CN209746025U - Current measurement system based on double fiber bragg gratings - Google Patents
Current measurement system based on double fiber bragg gratings Download PDFInfo
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- CN209746025U CN209746025U CN201920274502.1U CN201920274502U CN209746025U CN 209746025 U CN209746025 U CN 209746025U CN 201920274502 U CN201920274502 U CN 201920274502U CN 209746025 U CN209746025 U CN 209746025U
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Abstract
The utility model discloses a current measurement system based on two fiber grating, including light source, beam splitter, first optical circulator, second optical circulator, fiber grating demodulation appearance, host computer, constant intensity cantilever beam, permanent magnet, solenoid, FBG1 and FBG 2. The output port of the light source is connected with the input port of the optical beam splitter, one branch of the output port of the optical beam splitter is connected with the first port of the first optical circulator, the other branch of the output port of the optical beam splitter is connected with the first port of the second optical circulator, the second port of the first optical circulator is connected with the FBG1, the third port of the first optical circulator is connected with the input port of the fiber bragg grating demodulator, the second port of the second optical circulator is connected with the FBG2, the third port of the first optical circulator is connected with the input end of the fiber bragg grating demodulator, and the output end of the fiber bragg grating demodulator is connected with the input end of the upper computer. The utility model discloses a light path simple structure, convenient operation, measurement accuracy is high, and simultaneously, the influence of temperature has been avoided to the demodulation mode of differential type.
Description
Technical Field
The utility model belongs to the technical field of the optical current sensing, concretely relates to current measurement system based on two fiber grating.
background
In recent years, with the rapid development of modern industry, higher requirements are put on the transmission and detection of a power grid, and the traditional measurement means of high voltage and large current cannot meet the requirements more and more, so the current research of the optical fiber current sensor is focused. The fiber optic current sensor operates on the principle of the faraday magneto-optical effect, where current is passed through an electrical conductor (wire) to generate an induced magnetic field that, by the faraday effect, is a rotation of the plane of polarization in an optical fiber wound around a wire that conducts the current. When the sensing fiber forms a closed loop along the current, the rotation angle of the polarization plane is equal to: f ═ NV Φ LH · dL ═ NVI; where V denotes the verdet constant of the fiber material, I denotes the current, H denotes the magnetic field, and N denotes the number of turns of the sensing fiber coil.
although the optical fiber current sensor overcomes the defects of the traditional electromagnetic measuring equipment and has the advantages of large measuring dynamic range, strong anti-electromagnetic interference capability, low cost and the like, the optical fiber current sensor still faces some problems in engineering, such as the influence of environmental factors such as system dependence temperature and the like and the influence of factors such as strain on the optical fiber, and the like, and the practical process of the optical fiber current sensor is hindered.
Disclosure of Invention
Aiming at the defects of the prior art, the utility model provides a current measuring system based on double fiber bragg gratings, aiming at solving the technical problems of low current measuring precision caused by the influence of errors and the problem of complex structure of alternating current measuring equipment in the prior art; the method aims to improve the measurement accuracy of the current by eliminating the influence of temperature and strain errors on the optical fiber current sensor.
The utility model provides a current measurement system based on two fiber grating, include: a light source; a beam splitter connected to the light source; a first optical circulator connected to the beam splitter; a second optical circulator connected to the beam splitter; the fiber grating demodulator is connected with the first optical circulator and the second optical circulator; the upper computer is connected with the fiber bragg grating demodulator; one end of the constant-strength cantilever beam is fixed on the upper arm of the wooden frame; the permanent magnet is fixed at the free end of the constant-strength cantilever beam; the solenoid is fixed at the right arm of the wooden frame at one end and is communicated with the current to be measured; FBGs 1 and 2, which are adhered to the constant strength cantilever beam;
Preferably, the FBGs 1 and 2 are fiber bragg gratings of the same specification having the same center wavelength.
