CN101598748B - Thermo-compensation current sensing head as well as alternate current measurement method and system - Google Patents
Thermo-compensation current sensing head as well as alternate current measurement method and system Download PDFInfo
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- CN101598748B CN101598748B CN2009100231664A CN200910023166A CN101598748B CN 101598748 B CN101598748 B CN 101598748B CN 2009100231664 A CN2009100231664 A CN 2009100231664A CN 200910023166 A CN200910023166 A CN 200910023166A CN 101598748 B CN101598748 B CN 101598748B
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Abstract
The invention relates to a thermo-compensation current sensing head as well as an alternate current measurement method and a system thereof. A current sensing head is placed in a magnetic field generated by alternate current to be measured, and a fiber bragg grating FPI adhered on magnetostrictive material senses ambient temperature and magnetic induction. A light signal emitted by a monochromatic light source enters fiber bragg grating F-P cavity of a fiber bragg grating Fabry-Perot interferometer and forms a similar two beam light interference signal after interference to be output. Cavity length variation amount of the fiber bragg grating F-P cavity of the fiber bragg grating Fabry-Perot interferometer is obtained according to the two beam interference signal, and then alternate current measurement value is obtained according to the cavity length variation amount. And finally, compensation relation between current measurement value and actual value to be measured on temperature is utilized to obtain alternate current actual value. The performance of an original current sensor is improved, preparation technology is relatively simple, and simultaneous measurement of temperature and alternate current can be realized.
Description
Technical field
The present invention relates to a kind of current sensing head and exchange current measuring method and system of temperature compensating type, belong to Fibre Optical Sensor and optical measurement field.
Background technology
The principle of fiber-optic grating sensor is the drift value that is converted into the fiber grating bragg wavelength with to be measured, make simply, but its wavelength-modulated characteristic brings certain difficulty for the signal demodulation.Common optical fibre Fabry-perot interferometer (FPI) sensor has utilized optical fiber to pass light and F-P principle of interference, and measuring accuracy is high, but the manufacture craft difficulty is bigger.Fiber grating FPI constitutes by in same optical fiber, writing two identical fiber gratings; Combine the advantage of fiber grating and optical fiber FPI; Not only make simple; And have that volume is little, light weight, electrical insulating property are good, the advantages such as all optical fibre structure that are easy to the system that realizes, can reach the measuring accuracy of traditional fiber FPI sensor, received more and more widely and having paid close attention to.
In electric system, particularly important to the isoparametric monitoring of voltage, electric current, power of power transmission and transformation line.Along with improving constantly of line voltage, traditional electromagnetic sensor more and more can not meet the demands because of poor insulativity, complex structure, with high costs etc.For this reason, full optical fiber high-tension current sensor becomes one of focus of research.At present, the measuring method of fibre optic current sensor use has: polarization state mensuration, wavelength-modulated mensuration and optical interference measuring method.Wherein the principle of optical interference measuring method is that the phase differential that utilizes the outfield to change coherent light is measured " interferometric fiber optic current sensor " of for example 2006 " instrumental technique and the sensor " fourth phases.The interferometer structure that the interference-type optical fiber current sensor adopts mainly contains Mach-Zehnder (M-Z) interferometer, Michelson interferometer and FPI.The structure of Mach-Zehnder interferometer and Michelson interferometer is basic identical, is made up of signal arm optical fiber and reference arm optical fiber.The fibre optic current sensor of this structure is because sensing light beam and reference beam are respectively in two optical fiber, to transmit, so the interference of factors such as the birefringence of inside of optical fibre, environment temperature, vibration, bending can have a strong impact on the performance of sensor.The sensing light beam of FPI type fibre optic current sensor and reference beam are in same optical fiber, to transmit, and solved the problems such as birefringence, vibration and bending of optical fiber effectively, but Influence of Temperature can't solve all the time.
Summary of the invention
The technical matters that solves
Weak point for fear of prior art; The present invention proposes a kind of current sensing head and exchange current measuring method and system of temperature compensating type; Improved the performance of original current sensor, manufacture craft is simple relatively, measures when can realize temperature and exchange current.
