CN117783956A - Transformer anomaly detection system and sensors - Google Patents

Abstract

The application discloses abnormal detection system and sensor of transformer, this system includes: the device comprises an optical fiber laser, an optical fiber polarizer, a sensor, a receiving module and a calculating module; the fiber laser is used for generating first laser and emitting the first laser into the fiber polarizer; the optical fiber polarizer is used for converting the received laser into second laser with the target polarization direction and transmitting the second laser to the sensor; the sensor is arranged in the transformer to be tested, and is used for changing the polarization direction of at least part of received laser based on the magnetic field in the transformer to be tested and reflecting all the laser in the transformer to be tested; the receiving module is used for receiving third laser in the target polarization direction, wherein the third laser is laser reflected by the sensor; and the calculation module is used for judging whether the transformer to be tested is abnormal or not based on the information of the second laser and the third laser. Therefore, the magnetic field change of the transformer can be accurately detected, and whether the transformer is abnormal or not can be accurately and rapidly judged.

Description

Transformer anomaly detection system and sensors

Technical field

The invention relates to the technical field of transformer magnetic field measurement, and in particular to a transformer anomaly detection system and sensor.

Background technique

Transformers are very important equipment in the power system, responsible for the transmission and distribution of electrical energy. The magnetic field generated by a transformer can be an important indicator of its normal operation. Most faults that occur in transformers are caused by obstacles in the transformer windings and terminals. These faults can be detected by changes in the magnetic field produced by the transformer. However, since the main magnetic circuit of the transformer is the iron core, measurements are made outside the transformer casing. It cannot be accurately measured after passing through the oil environment and shell of the transformer. Therefore, how to detect whether there is an abnormality in the transformer has become an urgent problem to be solved in the existing technology.

Contents of the invention

In view of this, the purpose of the present invention is to provide a transformer abnormality detection system and sensor to overcome the current problem of being unable to accurately detect whether the transformer is abnormal.

To achieve the above objectives, the present invention adopts the following technical solutions:

In the first aspect, embodiments of the present application provide a transformer anomaly detection system, including: a fiber laser, a fiber polarizer, a sensor, a receiving module and a computing module;

The fiber laser is used to generate a first laser and emit the first laser into the fiber polarizer; the fiber polarizer is used to convert the received laser into a second laser with a target polarization direction, and transmit the second laser light to the sensor;

The sensor is arranged in the transformer to be tested, and is used to change the polarization direction of at least part of the received laser light based on the magnetic field inside the transformer to be tested, and to reflect all the laser light inside it;

The receiving module is used to receive a third laser in the target polarization direction, wherein the third laser is the laser reflected by the sensor;

The calculation module is used to determine the magnetic field state information of the transformer to be tested based on the information of the second laser and the third laser, and to determine whether the transformer to be tested is abnormal based on the magnetic field state information.

Further, the sensor includes: a transmission module, a Faraday magneto-optical effect material and a laser reflective layer;

The transmission module is used to transmit incident laser light into the Faraday magneto-optical effect material;

The Faraday magneto-optical effect material is used to change the polarization direction of at least part of the received laser light based on the magnetic field inside the transformer to be tested;

The laser reflective layer is used to reflect laser light passing through the Faraday magneto-optical effect material.

Further, the transmission module, Faraday magneto-optical effect material and laser reflection layer are arranged in sequence;

The laser light reflected by the laser reflection layer is emitted through the Faraday magneto-optical effect material and the transmission module.

Further, the transmission module includes: an optical fiber cladding and a fiber core wrapped by the optical fiber cladding.

Further, it also includes: fiber optic circulator;

The optical fiber circulator is provided with a first port, a second port and a third port;

The optical fiber circulator is used to receive the laser light emitted by the optical fiber polarizer through the first port, and transmit the laser light received by the first port to the sensor through the second port;

The fiber optic circulator is also used to receive the laser light reflected by the sensor through the second port, and transmit the laser light received by the second port to the receiving module through the third port.

