CN102997059B - Method and system for measuring propagation speed of natural gas pipe leakage vibration wave - Google Patents

Method and system for measuring propagation speed of natural gas pipe leakage vibration wave Download PDF

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CN102997059B
CN102997059B CN201110272474.8A CN201110272474A CN102997059B CN 102997059 B CN102997059 B CN 102997059B CN 201110272474 A CN201110272474 A CN 201110272474A CN 102997059 B CN102997059 B CN 102997059B
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light path
resistance
sensor
signal
fibre
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CN201110272474.8A
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CN102997059A (en
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张金权
王小军
李�东
焦书浩
王飞
刘素杰
赵锋
郭戈
杨文明
李维
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中国石油天然气集团公司
中国石油天然气管道局
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Abstract

The invention discloses a method and system for measuring propagation speed of natural gas pipe leakage vibration wave. The method and the system are on the basis of an optical fiber sensed natural gas pipe leakage monitoring method. A natural gas pipe leakage monitoring system selects a known sensing unit point to simulate pipe leakage in the form of hitting a pipe to initiate vibration; according to the number of pipe sections used in project construction and inspection and acceptance data, leakage signals transmitted to two adjacent sensing units are subjected to time-delay estimation; leakage vibration wave speed is measured by combining known pipe length; the distances from the current test point to two adjacent sensing unit points are accurately obtained; a simulating test point X is substituted into the formula that X is equal to L-[v*(tn+2-tn)]/2 to inversely solute the formula that v is equal to 2(L-X)/(tn+2-tn); and the propagation speed of vibration wave along the pipe is measured according to the distance between known sensing units and detected signal transmitting time. The method and the system are high in sensitivity and accuracy, and low in false alarm rate and are not easily affected by environmental factors.

Description

A kind of measuring vibration wave propagation velocity in case of natural gas pipeline leakage method and system
Technical field
The present invention is a kind of measuring vibration wave propagation velocity in case of natural gas pipeline leakage method and system, relates to the measurement of mechanical vibration, measurement and the piping system technical field of impact.
Background technology
At present, the pipeline overall length of building up in the world reaches 2,500,000 kilometers, and having exceeded 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 also exceedes 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 transportation becomes the major way of the allotment conveying of the strategic energy such as oil gas.
Pipeline, due to cross-regional wide, is subject to the reason such as disaster, third party's breakage in installation, has caused more pipe leakage accident to occur.External pipe safety situation also allows of no optimist very much, and natural gas line big bang occurs San Bruno city on September 9th, 2010 of the U.S., and blast causes long 51 meters a, hollow place of wide 9 meters on road surface.The pipeline of approximately 8 meters of one segment lengths, 76 centimetres of diameters is exploded heaven, flies out about 30 meters far away, and causes large-range fire disaster, causes 4 people's death, 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.
In proven technique, only have sound wave monitoring method comparatively effective for natural gas line leakage at present, but in order to improve the accuracy of real-time to leakage monitoring and leak source location, must on pipeline, add the layout density of large sensor, increase corresponding power supply, communication facilities simultaneously, cause system cost and installation and maintenance costly.
Along with the development of sensing technology is external as the companies such as U.S. CSI, ATMOSI, European TER have carried out the research of SCADA leakage monitoring system, 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 Fiber optic micro-vibration sensor of optical fiber composition in optical cable.Patent CN200620119429, CN200610113044.0 are the pipeline leakage monitor based on Sagnac fibre optic interferometer, and patent CN200610072879.6 is a kind of pipeline leakage monitor and method based on distributed optical fiber acoustic sensing technology.
" sensor and micro-system " the 26th the 7th phase of volume " the gas pipe line leakage detection method based on distributed fiberoptic sensor " discloses a kind of gas pipe line leak detecting device and method based on distributed fiberoptic sensor, it is installing optical fibres sensor on the pipeline body with certain intervals, the vibration wave signal that continuous real-time monitoring is propagated along pipeline body, the vibration wave signal gathering is carried out to analyzing and processing, comprise type identification and vibration source location, wherein type identification is whether to belong to leak type by the extraction and analysis of vibration wave feature is differentiated to it, propagate into the position at the time delay definite vibration of the velocity of propagation on pipeline body wave source place in conjunction with vibration wave of adjacent several Fibre Optical Sensors according to vibration wave simultaneously, the light intensity signal of sensor output is realized the determining of position of leakage point after opto-electronic 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 distributed optical fiber sensing monitoring method.But such technical monitoring is subject to the impact of the interference incident that pipeline occurs while leakage, have very high system false alarm rate, and antijamming capability is poor.And be equally also to there is very high system false alarm rate as the pipe leakage vibration wave velocity of propagation assay method in distributed optical fiber sensing monitoring method, antijamming capability is poor.
