Optical fiber interference remote calibration method based on giant magnetostrictive material and current transformer

Abstract

The invention discloses an optical fiber interference remote calibration method based on a giant magnetostrictive material and a current transformer. The current transformer comprises a laboratory end, a field end, a photoelectric detector and a terminal processor. The laboratory end is connected with the field end through an optical fiber and is used for generating a standard optical path difference delta standard and providing an optical signal for the field end; the field end is connected with the photoelectric detector through an optical fiber, the field end comprises a giant magnetostrictive material rod, a sensing optical fiber and a reference optical fiber, and the sensing optical fiber is connected with the sensing optical fiber; under the excitation of a measured current, the giant magnetostrictive material deforms, and after an optical signal passes through the sensing optical fiber, a to-be-measured optical path difference delta to be measured is generated between the optical signal and an optical signal of the reference optical fiber; the photoelectric detector detects the light intensity output by the field end; the photoelectric detector is connected with the terminal processor, when the standard optical path difference delta standard and the optical path difference delta to be measured, the photoelectric detector detects the maximum light intensity, and at the moment, the measured current value is calculated for remote calibration.

Description

Technical Field

[0001] The invention belongs to the technical field of electric power equipment, and more specifically, relates to an optical fiber interference remote calibration current transformer based on giant magnetostrictive material. Background Art

[0002] The power industry is a basic industry for national development and plays a pivotal role in national economic construction. In the power industry, the measurement of current and voltage plays a very important role. They provide the necessary information for metering, control and relay protection in the power system. With the development of industry, agriculture, transportation and national defense, the power consumption is increasing, resulting in the rated voltage and rated current levels in the power system increasing year by year. For a long time, in the operation of the power system, the current measurement task of the high-voltage power grid has been completed by traditional current transformers.

[0003] However, with the development of my country's smart grid and the increasing demand for electricity in society, the power system has increased the corresponding voltage level to improve the transmission efficiency. At the same time, the traditional electromagnetic current transformer has exposed many shortcomings: magnetic saturation, ferromagnetic resonance, hysteresis, narrow measurement frequency band, small dynamic range, poor insulation, etc. This traditional current transformer has been difficult to meet the development requirements of the power system. Research and development of new power measurement technology has become a very urgent need.

[0004] like Figure 1 As shown, in the prior art, a temperature automatic compensation all-fiber AC current sensor combining a sensing fiber Bragg grating (S-FBG) and a reference fiber Bragg grating (A-FBG) has appeared. This sensor cascades the sensing fiber Bragg grating and the reference fiber Bragg grating into a "cross shape" and then pastes them on a giant magnetostrictive material, and then places it in the narrow gap of the magnetic focusing loop; at the same time, the radial direction of the sensing fiber Bragg grating is controlled to be the same as the direction of the magnetic field, while the radial direction of the reference fiber Bragg grating is opposite to the direction of the magnetic field. Finally, the central wavelength of the S-FBG is placed on the sideband of the A-FBG reflection spectrum, and the current measurement and temperature automatic compensation are realized by detecting the change in the reflected light intensity of the two fiber Bragg grating cascades. The shortcomings of this AC current sensor at least include the inability to perform remote measurement and calibration.

[0005] like Figure 2As shown, the technical solutions disclosed in the prior art also include a high-sensitivity fiber Bragg grating large current sensor based on giant magnetostrictive material, which is composed of a magnetic strip made of ferrite, a neodymium iron boron permanent magnet, a magnetostrictive composite material, 304 stainless steel, a copper support structure, a copper screw and a fiber Bragg grating. The 304 stainless steel is placed on the upper end of the GMM material to form a T-shaped structure. This T-shaped structure is placed in the copper support structure, and a special copper screw is placed on the upper right side of the structure. The crossbeam of the T-shaped structure is pressurized by twisting it, thereby achieving the purpose of pressurizing the T-shaped structure. The shortcomings of this current sensor at least include that it can neither perform temperature compensation nor remote measurement and calibration.

[0006] like Figure 3 As shown, the prior art disclosed technical solutions also include a lever-type GMM-FBG optical fiber current sensor, which improves the current response sensitivity of the GMM-FBG current sensor through a lever structure, gives the working principle of the lever-type GMM-FBG current sensor, builds a theoretical model, and uses finite element simulation software for simulation analysis and parameter optimization design. The shortcomings of this optical fiber current sensor also include at least the inability to perform remote measurement and calibration.

[0007] like Figure 4 As shown, the prior art disclosed technical solutions also include a high-sensitivity dual-ring lever-type GMM-FBG current sensor with temperature compensation, which Figure 3 Based on the current sensor shown in the figure, the reasonable distance of the magnetic circuit spacing is obtained through COMSOL software, the feasibility of temperature compensation is verified, and the length of the FBG grid area is optimized. The shortcomings of this fiber optic current sensor also include at least the inability to perform remote measurement and calibration. Summary of the invention

[0008] In order to solve the deficiencies in the prior art, the present invention provides a fiber optic interference remote calibration current transformer based on giant magnetostrictive material. The magnetic field generated by alternating current acts on the giant magnetostrictive material, which causes the length of the material to change with the change of the external magnetic field. The fiber optic interference technology is used at the field end and the laboratory end to measure the dimensional change of the giant magnetostrictive material, and the information of the conductor current can be indirectly obtained, thereby realizing non-contact, high-precision remote calibration of the current.