Further, the receiving module includes a polarized optical fiber and a light intensity detector;

The polarized optical fiber is used to receive the laser light outputted from the third port of the optical fiber circulator and transmit it to the light intensity detector.

Further, the information about the second laser includes the light intensity of the second laser emitted by the optical fiber polarizer, and the information about the third laser includes the third laser in the target polarization direction received by the receiving module.

Further, determining the magnetic field state information of the transformer under test based on the information of the second laser and the third laser includes:

Based on the information of the second laser and the third laser and a preset formula, determining the angle at which the polarization direction of the laser of the transformer to be tested changes in the Faraday magneto-optical effect material;

Determine the magnetic field state information of the transformer under test based on the angle at which the polarization direction changes in the Faraday magneto-optical effect material;

Wherein, the preset formula is:

Wherein, Iin is the light intensity of the second laser emitted by the optical fiber polarizer; Iout is the third laser in the target polarization direction received by the receiving module; eta is the system laser loss; γ is the laser reflection layer The reflectivity; θ is the angle at which the polarization direction of the laser changes in the Faraday magneto-optical effect material.

Further, the information about the second laser includes the power of the second laser emitted by the optical fiber polarizer, and the information about the third laser includes the power of the third laser in the target polarization direction received by the receiving module. .

In a second aspect, embodiments of the present application also provide a sensor, including: a transmission module, a Faraday magneto-optical effect material, and a laser reflective layer;

The transmission module is used to transmit incident laser light into the Faraday magneto-optical effect material;

The Faraday magneto-optical effect material is used to change the polarization direction of at least part of the received laser light based on the magnetic field inside the transformer to be tested;

The laser reflective layer is used to reflect laser light passing through the Faraday magneto-optical effect material.

The transformer abnormality detection system provided by the invention includes: a fiber laser, a fiber polarizer, a sensor, a receiving module and a computing module; the fiber laser is used to generate a first laser and emit the first laser into the fiber polarizer; the fiber laser The polarizer is used to convert the received laser light into a second laser light with a target polarization direction, and transmit the second laser light to the sensor; the sensor is arranged in the transformer to be tested, and is used to change at least part of the laser beam based on the magnetic field inside the transformer to be tested. The polarization direction of the received laser light, and reflects all the laser light inside it; the receiving module is used to receive the third laser light in the target polarization direction, where the third laser light is the laser light reflected by the sensor; the calculation module is used to calculate the laser light based on the second laser light and The information of the third laser determines the magnetic field status information of the transformer under test, and determines whether the transformer under test is abnormal based on the magnetic field status information. In this way, changes in the magnetic field of the transformer can be accurately detected, thereby determining whether the transformer is operating abnormally based on the changes in the magnetic field of the transformer, and accurately and quickly determining whether the transformer is abnormal.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a transformer anomaly detection system provided by an embodiment of the present application;

FIG2 is a schematic diagram of the structure of a transformer abnormality detection system provided by another embodiment of the present application;

Figure 3 is a schematic structural diagram of a sensor in a transformer anomaly detection system provided by another embodiment of the present application.

Detailed ways

To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

Figure 1 is a schematic structural diagram of a transformer anomaly detection system provided by an embodiment of the present application. As shown in Figure 1, the transformer anomaly detection system provided by an embodiment of the present application may at least include: fiber laser 1, fiber polarizer 2, sensor 3, Receiving module 4 and calculation module 5;

The fiber laser 1 is used to generate a first laser and emit the first laser to the fiber polarizer 2; the fiber polarizer 2 is used to convert the received laser into a second laser with a target polarization direction, and convert the second laser into a second laser with a target polarization direction. The laser is transmitted to the sensor 3; the sensor 3 is arranged in the transformer to be tested, and is used to change the polarization direction of at least part of the received laser based on the magnetic field inside the transformer to be tested, and reflect all the laser inside it; the receiving module 4 is used to Receive the third laser in the target polarization direction, where the third laser is the laser reflected by the sensor 3; the calculation module 5 is used to determine the magnetic field state information of the transformer to be tested based on the information of the second laser and the third laser, and based on the magnetic field state The information determines whether the transformer under test is abnormal.