Summary of the invention
The object of the invention is to invent the measuring vibration wave propagation velocity in case of natural gas pipeline leakage method and system of the quasi-distributed leakage vibration monitor system of a kind of high sensitivity based on Fibre Optical Sensor.
In view of the sensitivity that above-mentioned a few class Leak Detection, monitoring technology exist is low, false alarm rate is high, be subject to the problems such as such environmental effects, the present invention is the natural gas line leakage system of using based on quasi-distributed optical fiber interference sensing technology, adopt high sensor time domain, frequency domain character in conjunction with incident of leakage, measure leaking vibration wave velocity of propagation.
This measuring vibration wave propagation velocity in case of natural gas pipeline leakage method: be to be based upon on the basis of natural gas line leakage method of Fibre Optical Sensor; Use natural gas line leakage system, select some known sensor points to cause vibration by knocking the form simulation pipe leakages such as pipeline, according to the quantity of the duct section using in engineering construction and examination data, carry out time delay estimation and realize the mensuration to leaking vibration wave speed in conjunction with known duct length propagating into the leakage signal of two adjacent sensors, accurately provide the distance of two adjacent sensor points of current test point distance, by this simulation test point position X substitution: X=L-[v × (t n+2-t n)]/2, counter solving: v=2 (L-X)/(t n+2-t n), realize according to the signal propagation time of known sensor spacing distance and mensuration and measure the speed of vibration wave along pipe transmmision.In formula, L is two distances between adjacent sensor points; X is the distance apart from first sensor points (apart from starting point), and v leaks vibration velocity of wave propagation.
Utilize with the common communications optical fibre in optical cable of oil and gas pipes laying in one ditch respectively as sending and receiving Transmission Fibers, pipeline is revealed to Fibre Optical Sensor to be connected between transmitting-receiving Transmission Fibers by Optical multiplexing technology is parallel with one another, form light circuit, pipeline is revealed Fibre Optical Sensor, and to be evenly laid in pipeline along the line, the optical fiber sensing system that formation can monitoring pipe road acoustic vibration.Utilize light source to reveal Fibre Optical Sensor scanning to each pipeline, reveal the distribution situation of Fibre Optical Sensor according to pipeline to the photoelectric conversion signal demodulation, the extraction that gather, the vibration information of realizing each pipeline leakage Fibre Optical Sensor obtains, detect analysis conduit and reveal Fibre Optical Sensor signal and judged whether that pipeline leakage event occurs, reveal Fibre Optical Sensor according to adjacent pipeline and detect that the time delay of arrival of signal realizes the mensuration of pipe leakage vibration wave velocity of propagation.
This system for measuring vibration wave propagation velocity in case of natural gas pipeline leakage is to melt in the natural gas line leakage system based on Fibre Optical Sensor.So this system for measuring vibration wave propagation velocity in case of natural gas pipeline leakage is exactly the natural gas line leakage system based on Fibre Optical Sensor.
The formation of the natural gas line leakage system based on Fibre Optical Sensor is shown in Fig. 1, and it comprises light path system and circuit two parts; A Fibre Optical Sensor is installed at a certain distance on pipeline body, multiple Fibre Optical Sensors form a Fibre Optical Sensor group, each Fibre Optical Sensor group connects light source and the photodetector to receiving end after a beam splitter being serially connected in optical fiber with an optical fiber, photodetector output connects the signals collecting and the processing module that comprise leakage signal identification and state event location function, and described signals collecting and processing module comprise that signal conditioner, signal picker, processing unit, terminal show and external interface; The signal conditioner output that connects photodetector output is connected in series signal picker and processing unit successively, and processing unit output has terminal to show and external interface.Signals collecting and processing module output connect microcomputer.Through the processing of signals collecting and processing module, the sensor group signal mixing based on frequency division multiplexing mode has been realized the demultiplexing of each sensor in sensor group, obtains original leakage vibration wave signal.
Send laser by light source, realize after beam splitting through transmission light path, part light is transferred to the Fibre Optical Sensor group being arranged on duct wall, Fibre Optical Sensor group is picked up after the leakage vibration signal and noise of pipe transmmision, again be transmitted back to the photodetector of system through transmission light path, carry out leakage signal demodulation and discriminance analysis by signals collecting and processing module, and leakage signal is carried out to time delay and estimate to realize the location to leakage point.
The light path system (seeing Fig. 4) of this natural gas line leakage system is mainly to design based on frequency division multiplexing principle, is made up of light path adapter, transmission cable and Fibre Optical Sensor three parts; Light path adapter is made up of beam splitter and combiner device; Fibre Optical Sensor adopts Mach-Zehnder interferometer or Michelson interferometer; Each Fibre Optical Sensor connects a light path adapter by two optical fiber, and all light path adapters are connected in series successively, by apart from the nearest light path adapter welding system main frame of receiving end.