Further, preferably, the FBGs 1 and 2 are attached to opposite sides of the constant strength cantilever beam.
further, as a preferred option, the first optical circulator includes a first port, a second port and a third port, one branch of the beam splitter is connected to the first port, the FBG2 is connected to the second port, and the fiber grating demodulator is connected to the third port.
Further, preferably, the second optical circulator includes a first port, a second port and a third port, the first port is connected to the other branch of the beam splitter, the second port is connected to the FBG1, and the third port is connected to the fiber grating demodulator.
further, it is preferable that the FBGs 1 and 2 are pre-stressed before being attached.
A current measuring system based on double fiber gratings comprises the following steps:
Step one, a light source is started, light emitted by the light source passes through a beam splitter and is evenly divided into two beams of light, wherein one beam of light enters the first optical circulator through a first port of the first optical circulator and is emitted out through a second port of the first optical circulator; the other beam of light enters the second optical circulator through the first port of the second optical circulator and is emitted out through the second port of the second optical circulator;
Step two, the light emitted through the second port of the first optical circulator enters the FBG1, the light meeting the Bragg condition is reflected, then enters the first optical circulator through the second port of the first optical circulator, and then is emitted through the third port of the first optical circulator; the light emitted through the second port of the second optical circulator enters the FBG2, the light meeting the Bragg condition is reflected, then enters the second optical circulator through the second port of the second optical circulator and is emitted through the third port of the second optical circulator;
Step three, light emitted from a third port of the first optical circulator and light emitted from a third port of the second optical circulator are simultaneously emitted into the fiber grating demodulator, and the reflection spectrum of the fiber grating demodulator is displayed;
step four, the power supply is switched on, and the solenoid is electrified to generate a magnetic field;
fifthly, the permanent magnet moves under the action of a magnetic field to drive the constant-strength cantilever beam connected with the permanent magnet to deform;
Step six, the strain of the constant-strength cantilever beam causes the central wavelengths of the FBGs 1 and 2 to shift to opposite directions;
And seventhly, processing the reflection spectrum displayed on the fiber grating demodulator, and displaying the reflection spectrum on an upper computer in a current mode.
The utility model has the advantages that:
1. The utility model discloses utilize the poor demodulation mode demodulation current of wavelength, realized the self-compensating of temperature, reduced the higher required precision to demodulation equipment simultaneously.
2. The utility model discloses make full use of the resource of differential type, less increase photoelectric element has the bandwidth of broad, has higher sensitivity.
3. The utility model discloses an optical circulator has avoided optical fiber coupler to have the optical power loss problem that the optic fibre abandonment of the same kind brought.
4. The utility model discloses an optical circulator up to the isolation more than 60dB, weakened polarization crosstalk noise, obviously improved optical fiber current sensor's detection precision.
5. the utility model discloses whole light path is connected simply reliably, is adjusted conveniently, is convenient for operate.
Drawings
The present invention will be better and more fully understood and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein the drawings described herein are for the purpose of providing a further understanding of the invention and constitute a part of the same, illustrative embodiments thereof and the description thereof serve to explain the same and do not constitute an undue limitation on the invention, and wherein the drawing is a schematic structural view of a two fiber grating based current measurement system of the present invention; the second diagram is a structural schematic diagram of the optical circulator.
Detailed Description
The present invention is further described in detail below with reference to specific embodiments and the accompanying drawings so that those skilled in the art can implement the invention based on the description.
