A kind of leak point positioning method and system of monitoring system of fiber optical sensing natural gas pipeline
Technical field
The present invention is a kind of for the accurate leak point positioning method and system of the monitoring system of fiber optical sensing natural gas pipeline of locating leaks in pipes point position, relates to the measurement of mechanical vibration, measurement and the pipe-line system technical field of impact.
Background technique
At present, the pipeline overall length of building up in the world reaches 2,500,000 kilometers, and having surpassed the railway total kilometrage becomes the main means of transportation of world energy sources, and the oil product of developed country and oil-producing area, the Middle East transports all realizes channelization.China's pipeline has also obtained very fast development in recent years, overall length is also above 70,000 kilometers, begun to take shape across thing, stretch from the north to the south, cover the whole nation, be communicated with the overseas large general layout of energy pipe network, pipeline transport becomes the major way of the allotment conveying of the strategic energy such as oil gas.
Pipeline is subjected to the reasons such as natural disaster, third party's breakage in installation owing to cross-regional wide, has caused more pipe leakage accident to occur.External pipe safety situation also allows of no optimist very much, and the natural gas line big bang occurs in U.S. San Bruno city on September 9th, 2010, and blast causes long 51 meters, wide 9 a meters hollow place on the road surface.The pipeline of about 8 meters of one segment length, 76 centimetres of diameters is exploded the Heaven, flies out about 30 meters far away, and causes large-range fire disaster, causes 4 people dead, and 3 people are missing, and at least 52 people are injured, 4 hectares of burnt areas, and tens of houses are burnt.People's safety, environmental consciousness significantly promote in recent years, are also more and more paid attention to as the pipeline transportation safety problem of high risk industries.
Only have the sound wave monitoring method comparatively effective for natural gas line leakage in the ripe technology at present, but in order to improve the real-time of leakage monitoring and the accuracy of leak source location, the layout density that must add at pipeline large sensor, increase simultaneously corresponding power supply, communications equipment, cause system cost and installation and maintenance costly.
Along with the development of sensory technique has been carried out the research of SCADA leakage monitoring system such as companies such as U.S. CSI, ATMOSI, European TER abroad, Sensornet company has also developed the leakage monitoring system based on distributed optical fiber temperature sensor, and portioned product has also been applied for patent protection at home; The units such as domestic University Of Tianjin, Tsing-Hua University, China Renmin People's Liberation Army Office Support Engineering Academy also further investigate the leakage monitoring method of pipeline.
Patent CN200410020046.6 discloses a kind of distribution type fiber-optic method for monitoring leak from oil gas pipe and monitoring device based on principle of interference.This monitoring system requires to lay side by side an optical cable at Near Pipelines along pipeline, utilizes the optical fiber in the optical cable to form a Fiber optic micro-vibration sensor.Patent CN200620119429, CN200610113044.0 are the pipeline leakage monitor based on the Sagnac fibre optic interferometer, and patent CN200610072879.6 is a kind of pipeline leakage monitor based on distributed optical fiber acoustic sensing technology and method.
" sensor and micro-system " the 7th phase of the 26th volume " based on the gas pipeline leakage detection method of distributed fiberoptic sensor " discloses a kind of gas pipeline leak detecting device and method based on distributed fiberoptic sensor, it is to have installing optical fibres sensor on the pipeline body of certain intervals, the vibration wave signal that continuous real-time monitoring is propagated along pipeline body, the vibration wave signal that gathers is carried out analysing and processing, comprise type identification and vibration source location, wherein whether type identification is for to belong to leak type by the extraction and analysis of vibration wave feature being differentiated it, the time lag that simultaneously propagates into adjacent several optical fiber transducers according to vibration wave determines that in conjunction with the velocity of propagation of vibration wave on pipeline body the position at vibration wave source place, the light intensity signal of sensor output realize position definite of leakage point after photoelectric conversion.
CN1837674A discloses a kind of pipeline leakage testing device and method based on distributed optical fiber acoustic sensing technology.
US2006/0225507A1 discloses a kind of pipeline leakage testing device and method based on distributed fiberoptic sensor.
Above-mentioned technology all belongs to the distributed optical fiber sensing monitoring method.But such technical monitoring is subject to the impact of the interference incident that pipeline occurs when leaking, have very high system's false alarm rate, and antijamming capability is relatively poor.
Summary of the invention
The objective of the invention is to invent a kind of high sensitivity based on Fibre Optical Sensor quasi-distributed highly sensitive, false alarm rate is low, the leak point positioning method and system of the monitoring system of fiber optical sensing natural gas pipeline of accurate positioning.
