Active compensation magneto-optical fiber current sensing device and method

Abstract

The invention belongs to the field of power equipment on-line monitoring, and particularly provides an active compensation magneto-optical fiber current sensing device and method.The active compensation magneto-optical fiber current sensing device comprises a light source connected with an optical fiber circulator, the optical fiber circulator is connected with a first optical switch, and a port I of the first optical switch is connected with a first input and output port of a temperature reference magneto-optical fiber sensing probe; a port II of the first optical switch is connected with a second input / output port of the magneto-optical fiber sensing probe, a port I of the second optical switch is connected with a first output port of the temperature reference magneto-optical fiber sensing probe, and a port II of the second optical switch is connected with a second output port of the magneto-optical fiber sensing probe; the magneto-optical fiber sensing probe is arranged in the current sensing solenoid, and the current sensing solenoid is connected in series between the tested current units. The temperature stability problem of the magneto-optical fiber current sensor can be solved, and the temperature application range of the magneto-optical current sensor is expanded.

Description

Technical Field

[0001] This invention belongs to the field of online monitoring of power and electrical equipment, and specifically relates to an active compensation magneto-optical fiber optic current sensing device and method. Background Technology

[0002] Current transformers, as sensors used for current measurement and monitoring, are widely used in industrial production, power system energy metering and relay protection control, and smart grids. Compared with traditional electromagnetic current transformers, optical current transformers have advantages such as high measurement accuracy, high linearity, immunity to electromagnetic interference, fast response speed, good insulation, small size, light weight, and convenient installation and disassembly.

[0003] With the increasing demands on the performance of measurement equipment in power systems, the temperature stability of optical current transformers has become a growing concern. Temperature changes can alter the refractive index of optical materials, magneto-optical effect parameters, and optical path length, thus affecting measurement accuracy and stability. Therefore, a series of studies have been conducted on the temperature stability of optical current transformers. One approach is to suppress temperature-induced current measurement errors by improving the optical path structure and device performance. However, this method is limited by material and device fabrication capabilities, making technological breakthroughs difficult and costly. Another feasible approach is to compensate for temperature-induced current measurement errors to improve temperature stability. In 2011, A. Zimmermann et al. from the Federal University of Santa Catarina proposed using artificial neural networks to compensate for temperature-induced errors in optical current transformers. A feedforward network-based signal processing method was employed, with the input layer containing five input neurons. These neurons are all measurement outputs of the optical current transformer, four of which are related to the transformer itself, and one is the actual temperature measurement output. In 2022, ZZ Liang et al. from Tianjin University proposed a BP neural network filtering algorithm based on the whale method for temperature compensation of fiber optic current transformers. Although neural network compensation algorithms have good compensation effects for temperature-induced current measurement errors, the algorithm needs to be retrained for each fiber optic current transformer due to the differences in device performance. In 2002, K. Bohnert et al. from ABB (Switzerland) discovered a negative temperature correlation between the λ / 4 waveplate and the Wilder constant of the fiber optic sensing loop. They utilized this characteristic to appropriately increase the fabrication length of the λ / 4 waveplate, thereby increasing the phase delay of the λ / 4 waveplate and enabling linear compensation of the Wilder constant of the fiber optic sensing loop across the entire temperature range. However, this method sacrifices current measurement accuracy at room temperature. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an active compensation magneto-optical fiber optic current sensing device and method, which performs online real-time temperature compensation, solves the temperature stability problem of magneto-optical fiber optic current sensors, and expands the temperature application range of magneto-optical current sensors.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: an actively compensated magneto-optical fiber optic current sensing device, comprising a light source, the light source being connected to a first port of a fiber optic circulator, a second port of the fiber optic circulator being connected to a first optical switch, port I of the first optical switch being connected to a first input / output port of a temperature reference magneto-optical fiber optic sensing probe, port II of the first optical switch being connected to a second input / output port of the magneto-optical fiber optic sensing probe, port I of the second optical switch being connected to a first output port of the temperature reference magneto-optical fiber optic sensing probe, and port II of the second optical switch being connected to a second output port of the magneto-optical fiber optic sensing probe, both the fiber optic circulator and the second optical switch being connected to a balanced photodetector, the output of the balanced photodetector being connected to a signal processing unit, the first optical switch and the second optical switch being controlled by a switch control unit, the magneto-optical fiber optic sensing probe being placed inside a current sensing solenoid for current amplification, and the current sensing solenoid being connected in series between the input and output terminals of the measured current unit.

