CN102997057B - Optical fiber sensor-based natural gas pipeline leakage monitoring method and system and installation method for system - Google Patents
Optical fiber sensor-based natural gas pipeline leakage monitoring method and system and installation method for system Download PDFInfo
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Abstract
The invention discloses an optical fiber sensor-based natural gas pipeline leakage monitoring method, an optical fiber sensor-based natural gas pipeline leakage monitoring system and a system construction method. Optical fibers in a communication optical cable which is laid in the same channel of an oil and gas pipeline respectively serve as a transmitting optical fiber and a returning optical fiber; pipeline leakage optical fiber sensors are connected in parallel between transceiving transmitting optical fibers to form an optical path by an optical multiplexing technology; the pipeline leakage optical fiber sensors are uniformly arranged along the pipeline; laser light emitted from a light source is subjected to beam splitting through a transmission optical path and is transmitted to the sensors arranged on the wall of the pipeline; after the sensors pick up leakage vibration signals and noises propagated along the pipeline, the leakage vibration signals and the noises are returned to a photoelectric detector part of the system through the transmission optical path; the acquired vibration wave signals are analyzed and processed; and the position of a vibration wave source is determined by combining the propagation speed of the vibration wave on a pipeline body according to the time delay of the vibration waves propagated to the adjacent optical fiber sensors. By the method and the system, the flexibility is high; and the positioning accuracy is high.
Description
Technical field
The present invention is a kind of natural gas line leakage system based on Fibre Optical Sensor and the installation method of system.Relate 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.
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.
Summary of the invention
The object of the invention is to invent a kind of sensitivity and accuracy is high, false alarm rate is low, be not subject to the natural gas line leakage system based on Fibre Optical Sensor of such environmental effects and the installation method of system.
In view of above-mentioned a few class Leak Detection, 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 is to provide the quasi-distributed leakage vibration monitor system of a kind of high sensitivity based on Fibre Optical Sensor, adopt high sensor to make micro-leakage to occur when pipeline, when the leakage primary stages such as seepage, monitored in time, and in conjunction with the time domain of incident of leakage, frequency domain character effectively reduces and disturbs the system false alarm rate causing, this technical scheme has overcome poor accuracy in monitoring technology before this and the deficiency of mounting process complexity, make related maintenance personnel can take in time counter-measure, avoid causing larger security incident.
After pipe leakage, can produce the sound wave of each frequency range, the shorter ultrasound wave of wavelength ratio apart from sound source not far position just gradually by Absorption of Medium, and wavelength is shorter, attenuation by absorption also faster, only have the distant of low-frequency sound wave and infrasonic wave propagation, can propagate a few km to tens kms.Adopt in the system of infrasonic sensor being installed compared with long pipeline two ends because available signal frequency range is narrower, to the accurate positioning effect of leakage signal not enough at present.
The present invention is based on one and there is highly sensitive quasi-distributed optical fiber sensing leakage vibration monitoring method, it is that a high sensitivity optical fiber interfere type leak sensor is installed at a certain distance on pipeline body, the leakage 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 leak 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, the velocity of propagation on pipeline body realizes determining vibration wave source position in conjunction with vibration wave simultaneously to propagate into the time delay of adjacent several Fibre Optical Sensors according to vibration wave, realize above-mentioned to incident of leakage is reported to the police the positional information of leakage point is provided after vibration wave signal analysis and processing simultaneously.The present invention has suitably increased the quantity of Fibre Optical Sensor on employing high sensitivity optical fiber sensor improves the basis of incident of leakage monitoring sensitivity, expanded the frequency range that can pick up monitor signal, and the time delay of carrying out in conjunction with multiple Fibre Optical Sensors estimates that localization method has ensured the accuracy of system location.
In the present invention, sensor is the key that realizes line leakage, and in the time that pipeline occurs to leak, leaking the vibration wave exciting will propagate to leakage point both sides along pipeline.A sensor is installed at a certain distance on pipeline body, is used for monitoring the leakage vibration wave on pipeline.Sensor adopts fibre optic interferometer structure, can be optical fiber Michelson interferometer or fiber Mach-Zehnder interferometer, for the induction sensitivity increasing leaking vibration can be by increasing the mode of sensor fibre length, the light intensity signal of its output can be write as after opto-electronic 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
ncircuit additional noise, φ
sserve as reasons and leak the phase difference signal that vibration wave causes, be the leakage vibration wave signal that will survey, φ
0for the initial phase of interferometer, be a constant, φ
nfor the low frequency wonder of phasic difference, be a Uncertainty, change with temperature and external environment impact.Can realize and leak vibration wave signal psi by the demultiplexing technology matching with modulation of source mode
sobtain, and to this signal psi
sthe time delay that arrives corresponding sensor estimates, having realized vibration wave source in conjunction with vibration wave along the speed v of pipe transmmision is determining of leakage point position.