Technical scheme
The current sensing head of proposition of the present invention is characterized in that comprising optical fiber optical grating Fabry-Perot interferometer 12, magnetostriction materials 8 and 2 permanent magnets 7; 2 permanent magnet 7 opposing parallel place the both sides of magnetostriction materials 8, and the fiber Bragg grating F-P chamber of optical fiber optical grating Fabry-Perot interferometer 12 sticks on the magnetostriction materials 8; The length of fibre grating F-P chamber of magnetostriction materials 8 is long or less than long 1.5 times in fiber Bragg grating F-P chamber; The length of 2 permanent magnets 7 is more than or equal to the long length in fiber Bragg grating F-P chamber; Said fiber Bragg grating F-P chamber is between two sections fiber gratings 6 of optical fiber optical grating Fabry-Perot interferometer.
Described 2 permanent magnets 7 are vertically fixed on the two ends of magnetostriction materials 8.
The reflectivity of said optical fiber optical grating Fabry-Perot interferometer is less than 5%.
Described magnetostriction materials 8 adopt isometric piezoelectric ceramics 11, and permanent magnet 7 adopts mutual inductor 10 and transmission line 9; Mutual inductor 10 is connected with piezoelectric ceramics 11 through transmission line 9.
A kind of method of utilizing any above-mentioned current sensing head to measure exchange current is characterized in that step is following:
Step 1: with the magnetic field that current sensing head places exchange current to be measured to produce, importing a wavelength is that λ, light intensity are I
0Light signal, two-beam interference signal that light intensity is I of current sensing head output;
Step 2: according to light intensity is that the two-beam interference signal of I obtains the long variable quantity in optical fiber optical grating Fabry-Perot interferometer fiber Bragg grating F-P chamber:
R wherein
λFor fiber grating FPI is the peak reflectivity of the monochromatic light intensity of λ to wavelength,
Be the initial phase of fiber Bragg grating F-P chamber interference signal, n is the refractive index of fiber core;
Step 3: according to the linear relationship of Δ h and strength of current, the measured value i ' that obtains strength of current for
wherein A to be scale-up factor obtained by the mode of normal experiment calibration;
Step 4: Temperature Compensation is concerned according to measured value i ' and actual value i
Drawing current actual value measured in the environment does
κ wherein
2Be the temperature magnetic field intensity cross sensitivity factors of magnetostriction materials, C
EffBe the magnetostriction coefficient of magnetostriction materials, and κ
2And C
EffTwo coefficient values are obtained by the mode of normal experiment calibration.
A kind of system that realizes above-mentioned measurement exchange current method is characterized in that: current sensing head is connected with a port of fiber coupler 4 one sides through single-mode fiber 3, and the another port places index-matching fluid 5 through single-mode fiber 3; Two ports of the opposite side of fiber coupler 4 are connected with Electro-Optical Sensor Set 2 respectively at monochromatic source 1.
Beneficial effect
The current sensing head of temperature compensating type provided by the invention can carry out current sensing head of the present invention and carry out exchange current measuring method and system.Temperature, electric current cross sensitivity problem that method and system of the present invention has solved the conventional current sensor have realized the compensating measure of temperature to electric current, have improved measuring accuracy.The present invention also can be limited by sensitivity and the range that magnetostriction element length dual mode partly improves current measurement to the action effect of magnetostriction element with the fiber Bragg grating F-P chamber through improving electric current.Simultaneously, the present invention has that volume is little, simple in structure, cost is low, stable performance, highly sensitive, electrical insulating property good, corrosion resistant advantage, can under mal-condition, work.
Description of drawings
Fig. 1: be the embodiment of the invention 1 fiber grating FPI current measuring device structural representation
Fig. 2: be the embodiment of the invention 2 fiber grating FPI current measuring device structural representations
Fig. 3: be the embodiment of the invention 3 fiber grating FPI current measuring device structural representations
Fig. 4: be monochromatic light intensity peak reflectivity R
λWith the relation curve of temperature, horizontal ordinate is a temperature, and ordinate is R
λ
1, monochromatic source; 2, Electro-Optical Sensor Set; 3, single-mode fiber; 4, fiber coupler; 5, index-matching fluid; 6, two of the optical fiber optical grating Fabry-Perot interferometer sections fiber gratings; 7, permanent magnet; 8, magnetostriction materials; 9, transmission line; 10, mutual inductor; 11, piezoelectric ceramics; 12, optical fiber optical grating Fabry-Perot interferometer.
