CN102628885A - Multi-closed-loop optical fiber mutual inductor with plurality of analog-to-digital conversion units - Google Patents
Multi-closed-loop optical fiber mutual inductor with plurality of analog-to-digital conversion units Download PDFInfo
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Abstract
The invention provides an optical fiber mutual inductor. The optical fiber mutual inductor comprises a light source, an optical device integrated component, a sensing head, a photoelectric detector, an amplification filtering unit and a signal processing unit. The optical fiber mutual inductor improves the measuring range and the linearity of the optical fiber mutual inductor by a multi-closed-loop control method and reduces measuring error and angular difference so as to simplify the structure of the optical fiber mutual inductor and effectively improve reliability, stability and detection accuracy.
Description
Technical field
The present invention relates to the optical fiber mutual inductor, relate in particular to optical fiber current mutual inductor or Fiber-Optic Voltage with a plurality of moduluses (AD) converting unit.
Background technology
Traditional current transformer or voltage transformer (VT) all are to adopt electromagnetic induction principle, and its sensing unit is coil and iron core.Continuous transformation and progress along with electric system; Especially strong intelligent grid construction, traditional mutual inductor has exposed a series of major defects: insulation difficulty, ferromagnetic resonance and the saturated hidden danger of magnetic hysteresis are arranged, volume is big, cost is high, can not survey direct current and analog quantity output or the like.
In the last few years, the full optical-fiber current or the voltage transformer (VT) technology that grow up based on Fibre Optical Sensor and optical fiber transmission technique were constantly progressive, had possessed the condition of applying gradually.It adopts magneto-optic Faraday effect and Pockels (Pockels) electrooptical effect principle, through measuring the variation of two bundle polarized light phase differential, records electric current to be measured and voltage swing indirectly.
But the optical fiber mutual inductor is (according to the difference of measuring object; Can be divided into optical fiber current mutual inductor or Fiber-Optic Voltage) in light signal sensing and transmission medium all be optical material (optical fiber or crystal); Very easily receive the interference of environmental factor; Therefore possibly increase compensation tache in the back end signal processing links, the structure of whole like this mutual inductor and signal processing flow are complicated, cause and produce inconvenience.
In addition, in order to improve the mutual inductor operational reliability, also be necessary the signal Processing scheme of unimodular number converting unit (hereinafter abbreviates AD conversion unit as AD) is improved.
In addition, output has also proposed the standard interface requirement to the numeral of optical fiber current mutual inductor in strong intelligent grid construction, the scheme of also the signal processing unit and the data acquisition unit of optical fiber current mutual inductor not carried out integrated design in the prior art.
Above-mentioned existing fibre optic current sensor technology is referring to CN100575959C, CN101299147B, CN101364475B, CN101521104B, CN101692401B, CN101915866A, CN101957395A, CN102087307A, CN102082606A etc.
The objective of the invention is to the following aspects: the structure of one, simplifying the optical fiber mutual inductor; Two, effectively improve the reliability and stability of optical fiber mutual inductor; Three, improve the accuracy (the accuracy of measurement higher position is that measuring error is little) that the optical fiber mutual inductor detects; Four, through the control mode of many closed loops, (linearity, that is, calibration curve is near the degree of agreement of regulation straight line to improve the measurement range, the linearity of optical fiber mutual inductor.Also can be described as under rated condition the number percent of maximum deviation between sensor calibration curve and fitting a straight line and full scale output.) and reduce measuring error (such as, ratio (be ratio error, the relative error of measured value and actual value is called ratio) and angular difference (be phase angle error, refer to the phase differential between measured value and the true primary current)); Five, improve the accuracy that feeble signal is measured.
Summary of the invention
For simplified system and effective system reliability that improves, be necessary to carry out integrated design to the signal processing unit and the data acquisition unit of mutual inductor.
For the responsive ability of the small-signal that improves the optical fiber mutual inductor, improve accuracy of measurement and the measurement range that enlarges mutual inductor simultaneously, the present invention proposes a kind of analog closed-loop input scheme and a kind of digital closed loop input scheme of optical fiber mutual inductor.No matter be analog closed-loop or digital closed loop, all the signal processing unit at the optical fiber mutual inductor adopts many technology of closed loop.3 closed loops of general design: first closed loop is the bias modulation and the feedback closed loop technology of two bundle cross polarization light, relates generally to ± pi/2 bias modulation technology and staircase waveform feedback technique; Second closed loop is the automatic correction technology of closed loop to the drift of optical phase modulator half-wave voltage; The 3rd closed loop is at first to detect the signal strength information that photo-detector is brought in the signal Processing link, is used for light source driven revising, and goes out the technology of closed loop of luminous power with stabilized light source.
Optical fiber mutual inductor of the present invention both can be used for analog closed-loop control, also can be used for digital closed loop control.In order effectively to improve the system stability and the operation stability of optical fiber mutual inductor, under the situation of analog closed-loop control, two AD are set in signal processing unit, under the situation of digital closed loop signal controlling, two AD are set in signal processing unit also.