In order to save input, in the natural gas line leakage method based on Fibre Optical Sensor, adopt Fibre Optical Sensor multiplex/demultiplex method.The method of the comprehensive frequency division multiplexing of the method and space division multiplexing, adopt the method generation leak detection light that tunable laser is carried out to optical frequency modulation, use Michelson interferometer as leak sensor, the laying structure of sensor is that a leak sensor is installed at a certain distance on natural gas tube pipeline outer wall, multiple sensors form a sensor group, and the light signal of each sensor group uses an optical fiber to pass system host back.Each sensor in sensor group is made into the poor different Michelson interferometer of light arm or Mach-Zehnder interferometer, the sense light signal frequency that each leak sensor is produced is all not identical, utilizes thus frequency division multiplexing principle the optical multiplexed signal of multiple sensor different frequencies of every group can be used in to the receiving end of passing system in an optical fiber back; And between multiple sensor groups, adopt space division multiplexing mode to distinguish connecting system main frame.The light signal of the each sensor group receiving uses independent opto-electronic conversion passage to realize the conversion of light signal to electric signal, transducing signal after conversion uses frequency division mode to realize the demultiplexing of each sensor in sensor group, and adopt phase carrier technology to demodulate the original acoustic signals of pipe leakage, pass through again identification and the positioning analysis of leakage signal, finally can Obtaining Accurate pipe leakage dot information.The phase carrier demodulation method that leaks acoustic signals is by the interference signal receiving, and first carries out bandpass filtering, a road output and cos (ω
0t) carry out low-pass filtering and differential processing, another road and sin (ω after multiplying each other
0t) carry out low-pass filtering and differential processing after multiplying each other; After the low-pass filtering output multiplication on differential output Yu Hou mono-tunnel on last road, the output of the differential on Yu Hou mono-tunnel is subtracted each other with the result of last low-pass filtering output multiplication again, successively through integration, high-pass filtering processing, finally export original leakage vibration wave signal (seeing Figure 17) afterwards.
In fact, in Michelson interferometer optical fiber with the corresponding refractive index n of two polarization modes
xand n
yunequal, simultaneously because micro-curved, the distortion of optical fiber, the variation of environment temperature make n
xand n
yrandom variation, causes optical fiber output polarization state random variation, is reflected in interference signal visibility V random variation between 0～1, and this phenomenon is the polarization inducement signal fade-out of interferometer.This phenomenon will cause the reduction of Michelson interferometer sensor detection sensitivity and signal to noise ratio (S/N ratio) and unstable.In order to overcome the polarization decay of sensor group, in the natural gas line leakage method based on Fibre Optical Sensor, adopt the anti-polarization decay method of gas pipeline leakage detecting sensor group.The anti-polarization decay method of this gas pipeline leakage detecting sensor group is that the sensor of a Michelson interferometer structure is installed at a certain distance on pipeline body, by the sensor of several Michelson interferometer structures by beam splitter and bundling device and be connected in launching fiber and passback optical fiber between; Two arms of Michelson interferometer are not isometric, each Michelson interferometer uses two faraday rotation mirrors as catoptron, the anglec of rotation is 45 degree, catoptrical polarization state is changed and just in time offset the polarization state variation of incident light, thereby make the visibility of interferometer remain 1.
In addition, in formula (1), due to low-frequency disturbance φ
nrandom variation, and amplitude is large, is subject to φ
nvariable effect, the signal to noise ratio (S/N ratio) of system output is changing, and as sin φ
n=0 o'clock, the complete blanking of signal, this be called the phase fading phenomenon of interferometer.
In order to eliminate the phase fading phenomenon of sensor, adopt phase carrier technology to detect leakage acoustic signals.Specific as follows:
While making Michelson interferometer, make interferometer two arms not isometric, two arm length difference are Δ L;
Using sawtooth wave or fall sawtooth signal as modulation signal, frequency is the twice of leaking sound wave frequency span, be applied to the adjustable laser instrument of optical frequency, laser instrument output optical frequency is according to the synchronous laser changing of modulation signal, be input to Michelson interferometer, because two arms are not isometric, laser by two arms will produce delay inequality, thereby the two bundle laser that participate in interfering are except sawtooth wave falling edge, the optical frequency in other moment is poor is a constant, therefore, the interference signal of interferometer output is the cosine signal of an approximate single-frequency, angular frequency
0two arm length difference Δ L are directly proportional to interferometer, and Δ L is larger, and interference signal frequency is higher;
Use bandpass filter to carry out filtering to interference signal, filter center frequency is interference signal centre frequency, and bandwidth is identical with saw wave modulator signal frequency.Can obtain the carrier signal of this interferometer after filtering, phase fading problem that can erasure signal according to the demodulation of aforesaid phase carrier demodulation method, obtains original leakage acoustic signals.
In order to overcome the phase fading of sensor group, in the natural gas line leakage method based on Fibre Optical Sensor, adopt a kind of anti-phase fading method for gas pipeline leakage fiber optic detection system.The anti-phase fading method of this gas pipeline leakage fiber optic detection system is: the sensor of a Michelson interferometer or mach-zehnder interferometer configuration is installed at a certain distance on pipeline body, by several sensors by beam splitter and bundling device and be connected in launching fiber and passback optical fiber between; Based on sawtooth wave or fall the laser instrument of saw wave modulator as light source, and the long Michelson interferometer of unequal arm or Mach-Zehnder interferometer are as sensor, in sensor signal, produce the cosine signal carrier wave of approximate single-frequency, sensor group signal carrier is the linear superposition of each sensor carrier signal, by dividing method, each sensor carrier signal is separated, use with each sensor carrier signal, with cosine and sinusoidal signal frequently, carrier signal is carried out to demodulation, obtain the original leakage acoustic signals of each sensor.