Embodiment
Combine embodiment, accompanying drawing that the present invention is further described at present:
The exchange current sensing head of a kind of temperature compensating type of the embodiment of the invention is comprising optical fiber optical grating Fabry-Perot interferometer 12, magnetostriction materials 8 and 2 permanent magnets; 2 permanent magnets are opposite to the both sides of magnetostriction materials 8 mutually, the optical fiber optical grating Fabry-Perot interferometer two sections fiber gratings 6 between the fiber grating FPI that forms stick on the magnetostriction materials 8.This sensing head can also replace with piezoelectric ceramics 11, mutual inductor 10 and transmission line 9 with magnetostriction materials 8 and 2 permanent magnets; Mutual inductor 10 is connected through transmission line 9 voltage signal of output with input piezoelectric ceramics 11.
The basic skills of the measurement exchange current that the embodiment of the invention proposes is: with the magnetic field that current sensing head places exchange current to be measured to produce, stick on temperature and the size of magnetic induction density in the fiber grating FPI sensing surrounding environment on the magnetostriction materials.The light signal that monochromatic source is sent gets in the fiber Bragg grating F-P chamber of optical fiber optical grating Fabry-Perot interferometer, interferes the back to form and is approximately the output of two-beam interference signal.Obtain the long variable quantity in chamber in the fiber Bragg grating F-P chamber of optical fiber optical grating Fabry-Perot interferometer according to the two-beam interference signal, obtain the measured value of exchange current again through the linear relationship of long variable quantity in chamber and electric current.Finally, utilize current measurement value and actual treating between the measured value Temperature Compensation to be concerned the actual value that draws exchange current.
The implement device of this method is; The fiber grating FPI of optical fiber optical grating Fabry-Perot interferometer sticks on the magnetostriction materials; And it is linked to each other with a port of fiber coupler through single-mode fiber; Monochromatic source links to each other with two other port of fiber coupler with Electro-Optical Sensor Set, and the 4th port of fiber coupler is inserted in the index-matching fluid through single-mode fiber.
Embodiment 1: consult accompanying drawing 1, be said fiber grating FPI current measuring device structural representation.Fiber grating FPI12 sticks on the magnetostriction materials 8; Permanent magnet 7 secured in parallel are in magnetostriction materials 8 both sides; Fiber grating FPI12 is connected with a port of fiber coupler 4 one sides through single-mode fiber 3; The another port links to each other with index-matching fluid 5, and two ports of the opposite side of fiber coupler 4 are connected with Electro-Optical Sensor Set 2 with monochromatic source 1 respectively.
The F-P chamber of said fiber grating FPI12 is limited by magnetostriction materials 8, two fiber grating parts 6 and freely places; Said fiber grating FPI12 reflectivity is less than 5%.
It is that λ, light intensity are I that said monochromatic source is sent wavelength
0Light signal, be transferred in the fiber grating FPI sensor probe through coupling mechanism.Because the reflectivity of fiber grating FPI is less than 5%, so the light signal of reflected back is approximately the two-beam interference signal, but approximate representation does
In the formula, R
λFiber grating FPI is the peak reflectivity of the monochromatic light intensity of λ to wavelength in the long change procedure in expression chamber, by the fiber grating decision at fiber grating FPI two ends; N representes the refractive index of fiber core; Δ h representes the stroke that the chamber is long;
The initial phase of expression fiber grating FPI interference signal to not influence of measurement result, is a normal value.The long variation delta h in chamber that obtains the fiber Bragg grating F-P chamber thus does
Said magnetostriction materials are operated in linear zone under the effect of permanent magnet.The action of a magnetic field around the exchange current causes the length generating period property variation of magnetostriction materials in magnetostriction materials.Deformation takes place in said fiber Bragg grating F-P chamber thereupon.Deformation is divided into two parts to the influence of optical fiber: the one, and the fiber core refractive index that elasto-optical effect causes changes; The 2nd, the variation of the fiber lengths that strain causes.Both actings in conjunction cause the light path generating period property variation that light signal transmits in FPI, thereby cause the cyclical variation of reflective light intensity size.When exchange current to be measured is
, and the relation of long variation delta h in the chamber in fiber Bragg grating F-P chamber and strength of current i is a linear relationship
A is a scale-up factor in the formula, can record through experiment.Therefore obtain under the situation of not account temperature influence, the measured value of electric current equates with actual value i, can be expressed as
Can find out by following formula, if during the frequencies omega of electric current to be measured, and nAi
0During＞λ, the frequency characteristic of reflected light signal I only with the amplitude i of electric current
0Relevant.Therefore just can obtain exchange current i ' to be measured through the frequency characteristic of analyzing reflected light signal I.