In analog closed-loop control, the effect of two AD is identical, all is that the output signal to the signal processing unit in the analog closed-loop carries out digital quantization, quantized result feed signals output module MU (merge cells).In MU, generally should be identical from the data of two AD, bigger if any difference or difference, promptly be regarded as exporting fault, provide warning message afterwards.
In digital closed loop control; The effect of two AD is simultaneously the simulating signal of sending here to be quantized; Their effect is different; Resolve link at follow-up signal the output of one of them AD extracted in order to the information as closed-loop control, and to the output of another AD extract in order to by way of compensation with the information of revising.
In view of the foregoing; The present invention provides a kind of optical fiber mutual inductor; Comprise light source, optical device integrated package, sensing head, photodetector, amplification filtering unit, signal processing unit, comprise phase-modulator and beam split splicer spare in the said optical device integrated package; Said optical device integrated package plays the light of light source output and is two bunch polarized lights partially and transfers to sensing head through beam split splicer spare; Reception interferes in said phase-modulator from light and the feasible light that returns that sensing head returns; Result of interference is outputed to photodetector; Reception is from the feedback modulation intelligence of signal processing unit; Said photodetector receives the light signal output of optical device integrated package, utilizes photoelectric effect to convert light signal into electric signal, and electric signal is outputed to signal processing unit; Receive the signal of the output of photodetector in the said signal processing unit, said signal is handled, and signal processing results is fed back to said optical device integrated package as the feedback modulation intelligence.
According to another implementation of the invention; Also comprise the light source driving units and second photodetector in the said optical fiber mutual inductor; The input end of second photodetector connects the output terminal of the beam split splicer spare in the optical device integrated package, and the output terminal of second photodetector is connected to the input end of light source driving units; Wherein second photodetector detects the light signal of beam split splicer spare output, and converts the control information of electric signal afterwards into through opto-electronic conversion, thereby regulates the output of light source driving units.
According to another implementation of the invention, said signal processing unit comprises: analog controlling unit, an AD converting unit, the 2nd AD converting unit and merge cells; The output of said photodetector is input to the analog closed-loop control module through after the amplification filtering unit amplification filtering; Said analog closed-loop control module is modulated the simulating signal of input; Thereby obtain exporting simulating signal; And will export simulating signal and output to an AD converting unit, the 2nd AD converting unit respectively; An AD converting unit, the 2nd AD converting unit output to merge cells with transformation result respectively then, then by merge cells to said optical fiber mutual inductor external output signal.
According to another implementation of the invention, judge by merge cells whether the data that an AD converting unit and the 2nd AD converting unit export respectively are distinct,, then send warning message if exist.
According to another implementation of the invention, said signal processing unit comprises: the 3rd AD converting unit, the 4th AD converting unit, digital closed loop signal processing unit, merge cells; The output of said photodetector is through after the amplification filtering unit amplification filtering; The simulating signal that obtains is outputed to the 3rd AD converting unit, the 4th AD converting unit respectively, and the 3rd AD converting unit, the 4th AD converting unit output to the digital closed loop signal processing unit respectively with result then; After the digital closed loop signal processing unit resolves the output result of the 3rd AD converting unit, the 4th AD converting unit; Feed back to light source driving units and optical device integrated package respectively, thereby the driving light source driver element controls and drives phase-modulator in the optical device integrated package so that the phase place of two bundle cross polarization light is modulated to light source; The digital closed loop signal processing unit outputs to merge cells with result, then by merge cells to said optical fiber mutual inductor external output signal.
According to another implementation of the invention; The 3rd AD converting unit, the 4th AD converting unit quantize said simulating signal simultaneously; The output of extracting the 3rd AD converting unit is as closed-loop control information, and the output of extracting the 4th AD converting unit by way of compensation and update information.
Shown in accompanying drawing, according to the detailed description of hereinafter to preferred forms, disclosed by the invention these will be more obvious with other purposes, feature and advantage.
Description of drawings
Fig. 1 is the theory structure synoptic diagram of an embodiment of optical fiber mutual inductor of the present invention;
Fig. 2 is the theory structure synoptic diagram of another embodiment of optical fiber mutual inductor of the present invention;
Fig. 3 is the principle assumption diagram of the multiple mode of optical device integrated package;
Fig. 4 is the structural drawing of an embodiment that is used for two AD optical fiber mutual inductors of analog closed-loop control;
Fig. 5 is the structural drawing of an embodiment that is used for two AD optical fiber mutual inductors of digital closed loop control;
Fig. 6 is the example structure figure that middle digital closed loop embodiment illustrated in fig. 5 and corrected signal are handled;
Fig. 7 is the signal modulation waveform synoptic diagram that is used for an embodiment of analog closed-loop control;
Fig. 8 is the signal modulation waveform synoptic diagram that is used for an embodiment of digital closed loop control.
Embodiment
Fig. 1 is the principle of work structural drawing of an embodiment of optical fiber mutual inductor involved in the present invention.The optical fiber mutual inductor comprises light source driving units, light source, optical device integrated package, sensing head, photodetector, amplification filtering unit, signal processing unit.According to one embodiment of present invention, the beam split splicer spare in the optical device integrated package adopts 2 * 2 coupling mechanisms.The structure of optical device integrated package will be described in detail hereinafter.
