CN1766657A - Current sensing method and device based on polarization degree demodulation - Google Patents
Current sensing method and device based on polarization degree demodulation Download PDFInfo
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Abstract
A current sensing method and device based on polarization degree demodulation of Faraday effect for electric power measurement of high voltage and strong current, the method is based on Faraday rotation effect of light polarization, which is characterized in that a multi-turn optical fiber ring of an optical fiber cavity with the multi-turn optical fiber ring is wound on an electric wire or a cable of the current to be measured, linearly polarized light passes through and is reflected back and forth for multiple times in the optical fiber cavity to be output, the optical wave with a single polarization plane rotation angle is converted into the superposition of optical waves with different polarization plane rotation angles, the superposed optical wave has a specific polarization degree, the specific polarization degree has a one-to-one correspondence relation with the intensity of the current passing through the multi-turn optical fiber ring, the correspondence relation is only related to the structure of the optical fiber cavity, thereby, the Faraday rotation effect of light is converted into the change of the polarization degree of light, and the measurement of the optical wave polarization plane rotation angle of the current is converted into the measurement of the optical wave polarization degree, to obtain current information for high voltage, high current.
Description
Technical field
The present invention relates to the measurement of high voltage, heavy current, particularly a kind of electric current sensing method and device of the polarization degree demodulating based on Faraday effect are mainly used in the high voltage that needs insulation measurement, the electric power sensor-based system of heavy current.
Background technology
Along with the continuous expansion that industry, military affairs and civilian occasion require electric power development, the power industry installed capacity constantly increases, and measurement how to carry out the high pressure forceful electric power becomes power industry and presses for one of problem of solution.
At the demand of power industry current sense, people had carried out many researchs.Traditional electric power sensing mainly is the current transformer (CT) based on electromagnetic induction.But this current transformer closes at the High Voltage electric field and has difficult, the problems such as cost is high, magnetic saturation, ferroresonance of insulation, and range of application is restricted, can not satisfy the requirement that power industry further develops.Optical current sensing (OCS) is subjected to extensive attention in recent years.Especially fiber-optic current sensor technology (AFOCS), it is to utilize the Faraday effect of light wave in magnetic field to measure electric current, has plurality of advantages such as simple in structure, in light weight, good insulation preformance, has showed good application prospect.
Faraday effect optical current sensing utilizes tested electric current generation magnetic field to cause the rotation of light wave polarization direction and carry out current sense.In the high pressure forceful electric power is used, the light wave that light source sends and through the signal of polarization direction, magnetic field all by Optical Fiber Transmission to ground.This is the significant advantage that optical fiber technology guarantees electrical insulating property.But in the Optical Fiber Transmission light path, because the variation of conditions such as environment temperature, stress, inside of optical fibre produces birefringence at random, makes the polarization direction that random variation take place, and has seriously influenced the reliability of measuring-signal.
In order to solve optical fiber random birefringence problem, people have carried out many-sided research.One of technology formerly, [Reciprocal reflection interferometer for a fiber-optic Faraday current sensor such as Guido, Applied Optics, 1994,6111-6122] first theoretical and experimentally studied the mutual reflection interferometer current sense scheme of utilizing polarization maintaining optical fibre.Formerly two of technology, [Optical fiber current sensors inhigh electric field environments such as Rose, J.Lightwave Techno, 1999,1042-1048] from theoretical and experimentally proved and reverse annealing optical fiber can reduce optical fiber widely under the condition of the temperature characterisitic of not obvious increase system residual birefringence.[Modified in-line Sagnac interferometer with passivedemodulation technique for environmental immunity of a fiber-optic current sensor such as H.Lin, Applied Optics, 1999,38 (13), 2760-2766] from the fiber optic component level, interferometer structure is improved on this basis, adopt high circular birefringence optical fiber as sensing head and guide wire, reduce the use of expensive polarization maintaining optical fibre as far as possible, and improved the instability of system.Formerly three of technology, [Temperatureand Vibration Insensitive Fiber-Optic Current Sensor such as K.Bohnert, J.Lightwave Techno., 2002,267-276] after adopting elliptical fiber and having improved the fibre-optical probe encapsulation technology, simplify system architecture, realized the high-temperature stability of current sense.Formerly four of technology, the yellow Hong Jia of Shanghai University etc. adopts guarantor's circular fiber of design preparation voluntarily in the faradic currents sensor-based system, overcome the influence of random birefringence to measurement stability.In optical fiber assembly and method for measuring strokes of lightning sensor-based system, the sensing head design also has very high technical requirement, particularly will overcome additional birefringence and temperature effect thereof that fibre-optical bending causes.Formerly five of technology, [Geometricalseparation betwwen the birefrngence components in Faraday-rotation fiber-optical currentsensors such as A.Ben-Kish, Optics Letter, 1991,687-689] utilize particular geometries, the control bend birefringence makes additional birefringent phase difference equal the integral multiple of 2 π, has alleviated the temperature effect that the fibre-optical bending birefringence causes significantly.