After entering sensor group, input optical fibre in the exploring laser light input transmission cable that laser instrument sends arrives first light path adapter, be divided into two bundle laser by the beam splitter of this light path adapter: a branch ofly enter first Fibre Optical Sensor through input optical fibre, another light beam passes to next light path adapter through time delay optical fiber, be divided into two bundle laser by the beam splitter in next light path adapter again, a branch ofly enter second Fibre Optical Sensor, another Shu Zaijing Transmission Fibers is transferred to next light path adapter, by that analogy, until laser arrives last Fibre Optical Sensor, every 2-10 adjacent Fibre Optical Sensor is divided into one group, and in group, the interference signal of each Fibre Optical Sensor, by combiner device access passback optical fiber, transfers back to system receiving terminal, at last Fibre Optical Sensor of sensor group, laser no longer, by light path adapter, directly enters Fibre Optical Sensor, and light signal after each Fibre Optical Sensor, by the combiner device in corresponding light path adapter separately, closes bundle with passing the light signal of coming below, finally reach the photoelectric conversion module of monitoring system through output optical fibre.
Wherein, the set of light path adapter beam splitter and combiner device; What input optical fibre used from output optical fibre is two different fibre cores in same transmission cable; Transmission cable is together in series all light path adapters; The length of the launching fiber on pipeline between adjacent two sensors and passback optical fiber is all greater than 1/2 of laser instrument coherent length, to prevent that signal cross-talk occurs between sensor.
Specifically linking as shown in Figure 5 between each optical device in described light path system, it is made up of light path adapter, transmission cable and Fibre Optical Sensor three parts; Light path adapter is made up of beam splitter and combiner device; Fibre Optical Sensor adopts Mach-Zehnder interferometer or Michelson interferometer; The leak detection light that light source sends enters the beam splitter I1 in light path adapter through Transmission Fibers I5, it is 24: 1 that this beam splitter I1 adopts splitting ratio, the output light that wherein ratio is 24 continues to propagate along time delay optical fiber 4, until light path adapter 2, and the output light that export ratio is 1 enters first sensor 2 through connecting optical fiber, sensor 2 adopts Mach-Zehnder interferometer structure, poor at 20m in order to ensure that sensor has certain sensitivity control interferometer arm, this interferometer is wound on the elastic body of elastomeric material, elastic body is close to duct wall, adopts protective cover to fix; Distance Accurate Measurement between each sensor, controls light source according to the light travel-time and exports; Beam splitter 1 in light path adapter 2 adopts the splitting ratio of 23: 1, the output light that wherein ratio is 23 continues to propagate until run into next light path adapter along input optical fibre, and the output light that export ratio is 1 enters second sensor 2 through connecting optical fiber, it is poor at 20m that this sensor adopts equally Mach-Zehnder interferometer structure and controls interferometer arm, be wound on the elastic body of elastomeric material, elastic body is close to duct wall and is fixed; In the time that the pipeline between first and second sensor 2 occurs to leak, leaking the vibration wave causing is picked up by two sensors respectively through the regular hour along pipe transmmision, import system photoelectric conversion module into by Transmission Fibers 5, the location that final system receives the mistiming of leakage signal and can realize leakage point in conjunction with vibration wave in ducted velocity of propagation according to sensor;
First the light signal being returned by monitoring light path enters in the photodetector of system, carry out opto-electronic conversion, entering signal acquisition processing module is processed afterwards, its process is: first carry out signal condition through modulate circuit, then gather through AD collector, then send into signal processing unit and carry out signal filtering and demodulation process, obtain original leakage vibration wave signal, finally leakage signal is carried out to signal identification and positioning analysis, and analysis result is shown in to terminal, signal acquisition process module principle is as shown in Figure 6;
Described light source is a kind of special light source system that is applicable to multiplexing and modulation /demodulation that comprises, forms (seeing Fig. 2) by the adjustable laser instrument of optical frequency and dedicated modulation signal generating module; Laser instrument output connects the D/A follower in modulation signal generation module, and D/A follower connects signal generator, and signal generator has frequency adjustment, amplitude adjusted and the sawtooth wave/selection of falling sawtooth wave input; Can select as sawtooth wave or the signal type of falling saw wave modulator by programming, adjust signalization amplitude and frequency; Modulation signal acts on laser instrument, and the laser that output optical frequency changes with modulation signal synchronous waveform, is input in sensing light path, realizes multiplexing, the signal carrier that forms multiple sensors of sensor;