[0009] The present invention adopts the following technical solution.

[0010] The first aspect of the present invention provides a fiber optic interferometer remote calibration current transformer based on giant magnetostrictive material, comprising: a laboratory end and a field end, a photoelectric detector and a terminal processor;

[0011] The laboratory end and the field end are connected by optical fiber to generate a standard optical path difference Δ标准 and provide optical signals to the field end;

[0012] The field end is connected to the photoelectric detector through an optical fiber. The field end includes: a giant magnetostrictive material rod, a sensing optical fiber and a reference optical fiber. The sensing optical fiber is connected to the sensing optical fiber. Under the excitation of the measured current, the giant magnetostrictive material produces a deformation, and the optical signal passes through the sensing optical fiber and generates a measured optical path difference Δ between the optical signal and the reference optical fiber. 待测 ;The photoelectric detector detects the light intensity output by the field end;

[0013] The photodetector is connected to the terminal processor and the standard optical path difference Δ 标准 The optical path difference Δ 待测 When the photoelectric detector detects the maximum light intensity, the measured current value is calculated for remote calibration.

[0014] Preferably, the laboratory end comprises: a first interferometer; the first interferometer comprises: a light source, a collimator, a beam splitter, a movable reflector, a fixed reflector, a first coupler and a precision translation stage;

[0015] The light source emits light, which passes through the collimator and then enters the beam splitter. After passing through the beam splitter, the light is irradiated onto the fixed reflector and the movable reflector respectively.

[0016] The first coupler is used to converge the reflected light of the movable reflector and the fixed reflector, guide it into the transmission optical fiber, and send it to the field end.

[0017] The precision translation stage is connected to the terminal processor and generates a set displacement under the control of the terminal processor.

[0018] Preferably, the distance between the fixed reflector and the beam splitter is not adjustable and remains a fixed value; the movable reflector is arranged on a precision displacement stage, and is used to adjust the distance between the movable reflector and the beam splitter;

[0019] Before calibration, adjust the distance between the movable reflector and the beam splitter to the same distance between the fixed reflector and the beam splitter. The optical path difference between the fixed reflector and the movable reflector at this time is called the standard optical path difference Δ 标准 .

[0020] Preferably, the field end includes: a second interference device, the second interference device is connected to the laboratory end via an optical fiber;

[0021] The second interference device also includes: a second coupler and a third coupler; light is introduced into the second interference device at the field end through the optical fiber, and is divided into two paths by the second coupler, one path enters the sensing optical fiber, and the other path enters the reference optical fiber, and the sensing optical fiber and the reference optical fiber have the same length; after the optical signal is respectively sensed by the sensing optical fiber and the reference optical fiber, it is introduced into the output optical fiber through the third coupler and sent to the photoelectric detector.

[0022] Preferably, the second interference device further comprises: a magnetic conductor; which is a magnetic focusing loop with a slit, the magnetostrictive material rod is placed in the slit of the magnetic focusing loop and fixed, and the sensing optical fiber is pasted on the giant magnetostrictive material;

[0023] The current to be measured is coupled to the magnetic conductor through the coil.

[0024] Preferably, the length of the magnetostrictive material rod is between 10 mm and 20 mm.

[0025] Preferably, the second interference device further includes: a bias current generating device, which is arranged on the magnetic focusing circuit and is used to provide a bias magnetic field.

[0026] Preferably, the terminal processor calculates the measured current value based on the following formula:

[0027]

[0028] Where:

[0029] Δl is the deformation of giant magnetostrictive material,

[0030] μ is the magnetic permeability of giant magnetostrictive material,

[0031] C is the magnetostriction coefficient,

[0032] l is the coherence length of the light source,

[0033] N is the number of turns of the measured current coil,

[0034] I is the measured current amplitude,

[0035] f is the measured current frequency,

[0036] t is time,

[0037] is the initial phase angle of the measured current,

[0038] H b is the bias magnetic field strength,

[0039] M is the magnetization intensity of the giant magnetostrictive material.

[0040] The second aspect of the present invention provides a method for remote calibration of a current transformer using optical fiber interference based on a giant magnetostrictive material, comprising the following steps:

[0041] Step 1, coupling the measured current to the optical fiber interference remote calibration current transformer, initializing the optical fiber interference remote calibration current transformer, and generating a standard optical path difference;

[0042] Step 2, turn on the light source to couple the light between the laboratory end and the field end;

[0043] Step 3, the laboratory end adjusts the optical path difference so that the photodetector receives the maximum light intensity, and records the adjustment amount;

[0044] Step 4: The terminal processor calculates the measured current value based on the adjustment amount in step 3, compares it with the electric meter, and calibrates the measurement result of the electric meter.

[0045] Preferably, in step 1, the distance between the movable reflector and the beam splitter is adjusted to be the same as the distance between the fixed reflector and the beam splitter. The optical path difference generated by the fixed reflector and the movable reflector is called the standard optical path difference, which is denoted by Δ 标准 .

[0046] Preferably, a bias current generating device is configured and turned on on the optical fiber interference remote calibration current transformer.

