CN102353833B - Annular cavity all-fiber current sensor capability of eliminating temperature sensitivity - Google Patents

Abstract

The invention discloses an annular cavity all-fiber current sensor capability of eliminating temperature sensitivity. The annular cavity all-fiber current sensor comprises a signal light source, an outer modulator, a polarizer, a first coupler, a second coupler and a polarization beam splitter in sequence, wherein polarized light output by the polarization beam splitter is received by a first light intensity detector and a second light intensity detector, and is input into a data processing system; the data processing system is used for obtaining light with a deflection angle by combining two beams of polarized light, and outputting the light to the outer modulator; one port of the first coupler is connected with one port of the second coupler to constitute a 2*2 port coupler; the other ports of the first coupler and the second coupler are connected with sensing optical fibers of a first sensing optical fiber ring and a second sensing optical fiber which are arranged symmetrically respectively to form an optical fiber annular cavity; and a detected electrified lead passes through the two sensing optical fiber rings. By taking an ordinary single-mode optical fiber as a magnet-optical medium, the manufacturing cost of a product can be reduced greatly; and double symmetrical sensing optical fiber ring structures and an optical fiber annular cavity ring-down technology are adopted, so that multiple functions of suppressing linear birefringence, eliminating the temperature sensitive characteristic of a current sensor, increasing the detection accuracy, reducing the size and the like are realized.

Description

A kind ofly eliminate temperature sensitive ring cavity type all-fiber current sensor

Technical field the present invention relates to optical current sensor, relates in particular to a kind ofly to suppress linear birefrigence, eliminate temperature sensitive ring cavity type all-fiber current sensor.

In recent years, the development of national economy is inseparable all the more with the development of electrical power transmission system for background technology, so the safety detection link of electric system also seems important all the more.Along with the development of various places power grid construction, the continuous increase of installed capacity, traditional electromagnetic type detection system has been difficult to meet the demand of current network system at aspects such as response speed, security and intellectualities.In light of this situation, since the later stage in last century, optical current sensor is as a kind of high speed, and anti-electromagnetic interference capability is strong, and the novel power grid monitoring technology that security performance is high obtains extensive concern both domestic and external.2010, Chinese Government clearly proposes the target of " strengthening power grid construction; development intelligent grid " in " the 12 five-year-plan outline ", therefore power network monitoring, as an important content of novel power grid system Construction research, is had higher requirement to having theoretical research and the application and development of the optical current sensing technology of independent intellectual property right.

Optical current sensor has had the history of more than 40 year till now from the proposition of concept, and common optical current sensor technology can be divided into mixed type and Full-optical.Mixed type optics current sensor remains based on undesirable mutual electromagnetic inductance principle, thus cannot break away from the impact of electromagnetic interference (EMI), and can only be as traditional current sensor a kind of transition scheme to full optical current sensor; Full-optical optical current sensor principle is based on Faraday magnetooptical effect, and due to it, to have anti-electromagnetic interference capability strong, can adverse environment resistant, and safe, the advantages such as long distance of signal transmission, just obtain extensive discussions from the seventies in last century.Rise the nineties in last century, and along with the progress of optical fiber technology of preparing and the corresponding sensing communication technology, Full-optical current sensor, particularly full fiber type current sensor, become the popular research topic of the developed countries such as USA and Europe.But, up to the present, regrettably most optical current sensors really do not realize practical, and the main detection means that domestic electrical network adopts to be still traditional electromagnetic type detect.

Fibre optic current sensor is just along photoelectric hybrid to Full-optical at present, and muting sensitivity is to high sensitivity, and large volume develops to market direction to small size, laboratory.Although obtained certain achievement in this field, but still have considerable not enough its further application and development of restriction, subject matter is summarized as follows:

1, core optics sensing material is difficult to meet application demand.Conventionally the block glass adopting, as the method for sensing core, is subject to material behavior restriction, and cost is high, processing difficulties, and the crystal life-span is short; And adopt low birefringent fiber as the method for sensing material, there is equally the problem that cost is high.