Said method all is to adopt polarization maintaining optical fibre and other special optical fibers to realize polarization direction stablizing in transmission course basically, perhaps compensates the variation in the transmission course.The cost height of polarization maintaining optical fibre and special optical fiber and supporting component thereof, price are expensive, and some special optical fiber aspect combination property not as good as ripe general communication optical fiber, brought other problems that need solve.
Summary of the invention
The technical problem to be solved in the present invention is to overcome the deficiency of above-mentioned technology formerly, a kind of electric current sensing method and device based on polarization degree demodulating is provided, to overcome the problem that random birefringence is disturbed in the optical transmission line in the conventional fiber assembly and method for measuring strokes of lightning sensing, reduce cost.
Technical scheme of the present invention is as follows:
A kind of high voltage that is used for, the electric current sensing method based on the polarization degree demodulating of Faraday effect of the power measurement of heavy current, this method is based on the Faraday rotation effect of light polarization, essence is that a multi-ring fiber ring with optical fiber cavity of multi-ring fiber ring is centered around on the electric wire or cable of electric current to be measured, make a linearly polarized light by and in described optical fiber cavity, repeatedly come back reflective after export, the light wave of single plane of polarization rotation angle is changed into the stack of the light wave of a plurality of different polarization face rotation angle, the light wave of this stack has specific degree of polarization, this specific degree of polarization has relation one to one with current's intensity by described multi-ring fiber ring, the relation of this correspondence is only relevant with the structure of optical fiber cavity, thus, faraday's polarization rotation effect of light is become the variation of polarisation of light degree, thereby the measurement of the light wave plane of polarization rotation angle of electric current is converted into the measurement of light wave degree of polarization, to obtain high voltage, the current information of heavy current.
A kind of current sensor device of electric current sensing method of the polarization degree demodulating based on described Faraday effect is characterised in that it is by nonpolarized light light source, first Transmission Fibers, the polarizer, optical fiber cavity, second Transmission Fibers and the light polarization analyser of polyphone constitute successively.
Described optical fiber cavity is made of first reverberator, fiber optic loop, second reverberator of polyphone, and described fiber optic loop is a multi-ring fiber ring around current cable to be measured, and the value of the reflectivity of described first reverberator and second reverberator is greater than 0, less than 1.
Described first reverberator and second reverberator are respectively first fiber grating and second fiber grating.
Described optical fiber cavity is made of one 2 * 2 fiber coupler and fiber optic loop: this 2 * 2 fiber coupler, first port of the output termination of the described polarizer, this fiber coupler second port is connected the two ends of described fiber optic loop with the 4th port, the 3rd port connects described second Transmission Fibers.
Described optical fiber cavity is connected and composed by described fiber coupler by two sections on the first multi-ring fiber ring and the second multi-turn light ring: an end of the first multi-ring fiber ring and the second multi-turn light ring is connected with the 4th port with second port of described fiber coupler respectively, the described first multi-ring fiber ring is connected first faraday rotator mirror and second faraday rotator mirror respectively with the other end of the second multi-turn light ring, and described second Transmission Fibers directly is connected with the 3rd port of described fiber coupler.