Specifically, the fiber laser 1 generates and emits a first laser, and the first laser passes through the fiber polarizer 2. The fiber polarizer 2 changes the first laser emitted by the fiber laser into a second laser with a target polarization direction such as polarization direction S. .

The second laser reaches the sensor 3. The sensor 3 is provided with a specific magneto-optical effect and a reflective material inside, which can change the polarization direction of at least part of the second laser entering the sensor 3, and reflect all the lasers entering the sensor 3 (including the second laser whose polarization direction has not been changed and the third laser formed by the changed polarization direction) to the receiving module 4.

The receiving module 4 only receives or allows only lasers with a specific polarization direction to pass, such as lasers with the same polarization direction as the second laser. In this way, the information of the second laser and the information of the third laser with the same polarization direction as the second laser received by the receiving module 4 can be determined based on the transmission power of the optical fiber laser, and the changes of the second laser after entering the sensor 3 can be obtained. Since the changes of the second laser after entering the sensor 3 depend on the magnetic field where the sensor 3 is located, in actual detection, it is only necessary to set the sensor 3 inside the transformer to be tested, and adjust the transmission directions of the first laser, the second laser and the third laser accordingly (of course, the transmission directions of the three can also be determined when the detection system is designed, so that they can be used directly later), and the magnetic field state information inside the transformer to be tested can be calculated by the calculation module 5, and then the magnetic field state information can be used to determine whether the transformer is operating abnormally.

It should be noted that when determining whether the transformer under test is operating abnormally based on the real-time detected magnetic field state information inside the transformer under test, it can be done by recording the magnetic field state information under normal state when the transformer under test is operating normally, and then comparing it with the magnetic field state information detected in real time later. If the difference between the two is different or exceeds the preset range, it is determined that the transformer under test is operating abnormally; if the two are the same or the difference does not exceed the preset range, it is determined that the transformer under test is operating normally. Or in some embodiments of the present application, a standard threshold value, such as magnetic flux and other information, can be determined through preliminary detection calculations, and the real-time detected magnetic field state information can be converted into a corresponding value, and then compared to determine whether the transformer under test is operating abnormally.

The transformer abnormality detection system provided by the invention includes: a fiber laser, a fiber polarizer, a sensor, a receiving module and a computing module; the fiber laser is used to generate a first laser and emit the first laser into the fiber polarizer; the fiber laser The polarizer is used to convert the received laser light into a second laser light with a target polarization direction, and transmit the second laser light to the sensor; the sensor is arranged in the transformer to be tested, and is used to change at least part of the laser beam based on the magnetic field inside the transformer to be tested. The polarization direction of the received laser light, and reflects all the laser light inside it; the receiving module is used to receive the third laser light in the target polarization direction, where the third laser light is the laser light reflected by the sensor; the calculation module is used to calculate the laser light based on the second laser light and The information of the third laser determines the magnetic field status information of the transformer under test, and determines whether the transformer under test is abnormal based on the magnetic field status information. In this way, changes in the magnetic field of the transformer can be accurately detected, thereby determining whether the transformer is operating abnormally based on the changes in the magnetic field of the transformer, and accurately and quickly determining whether the transformer is abnormal.

Figure 2 is a schematic structural diagram of a transformer anomaly detection system provided by another embodiment of the present application, as shown in Figure 2 (the solid arrow in Figure 2 is the incident laser for sensor 3, and the dotted arrow is for sensor 3 Emitting laser), in some embodiments of the present application, the transformer anomaly detection system may also include: a fiber optic circulator 6.