As shown in Figure 1, the output terminal of light source driving units is connected to light source, and light source is driven, and makes the light source operate as normal.The output terminal of light source is connected to 2 * 2 coupling mechanisms in the optical device integrated package; The effect of 2 * 2 coupling mechanisms is that the light that light source sends is divided into two light path outputs, and one of them output terminal of 2 * 2 coupling mechanisms is connected to other device in the optical device integrated package.2 * 2 coupling mechanisms are also accepted the back light information from the optical device integrated package, and it is coupled into photodetector, and photodetector is transformed into voltage signal with the light signal of light path system result of interference.The output terminal of optical device integrated package is connected to sensing head, and the sensing head effect is to be measured between two bundle polarized lights, to form phase differential through sensitivity.Because sensing head belongs to prior art, those skilled in the art can adopt multiple mode to realize according to actual conditions.
The output terminal of photodetector is connected to the amplification filtering unit, and the amplification filtering unit carries out computing amplification and Filtering Processing to photodetector output signal.The output terminal of amplification filtering unit is connected to signal processing unit.Signal processing unit is with the output of result feedback, thus the phase-modulator in the driving optical device integrated package, between two bundle cross polarization light, to introduce square wave bias modulation phase place and the modulation compensated phase place of feedback.Signal after signal processing unit will be handled is measured the result as mutual inductor simultaneously, exports according to predetermined format.The effect of optical device integrated package can realize effects such as branch actinic light, light play partially, light beam splitting, optically-coupled, optical modulation, and hereinafter will be described in detail the optical device integrated package.
According to one embodiment of present invention, the optical device integrated package is used to receive the light of light source output, and plays this light of light source output and be biased into linearly polarized light, is decomposed into this linearly polarized light two bunch polarized lights of orthogonal mode immediately again; In the optical device integrated package; Shake above-mentioned two bunch polarizations and be optically coupled on two orthogonal modess of same polarization maintaining optical fibre; Be the optical device integrated package see two bundle orthogonal modes off linearly polarized light along two orthogonal modes fl transmission of same polarization maintaining optical fibre to sensing head; And receiving the light beam that this two bunch polarized light returns along the original optical path modes swap subsequently after the responsive Faraday magnetooptical effect in sensing head place, the two-beam line that returns interferes in the optical device integrated package; The optical device integrated package also is used for the result of interference of two bunch polarized lights is outputed to photodetector through optical fiber; In addition, the optical device integrated package is accepted the feedback modulation intelligence from signal processing unit, with stack ± pi/2 bias modulation phase place between two bunch polarized lights and the phase difference that causes with measured physical quantity
FEqual and opposite in direction, feedback phase modulation φ in the opposite direction
R
Particularly, referring to Fig. 3, provided the numerous embodiments that realizes the optical integrated device assembly.The optical device integrated package is mainly realized several kinds of functions such as branch actinic light, light rise partially, polarized light decomposition, optically-coupled, light phase modulation.The optical device integrated package can have multiple embodiment.
Fig. 3 is the structural drawing of a plurality of embodiments of optical device integrated package among Fig. 1.
Shown in Fig. 3 (a), the optical device integrated package comprises beam split splicer spare, polarization maintaining optical fibre, optical phase modulator, light delay device.Except the sensing head part, the light path scheme of optical fiber current mutual inductor is an all risk insurance folk prescription case in this scheme, and promptly all optical fiber and device tail optical fiber all are polarization maintaining optical fibres.The linearly polarized light that sends in high polarisation source transmits in same polarization maintaining optical fibre through the 45 of tail optical fiber welding is divided into orthogonal mode to axle two bunch polarized light X, Y after through beam split splicer spare; Behind optical phase modulator and light delay device (light delay device itself can be extremely one section polarization maintaining optical fibre of thousands of meters of a hop count rice), then two orthogonal modess along same polarization maintaining optical fibre transfer to sensing head.After returning from sensing head, this two-beam modes swap is passed through optical phase modulator once more, reaches 45 ° of weld places and satisfies interference condition, interferes, and result of interference is coupled into photodetector through beam split splicer spare.
Shown in Fig. 3 (b), the optical device integrated package comprises beam split splicer spare, polarization maintaining optical fibre, the light polarizer, optical phase modulator, light delay device.Behind the light process beam split splicer spare and the light polarizer that light source sends; Welding is divided into orthogonal mode to axle two bunch polarized light X, Y transmit in same polarization maintaining optical fibre through the 45 of protecting inclined to one side tail optical fiber; Behind optical phase modulator and light delay device (light delay device itself can be extremely one section polarization maintaining optical fibre of thousands of meters of a hop count rice), then two orthogonal modess along same polarization maintaining optical fibre transfer to sensing head.After returning from sensing head, this two-beam modes swap is passed through optical phase modulator once more, reaches 45 ° of weld places and satisfies interference condition, interferes, and result of interference is coupled into photodetector through the light polarizer and beam split splicer spare.