Described current sensor device, the 3rd port that it is characterized in that described 2 * 2 fiber couplers connects optical fiber by another and connects a circulator another optical fiber cavity of contacting, or further one by one by circulator a plurality of described optical fiber cavities of contacting.
The ultimate principle of the inventive method is based on the Faraday rotation effect of light polarization, make a linearly polarized light in the optical fiber cavity structure of multi-ring fiber ring, repeatedly come back reflective, the light wave of single plane of polarization rotation angle is changed into the stack of the light wave of a plurality of different polarization face rotation angle, the light wave of this stack has specific degree of polarization, this specific degree of polarization has relation one to one with current's intensity by described multi-ring fiber ring, the relation of this correspondence is only relevant with the structure of optical fiber cavity, thus, faraday's polarization rotation effect of light is become the variation of polarisation of light degree, thereby the measurement of the light wave plane of polarization rotation angle of electric current is converted into the measurement of light wave degree of polarization.
It is as follows to utilize degree of polarization to make the theoretical analysis of current sense: the present invention adopts incoherent light to measure, the fiber optic loop number of turns of supposing current sensing head is N, electric current to be measured is I, optical fiber Faraday effect Verdet constant is V, after then light is advanced once in sensing head optical fiber, the angle of light signal polarization state rotation is θ=VNI, promptly changes the electric vector size of light signal and angle E with electric current
x, E
y, φ also will change with θ.Because the Verdet constant of optical fiber is very little, θ＜＜π, so can think that θ is with electric current I monotone variation to be measured.Utilize the Stokes vector in the variation of describing light wave polarization state in the sensing chamber on the poincare sphere, its each representation in components is:
S
0＝<|E
x|
2>+<|E
y|
2>，
S
1＝<|E
x|
2>-<|E
y|
2>，
S
2＝2<|E
x||E
y|cosφ>，
S
3＝2<|E
x||E
y|sinφ>。
In the formula＜represent statistical average.
The light wave degree of polarization is defined as
After light signal was repeatedly reciprocal in the sensing chamber, emergent light wave polarization degree can be written as the function with electric current:
θ in the formula
iPolarization rotation angle when the expression light signal reflects i time in optical fiber cavity, θ as previously mentioned
iHas relation one to one with sense current I; F (x) is the function relevant with the optical fiber cavity structure, and its concrete form is determined by the structure of light path.Therefore, promptly can obtain current value to be measured by measuring the output light-wave degree of polarization:
I＝f
-1(DOP) (2)
Advantage of the present invention and characteristics are:
(1) the present invention's Faraday rotation effect of being based on light polarization causes that the light signal plane of polarization changes with electric current, utilizes the variation of optical fiber cavity with light signal plane of polarization rotation becoming light signal degree of polarization, and the measuring light signal degree of polarization is directly relevant with current value.There are not hysteresis and magnetic saturation phenomenon in the current transformer.Also be different from the indirect measurement method that utilizes magnetostriction materials mechanical switch process.
(2) the present invention adopts full optical fiber approach, has realized insulation isolation detection, can be applicable to the sensing of High Voltage electric current.
(3) the present invention adopt polarization degree signal as demodulation parameter, overcome in the conventional fiber assembly and method for measuring strokes of lightning sensing problem that random birefringence is disturbed in the optical transmission line.Thus, can realize multiplexedly, set up the distributing optical fiber sensing network.
(4) the present invention adopts the optical fiber cavity structure faraday's polarization rotation effect to be become the variation of degree of polarization.The optical fiber cavity structure has bigger dirigibility among the present invention; Can obtain different detection sensitivity performances by the adjustment of the fiber optic loop number of turns in the sensing head; With most of fiber optic element device compatibilities, has the leeway that further develops.
(5) material of the present invention and components and parts maturation, cost price is cheap, helps applying.Have good cost performance, expection has good market outlook.
Description of drawings
Fig. 1 is the current sensor schematic diagram that the present invention is based on polarization degree demodulating.
