Independent double-strip optical current sensor and method for resisting interference of external temperature fluctuation

Abstract

The application discloses a kind of independent double strip optical current sensor and its anti outside temperature fluctuation interference method belonging to the field of intelligent measurement and sensing technology of electric power system.The sensor includes mutually connected sensing unit and signal processing unit, wherein the output end of multi-frequency modal decoupling signal processing device is connected with the input end of double strip optical current sensor signal processing device, the output end of double strip optical current sensor signal processing device is connected with the input end of measurement signal output device;Sensing unit is provided with double strip sensing unit main structure including measurement sensing optical path structure and temperature compensation sensing optical path structure, the vertical distance of the midpoint of measurement sensing optical path structure and temperature compensation sensing optical path structure to the current to be measured is equal.The application can realize the measurement function of temperature resistance while ensuring the long-term operation stability of single straight-through optical path type optical current sensor, and the advantages of simple structure.

Description

Technical Field

[0001] This invention relates to the field of intelligent measurement and sensing technology for power systems, and in particular to an independent dual-strip optical current sensor and its method for resisting interference from external temperature fluctuations. Background Technology

[0002] Traditional ferromagnetic current transformers suffer from problems such as ferromagnetic resonance, core magnetic saturation, large footprint, and high insulation costs. Therefore, traditional ferromagnetic current transformers are out of step with the development trend of smart and digital power grids. To meet the construction needs of smart grids and new power grids, electronic current transformers, represented by optical current transformers, are gradually demonstrating their application value. Magneto-optical glass optical current transformers (MOCTs) have attracted widespread attention from researchers due to their small size and relatively stable physical characteristics. MOCTs can be further divided into two sensing structures based on their sensor structure: closed-path and direct-path. The closed-path structure suffers from reflection phase shift due to structural limitations, resulting in poor long-term operational stability. However, the direct-path structure is simpler, has lower manufacturing costs, and exhibits better long-term operational stability. The invention patent application No. 202210600285.7 published by the Chinese Patent Office, entitled "A Stacked Optical Current Sensor and Its Anti-External Magnetic Interference Method," solves the problem of external magnetic interference in the measurement process of direct-path optical MOCT, but does not consider the impact of temperature fluctuations on the measurement accuracy of direct-path optical MOCT. With the resolution of the external magnetic interference problem, the elimination of photoelectric noise, and the application of high-performance magneto-optical materials in the measurement process of direct-path optical MOCT, direct-path optical MOCT has shown outstanding practical potential, but it still faces the influence of temperature interference.

[0003] To address the linear birefringence problem within magneto-optical materials, existing technologies have proposed various solutions from different perspectives, which can be listed as follows:

[0004] 1) Separating the Faraday effect and linear birefringence effect offline. A phase retardation plate is added between the magneto-optical material and the polarizer in the original measurement structure. No external magnetic field is applied to the magneto-optical material, but the incident light is linearly polarized. The formula for measuring the linear birefringence inside the magneto-optical material is derived using the Jones matrix calculation method, allowing direct measurement of the linear birefringence. However, this method cannot achieve simultaneous online detection of the Faraday rotation angle and the linear birefringence of the magneto-optical glass, limiting its practical application potential.

[0005] 2) Using the temperature characteristic curve of the magneto-optical sensing structure output beforehand to compensate for the temperature of the sensor output signal is also a sensor temperature compensation method. However, this method has high requirements for the heat transfer structure of the sensor, and it is difficult to obtain a repeatable correspondence between the sensor output signal and the ambient temperature curve, resulting in a large compensation error.

[0006] 3) Comparative Measurement-Based Optical Current Sensor: This method utilizes a permanent magnet to construct a comparative magneto-optical current sensor, essentially using a permanent magnet to build a reference sensing optical path. The reference sensing optical path and the actual measurement optical path can be approximated as being affected by ambient temperature in the same way. This method, by using a permanent magnet to construct a standard measurement sensing optical path, can compensate in real time for the decrease in measurement accuracy of the optical current sensor caused by temperature effects. However, the practicality of this method is limited by the permanent magnet, which is prone to demagnetization, resulting in poor long-term operational stability of the comparative measurement method.