Wherein laser instrument adopts the semiconductor laser that optical frequency can be modulated, and modulation signal acts on laser instrument Injection Current, realizes the modulation of optical frequency; Laser optical power 1-17mW, it is poor that laser instrument coherent length is greater than all the sensors interferometer brachium, but be less than the delay fiber lengths sum on launching fiber between adjacent two interferometers and passback optical fiber, can meet the requirement that postpones optical fiber between poor and adjacent two the sensor interferometer instrument of sensor interferometer instrument arm;
Wherein modulation signal generation module adopts digital form to realize, calculate according to wave mode, signal amplitude, frequency parameter the modulation signal segment that obtains one-period by digital form, then export by digital-to-analog conversion (D/A) mode, the modulated-analog signal of output is connected on laser instrument, wherein can select as sawtooth wave or the signal type of falling saw wave modulator capable of regulating signalization amplitude, direct current biasing and frequency by parameter configuration; Sawtooth wave or the be to the maximum ± 5V of the requirement of falling sawtooth signal amplitude of the output of modulation signal generation module, frequency is 200KHz to the maximum; The laser that laser instrument after modulation output optical frequency changes with modulation signal synchronous waveform, is input in sensing light path, can realize multiplexing, the signal carrier that forms multiple sensors of sensor;
Wherein as shown in Figure 3, it is mainly by operational amplifier U7, Distributed Feedback Laser U8, operational amplifier U9 and 2 triode Q4, Q5 group for modulation of source circuit; The 7 termination VDC of U7, after connecting with diode D8, capacitor C 41 after 6 terminating resistor R18, connect again with the circuit of capacitor C 38 parallel connections, after 6 terminating resistor R19, meet VDC, connect again the ground that is connected in series to of diode D4, D5, D6, D7 simultaneously, 4,7,8,9,10 end ground connection, 3 ends are ground connection after resistance R 17,2 ends and the end that meets U8; 1, the 14 end ground connection of U8,12 ends are through capacitor C 34 ground connection, 5,11 termination VDC, 4 termination PDne, 6 termination TEC+, 3 ends connect the collector of triode Q4 after choking coil L3 connects with resistance R 20, and 3 ends connect the collector of triode Q5 after choking coil L3 connects with resistance R 21 simultaneously; Between 1,2 ends of U9 after parallel resistance R22 and capacitor C 39 by 1 terminating resistor R25 to 6 ends, Pdne connecting resistance R30 again resistance in series R27 connects 3 ends of U9, connect the resistance R 30 and the ground connection of connecting after potentiometer resistance R31, resistance R 32, capacitor C 43 three's parallel connections of Pdne simultaneously, 5 ends meet VREF through resistance R 24, and 7 ends connect capacitor C 45 to ground through resistance R 28 and 8 ends altogether through resistance R 26; Pick out the base stage through diode D11, D12 to Q4 from the upper end of capacitor C 45, base stage connects capacitor C 44 to ground simultaneously, connects also arrive ground through diode D10 with resistance R 29 simultaneously, and the base stage of Q4 connects the base stage of Q5, and the grounded emitter of Q4, Q5;
The formation of described signals collecting and processing module is shown in Fig. 6, and it comprises that signal conditioner, signal picker, processing unit, terminal show and external interface; The signal conditioner output that connects photodetector output is connected in series signal picker and processing unit successively, and processing unit output has terminal to show and external interface;
Wherein as shown in Figure 7, it is mainly made up of operational amplifier U14, photoelectric diode U15 signal conditioner circuit; 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, 1 termination AD_OUT mouth, 2 ends are through resistance R 42 ground connection, the two parallel connection of connecting resistance R40 between 1,2 ends, capacitor C 59;
The present invention is pipeline leakage monitor and the method based on leaking vibration quasi-distributed optical fiber sensing, pick device using the Fibre Optical Sensor without power supply as leakage signal, the optical fiber that utilization and pipeline are laid with ditch and Optical multiplexing technology are realized the signal long-distance transmissions of optical fibre vibration sensor, solve a difficult problem for electric transducer power supply and telecommunication, laying optical fiber vibration transducer comparatively thick and fast, multisensor is combined and is carried out time delay estimation, improves measuring vibration wave propagation velocity in case of natural gas pipeline leakage precision.
Brief description of the drawings
Fig. 1 Fibre Optical Sensor system for measuring vibration wave propagation velocity in case of natural gas pipeline leakage schematic diagram
The modulation principle figure of Fig. 2 optical frequency adjustable type light source
Fig. 3 modulation of source circuit diagram
Fig. 4 monitoring system of fiber optical sensing natural gas pipeline light path system
Fig. 5 light path adapter structure and transmission index path
Fig. 6 signals collecting and processing module structural drawing
Signal conditioning circuit figure in Fig. 7 signals collecting and processing module
Embodiment
In conjunction with the accompanying drawings and embodiments the present invention is further described, but should limit the scope of the invention with this.