Shown in Fig. 3 (c), the optical device integrated package comprises the first beam split splicer spare, polarization maintaining optical fibre, Y type optical phase modulator, the second beam split splicer spare, light delay device.The light that light source sends arrives Y type optical phase modulator behind the first beam split splicer spare.Y type optical phase modulator has that light rises partially, the function of light beam splitting, optical modulation.Y type optical phase modulator belongs to prior art, no longer details.At Y type optical phase modulator place, light reaches the second beam split splicer spare along its two tail optical fiber propagated forward respectively after being played partially and be divided into the identical linearly polarized light of two bundle polarization modes.Before this; Tail optical fiber through Y type optical phase modulator and 90 ° of angles of a tail optical fiber of the second beam split splicer spare make above-mentioned two bunch polarized lights from the second beam split splicer spare, come out orthogonal mode ground, back along same polarization maintaining optical fibre propagated forward to the axle welding.Likewise; The polarized light of this two bundles orthogonal mode returns and through behind the second beam split splicer spare from sensing head; Again because the welding to axle at above-mentioned 90 ° of angles becomes two identical bunch polarized lights of pattern; And interfere at Y type optical phase modulator place, result of interference is coupled into photodetector through the first beam split splicer spare.
Shown in Fig. 3 (d), the optical device integrated package comprises the first beam split splicer spare, polarization maintaining optical fibre, Y type optical phase modulator, the second beam split splicer spare, light delay device.The light that light source sends arrives Y type optical phase modulator behind the first beam split splicer spare; At Y type optical phase modulator place; Light reaches the second beam split splicer spare along its two tail optical fiber propagated forward respectively after being played partially and be divided into the identical linearly polarized light of two bundle polarization modes.Second beam split splicer spare can assemble the linearly polarized light of the identical polarization mode in two tail optical fibers of forward path two bunch polarized lights of orthogonal mode and protect inclined to one side tail optical fiber continuation propagated forward along same; Two bunch polarized light of protecting orthogonal mode in the inclined to one side tail optical fiber in the backward channel can also be changed into two bunch polarized lights of model identical; And propagate along its two backward channel tail optical fibers respectively, promptly can be the polarization angle half-twist of a branch of polarized light in the two bundle polarized lights of propagating therein.Above-mentioned two bunch polarized lights come out orthogonal mode ground, back along same polarization maintaining optical fibre propagated forward from the second beam split splicer spare.Likewise; The polarized light of this two bundles orthogonal mode returns and through behind the second beam split splicer spare from sensing head; Change two identical bunch polarized lights of pattern again into, and interfere at Y type optical phase modulator place, result of interference is coupled into photodetector through the first beam split splicer spare.
More than listed the several specific embodiments that to realize in this patent, but any design that can realize above-mentioned functions is all within the protection domain of this patent about the optical device integrated package.
Optical fiber mutual inductor of the present invention adopts phase modulation-type light path scheme; It utilizes magneto-optic faraday (Faraday) effect or electric light (Pockels) Pockels effect; Through detecting two bundle polarized lights of orthogonal mode in the same optical fiber; Because magnetic field around the responsive electric current or the electric field around the voltage, the phase differential that is produced to measure indirectly current value or magnitude of voltage on the bus.
Particularly; During this optical fiber mutual inductor work; The light source driving units driving light source is luminous, light via the optical device integrated package after, form two bunch polarized lights of orthogonal mode; Two bunch polarized lights are along same polarization maintaining optical fibre (part between optical device integrated package and the sensing head), transfer to sensing head according to two pattern X, Y of orthogonal directions.
Two restraint polarized lights because responsive faraday (Faraday) magneto-optic effect or Pockels (Pockels) electrooptical effect form phase differential, and after modes swap, return along original optical path.Finally; The two-beam that carries Faraday effect phase information or Pockels effect phase information interferes in the optical device integrated package; Be coupled into photodetector by beam split splicer spare then; Result of interference converts electrical information into through photodetector, after the amplification filtering cell processing, gets into signal processing unit afterwards and carries out the follow-up signal processing.The reflection of above-mentioned sensing head and light, detection all belong to existing fiber mutual inductor technology, and this paper is not described in detail.
According to another embodiment of the invention, referring to optical fiber mutual inductor shown in Figure 2.This optical fiber mutual inductor comprises light source driving units, light source, optical device integrated package (wherein containing beam split splicer spare, such as 2 * 2 coupling mechanisms), first photodetector, second photodetector, amplification filtering unit, signal processing unit, sensing head.
As shown in Figure 2, the optical fiber mutual inductor of this embodiment structurally is similar to optical fiber mutual inductor shown in Figure 1.Be with the difference of optical fiber mutual inductor shown in Figure 1, be provided with second photodetector in the optical fiber mutual inductor among this embodiment.The input end of second photodetector connects an output terminal of the beam split splicer spare (such as 2 * 2 coupling mechanisms) in the optical device integrated package, and the output terminal of second photodetector is connected to the input end of light source driving units.Wherein second photodetector can detect the light signals such as output intensity of beam split splicer spare (such as 2 * 2 coupling mechanisms); And through converting the control information of electric signal after the opto-electronic conversion into; Thereby light source driving units is controlled, regulated the output of light source driving units.Like this, can be under the situation that does not increase branch actinic light parts to light source output control, made full use of beam split splicer spare (such as 2 * 2 coupling mechanisms).