[0007] Based on the above analysis of the shortcomings of various MOCT measurement temperature compensation methods, there is a need for an independent dual-strip optical current sensor and a method to resist external temperature fluctuation interference to eliminate the influence of ambient temperature fluctuation on the optical current sensor, while maintaining the characteristics of simple structure, low manufacturing cost and strong long-term operational stability of the direct-path MOCT. Summary of the Invention

[0008] The purpose of this invention is to propose an independent dual-strip optical current sensor and its method for resisting interference from external temperature fluctuations.

[0009] An independent dual-strip optical current sensor includes a sensing unit and a signal processing unit connected to each other. The signal processing unit includes a multi-frequency mode decoupling signal processing device, a dual-strip optical current sensor signal processing device, and a measurement signal output device. The output terminal of the multi-frequency mode decoupling signal processing device is connected to the input terminal of the dual-strip optical current sensor signal processing device, and the output terminal of the dual-strip optical current sensor signal processing device is connected to the input terminal of the measurement signal output device.

[0010] The sensing unit has a dual-strip sensing unit main structure that includes a measurement sensing optical path structure and a temperature compensation sensing optical path structure. The vertical distance from the midpoint of the measurement sensing optical path structure and the temperature compensation sensing optical path structure to the current to be measured is equal.

[0011] Furthermore, both the measurement sensing optical path structure and the temperature compensation sensing optical path structure are composed of a signal input optical fiber, an input collimator, a polarizer, a magneto-optical sensing material, an analyzer, an output collimator, and a signal output optical fiber connected in series.

[0012] Furthermore, in the measurement sensing optical path structure, the polarizer and analyzer are positioned with their optical axes 45° apart; in the temperature compensation sensing optical path structure, the polarizer and analyzer are positioned with their optical axes 0° apart.

[0013] Furthermore, the measurement sensing optical path structure and the temperature compensation sensing optical path structure are fixed on the insulating support structure; the insulating support structure is also provided with an insulating encapsulation cover.

[0014] As a preferred embodiment of the present invention, the internal connection structure of the independent dual-strip optical current sensor is as follows:

[0015] A high-precision adjustable current source, a controllable light source, and a beam splitter are connected in sequence. The beam splitter then splits into two paths, which are respectively connected to the measurement sensing optical path structure and the temperature compensation sensing optical path structure. The measurement sensing optical path structure and the temperature compensation sensing optical path structure are arranged in parallel. The measurement sensing optical path structure is connected to one input terminal of the multi-frequency mode decoupling signal processing device via a first photodetector and a first A / D converter. The temperature compensation sensing optical path structure is connected to the other input terminal of the multi-frequency mode decoupling signal processing device via a second photodetector and a second A / D converter.

[0016] As another preferred embodiment of the present invention, the internal connection structure of the independent dual-strip optical current sensor is as follows:

[0017] A high-precision adjustable current source is connected to a controllable light source, which is then directly connected to the measurement sensing optical path structure and the temperature compensation sensing optical path structure via optical fiber. The measurement sensing optical path structure and the temperature compensation sensing optical path structure are arranged in parallel. The measurement sensing optical path structure is connected to one input terminal of the multi-frequency mode decoupling signal processing device via a first photodetector and a first A / D converter. The temperature compensation sensing optical path structure is connected to the other input terminal of the multi-frequency mode decoupling signal processing device via a second photodetector and a second A / D converter.

[0018] As another preferred embodiment of the present invention, the internal connection structure of the independent dual-strip optical current sensor is as follows:

[0019] A high-precision adjustable current source, a controllable light source, and a beam splitter are connected in sequence. The beam splitter then splits into two paths, which are respectively connected to the measurement sensing optical path structure and the temperature compensation sensing optical path structure. The measurement sensing optical path structure and the temperature compensation sensing optical path structure are arranged perpendicularly, and their input ends are not adjacent. The measurement sensing optical path structure is connected to one input end of the multi-frequency mode decoupling signal processing device via a first photodetector and a first A / D converter. The temperature compensation sensing optical path structure is connected to the other input end of the multi-frequency mode decoupling signal processing device via a second photodetector and a second A / D converter.

[0020] As another preferred embodiment of the present invention, the internal connection structure of the independent dual-strip optical current sensor is as follows:

[0021] A high-precision adjustable current source is connected to a controllable light source, which is then directly connected to the measurement sensing optical path structure and the temperature compensation sensing optical path structure via optical fiber in two separate paths. The measurement sensing optical path structure and the temperature compensation sensing optical path structure are arranged perpendicularly, and their input ends are not adjacent. The measurement sensing optical path structure is connected to one input end of the multi-frequency mode decoupling signal processing device via a first photodetector and a first A / D converter. The temperature compensation sensing optical path structure is connected to the other input end of the multi-frequency mode decoupling signal processing device via a second photodetector and a second A / D converter.