In view of above-mentioned a few class Leak testtion, the sensitivity that monitoring technology exists is low, false alarm rate is high, be subject to the problems such as such environmental effects, the present invention provides the quasi-distributed incident of leakage monitoring and positioning method of a kind of high sensitivity based on Fibre Optical Sensor and system, adopt high sensor so that can little leakage occur when pipeline, the leakages such as seepage were in time monitored during the primary stage, and accurately calculate the position that incident of leakage occurs in conjunction with the time lag that the incident of leakage signal propagates into adjacent several sensors, this technological scheme has overcome poor accuracy in the monitoring technology before this and the deficiency of mounting process complexity, accurate positioning.
Optical fiber in the common communications optical cable of utilization and oil and gas pipes laying in one ditch is as emission and passback optical fiber, the pipe leakage optical fiber transducer is connected between emission and the passback optical fiber by Optical multiplexing technology is parallel with one another, form light circuit, the pipe leakage optical fiber transducer is laid on the pipeline, and formation can be monitored the optical fiber sensing system of pipe leakage vibrations.Utilize light source to each pipe leakage optical fiber transducer scanning, photoelectric conversion signal demodulation, the extraction of distribution situation to gathering according to the pipe leakage optical fiber transducer, the vibration information of realizing each pipe leakage optical fiber transducer obtains, detect analysis conduit leak optical fiber sensor signal and judged whether that the pipe leakage event occurs, detect the delay inequality realization of signal to the location of leakage point according to adjacent pipe leakage optical fiber transducer.
The optical fiber leak detecting device that is applicable to natural gas line that the signal remote transmission that utilization and pipeline are realized optical fibre vibration sensor with optical fiber and the Optical multiplexing technology of ditch laying is developed, solved the difficult problem of electric transducer power supply and telecommunication, laying optical fiber vibration transducer comparatively thick and fast improves the Location accuracy of leakage point.Sensor is the key that realizes line leakage, and when pipeline occurs to leak, leaking the vibration wave that excites will propagate to the leakage point both sides along pipeline.A sensor is installed on pipeline body at a certain distance, is used for monitoring the leakage vibration wave on the pipeline.Sensor adopts the fibre optic interferometer structure, can be optical fiber Michelson interferometer or fiber Mach-Zehnder interferometer as leaking the vibration wave detecting sensor, can be by increasing the mode of sensor fibre length, increase leaking the induction sensitivity of vibration, the light intensity signal of interferometer output can be write as after photoelectric conversion:
V
0∝1+Vcos(φ
s+φ
n+φ
0)+V
n(1)
Wherein, V
0Be the voltage signal of output, V is the visibility of interferometer, V
nThe circuit additional noise, φ
sServe as reasons and leak the phase difference signal that vibration wave causes, be the leakage vibration wave signal that to survey, φ
0Being the initial phase of interferometer, is a constant, φ
nBeing the low frequency wonder of phase difference, is a Uncertainty, changes with temperature and external environment impact.Can realize leaking the vibration wave signal psi by the demultiplexing technology that is complementary with the modulation of source mode
sObtain, and to this signal psi
sThe time lag that arrives corresponding sensor estimates, realized that along the speed v of pipe transmmision to the vibration wave source be determining of leakage point position in conjunction with vibration wave.
When leak occuring, leak and excite pipeline to produce vibration wave, along pipe transmmision, wherein two adjacent sensors are spaced apart setting value L to vibration wave with speed V, and establishing the time that signal is transmitted to sensor n is t
n, the time that is transmitted to sensor n+1 is t
N+1, the time that signal is transmitted to sensor n-1 is t
N-1, the time that is transmitted to sensor n+2 is t
N+2, have following formula to set up:
(2)
Unknown parameter (t wherein
N+1-t
n), (t
N-1-t
N+1), (t
N+2-t
n) and (t
N+2-t
N-1) be respectively to leak the delay inequality that vibration wave arrives sensor n and n-1, sensor n+1 and n-1, sensor n and n+2, sensor n-1 and n+2, can carry out correlation analysis by the signal that the several sensors of correspondence are received obtains, so just formed four detections to same unknown quantity event occurrence positions X, measured value is respectively X
1, X
2, X
3, X
4, these four measured values are got assembly average, namely obtain final measured value X.It is poor that a plurality of sensors of combined continuous receive signal time, compares the time difference measurements mode that only adopts two sensors and have more accurately locating effect.
System of the present invention consists of sees Fig. 1 and Fig. 2, and it includes light source, transmission light path part, optical fiber transducer, photodetector, signals collecting and puocessing module; An optical fiber transducer is installed on pipeline body at a certain distance, a plurality of optical fiber transducers consist of an optical fiber transducer group, each sensor is connected to light source and photodetector by the transmission light path, and photodetector output is connected in series signal condition unit, signal gathering unit and the processing unit in signals collecting and the puocessing module successively; Processing unit output has video terminal and external interface; Signals collecting and puocessing module output connect microcomputer by external interface;
The signal of collecting unit collection is carried out demultiplexing to processing unit and demodulation obtains original vibration wave signal, then carries out respectively the identification of leakage signal and the location of leakage point in recognition circuit and positioning circuit.