Embodiment. the formation of the natural gas line leakage system of this example Fibre Optical Sensor used is shown in Fig. 1, and it comprises light path system and circuit two parts; A Fibre Optical Sensor is installed at a certain distance on pipeline body, multiple Fibre Optical Sensors form a Fibre Optical Sensor group, each Fibre Optical Sensor group connects light source and the photodetector to receiving end after a beam splitter being serially connected in optical fiber with an optical fiber, photodetector output connects the signals collecting and the processing module that comprise leakage signal identification and state event location function, and described signals collecting and processing module comprise that signal conditioner, signal picker, processing unit, terminal show and external interface; The signal conditioner output that connects photodetector output is connected in series signal picker and processing unit successively, and processing unit output has terminal to show and external interface.Signals collecting and processing module output connect microcomputer.Through the processing of signals collecting and processing module, the sensor group signal mixing based on frequency division multiplexing mode has been realized the demultiplexing of each sensor in sensor group, obtains original leakage vibration wave signal.
This example on pipeline body at a certain distance as 5km install a Fibre Optical Sensor, 3 Fibre Optical Sensors form a Fibre Optical Sensor group, each Fibre Optical Sensor group is received light source and the photodetector of receiving end with an optical fiber, photodetector output connects the signals collecting and the processing module that comprise leakage signal recognition device and state event location device, and signals collecting and processing module output connect microcomputer.
This routine light path system (seeing Fig. 4) is to design based on frequency division multiplexing principle, and each Fibre Optical Sensor connects a light path adapter by two optical fiber, and all light path adapters are connected in series successively, by apart from the nearest light path adapter welding system main frame of receiving end; Concrete optical routing light path adapter, transmission cable and Fibre Optical Sensor three parts form; Light path adapter is made up of beam splitter and combiner device; Fibre Optical Sensor adopts Mach-Zehnder interferometer or Michelson interferometer.
Specifically linking as shown in Figure 5 between each optical device in described light path system, the leak detection light that light source sends enters the beam splitter I1 in light path adapter through Transmission Fibers I5, it is 24: 1 that this beam splitter I1 adopts splitting ratio, the output light that wherein ratio is 24 continues to propagate along time delay optical fiber 4, until light path adapter 2, and the output light that export ratio is 1 enters first sensor 2 through connecting optical fiber, sensor 2 adopts Mach-Zehnder interferometer structure, poor at 20m in order to ensure that sensor has certain sensitivity control interferometer arm, this interferometer is wound on the elastic body of elastomeric material, elastic body is close to duct wall, employing protective cover is fixed, distance Accurate Measurement between each sensor, controls light source according to the light travel-time and exports, beam splitter 1 in light path adapter 2 adopts the splitting ratio of 23: 1, the output light that wherein ratio is 23 continues to propagate until run into next light path adapter along input optical fibre, and the output light that export ratio is 1 enters second sensor 2 through connecting optical fiber, it is poor at 20m that this sensor adopts equally Mach-Zehnder interferometer structure and controls interferometer arm, be wound on the elastic body of elastomeric material, elastic body is close to duct wall and is fixed, in the time that the pipeline between first and second sensor 2 occurs to leak, leaking the vibration wave causing is picked up by two sensors respectively through the regular hour along pipe transmmision, import system photoelectric conversion module into by Transmission Fibers 5, the location that final system receives the mistiming of leakage signal and can realize leakage point in conjunction with vibration wave in ducted velocity of propagation according to sensor,
Described light source is a kind of special light source system that is applicable to multiplexing and modulation /demodulation that comprises, forms (seeing Fig. 2) by the adjustable laser instrument of optical frequency and dedicated modulation signal generating module; Laser instrument output connects the D/A follower in modulation signal generation module, and D/A follower connects signal generator, and signal generator has frequency adjustment, amplitude adjusted and the sawtooth wave/selection of falling sawtooth wave input; Can select as sawtooth wave or the signal type of falling saw wave modulator by programming, adjust signalization amplitude and frequency; Modulation signal acts on laser instrument, and the laser that output optical frequency changes with modulation signal synchronous waveform, is input in sensing light path, realizes multiplexing, the signal carrier that forms multiple sensors of sensor;