[0022] A method for resisting external temperature fluctuation interference in an independent dual-strip optical current sensor, wherein the axis perpendicular to the light transmission direction is taken as the x-axis, and the angle between the analyzer optical axis and the x-axis is . If the angle between the polarizer's optical axis and the x-axis is θ, then considering any arbitrary angle between the polarizer's optical axis and the optical current sensing structure, the optical current sensing model is as follows:

[0023]

[0024] in:

[0025]

[0026] cos(χ)=(δ / Δ)

[0027] sin(χ)=(2γ / Δ)

[0028] In the formula, E o E represents the total electric vector of the light output; o1 E o2 Let represent the electric vectors in the x and y directions of the output light, respectively; sin(χ) and cos(χ) represent variables related to the dielectric tensor matrix of the magneto-optical material, whose values ​​can be determined by γ and δ, where δ is the linear birefringence of the magneto-optical material, and ambient temperature interference information is mixed in the output signal of the optical current sensor in the form of linear birefringence; γ is the Faraday rotation angle containing the measured current information; Δ is the amount of mixing between linear birefringence δ and Faraday rotation angle γ; and δ >> γ, so Δ ≈ δ, which is a constant under the same temperature environment; j is the imaginary unit, and the light intensity signal J output by the measuring sensor optical path structure and the temperature-compensated sensor optical path structure is obtained when considering any angle of the analyzer. O All are the following formulas:

[0029]

[0030] When the relative angle θ between the optical axis and the x-axis of the polarizer (3) is 45°, the light intensity signal JO It becomes:

[0031]

[0032] In the formula, J i The incident light intensity is set; the angle θ between the incident linearly polarized light incident plane and the x-axis is kept at 45°, and the angle between the analyzer optical axis and the x-axis of the measurement sensor optical path structure is set. If the angle is 90°, then the electrical signal u1 output by the measuring sensor optical path structure is expressed as:

[0033]

[0034] In the formula, J o1 To measure the intensity of the emitted light from the sensor optical path structure, the angle between the analyzer optical axis and the x-axis of the temperature-compensated sensor optical path structure is set. If the angle θ between the polarizer optical axis and the x-axis is 45°, then the output signal u2 of the temperature compensation sensing optical path structure can be expressed as:

[0035]

[0036] In the formula, J o2 The intensity of the emitted light from the temperature-compensated sensing optical path structure is determined. Therefore, the signals output from both the measuring sensing optical path structure and the temperature-compensated sensing optical path structure are mixed AC / DC signals. Furthermore, noise is generated during the photodetector acquisition process and the digital-to-analog conversion process. Therefore, a multi-frequency mode decoupling signal processing device is used to obtain the AC signals related to the measured current (around 50Hz) and the temperature compensation signal.

[0037]

[0038] u4=cos(Δ)

[0039] The Faraday rotation angle, containing only the information of the measured current and eliminating the influence of linear birefringence, is obtained, and thus the measured current value is obtained. In actual measurements, the Faraday rotation angle is less than 90°. Since the arcsine function ranges from -π / 2 to π / 2, the formula for resisting external temperature fluctuation interference is derived as follows:

[0040]

[0041] The basic principle formula of the Faraday magneto-optical effect in optical current sensing is given by the following equation:

[0042]

[0043] In the formula, V is the Feld constant of the magneto-optical material, with the unit rad / A, which is an important parameter characterizing the magneto-optical properties of the material; The magnetic field information to be measured is given in A / m; l represents the length of the sensing optical path in m; I is the current value to be measured in A; N is a constant representing the number of revolutions of the linearly polarized light around the current; therefore, the final measurement signal output device outputs the measured signal as follows:

[0044]

[0045] By placing the polarizers for measuring the optical path structure and the temperature-compensated optical path structure according to the requirements of the polarizer anti-temperature fluctuation disturbance method, a high-precision optical current sensing measurement value with eliminated temperature interference information can be obtained.

[0046] The beneficial effects of this invention are as follows:

[0047] 1. The independent dual-strip optical current sensor structure proposed in this invention can basically eliminate the impact of ambient temperature fluctuations on the measurement accuracy of the optical current sensor.

