Method and system for resisting polarization fading of natural gas pipe leakage detecting sensor group

Abstract

The invention discloses a method and system for resisting polarization fading of a natural gas pipe leakage detecting sensor group. A special modulated signal generating module and a laser form a light source, and a 2*2 coupler and a Faraday rotatormirror form a leakage sonic sensor with a Michelson structure; the sensor with the structure is arranged on a pipe body at a certain interval, adjacent sensors form a sensor group, and each sensor is connected in parallel between a transmitting optical fiber and a returning optical fiber through a light beam splitter and a light beam combiner; and two arms of each sensor are not equal in length, two Faraday rotatormirrors serve as reflecting mirrors of each sensor, the rotation angle is 45 degrees, and the polarization state change of reflecting light just counteracts the polarization state change of incident light, so that the visibility of signals of the sensors and the sensor groups is kept the highest. The phenomenon of polarization inducing signal fading of the interferometer is overcome, the sensitivity and accuracy of leakage detection are improved, the false alarm rate is reduced, and the method and the system are not easily affected by environment factors.

Description

technical field [0001] The invention relates to an anti-polarization fading method and system for a natural gas pipeline leak detection sensor group. It involves the measurement of mechanical vibration, the measurement of impact and the technical field of piping system. Background technique [0002] At present, the total length of pipelines built in the world has reached 2.5 million kilometers, which has surpassed the total mileage of railways and has become the main mode of energy transportation in the world. Oil transportation in developed countries and oil-producing regions in the Middle East has all realized pipelines. my country's pipelines have also developed rapidly in recent years, with a total length of more than 70,000 kilometers. A large energy pipeline network has initially formed across the east, west, north and south, covering the whole country, and connecting overseas. Pipeline transportation has become the deployment of strategic energy such as oil and gas. T...

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Problems solved by technology

[0012] In view of the problems of low sensitivity, high false alarm rate, and susceptibility to environmental factors in the above-mentioned types of leak detection and monitoring technologies, the present invention provides a high-sensitivity quasi-distributed leak vibration monitoring method and system based on optical fiber sensing, The use of high-sensitivity sensors makes it possible to detect in time the primary stage of leakage such as micro-leakage and seepage in the pipeline, and combined with the time-domain and frequency-domain characteristics of leakage events, effectively reduces the false alarm rate of the system caused by interference. This technical solution It overcomes the shortcomings of poor accuracy and complex installation process in the previous monitoring technology, enabling relevant maintenance personnel to take timely countermeasures to avoid causing greater safety incidents

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