In addition, according to another embodiment of the invention, the output terminal of the signal processing unit among Fig. 2 also is connected to the input end of light source drive, makes signal processing unit also can carry out FEEDBACK CONTROL to light source driving units.
In addition, owing to be not limited to above-mentioned exemplary embodiment for the FEEDBACK CONTROL of light source, thereby might have multiple other exemplary embodiments.
Fig. 4 is the two AD optical fiber mutual inductor structural drawing that are used for analog closed-loop control.Fig. 4 has provided an embodiment of information process unit.Analog controlling unit among Fig. 4, an AD converting unit (A/D1), the 2nd AD converting unit (A/D 2), merge cells have constituted signal processing unit.
Wherein, the output of photodetector 1 is input to the analog closed-loop control module through after the amplification filtering unit amplification filtering.The analog closed-loop control module is modulated the simulating signal of input, thereby obtains exporting simulating signal.The output simulating signal outputs to an AD converting unit, the 2nd AD converting unit respectively, and an AD converting unit, the 2nd AD converting unit output to merge cells with result then, and merge cells is exported the result at last.
In addition, according to one embodiment of present invention, the analog closed-loop control module is also handled the simulating signal of amplification filtering unit output, obtains the FEEDBACK CONTROL simulating signal, and optical device integrated package and light source driving units are carried out FEEDBACK CONTROL respectively.
According to a specific embodiment of the present invention, the input simulating signal of the feedback element of analog closed-loop control module is as shown in Figure 7 with the output simulating signal, that is, the input simulating signal is a sawtooth wave, and the output simulating signal is a square wave.Wherein, the solid line among Fig. 7 upper waveform figure is represented t input waveform constantly, and dotted line is represented t+ τ input waveform constantly.
As shown in Figure 7, wherein simulate sawtooth wave phase place oblique wave modulation φ
PRAnd the feedback phase difference that produces is Δ φ
PRIn Fig. 7 the first half, the longitudinal axis is a phase differential, and transverse axis is the time.Solid line sawtooth wave is wherein represented t feedback sawtooth wave constantly, and the dotted line sawtooth wave is represented t+ τ feedback sawtooth wave constantly, is exactly the size of actual feedback amount in the difference in height of synchronization sawtooth wave.The latter half of Fig. 7 is corresponding with the first half, is subtracted each other by the solid line of the first half and dotted line to obtain, and its is actual, and what characterize is that sawtooth wave is in difference difference in height constantly.At periodic recessed portion, sign be the difference in height of sawtooth wave equally, just sawtooth wave is phase-accumulated to 2 π here, forms the flyback that resets, so non-highly low 2 π in the place that resets of its aspect ratio.
Because the optical fiber mutual inductor in the present embodiment is a kind of interfere type mutual inductor, its result of interference is the cosine information of phase difference
I
0＝I·(1+cpsφ) (1)
In order to improve the sensitivity of optical fiber mutual inductor, and confirm φ value symbol, between two bunch polarized lights,, make result of interference become through the square-wave frequency modulation introducing ± pi/2 phase place of setovering
Promptly can use anti-triangulo operation from following formula and calculate φ value size, and draw curtage information to be measured further.
But anti-triangulo operation is complicated, and can find out from following formula, and this moment, the measurement range of optical fiber mutual inductor received the sine function cycle limit.In order to reduce system output nonlinearity erron and to increase range of dynamic measurement, between the two-beam of transmission in opposite directions, introduce one with phase shift φ equal and opposite in direction, feedback compensation phase shift φ in the opposite direction
R, be used for offsetting the φ phase shift.Add feedback phase shift φ
RAfter, two bundle polarized light interference output informations are:
Because φ+φ
R≈ 0, so this moment, the optical fiber mutual inductor always worked in the best zero phase near zone of the linearity, it is the highest therefore to measure sensitivity, owing to realize closed loop and detect, also enlarged the measurement range of system simultaneously.Because frequency is the derivative of phase place; Phase-modulator in the utilization optical device integrated package applies phase place oblique wave modulation
(wherein
is slope), is equivalent to a frequency displacement
This sawtooth wave modulation treatment scheme allows near forward or negative sense work zero point, and this positive negative sense is relevant with the symbol of oblique wave gradient.Certainly, oblique wave can not infinitely rise, and in fact, the sawtooth wave modulation waveform must have very fast flyback time when resetting.The same with the bias modulation situation, on mutual inductor two beam reversal's wave travels, apply same phase place oblique wave feedback modulation φ
PR(t), postpone τ owing to exist, it is poor to produce a feedback phase:
Δφ
PR(t)＝φ
PR(t)-φ
PR(t-τ) (5)
During oblique wave, following formula equals
And in the incident τ after flyback, following formula equals
φ
RSIt is the height that phase place resets.
The output simulating signal is outputed to an AD converting unit and the 2nd AD converting unit respectively.In this embodiment; Owing to be applied to analog closed-loop; Therefore an AD converting unit is identical with the function of the 2nd AD converting unit, all is that the output signal to the analog closed-loop control module carries out digital quantization, and respectively the digital quantization result is sent in the merge cells.
Generally speaking, should be identical from the data of an AD converting unit and the 2nd AD converting unit, if the two data is distinct, in merge cells, promptly be regarded as exporting fault, then provide warning message when finding fault.