[0048] 2. This invention proposes a novel structural design for a temperature-compensated signal sensing arm, which enables the separation and detection of the measured current signal and the ambient temperature interference signal. By reasonably detecting the two signals, high-precision optical current sensing measurement results can be obtained.

[0049] 3. The independent dual-strip optical current sensor of the present invention can achieve the function of measuring temperature resistance while ensuring the advantages of strong long-term operational stability and simple structure of the single-strip direct-path optical current sensor.

[0050] 4. This invention uses the method of changing the angle of the analyzer to realize the construction of the optical current sensing measurement structure and the temperature compensation structure. It has the advantages of simple operation and simple manufacturing process, and increases the temperature resistance and practicality of MOCT.

[0051] 5. This invention utilizes the independent characteristics of each single-strip direct-through optical current sensor, which can be combined with a strip-shaped direct-through optical MOCT structure that resists other physical fields, such as external magnetic interference fields, thus laying the foundation for achieving multi-physical field interference immunity. Attached Figure Description

[0052] Figure 1 (a)(b)(c) are schematic diagrams of the parallel and equidistant placement structure of the independent dual-strip optical current sensor, the vertical and equidistant placement structure, and the schematic diagram of the insulating encapsulation cover, respectively.

[0053] Figure 2 This is a schematic diagram of the independent dual-strip optical current sensor and its signal processing device in Example 1;

[0054] Figure 3 This is a schematic diagram of the independent dual-strip optical current sensor and its signal processing device in Example 2;

[0055] Figure 4 This is a schematic diagram of the independent dual-strip optical current sensor and its signal processing device in Example 3;

[0056] Figure 5 This is a schematic diagram of the independent dual-strip optical current sensor and its signal processing device in Example 4;

[0057] Figure 6 This is a schematic diagram of the Faraday magneto-optical effect, which is the principle of MOCT measurement.

[0058] In the diagram: 1—Input signal fiber; 2—Light source input collimator; 3—Polarizer; 4—Magneto-optic sensing material; 5—Analyzer; 6—Light source output collimator; 7—Output signal fiber; 8—Measurement sensing optical path structure; 9—Temperature compensation sensing optical path structure; 10—Insulation bearing structure; 11—Insulation encapsulation cover; 12—High-precision adjustable current source; 13—Controllable light source; 14—Beam splitter; 15—Main structure of dual-strip sensing unit; 16—Photodetector; 17—A / D converter; 18—Multi-frequency mode decoupling signal processing device; 19—Dual-strip optical current sensor signal processing device; 20—Measurement signal output device; 21—Sensing unit; 22—Signal processing unit; 23—Current conductor under test. Detailed Implementation

[0059] This invention proposes an independent dual-strip optical current sensor and a method for resisting external temperature fluctuation interference. The invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0060] Figure 1 (a), (b), and (c) are schematic diagrams of the independent dual-strip optical current sensor with parallel and equidistant placement, vertical and equidistant placement, and insulating encapsulation cover, respectively.

[0061] The vertical distances from the midpoints of the two independent optical current sensing optical path structures to the current to be measured 23 are equal; the two optical current sensing optical path structures are placed and fixed on the insulating support structure 10; the insulating encapsulation cover 11 is placed above the main structure 15 of the dual-strip sensing unit and together with the insulating support structure 10 forms an insulating isolation device for the independent dual-strip optical current sensing device; the measurement sensing optical path structure 8 is composed of signal input fiber 1, input collimator 2, polarizer 3, magneto-optical sensing material 4, analyzer 5, output collimator 6, and signal output fiber 7 connected in series; the temperature compensation sensing optical path structure 9 is completely identical to the measurement sensing optical path structure 8 in terms of the types and order of components; the difference between the temperature compensation sensing optical path structure 9 and the measurement sensing optical path structure 8 lies in the difference in the optical axis angle of the analyzer.

[0062] The polarizer 3 and analyzer 5 in the measurement sensing optical path structure 8 are positioned with their optical axes 45° apart; the polarizer 3 and analyzer 5 in the temperature compensation sensing optical path structure 9 are positioned with their optical axes 0° apart; the two independent measurement sensing optical path structures 8 and temperature compensation sensing optical path structure 9 together form the magneto-optical sensing part of the main structure 15 of the independent dual-strip optical current sensor's independent dual-strip sensing unit.