[0006] In a preferred embodiment, both the first optical switch and the second optical switch are magneto-optical switches.

[0007] In a preferred embodiment, the first optical switch and the second optical switch are mechanical optical switches or MEMS optical switches.

[0008] In a preferred embodiment, both the temperature reference magneto-optical fiber optic sensing probe and the magneto-optical fiber optic sensing probe are individually shielded, and the magneto-optical fiber optic sensing probe and the current sensing solenoid are placed inside the same shield.

[0009] In a preferred embodiment, the temperature reference magneto-optical fiber optic sensing probe and the magneto-optical fiber optic sensing probe are placed in the same insulated box.

[0010] In a preferred embodiment, both the temperature reference magneto-optical fiber optic sensing probe and the magneto-optical fiber optic sensing probe include, in sequence, a dual fiber collimator, a Wollaston prism, a 22.5-degree Frandi rotator, a magneto-optical crystal, and a reflector.

[0011] The present invention also provides a detection method for an actively compensated magneto-optical fiber optic current sensing device, comprising the following steps: Step 1: Turn on the light source. The natural light emitted by the light source enters the first port of the fiber optic circulator, is conducted through the fiber optic circulator to its second port, and is then input to the first optical switch. Step 2: Control the first optical switch and the second optical switch to switch ports synchronously through the switch control unit, so that the optical signal is alternately connected to the temperature reference magneto-optical fiber optic sensing probe or the magneto-optical fiber optic sensing probe. When the first optical switch and the second optical switch are switched to port I simultaneously, the optical signal enters the first input / output port of the temperature reference magneto-optical fiber optic sensor through port I of the first optical switch. After being processed by the temperature reference magneto-optical fiber optic sensor, the optical signal carrying pure temperature information is output from its first input / output port and first output port, respectively. The optical signal is then transmitted to the balanced photodetector through port I of the first optical switch and the second optical switch. When the first optical switch and the second optical switch are switched to port II simultaneously, the optical signal enters the second input / output port of the magneto-optical fiber optic sensing probe through port II of the first optical switch. At the same time, the current sensing solenoid, connected in series between the input and output terminals of the measured current unit, generates a magnetic field corresponding to the measured current and acts on the magneto-optical fiber optic sensing probe. After being processed by the magneto-optical fiber optic sensing probe, the optical signal carrying composite information of temperature and measured current is output from its second input / output port and second output port, respectively. The optical signal is then transmitted to the balanced photodetector through port II of the first optical switch and the second optical switch. Step 3: The balanced photodetector converts the received optical signal into an electrical signal and transmits it to the signal processing unit; Step 4: The signal processing unit performs differential processing on the electrical signal carrying pure temperature information in Step 3 and the electrical signal carrying composite information of temperature and measured current in Step 4 to cancel the influence of temperature on magneto-optical effect, and finally calculates the current value of the measured current unit.

[0012] In the preferred embodiment, in step 2, both the first and second optical switches are magneto-optical switches with a switching speed on the order of microseconds and a switching period of T. Within one switching period T, the first half of the period controls the first and second optical switches to synchronously access port I to acquire the pure temperature signal from the temperature reference magneto-optical fiber optic sensing probe; the second half of the period controls both to synchronously access port II to acquire the composite signal of the temperature and the measured current from the magneto-optical fiber optic sensing probe, ensuring that the switching speed is much faster than the rate of change of the ambient temperature.