Fig. 2 is embodiment one: adopt the current sensor structural representation of fiber grating to the polarization degree demodulating of formation.
Fig. 3 is embodiment two: the current sensor structural representation that adopts the polarization degree demodulating of fiber coupler.
Fig. 4 is embodiment three: the current sensor structural representation that adopts the polarization degree demodulating of faraday rotator mirror.
Fig. 5 is embodiment four: the current sensor multiplexing structure synoptic diagram that adopts the polarization degree demodulating of faraday rotator mirror.
Embodiment
The invention will be further described below in conjunction with embodiment and accompanying drawing, but should not limit protection scope of the present invention with this.
Embodiment one: utilize fiber grating to constituting the scheme of optical fiber cavity, as shown in Figure 2.As seen from the figure, the current sensor device of the polarization degree demodulating of Faraday effect of the present invention is by nonpolarized light light source 1, first Transmission Fibers 21, the polarizer 3, optical fiber cavity, second Transmission Fibers 22 and the light polarization analyser 6 of polyphone constitute successively.Described optical fiber cavity is made of first reverberator 71, fiber optic loop 4, second reverberator 72 of polyphone, described fiber optic loop 4 is the multi-ring fiber rings around current cable 5 to be measured, the value of the reflectivity of described first reverberator 71 and second reverberator 72 is greater than 0, less than 1.
Described first reverberator 71 and second reverberator 72 are respectively first fiber grating 73 and second fiber grating 74.In this embodiment, optical fiber cavity is made up of a pair of wavelength identical first fiber grating 73 and second fiber grating 74.By the light process polarizer 3 that incoherent light source 1 is sent, become linear polarization and enter first fiber grating 73 and second fiber grating 74 and be centered around the sensing head that lead 5 to be measured multi-ring fiber ring 4 is on every side formed.From the light of sensing head transmission, measure its degree of polarization by polarization analysis instrument 6.
Embodiment two: utilize the scheme of fiber coupler formation fiber optic loop, as shown in Figure 3.
1,3,4,5,6,21,22 each elements are all identical with Fig. 1 among the figure.But, adopt a fiber coupler 75 to replace two reverberators that separate 71,72.It can play the effect of two reverberators.Described optical fiber cavity is made of one 2 * 2 fiber coupler 75 and fiber optic loop 4: this 2 * 2 fiber coupler of the output termination of the described polarizer 3 75 first port a, this fiber coupler 75 second port b are connected the two ends of described fiber optic loop 4 with the 4th port d, the 3rd port c connects described second Transmission Fibers 22.The splitting ratio of supposing this coupling mechanism is K%: (1-K) %, and so, light is after coupling mechanism first port a input, and (1-K) power of % is exported from the 3rd port c, and remaining K% power is exported from the 4th port d.This part luminous power will stand the polarization rotation of Faraday effect through the multi-ring fiber ring 4 around electric current to be measured; And get back to second input port b of fiber coupler.The luminous power of telling same ratio from the output port of coupling mechanism stands faraday's rotation for the second time for the second time by the sensing head fiber optic loop again.Stack so constantly.
Embodiment three: utilize the scheme of fiber coupler and faraday rotator mirror, as shown in Figure 4.Each elements such as 1,21,22,3,5,6,75 are all identical with Fig. 3 among the figure.Described optical fiber cavity is connected and composed by described fiber coupler 75 by 42 two sections on the first multi-ring fiber ring 41 and the second multi-turn light ring: an end of the first multi-ring fiber ring 41 and the second multi-turn light ring 42 is connected with the 4th port d with the second port b of described fiber coupler 75 respectively, the described first multi-ring fiber ring 41 is connected first faraday rotator mirror 81 and second faraday rotator mirror 82 respectively with the second multi-turn light ring, 42 other ends, and described second Transmission Fibers 22 directly is connected with the 3rd port c of described fiber coupler 75.