Wherein as shown in Figure 3, it is mainly by operational amplifier U7, Distributed Feedback Laser U8, operational amplifier U9 and 2 triode Q4, Q5 group for modulation of source circuit; The 7 termination VDC of U7, after connecting with diode D8, capacitor C 41 after 6 terminating resistor R18, connect again with the circuit of capacitor C 38 parallel connections, after 6 terminating resistor R19, meet VDC, connect again the ground that is connected in series to of diode D4, D5, D6, D7 simultaneously, 4,7,8,9,10 end ground connection, 3 ends are ground connection after resistance R 17,2 ends and the end that meets U8; 1, the 14 end ground connection of U8,12 ends are through capacitor C 34 ground connection, 5,11 termination VDC, 4 termination PDne, 6 termination TEC+, 3 ends connect the collector of triode Q4 after choking coil L 3 connects with resistance R 20, and 3 ends connect the collector of triode Q5 after choking coil L3 connects with resistance R 21 simultaneously; Between 1,2 ends of U9 after parallel resistance R22 and capacitor C 39 by 1 terminating resistor R25 to 6 ends, Pdne connecting resistance R30 again resistance in series R27 connects 3 ends of U9, connect the resistance R 30 and the ground connection of connecting after potentiometer resistance R31, resistance R 32, capacitor C 43 three's parallel connections of Pdne simultaneously, 5 ends meet VREF through resistance R 24, and 7 ends connect capacitor C 45 to ground through resistance R 28 and 8 ends altogether through resistance R 26; Pick out the base stage through diode D11, D12 to Q4 from the upper end of capacitor C 45, base stage connects capacitor C 44 to ground simultaneously, connects also arrive ground through diode D10 with resistance R 29 simultaneously, and the base stage of Q4 connects the base stage of Q5, and the grounded emitter of Q4, Q5;
Wherein:
Operational amplifier U7 selects AD623;
Laser instrument U8 selects internal modulation semiconductor light sources;
Operational amplifier U9 selects AD8572;
Triode Q4, Q5 select NPN9014;
The formation of described signals collecting and processing module is shown in Fig. 6, and it comprises that signal conditioner, signal picker, processing unit, terminal show and external interface; The signal conditioner output that connects photodetector output is connected in series signal picker and processing unit successively, and processing unit output has terminal to show and external interface;
Wherein as shown in Figure 7, it is mainly made up of operational amplifier U14, photoelectric diode U15 signal conditioner circuit; 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, 1 termination AD_OUT mouth, 2 ends are through resistance R 42 ground connection, the two parallel connection of connecting resistance R40 between 1,2 ends, capacitor C 59;
Wherein:
Operational amplifier U14 selects AD8572;
Photoelectric diode U15 selects OPA380AID;
Light source adopts the narrow cable and wide optical fiber laser of 100kHZ live width, laser instrument output connects beam splitter 1, it is 24: 1 that beam splitter 1 adopts splitting ratio, the output resume that wherein ratio is 24 is propagated until run into beam splitter 2 along transmission light path, the output terminal that beam splitter 1 export ratio is 1 enters sensor 1 through connecting optical fiber, sensor 1 adopts Mach-Zehnder interferometer structure, poor at 20m in order to ensure that sensor has certain sensitivity control interferometer arm, this interferometer is wound on the elastic body of elastomeric material, and elastic body is close to duct wall and is fixed.Beam splitter 2 adopts the splitting ratio of 23: 1, the output resume that wherein ratio is 23 is propagated until run into next beam splitter 3 along transmission light path, the output terminal that beam splitter 2 export ratios are 1 enters sensor 2 through connecting optical fiber, the same employing Mach-Zehnder interferometer structure of sensor 2 and control interferometer arm are poor at 20m, be wound on the elastic body of elastomeric material, elastic body is close to duct wall and is fixed.In the time that the pipeline between sensor 1 and sensor 2 occurs to leak, leak the vibration wave causing and picked up by sensor 1 and 2 respectively through the regular hour along pipe transmmision, the location that receives the mistiming of leakage signal and can realize leakage point in conjunction with vibration wave in ducted velocity of propagation according to sensor 1 and 2.
Along multiple sensing points are set in duct orientation, the distance Accurate Measurement between each sensor, controls light source output according to the light travel-time.
In the time that the pipeline between sensor n and sensor n+1 occurs to leak, leaking the vibration wave causing is picked up by sensor n-1, n, n+1 and n+2 respectively through the regular hour along pipe transmmision, receive the mistiming of leakage signal according to adjacent multiple sensors, just can measure vibration wave in ducted velocity of propagation.