[0013] In a preferred embodiment, in step 2, the temperature reference magneto-optical fiber optic sensing probe is equipped with a separate probe shield. This shield isolates it from external magnetic field interference, ensuring the probe is only affected by temperature. The output optical signal intensity is P, which is the same as the intensity output from the first input / output port. 11 and the P output from the first output port 12 And P 11 P 12 Carries only temperature information; The magneto-optical fiber optic sensing probe and the current sensing solenoid are housed together within the same probe shield. This shield isolates the probe from external magnetic field interference. The current sensing solenoid amplifies the current of the measured current unit into a corresponding magnetic field, which acts on the magneto-optical fiber optic sensing probe. This causes the optical signal intensity output by the magneto-optical fiber optic sensing probe to be P, which is the intensity of the signal output from the second input / output port. 21 P output from the second output port 22 And P 21 P 22 It also carries temperature information and magneto-optical effect information corresponding to the measured current.

[0014] In the preferred embodiment, the differential processing in step 6 is specifically performed as follows: the signal processing unit calculates P. 21 With P 11 The difference P 21 -P 11 P 22 With P 12 The difference P 22 -P 12 The two differences are used to offset the changes in the Wilder constant of the magneto-optical crystal and the optical path caused by temperature, thus eliminating the interference of temperature on the measurement. Then, based on the magneto-optical effect formula, combined with the difference signal and the inherent parameters of the magneto-optical crystal, the actual current value of the measured current unit is calculated.

[0015] In the preferred embodiment, during steps 1 to 4, the temperature reference magneto-optical fiber optic sensing probe and the magneto-optical fiber optic sensing probe are always placed in the same heat-insulating box. The heat-insulating box ensures that the temperature environment of the two probes is completely consistent, ensuring that the temperature has the same impact on the two probes and guaranteeing the temperature compensation effect of differential processing.

[0016] The present invention provides an actively compensated magneto-optical fiber optic current sensing device and method, which has the following beneficial effects: 1. By synchronously switching via an optical switch, pure temperature signals and temperature-current composite signals are alternately acquired. Differential processing can cancel temperature interference in real time and perform online temperature compensation without the need for offline calibration.

[0017] 2. It uses a temperature reference probe to directly obtain temperature-affected signals, avoiding electromagnetic interference and measurement errors introduced by electronic temperature sensors, and has strong anti-interference capabilities.

[0018] 3. The two probes have the same structure, materials and assembly, and are placed in the same insulated box with the same temperature environment. Differential processing can maximize the elimination of temperature error.

[0019] 4. Without sacrificing accuracy at specific temperatures (such as room temperature), stable measurement performance can be maintained over a wide temperature range.

[0020] 5. The probe shield can isolate external magnetic fields, ensuring that the temperature reference probe is only affected by temperature and the current sensing probe is only affected by the magnetic field corresponding to the measured current, resulting in high measurement stability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of an active temperature-compensated magneto-optical fiber optic current sensing device system. Figure 2 A schematic diagram of the structure of a magneto-optical fiber optic sensing probe or a temperature reference magneto-optical fiber optic sensing probe. Figure 3 The timing diagram shows the driving signal and the optical signals at ports I and II of the first and second optical switches; In the diagram: 1. Light source; 2. Fiber optic circulator; 3. First optical switch; 4. Temperature reference magneto-optical fiber optic sensor probe; 5. First input / output port 401; 6. First output port 402; 7. Magneto-optical fiber optic sensor probe; 8. Second input / output port 501; 9. Probe shield; 10. Heat insulation box; 11. Second optical switch; 12. Balanced photodetector; 13. Signal processing unit; 14. Current sensing solenoid; 15. Measured current unit; 16. Switch control unit; 17. Dual fiber collimator; 18. Wollaston prism; 19. 22.5-degree flange optical rotator; 20. Magneto-optical crystal; 20. Reflector. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0023] Example 1: An actively compensated magneto-optical fiber optic current sensing device, such as Figure 1As shown, the system includes a light source 1, which is a broadband stable light source (such as an LED light source). The light source 1 is connected to the first port of the fiber optic circulator 2. The second port of the fiber optic circulator 2 is connected to the first optical switch 3. Port I of the first optical switch 3 is connected to the first input / output port 401 of the temperature reference magneto-optical fiber optic sensing probe 4. Port II of the first optical switch 3 is connected to the second input / output port 501 of the magneto-optical fiber optic sensing probe 5. Port I of the second optical switch 8 is connected to the first output port 402 of the temperature reference magneto-optical fiber optic sensing probe 4. Port II of the second optical switch 8 is connected to the second output port 502 of the magneto-optical fiber optic sensing probe 5. Both the fiber optic circulator 2 and the second optical switch 8 are connected to a balanced photodetector 9. The output of the balanced photodetector 9 is connected to the signal processing unit 10. The first optical switch 3 and the second optical switch 8 are controlled by a switch control unit 13. The magneto-optical fiber optic sensing probe 5 is placed inside a current sensing solenoid 11 for current amplification. The current sensing solenoid 11 is connected in series between the input and output terminals of the measured current unit 12.