Incident light enters sensing head by a circulator 9; Can obtain the light signal that reflects from sensing head 4 from the 3rd port of circulator 9.Faraday rotator mirror 81 and 82 has the incident light total reflection and makes its plane of polarization revolve the effect that turn 90 degrees.Similar to the situation of embodiment two, stand the light wave of faraday's rotation that electric current to be measured causes, because the effect of fiber coupler also can cause the reduction of degree of polarization repeatedly through the fiber optic loop of sensing head.Theoretical analysis shows simultaneously, and behind the employing faraday rotator mirror, reflected light and incident light have orthogonal polarisation state in sensing head, can overcome in the sensing head like this and the birefringent influence of background in the Transmission Fibers, improves measuring stability greatly.This embodiment also can connect the sensor fibre ring 42 that connects coupling mechanism d port the c port of coupling mechanism 75.
Embodiment four: multiplexed a kind of embodiment, see Fig. 5.
Each element is identical with Fig. 4 among Fig. 5.But increased by one section optical fiber 23 that connects different test points, drawn two optical fiber cavities among the figure.The 3rd port c that is described 2 * 2 fiber couplers 75 connects second optical fiber cavity of a circulator 9 polyphones by another connection optical fiber.Can also be further one by one by a plurality of described optical fiber cavities of circulator 9 polyphones.
Polarized light signal is behind first sensing head of process, and the part luminous power is connect the circulator 9 of subordinate's sensing head by the c port output of coupling mechanism 75 with it by connection optical fiber 23 as the input of next stage sensing head.As long as light source power is enough, can also further extend to more test point.
Claims (7)
1, a kind of high voltage that is used for, the electric current sensing method based on the polarization degree demodulating of Faraday effect of the power measurement of heavy current, it is characterized in that this method is based on the Faraday rotation effect of light polarization, essence is that a multi-ring fiber ring with optical fiber cavity of multi-ring fiber ring is centered around on the electric wire or cable of electric current to be measured, make a linearly polarized light by and in described optical fiber cavity, repeatedly come back reflective after export, the light wave of single plane of polarization rotation angle is changed into the stack of the light wave of a plurality of different polarization face rotation angle, the light wave of this stack has specific degree of polarization, this specific degree of polarization has relation one to one with current's intensity by described multi-ring fiber ring, the relation of this correspondence is only relevant with the structure of optical fiber cavity, thus, faraday's polarization rotation effect of light is become the variation of polarisation of light degree, thereby the measurement of the light wave plane of polarization rotation angle of electric current is converted into the measurement of light wave degree of polarization, to obtain high voltage, the current information of heavy current.
2, a kind of current sensor device of electric current sensing method of the polarization degree demodulating based on the described Faraday effect of claim 1 is characterised in that it is by nonpolarized light light source (1), first Transmission Fibers (21), the polarizer (3), optical fiber cavity, second Transmission Fibers (22) and light polarization analyser (6) formation of polyphone successively.
3, current sensor device according to claim 2, it is characterized in that described optical fiber cavity is made of first reverberator (71), fiber optic loop (4), second reverberator (72) of polyphone, described fiber optic loop (4) is a multi-ring fiber ring around current cable to be measured (5), the value of the reflectivity of described first reverberator (71) and second reverberator (72) is greater than 0, less than 1.
4, current sensor device according to claim 3 is characterized in that described first reverberator (71) and second reverberator (72) are respectively first fiber grating (73) and second fiber grating (74).
5, current sensor device according to claim 2, it is characterized in that described optical fiber cavity is made of one 2 * 2 fiber coupler (75) and fiber optic loop (4): these 2 * 2 fiber coupler (75) first ports (a) of the output termination of the described polarizer (3), these fiber coupler (75) second ports (b) are connected the two ends of described fiber optic loop (4) with the 4th port (d), the 3rd port (c) connects described second Transmission Fibers (22).
6, current sensor device according to claim 2, it is characterized in that described optical fiber cavity is connected and composed by described fiber coupler (75) by (42) two sections on the first multi-ring fiber ring (41) and the second multi-turn light ring: an end of the first multi-ring fiber ring (41) and the second multi-turn light ring (42) is connected with the 4th port (d) with second port (b) of described fiber coupler (75) respectively, the described first multi-ring fiber ring (41) is connected first faraday rotator mirror (81) and second faraday rotator mirror (82) respectively with the other end of the second multi-turn light ring (42), and described second Transmission Fibers (22) directly is connected with the 3rd port (c) of described fiber coupler (75).