For the accurately position of locating leaks in pipes of energy, in the natural gas line leakage method based on Fibre Optical Sensor, adopt a kind of multisensor localization method based on quasi-distributed optical fiber sensing technology gas pipeline leakage event, in the time that pipe leakage event occurs, leak excited vibrational ripple and propagate to two reverse directions along pipeline, the delay inequality that system propagates into adjacent several sensors according to leakage signal realizes the location to leakage point.When leaking while occurring, leak and excite pipeline to produce vibration wave, vibration wave is with speed V along pipe transmmision, and wherein two adjacent sensors are spaced apart setting value L, 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 (2) to set up:
Wherein unknown parameter (t
n-1-t
n), (t
n-1-t
n+1), (t
n+2-t
n) and (t
n+2-t
n-1) be respectively the delay inequality of leaking vibration wave arrival 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 to assembly average, obtain final measured value X.It is poor that the multiple sensors of combined continuous receive signal time, compares and only adopt the time difference measurements mode of two sensors to have locating effect more accurately.This localization method can be monitored burst or given vent to leakage signal, has the advantages such as accurate positioning is good, stable performance.
For Environmental Random Vibration is disturbed and suppressed, in the natural gas line leakage method based on Fibre Optical Sensor, adopt a kind of intelligent identification Method of gas pipeline leakage event.With the temporal signatures P of the normal operation of pipeline and leakage status signals
t, frequency domain character P
fnoisiness P with current pipe transmmision signal
nand comprehensively analyze in conjunction with waveform recognition, set up and leak degree of confidence function model: R=a
1p
t+ a
2p
f-a
3p
n, the vibration wave signal picking up is leaked to assessment and judge whether pipeline leaks, according to on-the-spot pipeline feature, algorithms of different parameter a is set
1, a
2, a
3regulate degree of confidence model.Random accidental vibration and sudden, continuation leakage signal have effectively been distinguished in this recognition methods, have improved the accuracy rate of system alarm.
In order to measure pipe leakage vibration wave velocity of propagation, in the natural gas line leakage method based on Fibre Optical Sensor, adopt a kind of 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.
A kind of assay method of natural gas line absolute growth is also provided simultaneously, first the pipeline that excavates position to be measured buries soil, knock the vibration of pipeline simulation pipe leakage at this point, measure the position of analog site along the speed of pipe transmmision and the signal propagation time of mensuration according to known simulated leakage vibration wave, X=[L-v × (t
n+1-t
n)]/2, thereby realize the measurement of pipeline absolute distance.
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, adjacent multiple Fibre Optical Sensors form a Fibre Optical Sensor group, each Fibre Optical Sensor group shares a launching fiber and is connected with light source, and each Fibre Optical Sensor group is used a passback optical fiber to be connected with photodetector; Photodetector output connects the signals collecting and the processing module that comprise leakage signal identification and state event location function, and signals collecting and processing module output connect microcomputer by external interface.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.
In order to protect Fibre Optical Sensor, at Fibre Optical Sensor, Fibre Optical Sensor guard shield 16 is installed outward; Fibre Optical Sensor guard shield 16 is a bottom indent and the radian cover consistent with pipeline external surface.
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 source, 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 light path adapter by two optical fiber, and all light path adapters are connected in series successively with transmission cable, by apart from the nearest light path adapter welding system main frame of receiving end.
The flow process of whole light path system is: the launching fiber of light source in transmission cable sends exploring laser light, arrive after 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 launching fiber, 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 Optical Fiber Transmission is to next light path adapter, by that analogy, until laser arrives last Fibre Optical Sensor, at last Fibre Optical Sensor of sensor group, laser no longer, by beam splitter, 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, be back to the signal receiving end of monitoring system finally by the passback optical fiber transmission of corresponding sensor group.Wherein said light path adapter set beam splitter and combiner device; What launching fiber used from passback optical fiber 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 reach the object that prevents from occurring between sensor signal cross-talk.
For above-mentioned natural gas pipeline leakage optical fiber monitoring system, the invention discloses the special light source system of a kind of applicable multiplexed optical wave use and modulation /demodulation.This light-source system forms (seeing Fig. 2) by the adjustable laser instrument of optical frequency and dedicated modulation signal generating module; The signal producing in modulation signal generation module is exported by DA, connects laser modulation signal input part; Modulation signal generation module output signal has frequency adjustment, amplitude adjusted and sawtooth wave/selection function of falling sawtooth wave, can select as sawtooth wave or the signal type of falling saw wave modulator by programming, adjusts signalization amplitude and frequency; Modulation signal acts on laser instrument, the continuous laser that exportable optical frequency changes according to modulation signal waveform rule.