2, be easily subject to the impact of the problems such as ambient temperature and vibrations, current-voltage measurement resultant error is large, and reproducibility is poor.The impact of ectocine, particularly temperature variation is the practical bottleneck of restriction optical current sensor always, although there has been the method for plurality of stable and compensation to propose, but or need to sacrifice volume, or need to sacrifice sensitivity, and can bring make and cost on problem.

3, from the optical current sensor product of current release, still contradictory aspect volume and sensitivity, the volume of especially most products is still bigger than normal; And, also there is such or such problem in the multiple spot Distributed Detection of current released optical current sensor product transmission line of electricity on a large scale.

List of references:

[1].G.A.Sanders,J.N.Blake,A.H.Rose et a1,“Commercialization of Fiber-Optic Current and Voltage Sensors at NxtPhase”,IEEE Proc.7289,2002

[2].Klaus Bohnert,Philippe Gabus,

Peter Guggenbach,“Fiber-optic DC Current Sensor for The Electro-winning Industry”,17th Int.Conference on Optical Fibre Sensors,Proc SPIE 5855,2005

[3].ABB Research Ltd,“Fiber-optic Sensor Coil and Current or Magnetic-field Sensor”,EP:04405308.0,2004

[4].NxPhase Technology SRL st.James(BB),“Optical Sensor for Sensing of A Magnetic Field or a Voltage”,EP:02257844.7,2003

[5]. commercial circles English, Wu Jing, " commercialization of fibre optic current sensor and voltage sensor ", optical fiber cable transmission technology, 4,2004

[6].T.Wang,C.Luo,S.Zheng,“A Fiber-optic Current Sensor Based on A Differen-tiating Sagnac Interferometer”.IEEE Transactions on Instrumentation and Measurement,50(3),2001

[7]. Li Fuying, Chen Xiang, Ge Shangrong, " the current measuring method ”， Tsing-Hua University journal (natural science edition) based on Rogowski coil and voltage to frequency conversion, 3 (40), 2000

[8].B.V.Marques,O.Fraza～o,S.Mendonca,J.Perez,M.B.Marques,S.F.Santos,J.M.Baptista,“Optical Current Sensor Based on Metal Coated Hi-bi Fiber Loop Mirror”,Microwave and Optical Technology Letters,50(3),2008

[9].K.Bohnert,P.Gabus,J.Nehring,H.Brandle,“Temperature and Vibration Insensitive Fiber-optic Current Sensor”,J.Lightwave Technol,20,2002

[10].Watekar,R.Pramod,Ju.Seongmin,Kim Su-Ah,Jeong Seongmook,Kim Young-woong,Han Won-Taek,“Development of A Highly Sensitive Compact Sized Optical Fiber Current Sensor”,Optics Express,18(16),2010

Summary of the invention the object of this invention is to provide a kind of combination fiber annular cavity attenuation and vibration technique, has the temperature sensitive ring cavity type all-fiber current sensor of eliminating that suppresses linear birefrigence, eliminates temperature sensitivity and improve the functions such as measuring accuracy.

The present invention adopts following technical scheme: all-fiber current sensor, sequentially include signal optical source, external modulator, the polarizer, the first coupling mechanism, the second coupling mechanism, polarization beam apparatus, the polarized light of polarization beam apparatus output is by the first light intensity detector, input data processing system after the second light intensity detector receives, data handling system obtains two polarized lights combinations the light at belt deflector angle, export again external modulator to, wherein said the first coupling mechanism, a port of the second coupling mechanism is connected to form a 2X2 mouth coupling mechanism, another port connects respectively the first sensing fiber ring, the sensor fibre of the second sensing fiber ring, the first described sensing fiber ring, the second sensing fiber ring consists of coiling N number of turn sensor fibre on the first optical fiber semi-ring and the second optical fiber semi-ring respectively, the first described optical fiber semi-ring and the second optical fiber semi-ring opening are in opposite directions, be symmetrical arranged, described sensor fibre is identical with the coiling number of turn on the second optical fiber semi-ring at the first optical fiber semi-ring, the opposite direction detouring, and two sensor fibres interconnect, form optic fiber ring-shaped cavity, detected electrified wire runs through two optical fiber semi-rings, sensed current intensity is:

$I=\mathrm{\&Phi;}/2\mathrm{kN}[{\mathrm{<figure-callout\; id="0"\; label="V"\; filenames="HDA0000074493060000021.png"\; state="\{\{state\}\}">V</figure-callout>}}_0+\frac{K}{{\mathrm{k\&alpha;}}^{\&prime;}}(\ln {\mathrm{iP}}_I/P_O-{\mathrm{k\&alpha;}}_0)]$

Wherein

that signal optical source is subject to the spectroscopic signal deflection angle recording after k circulation of magneto-optic effect in optic fiber ring-shaped cavity,

that spectroscopic signal is subject to magneto-optic effect generation deflection angle once, V in sensing fiber ring ₀be sensor fibre Verdet constant with the constant term of temperature T Taylor expansion, K is the coefficient of first order of sensor fibre Verdet constant Taylor expansion; α ₀be intensity loss coefficient with the constant term of temperature T Taylor expansion, α ' is that intensity loss coefficient is with the coefficient of first order of temperature T Taylor expansion; P _iand P _orespectively the total light intensity of input optical fibre ring cavity of signal optical source and the output intensity of the k time optic fiber ring-shaped cavity.

Described signal optical source is converted to pulse signal by external modulator, through the polarizer, be converted to linearly polarized light, input the input end of the first coupling mechanism, and be that two parts are exported by the second coupling mechanism light splitting, part light signal is retained in and in fiber optic loop an actor's rendering of an operatic tune, constantly cycles through sensing fiber ring, the deflection angle of spectroscopic signal is constantly amplified, another part light signal outputs to polarization beam apparatus, be divided into S light and P light, by the first light intensity detector, the second light intensity detector, received and input data processing system respectively; Spectroscopic signal is subject to magneto-optic effect generation deflection angle once in sensing fiber ring:

The deflection angle of the k time:

Wherein V is the Verdet constant of sensor fibre, and N is the number of turn of the sensor fibre of coiling on single sensing fiber ring, and I is the strength of current of detected electrified wire.

Described another part light signal input polarization beam splitter, be decomposed into orthogonal S light and P light, by the first light intensity detector, the second light intensity detector, received respectively, the deflection angle that the strength signal measuring obtains polarized light through data handling system Orthogonal Composite is:

ψ＝arctan(I _S/I _P)

I wherein _sand I _pthe S light being received by the first light intensity detector, the second light intensity detector respectively and the detection light intensity of P light.

The present invention adopts above technical scheme, utilize the first coupling mechanism, the first sensing fiber ring that the second coupling mechanism and double-pass symmetric arrange, the second sensing fiber ring forms optic fiber ring-shaped cavity, detected electrified wire runs through two sensing fiber rings, pulse signal in optic fiber ring-shaped cavity ring-down time repeatedly deflection angle testing result carry out matching and average, although the V value of single-mode fiber is very little, but as long as still can guarantee that through enough circulations repeatedly the deflection angle obtaining is enough large so that measure, thereby eliminate the error causing because of extraneous factor perturbation, improve the accuracy of overall measurement result.Two sensor fibres are around adopting sense fiber optic loop to adopt coiling N number of turn sensor fibre on optical fiber semi-ring to form, and optical fiber semi-ring opening in opposite directions, be symmetrical arranged, sensor fibre coiling number of turn on two optical fiber semi-rings is identical, the opposite direction detouring, only there is nonreciprocal rotation effect by two sensing fiber rings in electrified wire like this, thereby elimination circular birefringence, simultaneously because direction of twist is contrary, the linear birefrigence that also can cancel out each other and detour and cause because of optical fiber.Because the loss of ring-down time in each circulation determines, and the intensity loss of each circulation is certain, so the measurement of ring-down time also can detect and draw from light intensity, the approximate linear relationship that obtains input and output light intensity and temperature T of Cong Zhongke.