Use this system, select some known sensor points to cause vibration by knocking the form simulation pipe leakages such as pipeline, according to the quantity of the duct section using in engineering construction and examination data, carry out time delay estimation and realize the mensuration to leaking vibration wave speed in conjunction with known duct length propagating into the leakage signal of two adjacent sensors, accurately provide the distance of two adjacent sensor points of current test point distance, by this simulation test point position X substitution: X=L-[v × (t n+2-t n)]/2, counter solving: v=2 (L-X)/(t n+2-t n), realize according to the signal propagation time of known sensor spacing distance and mensuration and measure the speed v of vibration wave along pipe transmmision.In formula, L is two distances between adjacent sensor points; X is the distance apart from first sensor points (apart from starting point), and v leaks vibration velocity of wave propagation.
This example is through test of many times, by being installed on duct wall, leakage vibration sensing interferometric sensor not only can realize the monitoring to any disturbance behavior along pipe transmmision, through realizing the mensuration to vibration wave propagation velocity in case of natural gas pipeline leakage to signal analysis and processing and Intelligent Recognition, and system sensitivity is high, accuracy is high, false alarm rate is low, be not subject to such environmental effects.

Claims (4)

1. a system for measuring vibration wave propagation velocity in case of natural gas pipeline leakage, is characterized in that it comprises light path system and circuit two parts; A Fibre Optical Sensor is installed at a certain distance on pipeline body, multiple Fibre Optical Sensors form a Fibre Optical Sensor group, each Fibre Optical Sensor group connects light source and the photodetector to receiving end after a beam splitter being serially connected in optical fiber with an optical fiber, photodetector output connects the signals collecting and the processing module that comprise leakage signal identification and state event location function, and described signals collecting and processing module comprise that signal conditioner, signal picker, processing unit, terminal show and external interface; The signal conditioner output that connects photodetector output is connected in series signal picker and processing unit successively, and processing unit output has terminal to show and external interface; Signals collecting and processing module output connect microcomputer;
Send laser by light source, realize after beam splitting through transmission light path, part light is transferred to the Fibre Optical Sensor group being arranged on duct wall, Fibre Optical Sensor group is picked up after the leakage vibration signal and noise of pipe transmmision, again be transmitted back to the photodetector of system through transmission light path, carry out leakage signal demodulation and discriminance analysis by signals collecting and processing module, and leakage signal is carried out to time delay and estimate to realize the location to leakage point;
Described light path system is based on frequency division multiplexing principle, is made up of light path adapter, transmission cable and Fibre Optical Sensor three parts; Light path adapter is made up of beam splitter and combiner device; Fibre Optical Sensor adopts Mach-Zehnder interferometer or Michelson interferometer; Each Fibre Optical Sensor connects a light path adapter by two optical fiber, and all light path adapters are connected in series successively, by apart from the nearest light path adapter welding system main frame of receiving end;
Described light source is a kind of special light source system that is applicable to multiplexing and modulation /demodulation that comprises, is made up of the adjustable laser instrument of optical frequency and dedicated modulation signal generating module; Laser instrument input connects the D/A follower in modulation signal generation module, and D/A follower connects signal generator, and signal generator has frequency adjustment, amplitude adjusted and the sawtooth wave/selection of falling sawtooth wave input; Select sawtooth wave or the signal type of falling saw wave modulator by programming, adjust signalization amplitude and frequency; Modulation signal acts on laser instrument, the laser that output optical frequency changes with modulation signal synchronous waveform; Laser optical power 1-17mW, it is poor that laser instrument coherent length is greater than all the sensors interferometer brachium, but be less than launching fiber and the delay fiber lengths sum returning on optical fiber between adjacent two interferometers;
Described dedicated modulation signal generating module is mainly made up of operational amplifier U7, Distributed Feedback Laser U8, operational amplifier U9 and 2 triode Q4, Q5; The 7 termination VDC of U7, the first connecting resistance R18 of 6 ends of U7, connect afterwards after a parallel circuit ground connection again, this parallel circuit comprises two branch roads, and wherein one route diode D8 and capacitor C 41 series connection form, another route capacitor C 38 forms, after the 5 terminating resistor R19 of U7, meet VDC, 5 ends of U7 connect being connected in series to of diode D4, D5, D6, D7 simultaneously again, the 4 end ground connection of U7,3 ends of U7 ground connection after resistance R 17,2 ends of U7 connect 2 ends of U8; 1, the 14 end ground connection of U8,12 ends of U8 are through capacitor C 34 ground connection, 5, the 11 termination VDC of U8, the 4 termination PDne of U8, the 6 termination TEC+ of U8,3 ends of U8 connect the collector of triode Q4 after choking coil L3 connects with resistance R 20, and 3 ends of U8 connect the collector of triode Q5 after choking coil L3 connects with resistance R 21 simultaneously; 2 ends of U9 connect 1 end that is connected U9 after the parallel circuit being formed with capacitor C 39 by resistance R 22, also contact resistance R25 of parallel circuit simultaneously that formed by resistance R 22 and capacitor C 39, be connected to afterwards 6 ends of U9, PDne connecting resistance R30 connects 3 ends of U9 again after resistance in series R27, simultaneously, the resistance R 30 that meets PDne also connects the parallel circuit being made up of resistance R 31, resistance R 32, capacitor C 43 threes, ground connection more afterwards, 5 ends of U9 meet VREF through resistance R 24, and 7 ends of U9 connect capacitor C 45 to ground through resistance R 28 and 8 ends of U9 altogether through resistance R 26; Pick out the base stage through diode D11, D12 to Q4 from the upper end of capacitor C 45, base stage connects capacitor C 44 to ground simultaneously, connects also arrive ground through diode D10 with resistance R 29 simultaneously, and the base stage of Q4 connects the base stage of Q5, and the grounded emitter of Q4, Q5.