The utility model relates to an optic fibre current sensor especially relates to a measure accurate photocurrent measurement system who comprises two FBGs, has provided a current measurement system based on two fiber bragg gratings. The device mainly comprises a light source 1, a beam splitter 2, a first optical circulator 3, a second optical circulator 4, a fiber grating demodulator 5, an upper computer 6, an equal-strength cantilever beam 7, a permanent magnet 8, an FBG 19, an FBG 210, a solenoid 11, a wooden frame 12 and a single-mode optical fiber 13; the tail optical fiber of the broadband light source 1 is connected with the beam splitter 2, a branch of the beam splitter 2 is connected with a first port of the first optical circulator 3, a second port of the first optical circulator 3 is connected with the FBG 19 through a single-mode optical fiber, a third port of the first optical circulator 3 is connected with an input port of the fiber grating demodulator 5, a second port of the second optical circulator 4 is connected with the FBG 210, the third port is connected with an input end of the fiber grating demodulator 5, an output port of the fiber grating demodulator 5 is connected with the upper computer 6, the FBGs 1 and the FBG2 apply prestress respectively and are symmetrically adhered to two sides of the constant-strength cantilever beam 7 through epoxy resin, one end of the constant-strength cantilever beam 7 is fixed on the upper side of the wooden frame 12, the other end of the constant-strength cantilever beam is connected with and suspended on the permanent magnet 8, one end of the solenoid 9 is fixed on the right arm of the wooden frame 12, and the center.
The utility model discloses utilize the poor demodulation mode demodulation current of wavelength, the influence of temperature has been avoided to the resource of make full use of differential type, and the photoelectric element who uses is less, and the bandwidth broad has improved measuring sensitivity. In addition, the optical circulator is adopted to replace the traditional optical fiber coupler, so that the problem of optical power loss caused by the abandonment of one path of optical fiber in the optical fiber coupler is solved, meanwhile, the isolation degree of the optical circulator used in the invention is as high as 60dB, the polarization crosstalk noise is weakened, and the detection precision of the optical fiber current sensor is obviously improved. Compared with the traditional optical fiber current sensor, the optical path connection of the optical fiber current sensor is simple and reliable, the adjustment is convenient, and the operation is convenient.
referring to the first embodiment, after the light source 1 is turned on, the light emitted from the light source 1 is uniformly split by the light splitter 2, one of the light enters the first optical circulator 3 through the first port of the first optical circulator 3, and is emitted from the second port of the first optical circulator 3, and is emitted into the FBG 19 through the single-mode fiber, according to the sensing principle of the fiber grating, that is, because the refractive index in the fiber core is periodically changed, the light waves in different transmission directions in the fiber Bragg grating are coupled, the light waves meeting the Bragg condition are coupled into the light waves transmitted backwards, and the light is emitted into the second port of the first optical circulator 3, the light emitted from the second port of the first optical circulator 3 is emitted from the third port of the first optical circulator 3, and is emitted into the fiber grating demodulator through the input port of the fiber grating demodulator 5, and at this time, the central wavelength of the reflection spectrum of the FBG1 displayed on the fiber grating demodulator is lambda 0; meanwhile, the other beam of light split by the light splitter is emitted into the second optical circulator 4 through the first port of the second optical circulator 4 and is emitted from the second port of the second optical circulator 4, and according to the sensing principle of the fiber bragg grating, the light meeting the bragg condition is emitted into the second optical circulator through the second port of the second optical circulator and is emitted from the third port of the second optical circulator and enters the fiber bragg grating demodulator. Since both the FBGs 1 and 2 are from the same type of photosensitive fiber, the reflection spectra of the FBGs 1 and 2 on the fiber grating demodulator are coincident and both are λ 0 when no current is applied.