[0024] The first optical switch 3 and the second optical switch 8 are magneto-optical switches with a switching speed of 5μs and a switching period of T=10μs.

[0025] Both the temperature reference magneto-optical fiber optic sensing probe 4 and the magneto-optical fiber optic sensing probe 5 are individually shielded with probe covers 6. The magneto-optical fiber optic sensing probe 5 and the current sensing solenoid 11 are placed inside the same probe shield 6. The temperature reference magneto-optical fiber optic sensing probe 4 and the magneto-optical fiber optic sensing probe 5 are placed in the same heat-insulated box 7.

[0026] The probe shield 6 is made of permalloy, and the heat insulation box 7 is made of polyurethane insulation material to ensure magnetic field isolation and constant temperature.

[0027] Both the temperature reference magneto-optical fiber optic sensing probe 4 and the magneto-optical fiber optic sensing probe 5 include a dual fiber collimator 14, a Wollaston prism 15, a 22.5-degree flanged optical rotator 16, a magneto-optical crystal 17, and a reflector 18 arranged sequentially. The dual fiber collimator 14, Wollaston prism 15, 22.5-degree flanged optical rotator 16, magneto-optical crystal 17, and reflector 18 of both the temperature reference magneto-optical fiber optic sensing probe 4 and the magneto-optical fiber optic sensing probe 5 use components from the same batch and with the same precision, ensuring consistency in materials and assembly.

[0028] The measurement process is as follows: 1. System startup: Turn on light source 1, balance photodetector 9, signal processing unit 10 and switch control unit 13, and preheat for 5 minutes to ensure stable operation of each component.

[0029] 2. Signal Acquisition and Switching: The switch control unit 13 outputs a drive signal to control the first optical switch 3 and the second optical switch 8 to switch synchronously within a period T = 10 μs: First 5μs (T / 2): The two optical switches switch to port I, acquiring the pure temperature signal (P) output by the temperature reference magneto-optical fiber optic sensing probe 4. 11 P 12 The optical signal is converted into an electrical signal U by the balanced photodetector 9. 11 U 12 The signal is transmitted to the signal processing unit 10. After 5μs (T / 2): The two optical switches are switched to port II to acquire the temperature-current composite signal (P) output by the magneto-optical fiber optic sensor probe 5. 21 P 22 ), converted into electrical signal U 21 U 22 The signal is transmitted to the signal processing unit 10.

[0030] 3. Signal processing and current output: The signal processing unit 10 (such as an FPGA chip) performs differential calculations on the electrical signal: ΔU1=U 21 -U 11 ΔU2=U 22 -U 12 To offset the U caused by temperature 11 U 12 interference; The signal processing unit 10 calculates the actual current value of the measured current unit 12 according to the magneto-optical effect formula and outputs it through the digital interface.

[0031] Example 2: A detection method for an actively compensated magneto-optical fiber optic current sensing device includes the following steps: Step 1: Start the light source 1. The natural light emitted by the light source 1 enters the first port of the fiber optic circulator 2, is conducted through the fiber optic circulator 2 to its second port, and is then input to the first optical switch 3.