[0063] Example 1

[0064] Figure 2 The diagram below shows the independent dual-strip optical current sensor and its signal processing device in Example 1. The method is described as follows: A high-precision adjustable current source 12 drives a controllable light source 13 to output a stable and reliable light source signal; the light source signal is split into two beams by a beam splitter 14; one beam serves as the input light signal to the measurement sensing optical path structure 8; the other beam serves as the input light signal to the temperature compensation sensing optical path structure 9; the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are placed parallel and symmetrically on the upper and lower sides of the current to be measured 23, and the midpoint of their optical path structures is connected to the current to be measured. The vertical distances of 23 are equal; the output light intensity signals modulated by the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are respectively input to the first A / D converter and the second A / D converter of the A / D converter 17 through the first photodetector and the second photodetector; the light signals output by the first A / D converter and the second A / D converter are processed by the multi-frequency mode decoupling signal processing device 18, the dual-strip optical current sensor signal processing device 19 and the measurement signal output device 20, and then output the accurate optical current sensing measurement result after resisting temperature disturbance.

[0065] Example 2

[0066] Figure 3 This is a schematic diagram of the independent dual-strip optical current sensor and its signal processing device in Embodiment 2. The independent dual-strip optical current sensor in this embodiment is represented as follows: The beam splitter 14 is removed, and the natural light generated by the stable and reliable controllable light source 13 is directly used as the input light signals for the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9, respectively. The output light intensity signals generated by the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are simultaneously input to the first photodetector and the second photodetector of the photodetector 16, respectively. The signals output by the first photodetector and the second photodetector are then output as output light intensity modulation signals to the first A / D converter and the second A / D converter of the A / D converter 17. The light intensity signal output by the A / D converter 17 is input to the signal processing unit 22 for signal processing, and then outputs the temperature-resistant measured current measurement result.

[0067] In this embodiment, it is necessary to ensure that the optical path structure 8 for measuring the current under test and the optical path structure 9 for temperature compensation are placed symmetrically and equidistantly on the upper and lower sides of the current under test.

[0068] Example 3

[0069] Figure 4 This is a schematic diagram of the independent dual-strip optical current sensor and its signal processing device in Example 3. The independent dual-strip optical current sensor in this embodiment is represented as follows, retaining the beam splitter 14; the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are placed at 90°, and the center points of the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are placed perpendicularly and equidistantly on the top and left sides of the current to be measured 23; the natural light signal generated by the controllable light source 13 is input to the input terminals of the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 respectively via the beam splitter 14; the output signals of the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are simultaneously input to the first photodetector and the second photodetector of the photodetector 16; the signals output by the first photodetector and the second photodetector are then output as an output light intensity modulation signal to the first A / D converter and the second A / D converter of the A / D converter 17; the light intensity signal output by the A / D converter 17 is input to the signal processing unit 22 for signal processing, and then outputs the temperature-resistant measurement result of the current to be measured.

[0070] In this embodiment, it is necessary to ensure that the input terminals of the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are not adjacent and are consistent in direction with respect to the external magnetic field.

[0071] Example 4

[0072] Figure 5This is a schematic diagram of the independent dual-strip optical current sensor and its signal processing device in Example 4. The independent dual-strip optical current sensor in this embodiment is represented as follows, excluding the beam splitter 14; the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are placed at a 90° angle, with their center points perpendicularly and equidistantly positioned above and to the left of the current to be measured 23; the natural light input signal emitted by the controllable light source 13 is directly input into the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9; the signal is transmitted via the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9. The measured current signal and the optical current sensing temperature compensation signal generated by the modulation of the structure 9 are collected and processed by the first photodetector and the second photodetector of the photodetector 16, respectively, and then input into the first A / D converter and the second A / D converter of the A / D converter 17. The measured current signal and the optical current sensing temperature compensation signal output by the first A / D converter and the second A / D converter are then processed by the multi-frequency mode decoupling signal processing device 18, the dual-strip optical current sensor signal processing device 19 and the measurement signal output device 20. Finally, the signal processing unit 22 outputs accurate temperature-resistant optical current sensing measurement results.

[0073] In this embodiment, it is necessary to ensure that the input terminals of the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 are not adjacent and are consistent in direction with respect to the external magnetic field.

[0074] Figure 6 The schematic diagram of the Faraday magneto-optical effect in MOCT measurement principle is shown below. The specific method for achieving resistance to environmental temperature fluctuation interference using independent dual-strip optical current sensors is as follows:

[0075] like Figure 1 As shown, the center points of the current measurement structure 8 and the temperature compensation measurement structure 9 are placed on both sides of the current to be measured, with the distance between their center points and the line connecting the current to be measured 23 equal, to ensure the consistency of the magnetic field information measured by the two sensing arms.