[0047] Preferably, in step 2, light is introduced into the interference device at the field end through an optical fiber and is divided into two paths by a coupler, one path passing through a sensing optical fiber pasted on a giant magnetostrictive material, and the other path serving as a reference optical fiber for the sensing optical fiber. After the light signal passes through the sensing optical fiber, there will be an optical path difference between the light signal and the reference optical fiber, which is called the optical path difference to be measured and is recorded as Δ 待测 ; The converged light will transmit the two optical signals to the photodetector through the optical fiber.

[0048] Preferably, in step 3, a precision translation stage is used to drive the movable reflector, and when the photodetector I 光电探测器 When the value of is the largest, the distance moved by the precision translation stage is obtained, and the expansion and contraction amount of the giant magnetostrictive material under the action of the magnetic field of the current to be measured is obtained.

[0049] Preferably, in step 4, the terminal processor calculates the measured current value based on the following formula:

[0050]

[0051] Where:

[0052] Δl is the deformation of giant magnetostrictive material,

[0053] μ is the magnetic permeability of giant magnetostrictive material,

[0054] C is the magnetostriction coefficient,

[0055] l is the coherence length of the light source,

[0056] N is the number of turns of the measured current coil,

[0057] I is the measured current amplitude,

[0058] f is the measured current frequency,

[0059] t is time,

[0060] is the initial phase angle of the measured current,

[0061] H b is the bias magnetic field strength,

[0062] M is the magnetization intensity of the giant magnetostrictive material.

[0063] Compared with the prior art, the beneficial effects of the present invention include at least: based on the magnetostrictive effect of giant magnetostrictive materials, the present invention uses optical fiber interference technology to measure the expansion and contraction amount of giant magnetostrictive materials without direct contact with the measured object, and can achieve non-contact measurement, thus avoiding the contact friction and loss problems that may occur in traditional measurement methods.

[0064] At the same time, fiber optic interferometry technology has the characteristics of high precision and can achieve accurate measurement results. Traditional calibration usually needs to be performed on-site, which is restricted by factors such as environmental conditions and equipment limitations. However, this invention uses optical fiber to transmit signals, which can remotely transmit measurement signals to laboratories and other places, and use more sophisticated instruments for calibration, greatly improving the accuracy and reliability of calibration.

[0065] The invention places the sensing fiber and the reference fiber in the same field environment and achieves the measurement target by measuring the optical path difference between the fibers. Since the sensing fiber and the reference fiber are in the same environment, the change in the optical path difference is mainly affected by the target being measured and is not affected by other environmental factors, such as temperature and magnetic field. Therefore, the invention can provide stable and reliable measurement results.

[0066] More specifically, in view of the shortcomings of the prior art solutions that are unable to perform temperature compensation and / or unable to perform remote measurement and calibration, the present invention avoids the influence of temperature on the optical fiber by setting a reference optical fiber, and adds a precision translation stage at the laboratory end, and uses optical fiber interferometry technology to achieve remote measurement of the expansion and contraction amount of the giant magnetostrictive material. There is no need to directly contact the measured object, and the optical fiber is used to transmit the signal, and the measurement signal is remotely transmitted to the laboratory or other places, and more precise instruments are used for calibration, which greatly improves the accuracy and reliability of the calibration.

[0067] In summary, the invention of the fiber optic interferometer remote calibration current transformer based on giant magnetostrictive material can achieve excellent results in the measurement and calibration of current transformers through the characteristics of non-contact, high-precision measurement and remote calibration, and freedom from interference from environmental factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is the schematic diagram of the GMM-FBGs current sensor;

[0069] Figure 2 It is a T-type sensor probe;

[0070] Figure 3 It is a schematic diagram of a lever-type current sensor;

[0071] Figure 4 It is a schematic diagram of a double-ring lever-type current sensor;

[0072] Figure 5 It is a schematic diagram of serial low-coherence interference;

[0073] Figure 6 This is a flow chart of the optical fiber interference remote calibration method based on giant magnetostrictive material of the present invention;

[0074] Figure 7 This is a structural block diagram of the optical fiber interference remote calibration current transformer based on giant magnetostrictive material of the present invention. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0076] It is worth noting that giant magnetostrictive material is a directional crystallized material that changes in volume and length in a magnetic field. It has the advantages of high precision, non-contact measurement, wide measurement range, fast response, and high stability. It is suitable for various application scenarios that require current measurement. Fiber optic interferometry technology is a technology that uses optical fibers to transmit optical signals and achieves precise measurement or sensing through the interference phenomenon of light. It is based on the principle of interferometer, uses optical fiber as the carrier of the sensor, and uses the transmission and interference characteristics of light in the optical fiber to measure changes in the measured physical quantity or environmental parameters. Using fiber optic interferometry technology to measure current has the advantages of non-contact, high precision, fast response, strong anti-interference ability, and suitability for long-distance transmission. It is of great significance for current measurement in various fields such as electricity, energy, and industry.

[0077] The present invention designs the structure of a fiber optic interference remote metering current transformer device based on giant magnetostrictive material and optimizes the design scheme. The measurement principle of the present invention is based on the magnetostrictive effect of the giant magnetostrictive material, that is, the magnetic lattice structure of the giant magnetostrictive material will deform under the action of an external magnetic field, and this deformation will cause the length of the material to change with the change of the external magnetic field, that is, cause the material to expand and contract. Then, the fiber optic interference technology is used, and a photoelectric detector is used to compare the optical path difference generated at the field end and the laboratory end, and the expansion and contraction amount of the giant magnetostrictive material is indirectly measured to obtain the current information.