What said fiber Bragg grating F-P chamber received environment temperature influences generation deformation.The influence of temperature on fiber is mainly reflected in the fiber core refractive index that fiber lengths changes and the optical fiber thermo-optic effect the causes variation that the optical fiber thermal expansion effects causes.Both actings in conjunction have caused the change of the fiber grating reflectivity at fiber grating FPI two ends, thereby cause R
λVariation.See also Fig. 4, be R
λWith the variation of temperature relation.Require R when measuring temperature
λIn a monotony interval, change.For obtaining maximum temperature measurement range, need choose suitable working point, concrete grammar is following: confirm variation of temperature scope to be measured, choose suitable operation wavelength, make R
λWhen medium temperature the half the of maximum reflectivity.
Because variation of temperature can change the character of magnetostriction materials, and then has influence on the measurement to electric current.Therefore, need revise current value.On the one hand, during temperature constant, the elongation of magnetostriction materials is directly proportional with the residing magnetic field intensity of material; On the other hand, when magnetic field was constant, the elongation of magnetostriction materials also was directly proportional with temperature.So, can suppose that magnetostriction materials receive temperature and the action of a magnetic field dependent variable ε afterwards to do
In the formula, to be the magnetostriction materials strain be the temperature magnetic field intensity cross sensitivity factors of magnetostriction materials to sensitivity coefficient, the κ 2 of temperature to κ 1, and Ceff is the magnetostriction coefficients of magnetostriction materials under a certain steady temperature.Three coefficient values can be obtained by the mode of experiment calibration.Therefore obtain through analysis, the relation of the actual correction value i of electric current and the current value i ' of actual measurement does
Therefore, measurement when can realize electric current and temperature with frequency characteristic through the intensity that detects the output light signal, and then obtain the actual current value after the temperature compensation.
Embodiment 2: consult accompanying drawing 2, be with the different of embodiment 1, said two permanent magnets 7 are separately fixed at the two ends of magnetostriction materials.
Embodiment 3: consult accompanying drawing 3, be with the different of embodiment 1, the driving element that makes fiber grating FPI12 chamber long periodicity change comprises transmission line 9, piezoelectric ceramics 11 and mutual inductor 10.The output of said mutual inductor 10 through transmission line 9, is connected with piezoelectric ceramics 11.
Said mutual inductor is converted into voltage with the electric current in the bus, through transmission line, is loaded on the piezoelectric ceramics.Deformation takes place in said piezoelectric ceramics under the driving of this voltage, act on the fiber Bragg grating F-P chamber, causes that the fiber Bragg grating F-P chamber produces deformation.
The implement device of this method is; The fiber grating FPI of optical fiber optical grating Fabry-Perot interferometer sticks on the magnetostriction materials; And it is linked to each other with a port of fiber coupler through single-mode fiber; Monochromatic source links to each other with two other port of fiber coupler with Electro-Optical Sensor Set, and the 4th port of fiber coupler is inserted in the index-matching fluid through single-mode fiber.In measuring process; The magnetic field that places exchange current to be measured to produce the exchange current sensing head; Used fiber grating FPI near the centre wavelength under the room temperature (20 ℃) is 1550nm, bandwidth＜0.2nm, optical grating reflection rate＜5%; With the modified acroleic acid ester gum F-P chamber is sticked on the magnetostriction materials surface, two affixed points spacings are 6cm.When the current value size of required measurement changes; The narrow band light that monochromatic source is sent; After fiber grating FPI emission; The signal that detects through Electro-Optical Sensor Set again, the cycle of the measured waveform that on oscillograph, shows can change, and obtains the size of current value according to the different cycles characteristic of waveform; When environment temperature changes, show on the oscillograph that the amplitude of the waveform that obtains can change, and then obtain the size of temperature according to the size of amplitude.Finally by the relation of the current value i ' of the actual correction value i of electric current and actual measurement, the current value that obtains after the temperature compensation is big or small.