[0076] Let the axis perpendicular to the direction of light transmission be the x-axis, and let the angle between the analyzer's optical axis and the x-axis be θ. If the angle between the polarizer's optical axis and the x-axis is θ, then considering any angle between the polarizer's optical axis and the analyzer's optical axis, the light intensity information output by the optical current sensing structure can be obtained as shown in the following formula:

[0077]

[0078] In the formula:

[0079] cos(χ)=(δ / Δ)

[0080] sin(χ)=(2γ / Δ)

[0081] In the formula, E o E represents the total electric vector of the light output; o1 E o2 γ and δ represent the electric vectors in the x and y directions of the output light, respectively; sin(χ) and cos(χ) represent variables related to the dielectric tensor matrix of the magneto-optical material, whose values ​​can be determined by γ and δ. δ is the linear birefringence of the magneto-optical material, and ambient temperature interference information is mixed into the output signal of the optical current sensor in the form of linear birefringence; γ is the Faraday rotation angle containing the measured current information; Δ is the amount of mixing between linear birefringence δ and Faraday rotation angle γ; and since δ >> γ, Δ ≈ δ, which can be considered constant under the same temperature conditions; the angle between the optical axis of analyzer 5 and the x-axis is... j is the imaginary unit, and the light intensity signal J output by the measuring sensor optical path structure 8 and the temperature-compensated sensor optical path structure 9 is obtained when considering any angle of the analyzer. O All are the following formulas:

[0082]

[0083] When the angle θ between the polarizer's optical axis and the x-axis is 45°, the light intensity signal J O It becomes:

[0084]

[0085] In the formula, J i To determine the incident light intensity; to maintain the angle θ between the incident plane of the linearly polarized light and the x-axis at 45°, the angle between the analyzer optical axis and the x-axis of the measuring sensor optical path structure 8 is set. If the angle is 90°, then the light intensity information u1 output by the measuring sensor optical path structure 8 can be expressed as:

[0086]

[0087] In the formula, J o1 To measure the intensity of the emitted light output from sensing optical path structure 8, the angle between the polarizer optical axis and the x-axis of the temperature-compensated sensing optical path structure 9 is set. If the angle between the incident plane of the incident ray-polarized light and the x-axis is 45°, then the output signal u2 of the temperature-compensated sensing optical path structure 9 can be expressed as:

[0088]

[0089] In the formula, J o2The intensity of the emitted light from the temperature-compensated sensing optical path structure 9 is used to measure the intensity of the emitted light. It can be concluded that the signals output from both the measuring sensing optical path structure 8 and the temperature-compensated sensing optical path structure 9 are mixed AC / DC signals. Furthermore, since noise is generated during the photodetector acquisition process and the digital-to-analog conversion process, a multi-frequency mode decoupling signal processing device can be used to obtain the AC signal related to the measured current information (around 50Hz) and the temperature compensation signal information. The specific signal expression can be represented as:

[0090]

[0091] u4=cos(Δ)

[0092] The Faraday rotation angle, after eliminating the influence of linear birefringence, can be measured, and thus the current value can be obtained. It should be noted that in actual measurements, the Faraday rotation angle is less than 90°. Since the arcsine function ranges from -π / 2 to π / 2, the principle formula for the temperature disturbance resistance method can be derived.

[0093]

[0094] The basic principle formula of the Faraday magneto-optical effect in MOCT sensing is given by the following equation:

[0095]

[0096] In the formula, V is the Feld constant of the magneto-optical material, with the unit rad / A, which is an important parameter characterizing the magneto-optical properties of the material;

[0097] The magnetic field information to be measured is given in A / m; l represents the length of the sensing optical path in m; I is the current value to be measured in A; N is a constant representing the number of revolutions of the linearly polarized light around the current. Therefore, the final measurement signal output device 20 outputs the measured signal as follows:

[0098]

[0099] By arranging the polarizers of the measurement sensing optical path structure 8 and the temperature compensation sensing optical path structure 9 according to the requirements of the polarizer anti-temperature disturbance method, high-precision optical current sensing measurement values ​​with eliminated temperature interference information can be obtained.