[0078] The outstanding substantive features of the present invention include at least: the sensing optical fiber is pasted on the giant magnetostrictive material, and when the length of the giant magnetostrictive material changes due to the influence of the magnetic field, the length of the sensing optical fiber pasted on the material will also change accordingly, thereby changing the phase of the wide field in the sensing optical fiber. At this time, there will be an optical path difference between the light in the sensing optical fiber and the reference optical fiber. After the two beams of light are converged, they are transmitted to the photoelectric detector through the optical fiber. When the optical path difference between the sensing optical fiber and the reference optical fiber is equal to the optical path difference generated in the laboratory, bright stripes will be generated and the light intensity will reach the maximum. At this time, the displacement of the precision displacement stage at the laboratory end is the expansion and contraction of the giant magnetostrictive material, and then according to the relationship between the expansion and contraction of the giant magnetostrictive material and the current, the information of the measured current can be indirectly obtained.

[0079] like Figure 7 As shown, embodiment 1 of the present invention provides a fiber optic interference remote calibration current transformer based on giant magnetostrictive material, including: a laboratory end and a field end, a photoelectric detector and a terminal processor.

[0080] The laboratory end and the field end are connected by optical fiber to generate a standard optical path difference Δ 标准 and provide optical signals to the field end;

[0081] The field end is connected to the photoelectric detector through an optical fiber. The field end includes: a giant magnetostrictive material rod, a sensing optical fiber and a reference optical fiber. The sensing optical fiber is connected to the sensing optical fiber. Under the excitation of the measured current, the giant magnetostrictive material produces a deformation, and the optical signal passes through the sensing optical fiber and generates a measured optical path difference Δ between the optical signal and the reference optical fiber. 待测 ;The photoelectric detector detects the light intensity output by the field end;

[0082] The photodetector is connected to the terminal processor and the standard optical path difference Δ 标准 The optical path difference Δ 待测 When the photoelectric detector detects the maximum light intensity, the measured current value is calculated for remote calibration.

[0083] The laboratory end includes: a first interferometer; the first interferometer includes: a light source, a collimator 1, a beam splitter 2, a movable reflector 3, a fixed reflector 4, a first coupler 5 and a precision translation stage 8.

[0084] The light source can emit light, and the emitted light is respectively irradiated on the fixed reflector 4 and the movable reflector 3 after passing through the beam splitter 2. The light is converged by the first coupler 5 and then introduced into the transmission optical fiber.

[0085] The light source may use a laser with a wide spectrum bandwidth. The light source may emit light, which passes through a collimator 1 and enters a beam splitter 2, and then irradiates a fixed reflector 4 and a movable reflector 3 respectively after passing through the beam splitter 2.

[0086] The distance between the fixed reflector 4 and the beam splitter 2 is not adjustable and remains fixed; the movable reflector 3 is set on the precision displacement stage 8, which is used to adjust the distance between the movable reflector 3 and the beam splitter 2. Before the calibration begins, the distance between the movable reflector 3 and the beam splitter 2 is adjusted to the same distance between the fixed reflector 4 and the beam splitter 2. The optical path difference generated by the positions of the fixed reflector 4 and the movable reflector 3 at this time is called the standard optical path difference, which is recorded as Δ 标准 .

[0087] The first coupler 5 is used to gather the reflected light of the movable reflector 3 and the fixed reflector 4, guide it into the transmission optical fiber, and send it to the field end, specifically, to the second interference device at the field end through the optical fiber.

[0088] The precision displacement stage 8 is connected to the terminal processor and can generate a set displacement under the control of the terminal processor.

[0089] The field end includes: a second interference device, which is connected to the laboratory end through an optical fiber, specifically, connected to the first interferometer at the laboratory end. The second interference device includes: a second coupler 6, a third coupler 7, a giant magnetostrictive material rod, a sensing optical fiber and a reference optical fiber, a bias current generating device, a measured current and a magnetic conductor. The measured current is coupled through the coil magnetic conductor.

[0090] The sensing fiber and the reference fiber have the same length and are protected by magnetic field shielding. Specifically, light is introduced into the second interference device at the field end through the optical fiber, and is divided into two paths by the second coupler 6, one path is the sensing fiber pasted on the giant magnetostrictive material, and the other path is the reference fiber of the sensing fiber. After the light signal passes through the sensing fiber, there will be an optical path difference Δ between the light signal of the reference fiber and the light signal of the reference fiber. 待测 Preferably, according to the characteristics of the giant magnetostrictive material and the working environment, when selecting the sensing optical fiber, an optical fiber with high strain resistance, high strength, wear resistance and adaptability to the working temperature should be selected.

[0091] After the optical signal is respectively sent to the sensing optical fiber and the reference optical fiber, it is introduced into the output optical fiber through the third coupler 7 and sent to the photoelectric detector.