The optical fiber circulator 6 is provided with a first port A, a second port B and a third port C; the optical fiber circulator 6 is used to receive the laser emitted by the optical fiber polarizer 2 through the first port A, and receive the laser through the first port A. The received laser light is transmitted to the sensor 3 through the second port B; the fiber optic circulator 6 is also used to receive the laser light reflected by the sensor 3 through the second port B, and transmit the laser light received by the second port B through the third port C. to the receiving module 4.

Specifically, the laser, such as the second laser, is emitted from the second port B through the first port A of the fiber optic circulator 6, and then enters the sensor 3; the sensor 3 is in the magnetic field generated by the transformer to be measured, and at this time, the laser light entering the sensor 3 Under the action of the internal materials of the transformer 3, the laser changes its polarization direction based on the magnetic field condition, and is reflected by the sensor 2 back to the second port B of the fiber optic circulator 6, and is emitted from the third port C.

Further, the receiving module 3 includes a polarizing optical fiber 41 and a light intensity detector 42 .

In practical applications, the laser (i.e., the third laser) emitted from the third port C of the optical fiber circulator 6 will pass through the polarized optical fiber 41. The polarized optical fiber 41 only allows the third laser in the target polarization direction to pass through and is transmitted to the light intensity detector. 42 in.

Figure 3 is a schematic structural diagram of a sensor in a transformer anomaly detection system provided by another embodiment of the present application. As shown in Figure 3, in some embodiments of the present application, the sensor 3 specifically includes: a transmission module 31, a Faraday magneto-optical effect material 32 and laser reflective layer 33.

The transmission module 31 is used to transmit the incident laser to the Faraday magneto-optical effect material 32; the Faraday magneto-optical effect material 32 is used to change the polarization direction of at least part of the received laser based on the magnetic field inside the transformer to be tested; the laser reflective layer 33 It is used to reflect the laser light passing through the Faraday magneto-optical effect material 32 . In this way, the magnetic field generated by the transformer under test can be accurately sensed through the Faraday magneto-optical effect material 32, thereby changing the polarization direction of the transmitted laser light and improving detection accuracy.

It should be noted that in some embodiments of the present application, the transmission module 31, the Faraday magneto-optical effect material 32 and the laser reflection layer 33 are arranged in sequence. In this way, the laser incident on the sensor passes through the transmission module 31, the Faraday magneto-optical effect material 32 and the laser reflection layer 33 in sequence. The effect material 32, the laser reflective layer 33, the Faraday magneto-optical effect material 32 and the transmission module 31 are then emitted. That is, after the incident laser enters the Faraday magneto-optical effect material 32 through the transmission module 31, the polarization direction of the laser will be changed according to the intensity and direction of the magnetic field in the Faraday magneto-optical effect material 32, and it will arrive after passing through the Faraday magneto-optical effect material 32 for the first time. After the laser reflection layer 33, the laser light will be reflected and pass through the Faraday magneto-optical effect material 32 for the second time. During the two passes through the Faraday magneto-optical effect material 32, the polarization direction of the laser light will change. In this way, the laser passes through the Faraday magneto-optical effect material 32 twice, which can enhance the change in the polarization direction of the laser and facilitate subsequent detection.

It should be noted that when the magnetic field generated by the transformer under test remains unchanged, the angle will change by the same angle twice. However, because the magnetic field inside the transformer is changing, the two changes will not be exactly the same.

Further, based on the above embodiments, in other embodiments of the present application, the transmission module 31 may include: an optical fiber cladding 311 and a fiber core 312 wrapped by the optical fiber cladding 311.

Furthermore, in the embodiment of the present application, the information of the second laser includes the light intensity of the second laser emitted by the optical fiber polarizer 2 , and the information of the third laser includes the third laser of the target polarization direction received by the receiving module 4 .

On this basis, the above-mentioned embodiment mentioned that the magnetic field state information of the transformer to be tested is determined based on the information of the second laser and the third laser, including: first, based on the information of the second laser and the third laser and a preset formula, determining the angle of change of the polarization direction of the laser of the transformer to be tested in the Faraday magneto-optical effect material; then, based on the angle of change of the polarization direction in the Faraday magneto-optical effect material, determining the magnetic field state information of the transformer to be tested.