Described light source is a kind of special light source system that is applicable to multiplexing and modulation /demodulation that comprises, the semiconductor laser that the laser instrument in light source adopts optical frequency to modulate, and modulation signal acts on laser instrument Injection Current, realizes the modulation of optical frequency; It is poor that laser instrument coherent length need to be greater than all the sensors interferometer brachium, and be less than launching fiber and the time delay optical fiber length sum returning on optical fiber between adjacent two interferometers.The modulation signal that modulation signal module outputs to laser instrument is sawtooth signal or the sawtooth signal of falling, and frequency is not less than the twice of leakage acoustic signals frequency to be detected; In the time injecting sawtooth wave or the optical frequency of falling sawtooth wave modulated laser, the interference signal of each sensor output is single-frequency cosine signal or approximate single-frequency cosine signal, the interference light signal of sensor group output is the stack of the approximate single-frequency cosine signal of each sensor output in sensor group, its frequency spectrum is made up of multiple independently spectral lines, and spectral line quantity is identical with sensor group inner sensor quantity;
Modulation signal generation module in light source 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 (DA) mode, the modulated-analog signal of output is connected on laser instrument, 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; 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 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.
The modulation principle of this light-source system relatively, natural gas pipeline leakage optical fiber monitoring system has adopted the vibration wave demodulation principle block diagram of Fibre Optical Sensor multiplex/demultiplex method to see Figure 16, interference signal output tape splicing pass filter, bandpass filtering is exported a road and cos ω
0t joins after (multiplying each other) and connects the first low-pass filtering, and this low-pass filtering output connects the first differentiating circuit, another road and sin ω
0t joins, and connects the second low-pass filtering after multiplying each other, and this low-pass filtering output connects the second differentiating circuit; The first differentiating circuit output and the output of the second low-pass filtering are joined, and after multiplying each other, join with the second differentiating circuit output and the first low-pass filtering output again, after multiplying each other, join again, after subtracting each other, successively through integration, high-pass filtering, export acoustic signals.
The formation of described signals collecting and processing module is shown in Fig. 6, and it comprises that signal condition unit, signal gathering unit, processing unit, terminal show and external interface, and processing unit comprises identification 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 to demultiplexing to processing unit and demodulation obtains original vibration wave signal, then in identification circuit and positioning circuit, carry out respectively leakage signal identification and the location of leakage point; Processing unit output has display terminal and external interface;
Wherein as shown in Figure 7, it is mainly made up of operational amplifier U14, photoelectric diode U15 conditioning unit 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;
As shown in figure 17, it is mainly made up of digital signal processor U1B and peripheral circuit identification circuit in processing unit, and the NC1-NC15 pin of U1B is unsettled; AVDD, AGND are analog power input, and AVDD connects 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 respectively the transmission for data with DR0PRI, RSCLK0, the RFS0 of positioning circuit digital signal processor U10; DAI9-DAI20 is expansion interface; DPI9, DPI10 connect external interface circuit;
Positioning circuit in processing unit as shown in figure 18, it is mainly made up of digital signal processor U10 and peripheral circuit and interface, DR0PRI, RSCLK0, the RFS0 of U10 are connected and are used for receiving data with DAI1, DAI3, the DAI4 of identification circuit digital signal processor U1B respectively, RX, TX, MOSI, MISO, SCK connect display terminal interface, and TCK, TDO, TDI, TMS, TRST#, EMU# are debugging interface.
Described sensor adopts Michelson interferometer.Each Fibre Optical Sensor is according to being equidistantly arranged on pipe surface; An every 2-10 adjacent sensor group of sensor composition, in every group, each sensor adopts parallel way to be connected to Transmission Fibers (being launching fiber and passback optical fiber), the place that each sensor is connected with Transmission Fibers is used beam splitter and bundling device realize the beam splitting of light and close bundle (being light path adapter), and the Transmission Fibers length between adjacent two sensors is greater than 1/2 of laser instrument coherent length; One of each sensor group correspondence is independently converted to the interference light signal of each sensor group the opto-electronic conversion passage of electric signal.
The I type structure of described Fibre Optical Sensor is shown in Figure 10, and I type structure is test tube road radial vibration signal, and each sensor comprises: elastic cylinder, fibre optic interferometer and tail fiber coiling box; Wherein, the interference arm of uniform sequential winding optical fiber interferometer in elastic cylinder periphery, and optical fiber and right cylinder are bonded together with bonding agent, after being wound around, remaining fibre optic interferometer and related device thereof are by neat being coiled in tail fiber coiling box; Tail fiber coiling box is fixed on elastic cylinder top by bonding agent.Described elastic cylinder bottom indent, and radian is consistent with pipeline external surface.The radial vibration producing when gas pipeline leakage allows elastic cylinder generation deformation, and deformation also occurs the fibre optic interferometer that drives elastic cylinder periphery to be wound around, and changes thus the state of the light of transmission in optical fiber, so that is arrived by leakage monitoring equipment Inspection.
The another kind of Fibre Optical Sensor II type structure for natural gas line leakage axial vibration signal is shown in Figure 11, and this Fibre Optical Sensor is made up of rectangle flexure strip, fibre optic interferometer and tail fiber coiling box; Concrete structure is on rectangle flexure strip, the fiber optic interferometric arm of fibre optic interferometer is evenly laid with sinusoidal wave shape, and optical fiber is close on rectangle flexure strip with bonding agent, remaining fibre optic interferometer and related device thereof are by neat being coiled in tail fiber coiling box; Tail fiber coiling box is fixed on above rectangle flexure strip by bonding agent.Described rectangle flexure strip is a bottom indent and the radian steel sheet consistent with pipeline external surface; The axial vibration producing when gas pipeline leakage allows rectangle flexure strip generation deformation, drives the fibre optic interferometer that rectangle flexure strip coils that deformation also occurs above, changes thus the state of the light of transmission in optical fiber, so that is detected by rear end equipment.