Beneficial effect of the present invention: the present invention is owing to introducing ring cavity structure, simple in structure, adopt general single mode fiber as magnet-optical medium, can reduce greatly the manufacturing cost of all-fiber current sensor, and by double-pass symmetric sensor fibre ring structure and fiber annular cavity attenuation and vibration technique, realize and suppress linear birefrigence, eliminate current sensor responsive to temperature characteristic and improve a plurality of functions such as accuracy of detection and reduced volume.

Accompanying drawing explanation is existing to be described in further details the present invention by reference to the accompanying drawings:

Fig. 1 is the structural representation of all-fiber current sensor of the present invention;

Fig. 2 is the structural representation of fiber optic loop an actor's rendering of an operatic tune in all-fiber current sensor of the present invention;

Fig. 3 is that signal optical source of the present invention is at the ring-down spectroscopy schematic diagram of optic fiber ring-shaped cavity.

Embodiment refers to Fig. 1, shown in 2 or 3, the present invention sequentially includes signal optical source 1, external modulator 2, the polarizer 3, the first coupling mechanism 4, the second coupling mechanism 5, polarization beam apparatus 6, the polarized light of polarization beam apparatus 6 outputs is by the first light intensity detector 7, input data processing system 9 after the second light intensity detector 8 receives, data handling system 9 obtains the light at belt deflector angle by two polarized lights combinations, then exports external modulator 2 to, it is characterized in that: the first described coupling mechanism 4, a port of the second coupling mechanism 5 is connected to form a 2X2 mouth coupling mechanism, and another port connects respectively the first sensing fiber ring 10, the sensor fibre 101 of the second sensing fiber ring 11, 111, the first described sensing fiber ring 10, the second sensing fiber ring 11 is respectively by coiling N number of turn sensor fibre 101 on the first optical fiber semi-ring 102 and the second optical fiber semi-ring 112, 111 form, and the first described optical fiber semi-ring 102 and the second optical fiber semi-ring 112 openings are in opposite directions, be symmetrical arranged described sensor fibre 101, 111 is identical with the coiling number of turn on the second optical fiber semi-ring 112 at the first optical fiber semi-ring 102, the opposite direction detouring, and two sensor fibres 101, 111 interconnect, and form optic fiber ring-shaped cavity, and detected electrified wire 12 runs through two optical fiber semi-rings 102, 112, sensed current intensity is:

$I=\mathrm{\&Phi;}/2\mathrm{kN}[{\mathrm{<figure-callout\; id="0"\; label="V"\; filenames="HDA0000074493060000021.png"\; state="\{\{state\}\}">V</figure-callout>}}_0+\frac{K}{{\mathrm{k\&alpha;}}^{\&prime;}}(\ln P_I/P_O-{\mathrm{k\&alpha;}}_0)]$

Wherein

that signal optical source is subject to the spectroscopic signal deflection angle recording after k circulation of magneto-optic effect in optic fiber ring-shaped cavity,

that spectroscopic signal is subject to magneto-optic effect generation deflection angle once, V in sensing fiber ring ₀be sensor fibre Verdet constant with the constant term of temperature T Taylor expansion, K is the coefficient of first order of sensor fibre Verdet constant Taylor expansion; α ₀be intensity loss coefficient with the constant term of temperature T Taylor expansion, α ' is that intensity loss coefficient is with the coefficient of first order of temperature T Taylor expansion; P _iand P _orespectively the total light intensity of input optical fibre ring cavity of signal optical source and the output intensity of the k time optic fiber ring-shaped cavity.