[0100] The independent dual-strip optical current sensor signal processing unit 22 can simultaneously perform real-time integrated processing on the output measurement signals of the current measurement sensing optical path structure 8 and the temperature compensation measurement sensing optical path structure 9 to obtain high-precision measurement results from the independent dual-strip optical current sensor that is resistant to temperature disturbances.

[0101] This invention can essentially eliminate the impact of ambient temperature fluctuations on the measurement accuracy of optical current sensors. It achieves temperature-resistant measurement while maintaining the advantages of long-term operational stability and simple structure of single-strip direct-path optical current sensors. It can be combined with strip-shaped direct-path MOCT structures that resist other physical fields, such as external magnetic interference fields, laying the foundation for multi-physics interference immunity.

Claims

1. A current detection method for an independent dual-strip optical current sensor, resistant to interference from external temperature fluctuations, characterized in that, Taking the axis perpendicular to the direction of light transmission as the x-axis, the angle between the optical axis of the analyzer (5) and the x-axis as φ, and the angle between the optical axis of the polarizer (3) and the x-axis as θ, the optical current sensing model of the optical current sensing structure is obtained as follows, considering that the angle between the optical axes of the polarizer and the analyzer is arbitrary: ； in: ； In the formula, E o E represents the total electric vector of the light output; o1 E o2 These represent the electric vectors in the x and y directions of the output light, respectively. , The variable representing the dielectric tensor matrix of the magneto-optical material can be determined by γ and δ. δ is the linear birefringence of the magneto-optical material. The ambient temperature interference information is mixed in the output signal of the optical current sensor in the form of linear birefringence. γ is the Faraday rotation angle containing the measured current information. ∆ is the amount of mixing of linear birefringence δ and Faraday rotation angle γ. And δ » γ, so ∆≈δ. It is a constant under the same temperature environment. j is the imaginary unit. The light intensity signal J output by the measuring sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) when considering any angle of the analyzer is obtained. O All are the following formulas: ； When the relative angle θ between the optical axis and the x-axis of the polarizer (3) is 45°, the light intensity signal J O It becomes: ； In the formula, J i Let the incident light intensity be θ; keep the incident polarized light incident plane at an angle θ of 45° with the x-axis, and set the analyzer optical axis of the measurement sensing optical path structure (8) at an angle φ of 90° with the x-axis. Then the electrical signal u1 output by the measurement sensing optical path structure (8) is expressed as: ； In the formula, J o1 To measure the intensity of the emitted light from the sensing optical path structure (8), the angle φ between the analyzer optical axis and the x-axis of the temperature-compensated sensing optical path structure (9) is set to 45°, and the angle θ between the polarizer optical axis and the x-axis is set to 45°. Then, the output signal u2 of the temperature-compensated sensing optical path structure (9) is expressed as: ； In the formula, J o2 The intensity of the emitted light output from the temperature compensation sensing optical path structure (9) is used to measure the light intensity. Therefore, the signals output from both the measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) are mixed AC / DC signals. Furthermore, since noise is generated during the photodetector acquisition process and the digital-to-analog conversion process, a multi-frequency mode decoupling signal processing device is used to obtain the AC signals related to the measured current information and temperature compensation signal information, which are located near the measured current frequency of 50Hz. ； ； The Faraday rotation angle, containing only the information of the measured current and eliminating the influence of linear birefringence, is obtained, and thus the measured current value is obtained. In actual measurements, the Faraday rotation angle is less than 90°. Since the arcsine function ranges from -π / 2 to π / 2, the formula for resisting external temperature fluctuation interference is derived as follows: ； The basic principle formula of the Faraday magneto-optical effect in optical current sensing is given by the following equation: ； In the formula, V is the Feld constant of the magneto-optical material, with the unit rad / A, which is an important parameter characterizing the magneto-optical properties of the material; The magnetic field information to be measured is expressed in A / m; l represents the length of the sensing optical path, in m; I is the current value to be measured, in A; N is a constant representing the number of loops of the linearly polarized light around the current; therefore, the final measurement signal output device (20) outputs the measured signal as follows: ； The polarizers of the measuring sensor optical path structure (8) and the temperature compensation sensor optical path structure (9) are arranged according to the requirements of the polarizer anti-temperature fluctuation disturbance method at the same angle, so as to obtain the high-precision optical current sensing measurement value that eliminates temperature interference information. The independent dual-strip optical current sensor includes a sensing unit (21) and a signal processing unit (22) connected to each other. The signal processing unit (22) includes a multi-frequency mode decoupling signal processing device (18), a dual-strip optical current sensor signal processing device (19), and a measurement signal output device (20). The output terminal of the multi-frequency mode decoupling signal processing device (18) is connected to the input terminal of the dual-strip optical current sensor signal processing device (19), and the output terminal of the dual-strip optical current sensor signal processing device (19) is connected to the input terminal of the measurement signal output device (20). The sensing unit (21) is provided with a dual-strip sensing unit main structure (15) including a measurement sensing optical path structure (8) and a temperature compensation sensing optical path structure (9). The vertical distance from the midpoint of the measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) to the current to be measured (23) is equal.