Wherein in the shell of two kinds of sensors, have sponge layer, mainly play isolating pipelines wall external interference signal and fixing protection sensor.
Theory diagram based on monitoring system of fiber optical sensing natural gas pipeline path multiplexing structure is shown in Figure 15, light source connects launching fiber after dedicated modulation signal generating module, launching fiber is connected in series multiple light path adapters, each light path adapter connects a Fibre Optical Sensor by an optical fiber, multiple Fibre Optical Sensors are a Fibre Optical Sensor group, the Fibre Optical Sensor of each Fibre Optical Sensor group is respectively connected to photoelectric commutator by a passback optical fiber again by an optical fiber and after connecing, and photoelectric commutator output connects signals collecting and processing module.
The installation method of the Fibre Optical Sensor of this natural gas line leakage system: the installation of Fibre Optical Sensor mainly comprises Fibre Optical Sensor, sensor shield two parts.No matter the elastic cylinder formula Fibre Optical Sensor shown in Figure 10, or the S shape coiling sensor shown in Figure 11, the method all becomes sensor global design a bottom indent and the radian a kind of structure consistent with pipeline external surface.This is mainly in order to make sensor fibre contact as far as possible pipeline outer wall, to increase its sensitivity.The inner spongy layer with damping effect of sensor shield, mainly plays isolating pipelines wall external interference signal and protection sensor.Before sensor installation, need the anticorrosive coat of the natural gas line outside surface of respective regions to remove clean, expose steel tube surface, when installation, use tackifier that sensor body is bonded on pipeline outer wall, this is also in order to make sensor fibre contact as far as possible pipeline outer wall, to increase its sensitivity.Afterwards sensor shield is covered on to sensor body outside, drawn from the cable groove that goes out of sensor shield bottom by the transmission cable of drawing in sensor body, finally use tackifier to carry out gluing at the seam crossing of guard shield and pipeline, and do corresponding pipeline corrosion protection processing, make itself and pipe surface anticorrosive coat slitless connection.This installation method can effectively be controlled the sensitivity of fiber-optic sensor probe, and the signal except natural gas leaking is disturbed and has good Isolated Shield effect.
The concrete installation method of this system Fibre Optical Sensor is as shown in Figure 13,14: first, the natural gas line external coating 18 of cleaning sensing installation region, removes the original anticorrosive coat of pipe surface and slightly polish, until expose smooth steel pipe walls 19; Then, evenly smear tackifier at outer surface of steel tube, together with Fibre Optical Sensor 15 bottoms are pressed on steel pipe walls 19, until tackifier solidifies completely; Then Fibre Optical Sensor guard shield 16 is covered to Fibre Optical Sensor 15 completely, and pad betwixt upper vibration damping interlayer, the cable groove that goes out of Fibre Optical Sensor guard shield 16 sides is tackled transmission cable 11 positions on quasi-fiber sensor when mounted; Finally carry out gluing and preservative treatment at Fibre Optical Sensor guard shield 16 with pipeline joint-seam place, use the material identical with natural gas line surface coating to carry out therebetween, finally make Fibre Optical Sensor entirety and pipe surface anticorrosive coat slitless connection.This installation method can effectively be controlled the sensitivity of fiber-optic sensor probe, and the signal except natural gas leaking is disturbed and has good Isolated Shield effect.
The pick device of the present invention 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 and estimate to improve positioning precision to leakage point; In addition the sensitivity of optical fibre vibration sensor is the several times of traditional sonic transducer, can significantly improve the accuracy that natural gas line minute leakage is detected;
And false alarm rate is low, be not subject to the impact of environmental factor.
Brief description of the drawings
Fig. 1 monitoring system of fiber optical sensing natural gas pipeline theory 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 condition element circuit figure in Fig. 7 signals collecting and processing module
Fig. 8 Michelson interferometer type Fundamentals of Sensors figure
Fig. 9 Mach-Zehnder interferometer Fundamentals of Sensors figure
Figure 10 Fibre Optical Sensor I type structural drawing
Figure 11 Fibre Optical Sensor II type structural drawing
Figure 12 Fibre Optical Sensor II type scheme of installation
Figure 13 installation structure of optical fiber sensor schematic diagram one
Figure 14 installation structure of optical fiber sensor schematic diagram two
Figure 15 monitoring system of fiber optical sensing natural gas pipeline path multiplexing structural drawing
Figure 16 monitoring system of fiber optical sensing natural gas pipeline vibration wave demodulation principle block diagram
Signal processing unit identification circuit figure in Figure 17 signals collecting and processing module
Signal processing unit positioning circuit figure in Figure 18 signals collecting and processing module
Wherein 1,1-1 ..., 1-n-beam splitter 2,2-1 ..., 2-n, 15-Fibre Optical Sensor
3,3-1 ..., 3-n-combiner device 4,5,6,7,8,9-time delay optical fiber
10-tail fiber coiling box 11-transmission cable
12-elastic cylinder 13-sensor fibre
14-rectangle flexure strip 16-sensor shield
17-pipeline body 18-natural gas line external surface coating
The outer steel pipe walls of 19-natural gas line
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 this example is as shown in Figure 1, on pipeline body, every 1.5km, a Fibre Optical Sensor is installed, 10 sensors are installed altogether, front 5 sensors and rear 5 sensors form respectively a sensor group, an optical fiber in all Fibre Optical Sensor group common transmitted optical cables is connected with system source, as launching fiber, each Fibre Optical Sensor group is used alone again an optical fiber in transmission cable to be connected with system photodetector simultaneously, as passback optical fiber; Photodetector output termination comprises signals collecting and the processing module of leakage signal identification and state event location function, and signals collecting and processing module output connect microcomputer by external interface.