2. a kind of system for measuring vibration wave propagation velocity in case of natural gas pipeline leakage according to claim 1, it is characterized in that arriving first light path adapter after input optical fibre in the described light path system exploring laser light that specifically laser instrument sends input transmission cable enters sensor group, be divided into two bundle laser by the beam splitter of this light path adapter: a branch ofly enter first Fibre Optical Sensor through input optical fibre, another light beam passes to next light path adapter through time delay optical fiber, be divided into two bundle laser by the beam splitter in next light path adapter again, a branch ofly enter second Fibre Optical Sensor, another Shu Zaijing Transmission Fibers is transferred to next light path adapter, by that analogy, until laser arrives last Fibre Optical Sensor, every 2-10 adjacent Fibre Optical Sensor is divided into one group, and in group, the interference signal of each Fibre Optical Sensor, by combiner device access passback optical fiber, transfers back to system receiving terminal, at last Fibre Optical Sensor of sensor group, laser no longer, by light path adapter, directly enters Fibre Optical Sensor, and light signal after each Fibre Optical Sensor, by the combiner device in corresponding light path adapter separately, closes bundle with passing the light signal of coming below, finally reach the photoelectric conversion module of monitoring system through output optical fibre,
The set of described light path adapter beam splitter and combiner device; What input optical fibre used from output optical fibre is two different fibre cores in same transmission cable; Transmission cable is together in series all light path adapters; The length of the launching fiber on pipeline between adjacent two sensors and passback optical fiber is all greater than 1/2 of laser instrument coherent length.
3. a kind of system for measuring vibration wave propagation velocity in case of natural gas pipeline leakage according to claim 2, it is characterized in that being specifically connected between each optical device in described light path system: the leak detection light that light source sends enters the beam splitter (1) in light path adapter through Transmission Fibers (5), it is 24: 1 that this beam splitter (1) adopts splitting ratio, the output light that wherein ratio is 24 continues to propagate along time delay optical fiber (4), until light path adapter (2), and the output light that export ratio is 1 enters first sensor (2) through connecting optical fiber, sensor (2) adopts Mach-Zehnder interferometer structure, control interferometer arm poor at 20m, this interferometer is wound on the elastic body of elastomeric material, elastic body is close to duct wall, employing protective cover is fixed, distance Accurate Measurement between each sensor, controls light source according to the light travel-time and exports, beam splitter (1) in light path adapter (2) adopts the splitting ratio of 23: 1, the output light that wherein ratio is 23 continues to propagate until run into next light path adapter along input optical fibre, and the output light that export ratio is 1 enters second sensor (2) through connecting optical fiber, it is poor at 20m that this sensor adopts equally Mach-Zehnder interferometer structure and controls interferometer arm, be wound on the elastic body of elastomeric material, elastic body is close to duct wall and is fixed.
4. a kind of system for measuring vibration wave propagation velocity in case of natural gas pipeline leakage according to claim 1, is characterized in that described signal condition element circuit is mainly made up of operational amplifier U14, photoelectric diode U15; 1,5,8 ends of U15 are unsettled, 3, the 4 end ground connection of U15, and 2 ends of U15 connect by connecing 6 ends after resistance R 39 and capacitor C 60 the two parallel circuit that form again, and 6 ends of U15 connect 3 ends of U14 through resistance R 43,8 ends of the 7 termination U14 of U15; The 4 end ground connection of U14,5 ends are unsettled, and 6,7 ends meet AD_VINI altogether, the 1 termination AD_OUT mouth of U14,2 ends of U14 are through resistance R 42 ground connection, the two parallel circuit of connecting resistance R40 between 1,2 ends of U14, capacitor C 59.
CN201110272474.8A 2011-09-14 2011-09-14 Method and system for measuring propagation speed of natural gas pipe leakage vibration wave CN102997059B (en)

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