The effect of merge cells comprises that the output data to an AD converting unit and the 2nd AD converting unit compares, the output data of an AD converting unit and the 2nd AD converting unit is put in order packing, receives external clock instruction (such as gps clock), confirmed the sequential relationship of external command clock and optical fiber mutual inductor output data, the electric light conversion of completion output data etc. according to the specific format (such as IEC61850-9-2 stipulations, IEC60044-8 stipulations) of The profile.
In addition; Those skilled in the art all should know; According to an aspect of the present invention; Above-mentioned analog closed-loop control module, an AD converting unit, the 2nd AD converting unit, these unit of merge cells both can be used as independently circuit unit, also can be used as the integrated circuit global formation, thus easy to use or debugging.
In addition, those skilled in the art all should know, according to an aspect of the present invention; In carrying out the analog closed-loop control procedure; Can also increase more AD converting unit in the optical fiber mutual inductor, thereby obtain different deal with data, to satisfy user's specific demand for control.
In above-mentioned optical fiber mutual inductor shown in Figure 4, formed two closed loops, thereby can improve accuracy of detection, increase sensing range.
First closed loop is the bias modulation and the feedback closed loop of two bundle cross polarization light, realizes through bias modulation and signal feedback.In the embodiment shown in fig. 4, this closed loop is made up of optical device integrated package, photodetector 1, amplification filtering unit, analog closed-loop control module.
Second closed loop is the signal strength information that in signal processing unit, detects photodetector output, is used for light source driven revising, and goes out the closed loop of luminous power with stabilized light source.In the embodiment shown in fig. 4, this closed loop is made up of light source driving units, light source, optical device integrated package, photodetector 1, amplification filtering unit, analog closed-loop control module.This closed loop is used for the stable control of source device output optical power.Light source driving units provides constant current and light source is carried out temperature control to light source; Can monitor light source bright dipping watt level in real time through photodetector; And feed back to light source driving units in real time; Carry out the fine setting of light source drive current, make light source in the long-term work process, send the optical information of firm power all the time.
Fig. 5 is the two AD optical fiber mutual inductor structural drawing that are used for digital closed loop control.Provided a kind of embodiment of signal processing unit among Fig. 5.In Fig. 5, constituted signal processing unit by the 3rd AD converting unit (A/D3), the 4th AD converting unit (A/D4), digital closed loop signal processing unit, merge cells.
Wherein, The output of photodetector 1 is through after the amplification filtering unit amplification filtering; The simulating signal that obtains is outputed to the 3rd AD converting unit, the 4th AD converting unit respectively, and the 3rd AD converting unit, the 4th AD converting unit output to the digital closed loop signal processing unit respectively with result then.
Fig. 6 is that two AD digital closed loops and corrected signal are handled block diagram.Provided a kind of embodiment of digital closed loop signal processing unit among Fig. 5 among Fig. 6.In Fig. 6, the square frame of dotted line is the digital closed loop signal processing unit.Wherein the output of the 3rd AD converting unit is carried out demodulation through signal demodulation unit, and the signal after the demodulation is transferred to the integral unit that adds up, and outputs to filter unit through the signal after the integration that adds up again and carries out filtering.And the output of the 4th AD converting unit obtains update information through resolving, and utilizes this update information to carrying out correcting process through the signal after the filtering unit filters, the output correction result then.As shown in Figure 6, realize main closed loop input loop with the 3rd AD converting unit, use and the 4th AD converting unit is resolved the update information that obtains the testing result in main closed loop loop is revised.The digital closed loop signal processing unit resolves the output result of the 3rd AD converting unit, the 4th AD converting unit; Resolve the result through after the digital-to-analog conversion; Feed back to light source driving units and optical device integrated package respectively, thereby the driving light source driver element controls and drives phase-modulator in the optical device integrated package so that the phase place of two bundle cross polarization light is modulated to light source.The digital closed loop signal processing unit outputs to merge cells with result, and merge cells is exported the result at last.In addition,, do not draw D/A conversion unit and auxiliary circuit thereof in the digital closed loop signal processing unit among Fig. 6, do not draw the feedback signal of digital closed loop signal processing unit yet light source driving units in order to give top priority to what is the most important.Those skilled in the art can realize D/A conversion unit and auxiliary circuit thereof with multiple embodiment, thereby light source driving units and optical device integrated package are carried out FEEDBACK CONTROL that this paper repeats no more fully according to instruction of the present invention.
The 3rd AD converting unit, the 4th AD converting unit quantize the simulating signal of sending here simultaneously; But their effect is generally different; In follow-up signal processing; Generally extract the information of the output of one of them AD converting unit, and extract the information of the output of another AD converting unit as compensation and correction as closed-loop control.
The effect of merge cells comprises the output signal that receives the digital closed loop signal processing unit, and this output data is put in order packing, receives external clock instruction (such as gps clock), confirmed the sequential relationship of external command clock and optical fiber mutual inductor output data, the electric light conversion of completion output data etc. according to the specific format (such as IEC61850-9-2 stipulations, IEC60044-8 stipulations) of The profile.Those skilled in the art all should know, and merge cells can be realized through the prior art mode.