[0032] Step 2: Control the first optical switch 3 and the second optical switch 8 to switch ports synchronously through the switch control unit 13, so that the optical signal is alternately connected to the temperature reference magneto-optical fiber optic sensing probe 4 or the magneto-optical fiber optic sensing probe 5.

[0033] When the first optical switch 3 and the second optical switch 8 are switched to port I simultaneously, the optical signal enters the first input / output port 401 of the temperature reference magneto-optical fiber optic sensing probe 4 through port I of the first optical switch 3. After being processed by the temperature reference magneto-optical fiber optic sensing probe 4, optical signals carrying pure temperature information are output from its first input / output port 401 and first output port 402, respectively. The optical signals are then transmitted to the balanced photodetector 9 through port I of the first optical switch 3 and the second optical switch 8.

[0034] When the first optical switch 3 and the second optical switch 8 are switched to port II simultaneously, the optical signal enters the second input / output port 501 of the magneto-optical fiber optic sensing probe 5 through port II of the first optical switch 3. At the same time, the current sensing solenoid 11, connected in series between the input and output terminals of the measured current unit 12, generates a magnetic field corresponding to the measured current and acts on the magneto-optical fiber optic sensing probe 5. After the optical signal is processed by the magneto-optical fiber optic sensing probe 5, optical signals carrying composite information of temperature and measured current are output from its second input / output port 501 and second output port 502, respectively. The optical signals are then transmitted to the balanced photodetector 9 through port II of the first optical switch 3 and the second optical switch 8.

[0035] Both the first optical switch 3 and the second optical switch 8 are magneto-optical switches with a switching speed on the order of microseconds and a switching period of T. Within one switching period T, the first half of the period controls the first optical switch 3 and the second optical switch 8 to synchronously access port I to acquire the pure temperature signal of the temperature reference magneto-optical fiber optic sensing probe 4. The second half of the period controls both to synchronously access port II to acquire the composite signal of temperature and measured current of the magneto-optical fiber optic sensing probe 5, ensuring that the switching speed is much faster than the rate of change of ambient temperature.

[0036] The temperature reference magneto-optical fiber optic sensing probe 4 is equipped with a separate probe shield 6 on its outer side. The probe shield 6 isolates external magnetic field interference, so that the temperature reference magneto-optical fiber optic sensing probe 4 is only affected by temperature. The intensity of the output optical signal is P, which is output from the first input / output port 401. 11 and the P output from the first output port 402 12 And P 11 P 12 Carries only temperature information; The magneto-optical fiber optic sensing probe 5 and the current sensing solenoid 11 are housed together within the same probe shield 6. The probe shield 6 isolates external magnetic field interference. The current sensing solenoid 11 amplifies the current of the measured current unit 12 into a corresponding magnetic field that acts on the magneto-optical fiber optic sensing probe 5, causing the optical signal intensity output by the magneto-optical fiber optic sensing probe 5 to be P, which is the intensity of the optical signal output by the second input / output port 501. 21 The P output from the second output port 502 22 And P 21 P22 It also carries temperature information and magneto-optical effect information corresponding to the measured current.

[0037] like Figure 3 As shown, within one period T, based on P 11 P 12 The first half-cycle balanced photodetector measures the signal caused only by temperature; based on P 21 P 22 The signal obtained in the second half of the cycle includes the measured current signal, which is affected by temperature. Subsequently, differential processing is performed on the signals from the first and second halves of the cycle to eliminate the influence of temperature on the measured current, thereby achieving temperature compensation. The switching speed of the magneto-optical switch can reach the microsecond level, which is far slower than the rate of change of ambient temperature.

[0038] Step 3: The balanced photodetector 9 converts the received optical signal into an electrical signal and transmits it to the signal processing unit 10.

[0039] Step 4: The signal processing unit 10 performs differential processing on the electrical signal carrying pure temperature information in step 3 and the electrical signal carrying composite information of temperature and measured current in step 4 to cancel the influence of temperature on magneto-optical effect, and finally calculates the current value of the measured current unit 12.