Described signal optical source 1 is converted to pulse signal by external modulator 2, through the polarizer 3, be converted to linearly polarized light, input the input end of the first coupling mechanism 4, and be that two parts are exported by the second coupling mechanism 5 light splitting, part light signal is retained in and in fiber optic loop an actor's rendering of an operatic tune, constantly cycles through sensing fiber ring, the deflection angle of spectroscopic signal is constantly amplified, another part light signal outputs to polarization beam apparatus 6, be divided into S light and P light, by the first light intensity detector 7, the second light intensity detector 8, received and input data processing system 9 respectively; Spectroscopic signal is subject to magneto-optic effect generation deflection angle once in sensing fiber ring 10,11:

The deflection angle of the k time:

Wherein V is the Verdet constant of sensor fibre, and N is the number of turn of the sensor fibre of coiling on single sensing fiber ring, and I is the strength of current of detected electrified wire.

Described another part light signal input polarization beam splitter 6, be decomposed into orthogonal S light and P light, by the first light intensity detector 7, the second light intensity detector 8, received respectively, the deflection angle that the strength signal measuring obtains polarized light through data handling system 9 Orthogonal Composite is:

ψ＝arctan(I _S/I _P)

I wherein _sand I _pthe S light being received by the first light intensity detector, the second light intensity detector respectively and the detection light intensity of P light.

The design of sensor is as Fig. 2: it is R that sensor fibre 101,111 is looped around respectively radius, internal diameter is on the semicircle pedestal 102,112 of r, the number of turn is all N, guarantees the contrary of coiling direction during fiber optic loop, guarantees that the coil of coiling is intensive to be beneficial to reduce volume simultaneously as far as possible.Two induction optical fiber 101,111 head and the tail are connected, and another two ends are connected into the port that the splitting ratio of 2 * 2 coupling mechanisms that are formed by connecting by two 1/2 coupling mechanisms 4,5 is 90, detected electrified wire 12 is by 2 sensing fiber rings 10,11.Pulsed light as detection signal is inputted from one of them port of 1/2 coupling mechanism 4, and a port of 1/2 coupling mechanism 5 is as output port.

The integrated connection of current sense detection system is as Fig. 1: continuous wave laser outputs to external modulator 2, and modulation becomes certain pulse signal of cycle, and signal becomes linearly polarized light by the polarizer 3, is input to the input end of aforementioned currents sensor as detection signal.Detection signal after each circulation is incorporated into polarization beam apparatus 6 from delivery outlet, is divided into P and S light is received by light power meter respectively.Due to P light and S orthogonal linearly polarized light only, the deflection angle that therefore can obtain flashlight by Orthogonal Composite is:

(3)

I wherein _sand I _prespectively S light and the P light light intensity that detector obtains.Wherein once the deflection angle of circulation is

(5)

ψ _sthat this measures deflection angle, it is the measurement result of last circulation.Because each measurement all unavoidably exists certain error, net result will carry out averaged by the repeatedly cycle detection result detecting in recurrence interval of enough large quantity, thereby the perturbation in single cycle is affected and suppressed.

As shown in Figure 3, this point can prove by the experimental result observation of ring cavity.If every circle intensity loss factor alpha, have the k time input and output intensity be related to P _out=P _ine ^-α, total the Relationship of Light intensity is: P _o=P _ie ^{-k α}, through the approximate pass that can obtain input and output light intensity and temperature T, be:

$T=\frac{\ln P_I/P_O-{\mathrm{k\&alpha;}}_0}{{\mathrm{k\&alpha;}}^{\&prime;}}---\left(6\right)$

α wherein ₀it is the coefficient of first order of intensity loss coefficient temperature T Taylor expansion.Due to the Verdet constant of many low Verdet coefficient materials and temperature be related to that the linearity is also fine, therefore can be made as:

V≈V ₀+KT (7)

Wherein K is that Verdet constant is with the coefficient of first order of temperature T Taylor expansion, by the deflection angle formula after k circulation of (6) (7) formula substitution

(2)

After arrangement, the strength of current after the temperature that can be eliminated impact is as follows:

$I=\mathrm{\&Phi;}/2\mathrm{kN}[{\mathrm{<figure-callout\; id="0"\; label="V"\; filenames="HDA0000074493060000021.png"\; state="\{\{state\}\}">V</figure-callout>}}_0+\frac{K}{{\mathrm{k\&alpha;}}^{\&prime;}}(\ln P_I/P_O-{\mathrm{k\&alpha;}}_0)]---\left(4\right)$

Wherein,

it is the magneto-optical deflection angle recording after k circulation.Can see, in this formula, deflection angle Φ and cycle index k and output intensity all obtain by system monitoring, and coefficient V ₀, K and α ₀relevant with concrete material, need to detect and obtain in advance, number of turn N is determined by coiling.In whole result, there is no the impact of temperature T on system.