This routine light path system (seeing Fig. 4) is to design based on frequency division multiplexing principle, each Fibre Optical Sensor connects light path adapter by two optical fiber, all light path adapters are connected in series successively with transmission cable, 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 the interferometer of Michelson-structure.
Specifically linking as shown in Figure 5 between each optical device in described light path system, the detection light that light source sends enters the beam splitter 1-1 in light path adapter through Transmission Fibers, it is 9: 1 that this beam splitter 1-1 adopts splitting ratio, the output light that wherein ratio is 9 continues to propagate along time delay optical fiber 4, until light path adapter 1-2, and the output light that export ratio is 1 enters first sensor 2-1, sensor 2-1 adopts Michelson interferometer structure, arm is poor is 5m, 3m long optical fibers on arm of this interferometer is wound on the elastic body of elastomeric material, elastic body is close to duct wall, employing protective cover is fixed, beam splitter 12 in light path adapter 1-2 adopts the splitting ratio of 8: 1, the output light that wherein ratio is 8 continues to be transmitted to next light path adapter along time delay optical fiber, and the output light that export ratio is 1 enters second sensor 2-2, it is poor at 7.5m that this sensor adopts equally Michelson interferometer structure and controls interferometer arm, the optical fiber that 3m on an arm is long is wound on the elastic body of elastomeric material, and elastic body is close to duct wall and is fixed, by that analogy, all the other sensor brachium difference Wei 10m, 12.5m, 15m, beam splitter splitting ratio in corresponding adapter is respectively 7: 1,6: 1,5: 1,4: 1,3: 1,2: 1,1: 1, and during to last sensor, laser directly enters sensor after time delay optical fiber, the output of sensor (2-1) in first sensor group-(2-4) is connected with a passback optical fiber with the bundling device in front four adapters respectively, the splitting ratio of 4 bundling devices is respectively 4: 1,3: 1,2: 1,1: 1, the input end that each sensor is all 1 with bundling device ratio is connected, sensor 25 outputs connect passback optical fiber, and then connect the bundling device in the 4th adapter, similarly, the arm length difference of five sensors in second sensor group is respectively 5m, 7.5m, 10m, 12.5m, 15m, same bundling device and another root passback optical fiber passing through in adapter is connected, and bundling device splitting ratio is respectively 4: 1,3: 1,2: 1,1: 1, two sensor groups are used two passback optical fiber to be connected with two ALT-CH alternate channels of photoelectric conversion module respectively altogether,
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; Modulation signal that light source adds is the sawtooth signal of frequency 10kHz, amplitude ± 1.4V, and the interference signal frequency spectrum of sensor group output is mainly made up of 40kHz, 60kHz, 80kHz, 100kHz, five spectral lines of 120kHz; Use respectively centre frequency for 40kHz, 60kHz, 80kHz, 100kHz, 120kHz, bandwidth is the bandpass filter of 4.5kHz interference signal is carried out to filtering, obtain the carrier signal of five sensors, corresponding predominant frequency is respectively 40kHz, 60kHz, 80kHz, 100kHz, 120kHz; Five carrier signals are used with cosine and sinusoidal signal frequently and carry out demodulation, obtain the leakage vibration wave signal of five sensors;
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 condition unit, signal gathering unit, processing unit, terminal show and external interface, and processing unit comprises identification 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 to demultiplexing to processing unit and demodulation obtains original vibration wave signal, then in identification circuit and positioning circuit, carry out respectively leakage signal identification and the location of leakage point; Processing unit output has display terminal and external interface;
Wherein as shown in figure 18, it is mainly made up of operational amplifier U14, photoelectric diode U15 conditioning unit 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;
As shown in figure 19, it is mainly made up of digital signal processor U1B and peripheral circuit identification circuit in processing unit, and the NC1-NC15 pin of U1B is unsettled; AVDD, AGND are analog power input, and AVDD connects 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 respectively the transmission for data with DR0PRI, RSCLK0, the RFS0 of positioning circuit digital signal processor U10; DAI9-DAI20 is expansion interface; DPI9, DPI10 connect external interface circuit; Wherein, digital signal processor U1B selects ADSP-21369;
Positioning circuit in processing unit as shown in Figure 6, it is mainly made up of digital signal processor U10 and peripheral circuit and interface, DR0PRI, RSCLK0, the RFS0 of U10 are connected and are used for receiving data with DAI1, DAI3, the DAI4 of identification circuit digital signal processor U1B respectively, RX, TX, MOSI, MISO, SCK connect display terminal interface, and TCK, TDO, TDI, TMS, TRST#, EMU# are debugging interface; Wherein digital signal processor U10 selects BF561.