[0092] The magnetizer is a magnetic concentrating loop with a slit, and a magnetostrictive material rod is placed in the slit of the magnetic concentrating loop and fixed, preferably but not limited to being fixed by a clamping device. As a prominent substantial feature of the present invention and one of the significant advances brought to the prior art, this method does not use any adhesive or welding, so no additional materials or structures are introduced. When the magnetostrictive material rod is placed in the slit of the magnetic concentrating loop, the magnetic field must pass through the magnetostrictive material to be transmitted to the next part.

[0093] Due to the low magnetic permeability of magnetostrictive materials, the transmission of magnetic fields may be hindered to a certain extent. In order to minimize the influence of magnetostrictive material rods on magnetic permeability, magnetostrictive materials with higher magnetic permeability are selected, the width of the slit is minimized, and the length of the magnetostrictive material rod is designed to be between 10mm and 20mm to reduce the weakening of the magnetic field during the transmission of the magnetic field, ensure close contact between the magnetostrictive material and the slit, and improve the transmission efficiency of the magnetic field.

[0094] Preferably, but not limited to, for a general sensing fiber interferometric measurement system, the fiber deformation that can be measured is in the range of hundreds of microns to millimeters. When the deformation exceeds the resolution limit of the measuring device and can generate a sufficient signal-to-noise ratio, the measuring device can accurately observe and calculate the corresponding deformation.

[0095] The bias current generating device is arranged on the magnetic focusing circuit to provide a bias magnetic field. When the magnetostrictive material is in an alternating magnetic field working environment, the frequency doubling phenomenon is prone to occur. The frequency doubling phenomenon means that when the sensor is in an alternating magnetic field working environment, the strain frequency of its output change is twice the input frequency. The frequency doubling phenomenon will seriously affect the sensitivity and measurement accuracy of the sensor. Therefore, it is necessary to prevent the frequency doubling phenomenon. As one of the outstanding substantial features of the present invention and the significant progress brought to the prior art, a suitable bias magnetic field is added in the magnetic circuit so that the frequency of the sensor output remains the same as the input frequency. The bias magnetic field can be provided by a bias current, so that the magnetostrictive composite material is in a linear working area in the material properties, which helps to improve the output performance of the sensor.

[0096] The photodetector is used to receive and analyze the optical signal transmitted by the third coupler 7 at the field end, and upload the result to the terminal processor, which also accurately controls the precision displacement stage 8 and obtains displacement information in real time. As the displacement of the movable reflector 3 increases or decreases, the interference fringes emerge or shrink from the center. When the photodetector 1 光电探测器When the value of is maximum, the two optical path differences are equal. At this time, the central stripe with the highest light intensity will be observed on the photodetector, and the displacement of the movable mirror in the first interferometer is equal to the deformation of the giant magnetostrictive material Δd=Δl.

[0097] Specifically, the photodetector is connected to the interference device at the field end through an optical fiber, and is used to receive the light converged by the third coupler 7 at the field end.

[0098] The terminal processor is connected to the photoelectric detector and processes the light intensity signal received from the photoelectric detector. 待测 The optical path difference Δ generated by the laboratory end 标准 When the values ​​of are equal, bright stripes will be generated, the light intensity reaches the maximum value, and the photodetector will detect a stronger light intensity. At this time, the distance moved by the precision translation stage is the expansion and contraction amount of the giant magnetostrictive material under the action of the magnetic field of the current to be measured, and the moving distance is obtained by the laser interferometer.

[0099] The terminal processor obtains the measured current value based on the displacement calculation of the precision translation stage, compares it with the electric meter to be tested, and calibrates the measurement result of the electric meter.

[0100] The terminal processor calculates the measured current value using the following formula:

[0101]

[0102] Where:

[0103] μ is the magnetic permeability of giant magnetostrictive material,

[0104] C is the magnetostriction coefficient,

[0105] l is the coherence length of the light source,

[0106] N is the number of turns of the measured current coil,

[0107] I is the measured current amplitude,

[0108] f is the measured current frequency,

[0109] t is time,

[0110] is the initial phase angle of the measured current,

[0111] H b is the bias magnetic field strength. It can be understood that when the bias current generating device is not installed or turned on, H b =0,

[0112] M is the magnetization intensity of the giant magnetostrictive material.

[0113] like Figure 6As shown, embodiment 2 of the present invention provides a remote calibration method, which utilizes the optical fiber interferometry based on giant magnetostrictive material described in embodiment 1 to remotely calibrate the current transformer, including the following steps:

[0114] Step 1: coupling the measured current to the optical fiber interferometer remote calibration current transformer, initializing the optical fiber interferometer remote calibration current transformer, and generating a standard optical path difference.

[0115] Specifically, the light emitted by the light source at the laboratory end will pass through the beam splitter 2 and then illuminate the fixed reflector 4 and the movable reflector 3 respectively. First, the distance between the movable reflector 3 and the beam splitter 2 is adjusted to the same distance between the fixed reflector 4 and the beam splitter 2. The optical path difference generated by the fixed reflector 4 and the movable reflector 3 is called the standard optical path difference, which is recorded as Δ 标准 .

[0116] Preferably, a bias current generating device is configured and turned on on the optical fiber interference remote calibration current transformer.

[0117] Step 2, turn on the light source to couple the light between the laboratory end and the field end.