[0040] Signal processing unit 10 calculates P 21 With P 11 The difference (P) 21 -P 11 ), P 22 With P 12 The difference (P) 22 -P 12 The two differences are used to offset the changes in the Wilder constant and optical path of the magneto-optical crystal 17 caused by temperature, thereby eliminating the interference of temperature on the measurement. Then, based on the magneto-optical effect formula, combined with the difference signal and the inherent parameters of the magneto-optical crystal 17, the actual current value of the measured current unit 12 is calculated.

[0041] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A magnetooptic fiber current sensor device with active compensation, characterized in that, The application relates to a temperature reference magneto-optic fiber sensor system, which comprises a light source (1), a first port of a fiber ring (2) connected with the light source (1), a second port of the fiber ring (2) connected with a first optical switch (3), a first input / output port (401) of a temperature reference magneto-optic fiber sensor probe (4) connected with a port I of the first optical switch (3), a second input / output port (501) of a magneto-optic fiber sensor probe (5) connected with a port II of the first optical switch (3), a first output port (402) of the temperature reference magneto-optic fiber sensor probe (4) connected with a port I of a second optical switch (8), a second output port (502) of the magneto-optic fiber sensor probe (5) connected with a port II of the second optical switch (8), the fiber ring (2) and the second optical switch (8) both connected with a balanced photoelectric detector (9), the balanced photoelectric detector (9) connected with a signal processing unit (10), the first optical switch (3) and the second optical switch (8) controlled by a switch control unit (13), the magneto-optic fiber sensor probe (5) placed in a current sensing solenoid (11) for current amplification, and the current sensing solenoid (11) connected in series between input and output ends of a measured current unit (12).

2. The actively compensated magneto-optical fiber-optic current sensor according to claim 1, characterized in that The first optical switch (3) and the second optical switch (8) are both magneto-optic switches.

3. The active compensated magneto-optical fiber current sensor device according to claim 1, characterized in that The first optical switch (3) and the second optical switch (8) are mechanical optical switches or MEMS optical switches.

4. The actively compensated magneto-optical fiber-optic current sensor of claim 1, wherein, The temperature reference magneto-optic fiber sensor probe (4) and the magneto-optic fiber sensor probe (5) are both provided with a probe shielding cover (6) outside.

5. The actively compensated magneto-optical fiber-optic current sensor of claim 1, wherein, The temperature reference magneto-optic fiber sensor probe (4) and the magneto-optic fiber sensor probe (5) are placed in a same heat insulation box (7).

6. The actively compensated magneto-optical fiber-optic current sensor of claim 1, wherein, The temperature reference magneto-optic fiber sensor probe (4) and the magneto-optic fiber sensor probe (5) both comprise a double-fiber collimator (14), a Wollaston prism (15), a 22.5-degree flange first optical rotator (16), a magneto-optic crystal (17) and a reflector (18) arranged in sequence.

7. A method of detection of a magnetic-optical fiber current sensor with active compensation according to any of claims 1 to 6, characterized in that, The application further discloses a temperature reference magneto-optic fiber sensor system. Step 1: starting the light source (1), natural light emitted by the light source (1) enters a first port of the fiber ring (2), is conducted to a second port of the fiber ring (2) and then is input to the first optical switch (3); Step 2: controlling the first optical switch (3) and the second optical switch (8) to synchronously switch ports through the switch control unit (13), so that optical signals are alternately input to the temperature reference magneto-optic fiber sensor probe (4) or the magneto-optic fiber sensor probe (5); Step 3: the optical signals are converted into electrical signals by the balanced photoelectric detector (9) and then are input to the signal processing unit (10) for processing. When the first optical switch (3) and the second optical switch (8) are switched to port I synchronously, the optical signal enters the first input / output port (401) of the temperature reference magneto-optic fiber sensor probe (4) through port I of the first optical switch (3), and after being processed by the temperature reference magneto-optic fiber sensor probe (4), the optical signal carrying pure temperature information is output from the first input / output port (401) and the first output port (402) of the temperature reference magneto-optic fiber sensor probe (4) respectively, and then transmitted to the balanced photodetector (9) through port I of the first optical switch (3) and port I of the second optical switch (8); When the first optical switch (3) and the second optical switch (8) are switched to port II synchronously, the optical signal enters the second input / output port (501) of the magneto-optic fiber sensor probe (5) through port II of the first optical switch (3), and at the same time, the current sensing solenoid (11) generates a magnetic field corresponding to the measured current and acting on the magneto-optic fiber sensor probe (5) due to being connected in series between the input and output terminals of the measured current unit (12). After being processed by the magneto-optic fiber sensor probe (5), the optical signal carrying temperature and measured current composite information is output from the second input / output port (501) and the second output port (502) of the magneto-optic fiber sensor probe (5) respectively, and then transmitted to the balanced photodetector (9) through port II of the first optical switch (3) and port II of the second optical switch (8). Step 3: The balanced photodetector (9) converts the received optical signal into an electrical signal and transmits it to the signal processing unit (10). Step 4: The signal processing unit (10) differentially processes the electrical signal carrying pure temperature information in step 3 and the electrical signal carrying temperature and measured current composite information in step 4, offsets the influence of temperature on magneto-optic effect, and finally calculates the current value of the measured current unit (12).