Among them, the default formula is:

In this formula, Iin is the light intensity of the second laser emitted by the optical fiber polarizer 2; Iout is the third laser of the target polarization direction received by the receiving module 4; η is the system laser transmission coupling loss; γ is the reflectivity of the laser reflection layer; θ is the angle of change of the polarization direction of the laser in the Faraday magneto-optical effect material.

Among them, the system laser transmission coupling loss is the sum of all transmission and coupling losses in the system. Generally, the overall system loss is directly measured after the system is completed. The specific methods are:

Determine the direction and intensity of a magnetic field through calculation, the formula is: θ = VBL, θ is the deflection angle; V is the Verde constant; B is the component of the magnetic induction intensity in the direction of light propagation; L is the intensity of the laser passing through the magneto-optical material length.

Under this magnetic field, the angle of the laser changes by 90° each time it passes through the Faraday magneto-optical material. After two passes, the angle changes by 180° in total, becoming the same polarization direction as before. At this time, the ratio of the intensity of the outgoing laser to the incident laser is the total loss of the system, which also includes the reflectivity γ of the laser reflection layer. As long as this total loss is divided by γ, η can be obtained.

In this way, based on the above formula, under the condition that other parameters of the detection system remain unchanged, η and γ are both constant values, so the incident second laser light intensity I _in is equal to the outgoing (that is, detected) laser light intensity I The ratio of _out is only related to the angle θ at which the polarization direction of the laser changes in the Faraday magneto-optical effect material, and this angle is only related to the change in the direction and size of the magnetic field in the environment where the sensor is located. Therefore, the change of the magnetic field in the transformer under test can be characterized by the ratio of I _in and I _out , and then the operating status of the transformer under test can be determined.

In practical applications, the above-mentioned I _in and I _out can also be reflected by monitoring the ratio of the second laser power emitted by the optical fiber polarizer 2 and the third laser power received by the final receiving module 4, thereby increasing system operability.

Based on the same inventive concept, this application also provides a sensor, which is used in the above detection system. The sensor may specifically include: a transmission module, a Faraday magneto-optical effect material and a laser reflective layer;

The transmission module is used to transmit the incident laser to the Faraday magneto-optical effect material; the Faraday magneto-optical effect material is used to change the polarization direction of at least part of the received laser based on the magnetic field inside the transformer to be tested; the laser reflection layer is used to convert the passing laser into the Faraday magneto-optical effect material. Faraday magneto-optical effect materials reflect laser light.

Regarding the sensors in the above embodiments, the specific manner in which each module performs operations has been described in detail in the embodiments related to the detection system, and will not be described in detail here.

It can be understood that the same or similar parts in the above-mentioned embodiments can be referred to each other, and the content that is not described in detail in some embodiments can be referred to the same or similar content in other embodiments.

It should be noted that in the description of the present invention, the terms "first", "second", etc. are only used for description purposes and cannot be understood as indicating or implying relative importance. Furthermore, in the description of the present invention, unless otherwise stated, the meaning of "plurality" means at least two.

Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

It should be understood that various parts of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if it is implemented in hardware, as in another embodiment, it can be implemented by any one or a combination of the following technologies known in the art: a logic gate circuit with a logic gate circuit for implementing a logic function on a data signal. Discrete logic circuits, application specific integrated circuits with suitable combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), etc.

Those of ordinary skill in the art can understand that all or part of the steps involved in implementing the methods of the above embodiments can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium, and the program can be stored in a computer-readable storage medium. When executed, one of the steps of the method embodiment or a combination thereof is included.