[0118] Specifically, the light is converged by the coupler 5 and then introduced into the optical fiber. The light is introduced into the interference device at the field end through the optical fiber and is divided into two paths by the coupler 6. One path passes through the sensing optical fiber pasted on the giant magnetostrictive material, and the other path is used as the reference optical fiber of the sensing optical fiber. After the light signal passes through the sensing optical fiber, there will be an optical path difference between the light signal of the reference optical fiber and the light signal of the reference optical fiber, which is called the optical path difference to be measured, recorded as Δ 待测 The converged light transmits the two optical signals to the photodetector through the optical fiber.

[0119] Step 3: Adjust the optical path difference at the laboratory end so that the photodetector receives the maximum light intensity and record the adjustment amount.

[0120] Specifically, a precision translation stage is used to drive the movable reflector 3, and when the optical path difference Δ 待测 The optical path difference Δ generated by the laboratory end 标准 When the values ​​of are equal, bright stripes will be generated, the light intensity reaches the maximum value, and the photodetector will detect a stronger light intensity. At this time, the distance moved by the precision translation stage is the expansion and contraction amount of the giant magnetostrictive material under the action of the magnetic field of the current to be measured.

[0121] Step 4: The terminal processor calculates the measured current value based on the adjustment amount in step 3, compares it with the electric meter, and calibrates the measurement result of the electric meter.

[0122] Specifically, the terminal processor calculates the measured current value based on the following formula:

[0123]

[0124] Where:

[0125] Δl is the deformation of giant magnetostrictive material,

[0126] μ is the magnetic permeability of giant magnetostrictive material,

[0127] C is the magnetostriction coefficient,

[0128] l is the coherence length of the light source,

[0129] N is the number of turns of the measured current coil,

[0130] I is the measured current amplitude,

[0131] f is the measured current frequency,

[0132] t is time,

[0133] is the initial phase angle of the measured current,

[0134] H b is the bias magnetic field strength,

[0135] M is the magnetization intensity of the giant magnetostrictive material.

[0136] In order to more clearly introduce the core concept of the present invention, the principles involved in the present invention are introduced below.

[0137] When two light waves with the same frequency, the same vibration direction, the same phase or a constant phase difference propagate in the same medium, they will superimpose, causing the vibrations in certain areas to be strengthened or weakened, resulting in the appearance of regular light and dark stripes. This phenomenon is called interference of light, and the two light beams are called coherent light.

[0138] Optical interference occurs only within the coherence length of the light source, which is:

[0139]

[0140] Where:

[0141] l is the coherence length of the light source;

[0142] λ is the wavelength of the light source;

[0143] Δλ is the spectral width of the light source.

[0144] The superposition of waves means that the combined vibration of several waves at the meeting point is the vector sum of the vibrations of each wave at that point. The light intensity after the superposition of two beams of light is:

[0145]

[0146] Where:

[0147] I is the light intensity after the two beams are superimposed;

[0148] A is the vector sum of the combined vibrations of the two beams at the point of encounter;

[0149] a1 is the phase of the first beam, and a2 is the phase of the second beam.

[0150] The magnitude of the composite light intensity depends on the phase difference:

[0151]

[0152] Where:

[0153] δ is the phase difference between the first light beam and the second light beam;

[0154] n is the refractive index of light in the medium;

[0155] r1 is the path length of the first beam of light in the medium; r2 is the path length of the second beam of light in the medium;

[0156] Δ represents the optical path difference.

[0157] The optical path difference Δ=n(r1-r2) determines the light intensity, and the maximum light intensity is obtained when δ=2mπ, where m is an integer.

[0158] The interference of light is a special form of superposition. The intensity of the superposition of two beams of light with amplitudes E1 and E2 is:

[0159] I=E·E * =(E1+E2)·(E1+E2) * (4)

[0160]

[0161] Where:

[0162] E is the amplitude after the two beams of light are superimposed;

[0163] The superscript * indicates a conjugate vector;

[0164] is the average intensity of light, is the average intensity of the first beam of light, is the average intensity of the second light beam, is the average intensity of the mutual interference term between the two beams of light;

[0165] T is the time period, t is the time;

[0166] <·> represents the vector inner product.

[0167] For two plane simple harmonics:

[0168] E1=A1cos(k1·r1-ω1t+δ1) (6)

[0169] E2=A2cos(k2·r2-ω2t+δ2) (7)

[0170] Where:

[0171] A1 is the amplitude of the first wave, A2 is the amplitude of the second wave;

[0172] k1 is the wave vector of the first wave, k2 is the wave vector of the second wave;

[0173] ω1 is the angular frequency of the first wave, ω2 is the angular frequency of the second wave;

[0174] δ1 is the phase of the first wave, and δ2 is the phase of the second wave.

[0175] We can get:

[0176]

[0177] δ=[(k1·r1-k2·r2)+(δ1-δ2)-(ω1-ω2)t] (9)

[0178] Therefore, the interference light intensity distribution is related to the optical path difference r1-r2.

[0179] like Figure 5 As shown, the low coherence light source is irradiated through the first interferometer, and the optical path difference generated is |D0-D1|. After passing through the optical fiber, it is irradiated into the second interferometer, and the optical path difference generated is |D2-D3|.

[0180] Assuming the light source is S, the light intensity generated at any point P in the first interferometer is:

[0181]

[0182] Where:

[0183] I(P) is the light intensity generated at any point P;

[0184] I1 is the intensity of the first beam of light, and I2 is the intensity of the second beam of light;

[0185] ΔL is the difference between the two mirrors of the first interferometer, i.e. |D0-D1|;

[0186] λ is the wavelength of light.