8. The detection method of the active compensation magneto-optical fiber current sensor device according to claim 7, characterized in that, In step 2, the first optical switch (3) and the second optical switch (8) are both magneto-optic switches, and the switching speed is in the order of microseconds, and the switching period is set to T. In one switching period T, the first optical switch (3) and the second optical switch (8) are controlled to be connected to port I synchronously in the first half period to collect the pure temperature signal of the temperature reference magneto-optic fiber sensor probe (4), and connected to port II synchronously in the second half period to collect the temperature and measured current composite signal of the magneto-optic fiber sensor probe (5), ensuring that the switching speed is much faster than the rate of change of the ambient temperature.

9. The detection method of the actively compensated magneto-optical fiber optic current sensing device according to claim 7, characterized in that, In step 2, the temperature reference magneto-optical fiber sensor probe (4) is provided with a separate probe shield (6) outside, which isolates external magnetic field interference, so that the temperature reference magneto-optical fiber sensor probe (4) is only affected by temperature, and the output light signal light intensity is P 11 and P 12 output by the first input / output port (401) and the second output port (402), respectively, and only carries temperature information. 11 12 ​​ The magneto-optical fiber sensing probe (5) and the current sensing solenoid (11) are placed in the same probe shield (6), the probe shield (6) isolates the external magnetic field interference, the current sensing solenoid (11) amplifies the current of the measured current unit (12) to the corresponding magnetic field acting on the magneto-optical fiber sensing probe (5), so that the light signal light intensity output by the magneto-optical fiber sensing probe (5) is P 21 and P 22 output by the second output port (502), and P 21 , P 22 carry the temperature information and the magneto-optical effect information corresponding to the measured current at the same time.

10. The detection method of the active compensation magneto-optical fiber current sensor device according to claim 9, characterized in that, The specific method of differential processing in step 6 is as follows: the signal processing unit (10) calculates P 21 With P 11 The difference P 21 -P 11 P 22 With P 12 The difference P 22 -P 12 The two differences are used to offset the changes in the Wilder constant and optical path of the magneto-optical crystal (17) caused by temperature, thereby eliminating the interference of temperature on the measurement. Then, based on the magneto-optical effect formula, combined with the difference signal and the inherent parameters of the magneto-optical crystal (17), the actual current value of the measured current unit (12) is calculated.

11. The method of claim 7, wherein the method is a method of detecting a magnetic-optic fiber current sensor device with active compensation, the method comprising: applying a magnetic field to the fiber current sensor device; and detecting a change in the magnetic field caused by a change in the current in the fiber current sensor device. In the process of steps 1 to 4, the temperature reference magneto-optic fiber sensor probe (4) and the magneto-optic fiber sensor probe (5) are always placed in the same heat insulation box (7), and the heat insulation box (7) makes the temperature environments of the two probes completely consistent, ensuring that the influence of temperature on the two probes is the same and guaranteeing the temperature compensation effect of differential processing.

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