develop a set of distributed optical fiber pipeline safe detection system based on phase adjustment optical sensing mechanism. The system should have high detection sensitivity, position precision and simple structure to fulfill safe pipeline detection requirements. The study is funded by National Nature and Science Foundation (NNSF)—"Study on new method and key technology of fluid-filled pipeline network leakage detection"(Important Item, Funded Number: 60534050).A new and safe pipeline detection method based on distributed optical fiber is put forward in this dissertation and distributed optical fiber sensor based on principle of optical interferometer was designed. Factors that may affect detection sensitivity of optical fiber sensor were analyzed and a simple, practical scheme which can be used to restrain negative influence of temperature variation on detection sensitivity is brought forward. High resolution sensing optical cable structure is designed taking consideration of influence of various coating on detection sensitivity of the detection system.Working principle of each component in the detection system is studied in detail in this dissertation. On the basis of that, a distributed optical fiber pipeline safe detection system is developed. A set of distributed optical fiber detection software system based on virtual instrument technology is programmed for the pipeline safe detection system. Signal acquisition, storage, process and other relative calculating functions can all be fulfilled by the software.Principle and method of wavelet threshold noise reduction is analyzed in this dissertation. Wavelet soft threshold noise reduction method is adopted to process signals acquired on site, and denoising result is excellent. Thus, detection sensitivity of the system is increased effectively."Frequency band - energy"eigenvector extraction method based on wavelet package is brought forward and used in characteristics extraction in the distributed...