According to a specific embodiment of the present invention, except that the square wave bias modulation signal, the staircase waveform feedback signal of digital closed loop signal processing unit is as shown in Figure 8, that is, modulation input number word signal is a staircase waveform.Wherein, the solid line among Fig. 8 upper waveform figure is represented t input waveform constantly, and dotted line is represented t+ τ input waveform constantly.
As shown in Figure 8, adopt the modulation of staircase waveform feedback to produce feedback phase difference φ
RThe said signal of formula (3) is carried out demodulation, and method is to get before and after it semiperiod information according to demodulation principle to subtract each other, and then to the demodulation result integration that adds up, forms the bench height So of digital staircase waveform.So does not show in Fig. 8 that it is an intermediate quantity, and it becomes voltage signal after through digital-to-analog conversion, drives the phase-modulator in the optical device integrated package afterwards, obtains modulation result as shown in Figure 8.Then So is further carried out accumulating operation.Specific algorithm is: every add up 1 time at a distance from the τ time, τ be two bundle polarized lights from being separated into the time of being experienced when finally interfering, also be the eigenperiod of optical fiber mutual inductor, thereby form digital staircase waveform.
So forms the phase-modulator in the analogue step ripple rear drive optical device integrated package through digital-to-analog conversion in the digital closed loop signal processing unit and auxiliary circuit (not drawing in the accompanying drawings) thereof on the one hand, differs φ between two-beam, to introduce compensation
R, So reflects the size and Orientation of curtage information to be measured as the numeral output of optical fiber mutual inductor simultaneously.
If the analogue step ripple that forms through digital-to-analog conversion is Δ V
R(t)=V
R(t)-V
R(t-τ), its codomain be (∞ ,+∞), the additional phase shift that then between two bunch polarisations, produces is:
φ
R＝K
fpV
R(t)-K
fpV
R(t-τ)
＝K
fp(V
R(t)-V
R(t-τ))
＝K
fpΔV
R(t) (6)
τ is the transit time of light beam in fibre delay line in the formula, K
FpIt is the phase-modulator index of modulation.
As shown in Figure 8, in Fig. 8 the first half, the longitudinal axis is a phase differential, and transverse axis is the time.Solid line staircase waveform is wherein represented t feedback staircase waveform constantly, and the dotted line staircase waveform is represented t+ τ feedback staircase waveform constantly.The size of the bench height actual feedback amount of staircase waveform.FW (solid line) expression t feedback staircase waveform constantly, BW (dotted line) expression t+ τ feedback staircase waveform constantly.V in the following formula
R(t) expression expression t feeds back the actual voltage value of staircase waveform constantly.
Fig. 8 the latter half is corresponding with the first half, is subtracted each other by the solid line of the first half and dotted line to obtain, and its is actual, and what characterize is the bench height of staircase waveform.At periodic recessed portion, sign be the height value of staircase waveform equally, just here staircase waveform phase-accumulated formation resets to 2 π, so non-highly low 2 π in the place that resets of its aspect ratio.Formula (6) explains that the phase differential that the staircase waveform modulation produces is directly proportional with the staircase waveform bench height.But, the codomain scope (∞ ,+∞) to go up the staircase waveform that constantly rises be impossible realize.Because interfering the output signal is the cycle with 2 π, so in the digital closed loop scheme, adopting shape codomain scope as shown in Figure 8 be that the staircase waveform of (0,2 π) replaces codomain for (∞ ,+∞) staircase waveform is promptly worked as staircase waveform phase modulation K
FpV
R(t)=2 automatically reset during π.Adopt this method also can not exert an influence to system accuracy.
Those skilled in the art all should know; According to an aspect of the present invention; Above-mentioned digital closed loop signal processing unit, the 3rd AD converting unit, the 4th AD converting unit, these unit of merge cells both can be used as independently circuit unit; Also can be used as the integrated circuit global formation, thus easy to use or debugging.
Those skilled in the art all should know, and according to an aspect of the present invention, in carrying out the digital closed loop control procedure, can also increase more AD converting unit in the optical fiber mutual inductor, thereby obtain different deal with data, to satisfy user's specific demand for control.In above-mentioned optical fiber mutual inductor, formed three closed loops, thereby can improve accuracy of detection, increase sensing range.
First closed loop is the bias modulation and the feedback closed loop of two bundle cross polarization light, realizes through bias modulation and signal feedback.In the embodiment shown in fig. 5, this closed loop is made up of optical device integrated package, photodetector 1, amplification filtering unit, the 3rd AD converting unit, the 4th AD converting unit and digital closed loop signal processing unit.
Second closed loop is the signal strength information that in the digital closed loop signal processing unit, detects photodetector output, is used for light source driven revising, and goes out the closed loop of luminous power with stabilized light source.In the embodiment shown in fig. 5, this closed loop is made up of light source driving units, light source, optical device integrated package, photodetector 1, amplification filtering unit, digital closed loop signal processing unit.This closed loop is used for the stable control of source device output optical power.Light source driving units provides constant current and light source is carried out temperature control to light source; Can monitor light source bright dipping watt level in real time through photodetector; And feed back to light source driving units in real time; Carry out the fine setting of light source drive current, make light source in the long-term work process, send the optical information of firm power all the time.