Described sensor construction I type, as Figure 10, is made up of elastic cylinder 12 and sensor fibre 13; While installing and using on pipeline, elastic cylinder is attached on natural gas line; Sensor construction II type is as Figure 11, be made up of sensor fibre 13, fiber management tray 10 and flexure strip 14, production method forms according to the form coiling of Figure 11, when installation, sticks on and digs the pipe surface of opening anticorrosive coat by adhesive glue, mounting means as shown in Figure 12, is realized picking up pipeline body vibration;
The concrete installation method of this system Fibre Optical Sensor is as shown in Figure 13,14: first, the natural gas line external coating 18 of cleaning sensing installation region, removes the original anticorrosive coat of pipe surface and slightly polish, until expose smooth steel pipe walls 19; Then, evenly smear tackifier at outer surface of steel tube, together with Fibre Optical Sensor 15 bottoms are pressed on outer surface of steel tube 19, until tackifier solidifies completely; Then Fibre Optical Sensor guard shield 16 is covered to Fibre Optical Sensor 15 completely, and pad betwixt upper vibration damping interlayer, the cable groove that goes out of Fibre Optical Sensor guard shield 16 sides is tackled transmission cable 11 positions on quasi-fiber sensor when mounted; Finally carry out gluing and preservative treatment at Fibre Optical Sensor guard shield 16 with pipeline joint-seam place, use the material identical with natural gas line surface coating to carry out therebetween, finally make Fibre Optical Sensor entirety and pipe surface anticorrosive coat slitless connection.
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, and can realize more accurately the location of leakage point in conjunction with vibration wave in ducted velocity of propagation.
This example is through test of many times, by being installed on duct wall, leakage vibration sensing interferometric sensor can realize the monitoring to any disturbance behavior along pipe transmmision, through realizing incident of leakage reported to the police and provided leakage point position signal analysis and processing and Intelligent Recognition, system sensitivity is high, by the Intelligent Recognition of leaking has been reduced to the system false alarm rate that incident causes largely.
Claims (9)
1. the natural gas line leakage system based on Fibre Optical Sensor, it 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, adjacent multiple Fibre Optical Sensors form a Fibre Optical Sensor group, each Fibre Optical Sensor group shares a launching fiber and is connected with light source, and each Fibre Optical Sensor group is used a passback optical fiber to be connected with photodetector; Photodetector output connects the signals collecting and the processing module that comprise leakage signal identification and state event location function, and signals collecting and processing module output connect microcomputer by external interface;
Send laser by light source, after realizing beam splitting, transmission light path 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 modulation input connects the D/A output in modulation signal generation module, and modulation signal generation module 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;
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 natural gas line leakage system based on Fibre Optical Sensor 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, adjacent multiple Fibre Optical Sensors are 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, the finally photoelectric conversion module to monitoring system through the passback optical fiber transmission of corresponding sensor group,
The set of described light path adapter beam splitter and combiner device; What launching fiber used from passback optical fiber 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.
3. a kind of natural gas line leakage system based on Fibre Optical Sensor according to claim 1, it is characterized in that described signals collecting and processing module comprise that signal condition unit, signal gathering unit, processing unit, terminal show and external interface, processing unit comprises identification 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 to demultiplexing to processing unit and demodulation obtains original vibration wave signal, then in identification circuit and positioning circuit, carry out respectively leakage signal identification and the location of leakage point; Processing unit output has display terminal and external interface.
4. a kind of natural gas line leakage system based on Fibre Optical Sensor according to claim 3, 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.
5. a kind of natural gas line leakage system based on Fibre Optical Sensor according to claim 3, it is characterized in that described processing unit comprises identification circuit and positioning circuit, wherein identification circuit is made up of digital signal processor U1B and peripheral circuit, and the NC1-NC15 pin of U1B is unsettled; AVDD, AGND are analog power input, and AVDD connects 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 respectively the transmission for data with DR0PRI, RSCLK0, the RFS0 of positioning circuit digital signal processor U10; DAI9-DAI20 is expansion interface; DPI9, DPI10 connect external interface circuit; Positioning circuit is mainly made up of digital signal processor U10 and peripheral circuit and interface, DR0PRI, RSCLK0, the RFS0 of U10 are connected and are used for receiving data with DAI1, DAI3, the DAI4 of identification circuit digital signal processor U1B respectively, RX, TX, MOSI, MISO, SCK connect display terminal interface, and TCK, TDO, TDI, TMS, TRST#, EMU# are debugging interface.