[0187] I1, I2 are the points where the light source passes through the reflector, so:

[0188] I0=I1=I2 (11)

[0189]

[0190] Where:

[0191] I0 is the intensity of the incident light.

[0192] After optical fiber coupling, point P is seen as a point light source, and the intensity of the point light source is:

[0193]

[0194] Where:

[0195] P′ is the output point of the light after fiber coupling;

[0196] η is the optical coupling efficiency.

[0197] The coherent light at point P after passing through the second interferometer is incident on the photodetector, and the light intensity detected by the photodetector is:

[0198]

[0199] Where:

[0200] ΔL2 is the difference between the two mirrors of the second interferometer, that is, the value of |D2-D3|. Substituting it into the equation, we get:

[0201]

[0202] Therefore, when I 光电探测器 When the value of is maximum, the two optical path differences are equal. At this time, the central fringe with the highest light intensity will be observed on the photodetector.

[0203] As the displacement of the reflector increases or decreases, the interference fringes emerge or shrink from the center. When the change in the fringes is N, we have:

[0204]

[0205] Where:

[0206] Δd is the displacement of the reflector.

[0207] Giant magnetostrictive materials produce magnetostrictive effect under the action of an external magnetic field. Generally speaking, the giant magnetostrictive effect can be described by the linear magnetostriction coefficient, that is, the ratio of the length change of the material under unit magnetic field strength. The relationship between the elongation of the giant magnetostrictive material and the magnetic induction intensity is:

[0208] Δl=CBl (17)

[0209] Where:

[0210] Δl is the elongation of the giant magnetostrictive material, l is the initial length of the giant magnetostrictive material;

[0211] C is the magnetostriction coefficient;

[0212] B is the magnetic induction intensity.

[0213] According to Ampere's loop theorem, the loop integral of the total magnetic flux of the magnetic field along a closed loop is equal to the total current passing through the closed loop. When a current of a certain amplitude is passed into the excitation coil, the magnetic field strength of the magnetostrictive material rod under an AC current environment is:

[0214]

[0215] Where:

[0216] H b is the bias magnetic field strength,

[0217] N is the number of turns of the unit coil,

[0218] I is the input current amplitude,

[0219] f is the input current frequency,

[0220] is the initial phase angle of the input current.

[0221] The magnetic induction intensity of giant magnetostrictive material GMM can be expressed by the external magnetic field intensity and magnetization intensity:

[0222] B=μ(H+M) (19)

[0223] Where:

[0224] μ is the magnetic permeability,

[0225] B is the magnetic induction intensity,

[0226] M is the magnetization intensity.

[0227] Since the displacement of the movable reflector in the first interferometer at the laboratory end is Δd=Δl, and it can be known from equations (17) and (19) that the relationship between the giant magnetostrictive material and the external magnetic field intensity is:

[0228] Δd=Δl=μCl(H+M) (20)

[0229] Substituting formula (18) into the equation, we can obtain:

[0230]

[0231] Where:

[0232] Δl is the deformation of giant magnetostrictive material.

[0233] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0234] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A fiber optic interferometer remote calibration current transformer based on giant magnetostrictive material, characterized in that: include: Laboratory end and field end, photoelectric detector and terminal processor; The laboratory end and the field end are connected by optical fiber to generate a standard optical path difference Δ 标准 and provide optical signals to the field end; The field end is connected to the photoelectric detector through an optical fiber. The field end includes: a giant magnetostrictive material rod, a sensing optical fiber and a reference optical fiber. The sensing optical fiber is connected to the sensing optical fiber. Under the excitation of the measured current, the giant magnetostrictive material produces a deformation, and the optical signal passes through the sensing optical fiber and generates a measured optical path difference Δ between the optical signal and the reference optical fiber. 待测 ;The photoelectric detector detects the light intensity output by the field end; The photodetector is connected to the terminal processor and the standard optical path difference Δ 标准 The optical path difference Δ 待测 When the photoelectric detector detects the maximum light intensity, the measured current value is calculated for remote calibration.

2. The optical fiber interference remote calibration current transformer based on giant magnetostrictive material according to claim 1, characterized in that: The laboratory end comprises: a first interferometer; the first interferometer comprises: a light source, a collimator (1), a beam splitter (2), a movable reflector (3), a fixed reflector (4), a first coupler (5) and a precision displacement stage (8); The light source emits light, which passes through the collimator (1) and then enters the beam splitter (2). After passing through the beam splitter (2), the light is respectively irradiated onto the fixed reflector (4) and the movable reflector (3); The first coupler (5) is used to gather the reflected light of the movable reflector (3) and the fixed reflector (4), guide it into the transmission optical fiber, and send it to the field end. The precision displacement stage (8) is connected to the terminal processor and generates a set displacement under the control of the terminal processor.