An optical fiber transducer is installed on pipeline body at a certain distance, and each optical fiber transducer is connected with the transmission light path by the light path ABAP Adapter, and the transmission light path connects light source and photodetector; Photodetector output connects signals collecting and the puocessing module that comprises leakage signal identification and state event location function, and signals collecting and puocessing module output connect microcomputer.Through the processing of signals collecting and puocessing module, realized demultiplexing and the demodulation of each sensor signal obtaining original leakage vibration wave signal based on the sensor of frequency division multiplexing mode.
Described sensor adopts the fibre optic interferometer structure, can be the form of optical fiber Michelson interferometer or fiber Mach-Zehnder interferometer;
The formation of described signals collecting and puocessing module is seen Fig. 3, and it comprises signal condition unit, signal gathering unit, processing unit, video terminal and external interface, and processing unit comprises recognition circuit and positioning circuit; The signal of photodetector output is connected in series signal condition unit, signal gathering unit and processing unit successively, the signal of collecting unit collection is carried out demultiplexing to processing unit and demodulation obtains original vibration wave signal, then in recognition circuit and positioning circuit, carry out respectively leakage signal identification and the location of leakage point; Processing unit output has video terminal and external interface;
Wherein the conditioning unit circuit as shown in Figure 4, it mainly is comprised of operational amplifier U14, photoelectric diode U15; 1,5,8 ends of U15 are unsettled, 3,4 end ground connection, and 2 ends connect 6 ends after resistance R 39, capacitor C 60 the two parallel connection, and 6 ends connect 3 ends of U14,8 ends of 7 termination U14 through resistance R 43; The 4 end ground connection of U14,5 ends are unsettled, and 6,7 ends meet AD_VINI altogether, and 1 termination AD_OUT mouth, 2 ends be through resistance R 42 ground connection, the two parallel connection of connecting resistance R40 between 1,2 ends, capacitor C 59;
Recognition circuit in the processing unit as shown in Figure 5, it mainly is comprised of DSP digital signal processor U1B and peripheral circuit, the NC1-NC15 pin of U1B is unsettled; AVDD, AGND are the analog power input, and AVDD connects the 1.3V power supply by magnetic bead FER1, and 3 capacitor C 22, C23, C24 in parallel carry out decoupling filtering between AVDD and AGND; DAI 1, DAI 3, DAI 4 are connected with DR0PRI, RSCLK0, the RFS0 of positioning circuit DSP digital signal processor U10 respectively and are used for data transfer; DAI9-DAI20 is expansion interface; DPI9, DPI10 connect external interface circuit;
Positioning circuit in the processing unit as shown in Figure 6, it mainly is comprised of DSP digital signal processor U10 and peripheral circuit and interface, the DR0PRI of U10, RSCLK0, RFS0 are connected with DAI1, DAI3, the DAI4 of recognition circuit DSP digital signal processor U1B respectively and are used for receive data, RX, TX, MOSI, MISO, SCK connect the video terminal interface, and TCK, TDO, TDI, TMS, TRST#, EMU# are debugging interface.
The present invention is with the optical fiber transducer that need not the to power pick device as leakage signal, utilize the signal remote transmission that realizes optical fiber transducer with optical fiber and the Optical multiplexing technology of ditch laying with pipeline, solved the difficult problem of electric transducer power supply and telecommunication, laying optical fiber sensor comparatively thick and fast, multisensor are united and are carried out time delay and estimate to improve Location accuracy to leakage point; The sensitivity of optical fiber transducer is the several times of traditional sonic transducer in addition, can significantly improve the degree of accuracy that the natural gas line minute leakage is detected and locates.
Description of drawings
Fig. 1 monitoring system of fiber optical sensing natural gas pipeline schematic diagram of device
Fig. 2 Fibre Optical Sensor gas pipeline leakage positioning principle figure
Fig. 3 signals collecting and puocessing module theory diagram
Signal condition element circuit figure in Fig. 4 signals collecting and the puocessing module
Signal processing unit recognition circuit figure in Fig. 5 signals collecting and the puocessing module
Signal processing unit positioning circuit figure in Fig. 6 signals collecting and the puocessing module
Embodiment
In conjunction with the accompanying drawings and embodiments the present invention is further specified, but should not limit protection scope of the present invention with this.
Embodiment. the formation of this example is that an optical fiber transducer is installed on pipeline body at a certain distance as shown in Figure 1, and each optical fiber transducer is connected with the transmission light path by the light path ABAP Adapter, and the transmission light path connects light source and photodetector; Photodetector output connects signals collecting and the puocessing module that comprises leakage signal identification and state event location function, and signals collecting and puocessing module output connect microcomputer by external interface.Through the processing of signals collecting and puocessing module, realized demultiplexing and the demodulation of each sensor signal obtaining original leakage vibration wave signal based on the sensor of frequency division multiplexing mode.