7, current sensor device according to claim 6, the 3rd port (c) that it is characterized in that described 2 * 2 fiber couplers (75) connects optical fiber by another and connects a circulator (9) another optical fiber cavity of contacting, or further one by one by a plurality of described optical fiber cavities of circulator (9) polyphone.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101294988B (en) * | 2008-06-23 | 2011-06-15 | 福建省电力试验研究院 | Optical fiber type electric mutual inductor |
| CN102156213A (en) * | 2011-03-24 | 2011-08-17 | 东北大学 | Fiber bragg grating current measurement method based on birefrigent effect |
| CN103176023A (en) * | 2011-12-21 | 2013-06-26 | 北京首量科技有限公司 | All-fiber current sensor system and current detection method |
| CN103715650A (en) * | 2014-01-20 | 2014-04-09 | 哈尔滨工业大学 | Differential protection device based on Faraday magneto-optical effect |
| CN103777063A (en) * | 2013-12-13 | 2014-05-07 | 国家电网公司 | Fiber current sensor |
| CN103777062A (en) * | 2013-12-13 | 2014-05-07 | 国家电网公司 | Interference ring type all-fiber current transformer |
| CN104246519A (en) * | 2012-02-10 | 2014-12-24 | 阿尔斯通技术有限公司 | Large bandwidth, very high precision HVDC current-measuring device |
| CN104597304A (en) * | 2015-01-07 | 2015-05-06 | 贵州电力试验研究院 | Ring cavity type all-fiber current sensor |
| CN105353191A (en) * | 2015-10-13 | 2016-02-24 | 合肥乐然物联网技术有限公司 | High-precision optical sensor applied to IOT (Internet of Things) |
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2005
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101294988B (en) * | 2008-06-23 | 2011-06-15 | 福建省电力试验研究院 | Optical fiber type electric mutual inductor |
| CN102156213A (en) * | 2011-03-24 | 2011-08-17 | 东北大学 | Fiber bragg grating current measurement method based on birefrigent effect |
| CN103176023A (en) * | 2011-12-21 | 2013-06-26 | 北京首量科技有限公司 | All-fiber current sensor system and current detection method |
| CN104246519A (en) * | 2012-02-10 | 2014-12-24 | 阿尔斯通技术有限公司 | Large bandwidth, very high precision HVDC current-measuring device |
| CN104246519B (en) * | 2012-02-10 | 2016-12-21 | 阿尔斯通技术有限公司 | Wide bandwidth, superelevation degree of accuracy HVDC current measure device |
| CN103777063B (en) * | 2013-12-13 | 2016-09-21 | 国家电网公司 | A kind of fibre optic current sensor |
| CN103777063A (en) * | 2013-12-13 | 2014-05-07 | 国家电网公司 | Fiber current sensor |
| CN103777062A (en) * | 2013-12-13 | 2014-05-07 | 国家电网公司 | Interference ring type all-fiber current transformer |
| CN103715650A (en) * | 2014-01-20 | 2014-04-09 | 哈尔滨工业大学 | Differential protection device based on Faraday magneto-optical effect |
| CN103715650B (en) * | 2014-01-20 | 2016-06-29 | 哈尔滨工业大学 | Differential protection based on Faraday magnetooptical effect |
| CN104597304A (en) * | 2015-01-07 | 2015-05-06 | 贵州电力试验研究院 | Ring cavity type all-fiber current sensor |
| CN104597304B (en) * | 2015-01-07 | 2018-03-30 | 贵州电力试验研究院 | A kind of annular cavate all-fiber current sensor |
| CN105353191A (en) * | 2015-10-13 | 2016-02-24 | 合肥乐然物联网技术有限公司 | High-precision optical sensor applied to IOT (Internet of Things) |
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