The current I to be measured is sent into the solenoid 11, after the solenoid 11 is electrified, a magnetic field is generated, the magnetic field strength B at the position where the permanent magnet 8 is placed is equal to mu 0NI (wherein N is the number of turns of a coil, and mu 0 is the magnetic conductivity in vacuum), at the moment, the magnetic force applied to the permanent magnet 8 (wherein S is the stressed area of the permanent magnet placed in the magnetic field) is provided, the permanent magnet 8 generates displacement under the action of the magnetic force and simultaneously drives the cantilever beam 7 to move, and the axial strain of any point on the uniform-strength cantilever beam 7 is changed (wherein x is the working length of the cantilever beam, namely the distance from a force action point to a fixed point, E is the elastic modulus of the cantilever beam, B is the width of the uniform-strength cantilever beam, and h is the thickness. At this time, it can be observed from the fiber grating demodulator that the reflection spectra of the FBGs 19 and 210 adhered to the constant strength cantilever beam 7 drift in opposite directions, the drift value of the fiber grating center wavelength caused by the axial strain epsilon is Δ λ ═ k epsilon (k epsilon is the strain sensitivity, the strain sensitivity to the fiber grating with fixed wavelength is a fixed value), according to the above equation, since the specifications of the two fiber gratings are the same, the stress magnitude is the same, the directions are opposite, and the wavelength variation of the two fiber gratings is the same, the directions are opposite and at the same temperature, the equation is input into the program of the upper computer 6, according to the fiber grating wavelength variation displayed in the fiber grating demodulator, the magnitude of the current to be measured can be directly read after the processing of the upper computer, and the current detection is finished.
Although specific embodiments of the present invention have been described above, it will be understood by those skilled in the art that these specific embodiments are merely illustrative and that various omissions, substitutions and changes in the form and details of the methods and systems described above may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is within the scope of the present invention to combine the above-described method steps to perform substantially the same function in substantially the same way to achieve substantially the same result. Accordingly, the scope of the invention is to be limited only by the following claims. .
Claims (4)
1. A dual fiber grating-based current measurement system, comprising: a light source; a beam splitter connected to the light source; a first optical circulator connected to the beam splitter; a second optical circulator connected to the beam splitter; the fiber grating demodulator is connected with the first optical circulator and the second optical circulator; the upper computer is connected with the fiber bragg grating demodulator; one end of the constant-strength cantilever beam is fixed on the upper arm of the wooden frame; the permanent magnet is fixed at the free end of the constant-strength cantilever beam; the solenoid is fixed at the right arm of the wooden frame at one end and is communicated with the current to be measured; FBGs 1 and 2 affixed to the constant strength cantilever beam.
2. the FBG-based current measurement system of claim 1 wherein the FBGs 1 and 2 are light sensitive fibers from the same model, having the same center wavelength.
3. The FBG-based current measuring system of claim 2, wherein the FBGs 1 and 2 are symmetrically adhered to both sides of the constant strength cantilever beam, and a certain pre-stress is applied before the adhesion.
4. The FBG-based current measurement system of claim 1, wherein the first optical circulator comprises a first port, a second port and a third port, one branch of the output of the beam splitter is connected to the first port, the FBG1 is connected to the second port, and the input of the fiber grating demodulator is connected to the third port; the second optical circulator comprises a first port, a second port and a third port, the first port is connected with the other branch of the output end of the beam splitter, the second port is connected with the FBG2, and the third port is connected with the input end of the fiber grating demodulator.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920274502.1U CN209746025U (en) | 2019-03-05 | 2019-03-05 | Current measurement system based on double fiber bragg gratings |
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| CN201920274502.1U CN209746025U (en) | 2019-03-05 | 2019-03-05 | Current measurement system based on double fiber bragg gratings |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109709375A (en) * | 2019-03-05 | 2019-05-03 | 哈尔滨理工大学 | A kind of current measurement system and current measuring method based on double optical fiber grating |
| CN111736001A (en) * | 2020-06-12 | 2020-10-02 | 河南大学 | Novel optical current sensor, system and method based on magnetofluid and grating |
-
2019
- 2019-03-05 CN CN201920274502.1U patent/CN209746025U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109709375A (en) * | 2019-03-05 | 2019-05-03 | 哈尔滨理工大学 | A kind of current measurement system and current measuring method based on double optical fiber grating |
| CN111736001A (en) * | 2020-06-12 | 2020-10-02 | 河南大学 | Novel optical current sensor, system and method based on magnetofluid and grating |
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Granted publication date: 20191206 |