Study On Several Key Techniques Of The Long-distance Pipeline Security Pre-warning System

This paper mainly proposes three pre-warning systems separately using technologies of phase-sensitive distributed optic fiber, pipeline acoustics as well as Fiber Bragg Grating to prevent a third-part interference along with geo-harzards such as illegal drilling, machine excavation, geological landslide etc. and also to meet the requirement of safety operation. Additionally, further researches concentrating on the above three key technologies are analyzed and have achieved favorable pre-warning outcome.1. Based on the previous researches,a 3×3 optic coupler phase-sensitive distributed pipeline pre-warning system is put forward. Furthermore, the double Mach-Zehdner interferometers, to which five fiber cores were employed, were also analyzed theoretically. The "band - energy" feature extraction methods for detection based on wavelet packet analysis, and support vector machine are adopted in the pre-warning system to identify the threats incident effectively.2. After analyzed the transmission mechanism and the discipline of acoustic vibration in buried steel pipeline caused by third-party intrusion and researched limitations and defects of present acoustic pre-warning system, a new Pipeline Acoustic Pre-warning System has been designed, which adopted GPRS/GSM wireless communication and powered by battery. Because of the special wake-up and sleep mode and"two levels-three times"event identification method, the whole design of full-field surveillance terminal structure buried is realized. This paper has focused on research and analysis of the system hardware and software structures, low-power design concept, and"two levels-three times"event identification method. Field application has showed that the PAPS pre-warning system has high accuracy, fast response, simple operation, easy realization of the remote maintenance and can be widely used for pipeline security.3. In order to monitor the security status of pipes crossing over regions with frequent natural disasters, a new type of FBG (fiber Bragg grating) geological landslide pre-warning system that integrates four sorts of sensors, including pipe body strain sensor, pipe soil pressure sensor, surface displacement sensor and deep displacement sensor, is designed in accordance with FBG sensing principle. In addition, a terminal to collect on-site data is established by making use of sensor array mentioned above. Such data is remotely transferred to monitoring center by means of GPRS wireless module, and the monitoring center analyzes the data and gives automatic alarm of the right pre-warning class. This paper provides specific alarm thresholds gained from effective data processing and gives details about the problem of temperature compensation. The system is explosion proof, anti-electromagnetic interference, corrosion resistant, convenient and flexible. The pre-warning demonstration project monitored impact of Wenchuan Earthquake on landslide and pipes, which would serve as a guide for landslide control.After a long period of field test and use in Gangzao, Tieda, Qinjing pipelines, this system has proved stable, economical, practical and easy to configure, so it has a prosperous future. The above research was supported by National Natural Science Foundation of China (NO.60534050).