In addition, each functional unit in various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The above integrated modules can be implemented in the form of hardware or software function modules. If the integrated module is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims (10)

1. A transformer anomaly detection system, comprising: the device comprises an optical fiber laser, an optical fiber polarizer, a sensor, a receiving module and a calculating module;

the optical fiber laser is used for generating first laser and transmitting the first laser into the optical fiber polarizer; the optical fiber polarizer is used for converting the received laser into second laser with a target polarization direction and transmitting the second laser into the sensor;

the sensor is arranged in the transformer to be tested, and is used for changing the polarization direction of at least part of received laser based on the magnetic field in the transformer to be tested and reflecting all the laser in the transformer to be tested;

the receiving module is used for receiving third laser in the target polarization direction, wherein the third laser is laser reflected by the sensor;

the calculation module is used for determining magnetic field state information of the transformer to be tested based on the information of the second laser and the third laser, and judging whether the transformer to be tested is abnormal or not based on the magnetic field state information.

2. The transformer anomaly detection system of claim 1, wherein the sensor comprises: the device comprises a transmission module, a Faraday magneto-optical effect material and a laser reflecting layer;

the transmission module is used for transmitting incident laser to the Faraday magneto-optical effect material;

the Faraday magneto-optical effect material is used for changing the polarization direction of at least part of received laser based on the magnetic field inside the transformer to be tested;

the laser reflecting layer is used for reflecting the laser passing through the Faraday magneto-optical effect material.

3. The transformer anomaly detection system of claim 2, wherein the transmission module, faraday magneto-optical effect material, and laser reflection layer are disposed in sequence;

the laser reflected by the laser reflecting layer is emitted through the Faraday magneto-optical effect material and the transmission module.

4. A transformer anomaly detection system according to claim 3, wherein the transmission module comprises: an optical fiber cladding and a core surrounded by the optical fiber cladding.

5. The transformer anomaly detection system of claim 2, further comprising: an optical fiber circulator;

the optical fiber circulator is provided with a first port, a second port and a third port;

the optical fiber circulator is used for receiving the laser emitted by the optical fiber polarizer through the first port and transmitting the laser received by the first port to the sensor through the second port;

the optical fiber circulator is also used for receiving the laser reflected by the sensor through the second port and transmitting the laser received by the second port to the receiving module through the third port.

6. The transformer anomaly detection system of claim 5, wherein the receiving module comprises a polarizing fiber and a light intensity detector;

the polarization optical fiber is used for receiving the laser output by the third port of the optical fiber circulator and transmitting the laser to the light intensity detector.

7. The transformer anomaly detection system of claim 6, wherein the information of the second laser includes a light intensity of the second laser light emitted by the fiber polarizer, and the information of the third laser light includes a third laser light of the target polarization direction received by the receiving module.

8. The transformer anomaly detection system of claim 7, wherein the determining magnetic field status information of the transformer under test based on information of the second laser and the third laser comprises:

determining an angle of change of the polarization direction of the laser of the transformer to be tested in the Faraday magneto-optical effect material based on the information of the second laser and the third laser and a preset formula;

determining magnetic field state information of the transformer to be tested based on the angle of polarization direction change in the Faraday magneto-optical effect material;

wherein, the preset formula is:

wherein I is _in The light intensity of the second laser emitted by the optical fiber polarizer; i _out A third laser light of the target polarization direction received by the receiving module; η is the system laser loss; gamma is the reflectivity of the laser reflecting layer; θ is the angle at which the polarization direction of the laser light changes in the faraday magneto-optical effect material.

9. The transformer anomaly detection system of claim 1, wherein the information of the second laser includes a power of the second laser emitted by the fiber polarizer, and the information of the third laser includes a power of the third laser in the target polarization direction received by the receiving module.

10. A sensor, comprising: the device comprises a transmission module, a Faraday magneto-optical effect material and a laser reflecting layer;

the transmission module is used for transmitting incident laser to the Faraday magneto-optical effect material;

the Faraday magneto-optical effect material is used for changing the polarization direction of at least part of received laser based on the magnetic field inside the transformer to be tested;

the laser reflecting layer is used for reflecting the laser passing through the Faraday magneto-optical effect material.