6. a kind of natural gas line leakage system based on Fibre Optical Sensor according to claim 1, is characterized in that the structure of described Fibre Optical Sensor is divided into the I type structure of test tube road radial vibration signal and the II type structure of survey Axial Vibration of Straight Pipes signal; The Fibre Optical Sensor I type structure of test tube road radial vibration signal comprises: elastic cylinder, fibre optic interferometer and tail fiber coiling box; Wherein, the interference arm of uniform sequential winding optical fiber interferometer in elastic cylinder periphery, and optical fiber and right cylinder are bonded together with bonding agent, after being wound around, remaining fibre optic interferometer and related device thereof are by neat being coiled in tail fiber coiling box; Tail fiber coiling box is fixed on elastic cylinder top by bonding agent; Described elastic cylinder bottom indent, and radian is consistent with pipeline external surface; The Fibre Optical Sensor II type structure of surveying Axial Vibration of Straight Pipes signal is made up of rectangle flexure strip, fibre optic interferometer and tail fiber coiling box; On rectangle flexure strip, the fiber optic interferometric arm of fibre optic interferometer is evenly laid with sinusoidal wave shape, and optical fiber is close on rectangle flexure strip with bonding agent, remaining fibre optic interferometer and related device thereof are by neat being coiled in tail fiber coiling box; Tail fiber coiling box is fixed on above rectangle flexure strip by bonding agent; Described rectangle flexure strip is a bottom indent and the radian steel sheet consistent with pipeline external surface.
7. a kind of natural gas line leakage system based on Fibre Optical Sensor according to claim 1, the theory diagram that it is characterized in that described path multiplexing structure is: the modulation signal effect that dedicated modulation signal generating module is sent connects modulation of source input, light source output connects launching fiber, launching fiber is connected in series multiple light path adapters, each light path adapter connects a Fibre Optical Sensor by an optical fiber, multiple Fibre Optical Sensors are a Fibre Optical Sensor group, the Fibre Optical Sensor of each Fibre Optical Sensor group is respectively connected to photodetector by a passback optical fiber again by an optical fiber and after connecing, photodetector output connects signals collecting and processing module.
8. an installation method for the natural gas line leakage system based on Fibre Optical Sensor as claimed in claim 1, is characterized in that the installation of Fibre Optical Sensor mainly comprises Fibre Optical Sensor, sensor shield two parts; The I type structured optical fiber sensor of test tube road radial vibration signal all becomes sensor global design a bottom indent and the radian a kind of structure consistent with pipeline external surface with the II type structured optical fiber sensor of surveying Axial Vibration of Straight Pipes signal; Sensor shield is inner with vibration damping protective seam; Before sensor installation, need the anticorrosive coat of the natural gas line outside surface of respective regions to remove totally, expose steel tube surface, when installation, use tackifier that sensor body is bonded on pipeline outer wall; Afterwards sensor shield is covered on to sensor body outside, drawn from the cable groove that goes out of sensor shield bottom by the transmission cable of drawing in sensor body, finally use tackifier to carry out gluing at the seam crossing of guard shield and pipeline, and do corresponding pipeline corrosion protection processing, make itself and pipe surface anticorrosive coat slitless connection.
9. the installation method of a kind of natural gas line leakage system based on Fibre Optical Sensor according to claim 8, it is characterized in that concrete installation method is: first, the natural gas line external coating (18) of cleaning sensing installation region, remove the original anticorrosive coat of pipe surface and slightly polish, until expose smooth steel pipe walls (19); Then, evenly smear tackifier at outer surface of steel tube, together with Fibre Optical Sensor (15) bottom is pressed on steel pipe walls (19), until tackifier solidifies completely; Then Fibre Optical Sensor guard shield (16) is covered to Fibre Optical Sensor (15) completely, and padding betwixt upper vibration damping interlayer, the cable groove that goes out of Fibre Optical Sensor guard shield (16) side is tackled transmission cable (11) position on quasi-fiber sensor when mounted; Finally carry out gluing and preservative treatment at Fibre Optical Sensor guard shield (16) with pipeline joint-seam place, use the material identical with natural gas line surface coating to carry out therebetween, finally make Fibre Optical Sensor entirety and pipe surface anticorrosive coat slitless connection.
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| CN202252869U (en) * | 2011-09-14 | 2012-05-30 | 中国石油天然气集团公司 | Natural gas pipeline leakage monitoring system based on fiber sensing |
| CN102997062A (en) * | 2011-09-14 | 2013-03-27 | 中国石油天然气集团公司 | Optical fiber sensor-based natural gas pipeline leakage monitoring method and system and installation method for system |
| CN102997051A (en) * | 2011-09-14 | 2013-03-27 | 中国石油天然气集团公司 | Optical fiber sensor-based natural gas pipeline leakage monitoring method and system |
| CN102997061A (en) * | 2011-09-14 | 2013-03-27 | 中国石油天然气集团公司 | Optical fiber sensor-based natural gas pipeline leakage monitoring system |
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Effective date of registration: 20170315 Address after: 100007 Beijing, Dongzhimen, North Street, No. 9, No. Patentee after: China National Petroleum Corporation Patentee after: China Petroleum Pipeline Bureau Engineering Co., Ltd. Address before: 100007 Dongcheng District, Dongzhimen, China, North Street, No. 9 Oil Mansion, No. Patentee before: China National Petroleum Corporation Patentee before: China Petroleum and Natural Gas Pipeline Bureau |