2. The current detection method for the independent dual-strip optical current sensor according to claim 1, characterized in that, Both the measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) are composed of signal input fiber (1), input collimator (2), polarizer (3), magneto-optical sensing material (4), analyzer (5), output collimator (6), and signal output fiber (7) connected in series.

3. The current detection method for the independent dual-strip optical current sensor according to claim 2, characterized in that, The polarizer (3) and analyzer (5) in the measurement sensing optical path structure (8) are positioned with their optical axes 45° apart; the polarizer (3) and analyzer (5) in the temperature compensation sensing optical path structure (9) are positioned with their optical axes 0° apart.

4. The current detection method for the independent dual-strip optical current sensor according to claim 3, characterized in that, The measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) are fixed on the insulating support structure (10); the insulating support structure (10) is also provided with an insulating encapsulation cover (11).

5. The current detection method for the independent dual-strip optical current sensor according to claim 1, characterized in that, The internal connection structure of the independent dual-strip optical current sensor is as follows: A high-precision adjustable current source (12), a controllable light source (13), and a beam splitter (14) are connected in sequence. Then, the beam splitter (14) is connected to the measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) in two separate paths. The measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) are set in parallel. The measurement sensing optical path structure (8) is connected to one input terminal of the multi-frequency mode decoupling signal processing device (18) in sequence through the first photodetector and the first A / D converter. The temperature compensation sensing optical path structure (9) is connected to the other input terminal of the multi-frequency mode decoupling signal processing device (18) in sequence through the second photodetector and the second A / D converter.

6. The current detection method for the independent dual-strip optical current sensor according to claim 1, characterized in that, The internal connection structure of the independent dual-strip optical current sensor is as follows: A high-precision adjustable current source (12) is connected to a controllable light source (13), and then the controllable light source (13) is directly connected to the measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) respectively through optical fiber. The measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) are set in parallel. The measurement sensing optical path structure (8) is connected to one input terminal of the multi-frequency mode decoupling signal processing device (18) in sequence through the first photodetector and the first A / D converter. The temperature compensation sensing optical path structure (9) is connected to the other input terminal of the multi-frequency mode decoupling signal processing device (18) in sequence through the second photodetector and the second A / D converter.

7. The current detection method for the independent dual-strip optical current sensor according to claim 1, characterized in that, The internal connection structure of the independent dual-strip optical current sensor is as follows: A high-precision adjustable current source (12), a controllable light source (13), and a beam splitter (14) are connected in sequence. Then, the beam splitter (14) is connected to the measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) in two separate paths. The measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) are set perpendicularly and their input ends are not adjacent. The measurement sensing optical path structure (8) is connected to one input end of the multi-frequency mode decoupling signal processing device (18) in sequence through the first photodetector and the first A / D converter. The temperature compensation sensing optical path structure (9) is connected to the other input end of the multi-frequency mode decoupling signal processing device (18) in sequence through the second photodetector and the second A / D converter.

8. The current detection method for the independent dual-strip optical current sensor according to claim 1, characterized in that, The internal connection structure of the independent dual-strip optical current sensor is as follows: A high-precision adjustable current source (12) is connected to a controllable light source (13). The controllable light source (13) is then directly connected to the measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) via optical fiber. The measurement sensing optical path structure (8) and the temperature compensation sensing optical path structure (9) are set perpendicularly and their input ends are not adjacent. The measurement sensing optical path structure (8) is connected to one input end of the multi-frequency mode decoupling signal processing device (18) via the first photodetector and the first A / D converter. The temperature compensation sensing optical path structure (9) is connected to the other input end of the multi-frequency mode decoupling signal processing device (18) via the second photodetector and the second A / D converter.

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