Claims (2)
1. a current sensing head that utilizes temperature compensating type is measured the method for exchange current,
The current sensing head of said temperature compensating type comprises: optical fiber optical grating Fabry-Perot interferometer (12), magnetostriction materials (8) and 2 permanent magnets (7); 2 permanent magnets (7) opposing parallel places both sides or the vertical fixing of magnetostriction materials (8) in the two ends of magnetostriction materials (8), and the fiber Bragg grating F-P chamber of optical fiber optical grating Fabry-Perot interferometer (12) sticks on the magnetostriction materials (8); The length of magnetostriction materials (8) is less than 1.5 times of fiber Bragg grating F-P chamber length; The length of 2 permanent magnets (7) is more than or equal to the long length in fiber Bragg grating F-P chamber; Said fiber Bragg grating F-P chamber is positioned between two sections fiber gratings (6) of optical fiber optical grating Fabry-Perot interferometer;
It is characterized in that step is following:
Step 1: with the magnetic field that current sensing head places exchange current to be measured to produce, importing a wavelength is that λ, light intensity are I
0Light signal, two-beam interference signal that light intensity is I of current sensing head output;
Step 2: according to light intensity is that the two-beam interference signal of I obtains the long variable quantity in optical fiber optical grating Fabry-Perot interferometer fiber Bragg grating F-P chamber:
R wherein
λFor the fiber Bragg grating F-P chamber is the peak reflectivity of the monochromatic light intensity of λ to wavelength,
Be the initial phase of fiber Bragg grating F-P chamber interference signal, n is the refractive index of fiber core;
Step 3: according to the linear relationship of Δ h and strength of current, the measured value i ' that obtains strength of current for
wherein A to be scale-up factor obtained by the mode of normal experiment calibration;
Step 4: Temperature Compensation is concerned according to measured value i ' and actual value i
Drawing current actual value measured in the environment does
κ wherein
2Be the temperature magnetic field intensity cross sensitivity factors of magnetostriction materials, C
EffBe the magnetostriction coefficient of magnetostriction materials, and κ
2And C
EffTwo coefficient values are obtained by the mode of normal experiment calibration.
2. system that realizes the described measurement exchange current of claim 1 method; It is characterized in that: current sensing head is connected with a port of fiber coupler (4) one sides through single-mode fiber (3), and the another port places index-matching fluid (5) through single-mode fiber (3); Two ports of the opposite side of fiber coupler (4) are connected with Electro-Optical Sensor Set (2) respectively at monochromatic source (1).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101871959B (en) * | 2010-06-08 | 2012-06-27 | 电子科技大学 | Optical fiber Fabry-perot current sensor and preparation method thereof |
| BRPI1101872B1 (en) * | 2011-04-01 | 2017-03-07 | Faculdades Católicas Mantenedora Da Pontifícia Univ Católica Do Rio De Janeiro - Puc Rio | fiber optic magnetic force sensor, manufacturing process and use |
| CN102735273B (en) * | 2012-06-29 | 2014-11-05 | 中国科学院半导体研究所 | Optical fiber sensor based on Fabry-Perot cavity |
| CN103207311A (en) * | 2013-03-21 | 2013-07-17 | 哈尔滨工业大学 | Magnetostriction current sensor for power system |
| CN103293361B (en) * | 2013-06-03 | 2015-07-29 | 哈尔滨理工大学 | Can the current sensor of temperature compensation and electric current detecting method thereof based on double magnetic circuit |
| CN106093525B (en) * | 2016-06-23 | 2018-09-25 | 华中科技大学 | A kind of current sensor based on microdisplacement measurement |
| CN109813950A (en) * | 2019-01-10 | 2019-05-28 | 太原理工大学 | A kind of fiber bragg grating current transformer based on giant magnetostrictive material |
| CN110907683B (en) * | 2019-12-03 | 2021-09-10 | 南京理工大学 | Resonant current sensor for measuring PCB current |
| CN113494890B (en) * | 2021-06-30 | 2023-03-17 | 北京航天控制仪器研究所 | Fiber bragg grating strain sensor precision measuring device and method based on FPI interferometer |
| CN114337073B (en) * | 2021-12-30 | 2023-12-15 | 江苏法尔胜光电科技有限公司 | Motor abnormal vibration monitoring device based on weak reflection fiber bragg grating |
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| CN201226009Y (en) * | 2008-07-17 | 2009-04-22 | 西北工业大学 | Sensing head of optical fiber optical grating Fabry-Perot current sensor |
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| CN201226009Y (en) * | 2008-07-17 | 2009-04-22 | 西北工业大学 | Sensing head of optical fiber optical grating Fabry-Perot current sensor |
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