3. The optical fiber interference remote calibration current transformer based on giant magnetostrictive material according to claim 2, characterized in that: The distance between the fixed reflector (4) and the beam splitter (2) is not adjustable and remains at a fixed value; the movable reflector (3) is arranged on a precision displacement stage (8) and is used to adjust the distance between the movable reflector (3) and the beam splitter (2); Before calibration begins, the distance between the movable reflector (3) and the beam splitter (2) is adjusted to the same distance between the fixed reflector (4) and the beam splitter (2). The optical path difference between the fixed reflector (4) and the movable reflector (3) at this time is called the standard optical path difference Δ 标准 .

4. The optical fiber interference remote calibration current transformer based on giant magnetostrictive material according to any one of claims 1 to 3, characterized in that: The field end includes: a second interference device, which is connected to the laboratory end through an optical fiber; The second interference device also includes: a second coupler (6) and a third coupler (7); light is introduced into the second interference device at the field end through an optical fiber, and is divided into two paths by the second coupler (6), one path entering the sensing optical fiber and the other path entering the reference optical fiber, the sensing optical fiber and the reference optical fiber having the same length; after the optical signal is respectively sent to the sensing optical fiber and the reference optical fiber, it is introduced into the output optical fiber through the third coupler (7) and sent to the photoelectric detector.

5. The optical fiber interference remote calibration current transformer based on giant magnetostrictive material according to claim 4, characterized in that: The second interference device also includes: a magnetic conductor; which is a magnetic focusing loop with a slit, the magnetostrictive material rod is placed in the slit of the magnetic focusing loop and fixed, and the sensing optical fiber is pasted on the giant magnetostrictive material; The current to be measured is coupled to the magnetic conductor through the coil.

6. The optical fiber interference remote calibration current transformer based on giant magnetostrictive material according to claim 5, characterized in that: The length of the magnetostrictive material rod is between 10 mm and 20 mm.

7. The optical fiber interference remote calibration current transformer based on giant magnetostrictive material according to claim 5 or 6, characterized in that: The second interference device also includes: a bias current generating device, which is arranged on the magnetic focusing circuit and is used to provide a bias magnetic field.

8. The optical fiber interference remote calibration current transformer based on giant magnetostrictive material according to claim 7, characterized in that: The terminal processor calculates the measured current value based on the following formula, Where: Δl is the deformation of giant magnetostrictive material, μ is the magnetic permeability of giant magnetostrictive material, C is the magnetostriction coefficient, l is the coherence length of the light source, N is the number of turns of the measured current coil, I is the measured current amplitude, f is the measured current frequency, t is time, is the initial phase angle of the measured current, H b is the bias magnetic field strength, M is the magnetization intensity of the giant magnetostrictive material.

9. A method for remote calibration using optical fiber interference based on giant magnetostrictive materials, using an optical fiber interference based on giant magnetostrictive materials remote calibration current transformer according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1, coupling the measured current to the optical fiber interference remote calibration current transformer, initializing the optical fiber interference remote calibration current transformer, and generating a standard optical path difference; Step 2, turn on the light source to couple the light between the laboratory end and the field end; Step 3, the laboratory end adjusts the optical path difference so that the photodetector receives the maximum light intensity, and records the adjustment amount; Step 4: The terminal processor calculates the measured current value based on the adjustment amount in step 3, compares it with the electric meter, and calibrates the measurement result of the electric meter.

10. The optical fiber interference remote calibration method based on giant magnetostrictive material according to claim 9, characterized in that: In step 1, the distance between the movable reflector (3) and the beam splitter (2) is first adjusted to be the same as the distance between the fixed reflector (4) and the beam splitter (2). The optical path difference generated by the fixed reflector (4) and the movable reflector (3) is called the standard optical path difference, which is denoted by Δ 标准 .

11. The optical fiber interference remote calibration method based on giant magnetostrictive material according to claim 10, characterized in that: A bias current generating device is configured and turned on on the optical fiber interferometer remote calibration current transformer.

12. The optical fiber interference remote calibration method based on giant magnetostrictive material according to claim 11, characterized in that: In step 2, light is introduced into the interference device at the field end through an optical fiber and is divided into two paths by a coupler (6). One path passes through the sensing optical fiber pasted on the giant magnetostrictive material, and the other path is used as a reference optical fiber for the sensing optical fiber. After the light signal passes through the sensing optical fiber, there will be an optical path difference between the light signal of the reference optical fiber and the light signal of the reference optical fiber, which is called the optical path difference to be measured and is recorded as Δ 待测 ; The converged light will transmit the two optical signals to the photodetector through the optical fiber.

13. The optical fiber interference remote calibration method based on giant magnetostrictive material according to claim 12, characterized in that: In step 3, a precision translation stage is used to drive the movable reflector (3), and when the photodetector I 光电探测器 When the value of is the largest, the distance moved by the precision translation stage is obtained, and the expansion and contraction amount of the giant magnetostrictive material under the action of the magnetic field of the current to be measured is obtained.

14. The optical fiber interference remote calibration method based on giant magnetostrictive material according to claim 12, characterized in that: In step 4, the terminal processor calculates the measured current value based on the following formula: Where: Δl is the deformation of giant magnetostrictive material, μ is the magnetic permeability of giant magnetostrictive material, C is the magnetostriction coefficient, l is the coherence length of the light source, N is the number of turns of the measured current coil, I is the measured current amplitude, f is the measured current frequency, t is time, is the initial phase angle of the measured current, H b is the bias magnetic field strength, M is the magnetization intensity of the giant magnetostrictive material.

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