The 3rd ring closure is the automatic adjustment to the 2 π resetting voltages of the phase-modulator in the feedback element optical device integrated package.The feedback electrical information of signal processing unit drives the phase-modulator in the optical device integrated package, produces the feedback phase modulation.This feedback electrical information is continuous integration or add up all the time, when its modulation voltage corresponding modulating phase place that causes reaches 2 π, can reset timely.Feedback levels when usually, resetting just in time equals the half-wave voltage of phase-modulator.But in the long-time running process, the half-wave voltage of phase-modulator may change, and at this moment can bring an instant detection error, promptly should detect error through measuring in real time, revises the size of reset level immediately.
According to an aspect of the present invention, the digital closed loop signal processing unit can be realized by technology such as FPGA, DSP.
In sum; No matter be that analog closed-loop detects or digital closed loop detects; All resolve the digital output signal that link obtains to the optical fiber mutual inductor through signal and directly be sent to merge cells; By merge cells this digital output data is carried out stipulations arrangement and further electric light conversion, and combine the external clock command information, packing exports rear end equipment to.
It will be understood by those of skill in the art that in the scope and equivalency range thereof of accompanying claims,, various modifications, merging, subitem merging and variation can occur according to designing requirement and other factors.
Claims (7)
1. an optical fiber mutual inductor comprises light source, optical device integrated package, sensing head, photodetector, amplification filtering unit, signal processing unit, it is characterized in that,
Comprise phase-modulator and beam split splicer spare in the said optical device integrated package;
Said optical device integrated package plays the light of light source output and is two bunch polarized lights partially and transfers to sensing head through beam split splicer spare; Reception interferes in said phase-modulator from light and the feasible light that returns that sensing head returns; Result of interference is outputed to photodetector; Reception is from the feedback modulation intelligence of signal processing unit;
Said photodetector receives the light signal output of optical device integrated package, utilizes photoelectric effect to convert light signal into electric signal, and electric signal is outputed to signal processing unit;
Said signal processing unit receives the signal of the output of photodetector, said signal is handled, and signal processing results is fed back to said optical device integrated package as the feedback modulation intelligence.
2. optical fiber mutual inductor according to claim 1 is characterized in that, also comprises the light source driving units and second photodetector in the said optical fiber mutual inductor,
The input end of said second photodetector connects the output terminal of the beam split splicer spare in the optical device integrated package, and the output terminal of second photodetector is connected to the input end of light source driving units; Wherein second photodetector detects the light signal of beam split splicer spare output, and through converting the control information of electric signal after the opto-electronic conversion into, regulates the output of light source driving units.
3. optical fiber mutual inductor according to claim 1 and 2 is characterized in that, said signal processing unit comprises: analog closed-loop control module, an AD converting unit, the 2nd AD converting unit and merge cells;
The output of said photodetector is input to the analog closed-loop control module through after the amplification filtering unit amplification filtering;
Said analog closed-loop control module is modulated the simulating signal of input; Obtain exporting simulating signal; And will export simulating signal and output to an AD converting unit, the 2nd AD converting unit respectively; An AD converting unit, the 2nd AD converting unit output to merge cells with result respectively then, then by merge cells to said optical fiber mutual inductor external output signal.
4. optical fiber mutual inductor according to claim 3 is characterized in that, judges by merge cells whether the data that an AD converting unit and the 2nd AD converting unit export respectively are distinct, if exist, then sends warning message.
5. optical fiber mutual inductor according to claim 1 and 2 is characterized in that, said signal processing unit comprises: the 3rd AD converting unit, the 4th AD converting unit, digital closed loop signal processing unit, merge cells;
The output of said photodetector is through after the amplification filtering unit amplification filtering; The simulating signal that obtains is outputed to the 3rd AD converting unit, the 4th AD converting unit respectively, and the 3rd AD converting unit, the 4th AD converting unit output to the digital closed loop signal processing unit respectively with result then;
The digital closed loop signal processing unit carries out forming after closed loop is resolved this link output signal with the output result of the 3rd AD converting unit, the 4th AD converting unit; Feed back to light source driving units and optical device integrated package respectively; The driving light source driver element is controlled light source, and the phase-modulator in the driving optical device integrated package is to modulate the phase place of two bundle cross polarization light;
The digital closed loop signal processing unit outputs to merge cells with result, then by merge cells to said optical fiber mutual inductor external output signal.
6. optical fiber mutual inductor according to claim 5; It is characterized in that; The 3rd AD converting unit, the 4th AD converting unit quantize said simulating signal simultaneously; The output of extracting the 3rd AD converting unit is as closed-loop control information, and the output of extracting the 4th AD converting unit by way of compensation and update information.
7. according to the described optical fiber mutual inductor of claim 1-6, it is characterized in that, adopt square wave bias modulation mode introducing ± pi/2 bias modulation phase differential between two bundle cross polarization light; Adopt sawtooth wave or staircase waveform feedback system between two bundle cross polarization light, to introduce the phase information equal and opposite in direction nonreciprocal to be measured that forms with the sensing head place, phase differential in the opposite direction.
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