Claims (3)

1. can eliminate temperature sensitive ring cavity type all-fiber current sensor for one kind, sequentially include signal optical source, external modulator, the polarizer, the first coupling mechanism, the second coupling mechanism, polarization beam apparatus, the polarized light of polarization beam apparatus output is by the first light intensity detector, input data processing system after the second light intensity detector receives, data handling system obtains two polarized lights combinations the light at belt deflector angle, export again external modulator to, it is characterized in that: the first described coupling mechanism, a port of the second coupling mechanism is connected to form a 2X2 mouth coupling mechanism, another port connects respectively the first sensing fiber ring, the sensor fibre of the second sensing fiber ring, the first described sensing fiber ring, the second sensing fiber ring consists of coiling N number of turn sensor fibre on the first optical fiber semi-ring and the second optical fiber semi-ring respectively, the first described optical fiber semi-ring and the second optical fiber semi-ring opening are in opposite directions, be symmetrical arranged, described sensor fibre is identical with the coiling number of turn on the second optical fiber semi-ring at the first optical fiber semi-ring, the opposite direction detouring, and two sensor fibres interconnect, form optic fiber ring-shaped cavity, detected electrified wire runs through two optical fiber semi-rings, sensed current intensity is:

Wherein

that signal optical source is subject to the spectroscopic signal deflection angle recording after k circulation of magneto-optic effect in optic fiber ring-shaped cavity,

that spectroscopic signal is subject to magneto-optic effect generation deflection angle once, V in sensing fiber ring ₀be sensor fibre Verdet constant with the constant term of temperature T Taylor expansion, K is the coefficient of first order of sensor fibre Verdet constant Taylor expansion; α ₀be intensity loss coefficient with the constant term of temperature T Taylor expansion, α ' is that intensity loss coefficient is with the coefficient of first order of temperature T Taylor expansion; P _iand P _orespectively the total light intensity of input optical fibre ring cavity of signal optical source and the output intensity of the k time optic fiber ring-shaped cavity.

2. a kind of temperature sensitive ring cavity type all-fiber current sensor of eliminating according to claim 1, it is characterized in that: described signal optical source is converted to pulse signal by external modulator, through the polarizer, be converted to linearly polarized light, input the input end of the first coupling mechanism, and be that two parts are exported by the second coupling mechanism light splitting, part light signal is retained in and in fiber optic loop an actor's rendering of an operatic tune, constantly cycles through sensing fiber ring, the deflection angle of spectroscopic signal is constantly amplified, another part light signal outputs to polarization beam apparatus, be divided into S light and P light, respectively by the first light intensity detector, the second light intensity detector receives and input data processing system, spectroscopic signal is subject to magneto-optic effect generation deflection angle once in sensing fiber ring:

The deflection angle of the k time:

Wherein V is the Verdet constant of sensor fibre, and N is the number of turn of the sensor fibre of coiling on single sensing fiber ring, and I is the strength of current of detected electrified wire.

3. a kind of temperature sensitive ring cavity type all-fiber current sensor of eliminating according to claim 2, it is characterized in that: described another part light signal input polarization beam splitter, be decomposed into orthogonal S light and P light, by the first light intensity detector, the second light intensity detector, received respectively, the deflection angle that the strength signal measuring obtains polarized light through data handling system Orthogonal Composite is:

ψ＝arctan(I _S/I _P)

I wherein _sand I _pthe S light being received by the first light intensity detector, the second light intensity detector respectively and the detection light intensity of P light.

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