Described sensor adopts the fibre optic interferometer structure, can be the form of optical fiber Michelson interferometer or fiber Mach-Zehnder interferometer;
The formation of described signals collecting and puocessing module is seen Fig. 3, and it comprises that signal condition unit, signal gathering unit, processing unit, terminal show and external interface that processing unit comprises recognition circuit and positioning circuit; The signal of photodetector output is connected in series signal condition unit, signal gathering unit and processing unit successively, the signal of collecting unit collection is carried out demultiplexing to processing unit and demodulation obtains original vibration wave signal, then in recognition circuit and positioning circuit, carry out respectively leakage signal identification and the location of leakage point; Processing unit output has video terminal and external interface;
Wherein the conditioning unit circuit as shown in Figure 4, it mainly is comprised of operational amplifier U14, photoelectric diode U15; 1,5,8 ends of U15 are unsettled, 3,4 end ground connection, and 2 ends connect 6 ends after resistance R 39, capacitor C 60 the two parallel connection, and 6 ends connect 3 ends of U14,8 ends of 7 termination U14 through resistance R 43; The 4 end ground connection of U14,5 ends are unsettled, and 6,7 ends meet AD_VINI altogether, and 1 termination AD_OUT mouth, 2 ends be through resistance R 42 ground connection, the two parallel connection of connecting resistance R40 between 1,2 ends, capacitor C 59.
Recognition circuit in the processing unit as shown in Figure 5, it mainly is comprised of DSP digital signal processor U1B and peripheral circuit, the NC1-NC15 pin of U1B is unsettled; AVDD, AGND are the analog power input, and AVDD connects the 1.3V power supply by magnetic bead FER1, and 3 capacitor C 22, C23, C24 in parallel carry out decoupling filtering between AVDD and AGND; DAI1, DAI3, DAI4 are connected with DR0PRI, RSCLK0, the RFS0 of positioning circuit DSP digital signal processor U10 respectively and are used for data transfer; DAI9-DAI20 is expansion interface; DPI9, DPI10 connect external interface circuit;
Positioning circuit in the processing unit as shown in Figure 6, it mainly is comprised of DSP digital signal processor U10 and peripheral circuit and interface, the DR0PRI of U10, RSCLK0, RFS0 are connected with DAI1, DAI3, the DAI4 of recognition circuit DSP digital signal processor U1B respectively and are used for receive data, RX, TX, MOSI, MISO, SCK connect the video terminal interface, and TCK, TDO, TDI, TMS, TRST#, EMU# are debugging interface.
Components and parts model and numerical value in conditioning unit, recognition circuit, the positioning circuit are seen Fig. 4-6.
Light source adopts the 100kHZ narrow cable and wide optical fiber laser, laser output connects the transmission light path, each sensor is connected with the transmission light path by the beam splitting apparatus that closes in the light path ABAP Adapter on the pipeline, the beam splitting apparatus splitting ratio that closes of distal-most end is 1: 1, other close the beam splitting apparatus splitting ratio draw near be followed successively by 2: 1,3: 1,4: 1 ..., 9: 1, wherein respectively close the beam splitting apparatus ratio and be 1 output/input and be connected with sensor, the output/input end that closes another ratio of beam splitting apparatus is connected with the beam splitting apparatus that closes of back by the transmission light path; Sensor adopts the Mach-Zehnder interferometer structure, arm length difference be respectively 5m, 10m, 15m ..., 50m, long arm of each sensor is wound on the elastomer of rubber material, elastomer is close to tube wall and is fixed;
A plurality of sensors are being set along duct orientation, when the pipeline between sensor n and the sensor n+1 occurs to leak, leaking the vibration wave that causes is picked up by sensor n-1, n, n+1 and n+2 respectively through the regular hour along pipe transmmision, detection is leaked the delay inequality of oscillating signal according to the sensor of leakage point both sides, namely obtain four delay inequalities by the signal analysis to sensor n-1 and n+1, n and n+1, n and n+2, n-1 and four pairs of sensors of n+2, and then calculate 4 leak position measured value X
1, X
2, X
3, X
4, these 4 measured values are got assembly average can obtain accurately leakage point position X.
This example is through test of many times, by being installed at tube wall, can realize the monitoring along the pipe natural gas leakage by leakage vibration sensing interferometric sensor, through realizing the incident of leakage warning to signal analysis and processing and providing the leakage point position, system sensitivity is high, shakes system's false alarm rate that interference causes along the line by the intelligent recognition of leaking having been reduced largely pipeline.