Multi-channel magnetic flux leakage measurement method and system for intrusive monitoring of power transformer

Abstract

The invention relates to the technical field of power transformer monitoring, in particular to a multi-channel magnetic flux leakage measurement method and system for intrusive monitoring of a power transformer. Comprising N magnetic flux leakage sensors which are respectively arranged on measuring points on the wall of a transformer oil tank and are used for acquiring magnetic flux leakage signals in the transformer, and the measuring points are respectively located between two magnetic shields on the wall of the transformer oil tank; and the channel signal acquisition module is electrically connected with each magnetic flux leakage sensor, and is used for acquiring the magnetic flux leakage signals of each measurement point, processing and synchronously uploading the acquired magnetic flux leakage signals, and carrying out real-time fault monitoring according to the phase difference change condition of the magnetic flux leakage signals of different measurement points. The system can accurately and effectively monitor faults in real time.

Description

Technical Field

[0001] The invention relates to the technical field of power transformer monitoring, and in particular to a multi-channel magnetic leakage measurement method and system for intrusive monitoring of power transformers. Background Art

[0002] In recent years, large power transformers have experienced internal high-energy discharges, causing transformer shells to rupture and catch fire, resulting in huge economic losses. Large power transformers usually use tangled windings. When a single-turn short-circuit fault occurs due to local insulation damage, it will cause the interval coils in the same coil to form a short-circuit coil. The current technical means of differential protection for power transformers are limited. When a turn-to-turn short-circuit occurs in a power transformer, the characteristic quantity sensed from the outside by the differential protection changes slightly, and can actually only reflect multi-turn short-circuit faults of more than 2% to 3% of the turns, and cannot reflect single-turn turn-to-turn faults in the early stage of internal discharge faults. Therefore, it is necessary to propose an online monitoring system for power transformers to quickly, accurately and effectively monitor and identify transformer turn-to-turn short-circuit faults.

[0003] There are two types of online monitoring methods for power transformers: intrusive and non-intrusive. Intrusive magnetic flux leakage monitoring meets the requirements of rapid, accurate and effective monitoring and identification of transformer inter-turn short-circuit faults. Intrusive magnetic flux leakage sensors need to be arranged inside the oil tank of the power transformer. It is necessary to solve the compatibility problems between the sensor and the transformer oil, the compatibility problems between the sensor and the transformer time-varying electromagnetic field, and the communication problems between the sensor and the external host computer. It is necessary to provide a reliable and applicable method for arranging the magnetic flux leakage measurement system. Summary of the invention

[0004] The present invention provides a multi-channel magnetic flux leakage measurement method and system for intrusive monitoring of power transformers, aiming to solve the problem of inaccurate monitoring of magnetic flux leakage monitoring strategies.

[0005] The objective of the present invention is achieved by the following technical solutions:

[0006] A multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers, comprising:

[0007] N magnetic flux leakage sensors, each of which is disposed at a measuring point on the wall of the transformer oil tank, for obtaining a magnetic flux leakage signal in the transformer, and each of which is located between two magnetic shields on the wall of the transformer oil tank, wherein N≥2;

[0008] The channel signal acquisition module is electrically connected to each leakage magnetic sensor and is used to collect the leakage magnetic signal of each measuring point, process the collected leakage magnetic signal and upload it synchronously, and perform real-time fault monitoring according to the phase difference change of the leakage magnetic signal at different measuring points.

[0009] As a further improvement of the present invention, the sensing end of the leakage magnetic sensor includes a one-dimensional transverse Hall probe and a constant current source circuit, and the processing end includes a signal processing module, and the constant current source circuit is used to provide a constant current for the Hall probe; the interior of the Hall probe includes a semiconductor, and the carriers in the semiconductor are subjected to the Lorentz force in the leakage magnetic field, causing the motion trajectory to deviate; the signal processing module obtains the leakage magnetic signal according to the output voltage between two electrodes perpendicular to the current direction.

[0010] As a further improvement of the present invention, the channel signal acquisition module includes a detection and conditioning module and an analog-to-digital conversion module which are unidirectionally connected in sequence. The input side of the detection and conditioning module is connected to the output side of the processing end of each leakage magnetic sensor, and is used to synchronously collect the leakage magnetic signal of each measuring point, and transmit each leakage magnetic signal to the analog-to-digital conversion module for conversion between analog signals and digital signals.

[0011] As a further improvement of the present invention, the system also includes a channel signal amplification module, the input side of which is electrically connected to the leakage magnetic sensor, and the output side is connected to the input side of the channel signal acquisition module, for amplifying and processing the acquired leakage magnetic signals.

[0012] As a further improvement of the present invention, the channel signal amplification module includes a channel signal conditioning circuit and a channel signal amplification circuit connected in sequence; the channel signal conditioning circuit is connected to multiple leakage magnetic sensor output ends using multiple multi-core cables to eliminate the DC bias of the leakage magnetic sensor output voltage; the channel signal amplification circuit is used to collect the output signal of the channel signal conditioning circuit and perform lossless amplification processing.

[0013] As a further improvement of the present invention, the system also includes a communication optical fiber and a photoelectric conversion module, the input side of the photoelectric conversion module is connected to the output side of the channel signal acquisition module, and the output side is connected to the communication optical fiber. The photoelectric conversion module is used to include an ARM core board and a photoelectric conversion chip connected in sequence. The ARM core board is connected to the output side of the channel acquisition module, and is also connected to the photoelectric conversion chip through a PCB circuit, and is used to transcode the multi-channel leakage magnetic signals sampled by the channel signal acquisition module into pulse code modulation information, and use the photoelectric conversion chip to convert them into optical signals for transmission through the communication optical fiber.

[0014] As a further improvement of the present invention, the power supply of the system is completed by an energy acquisition and storage module, which includes an energy acquisition coil, a rectifier circuit and an energy storage module; the energy acquisition coil is arranged inside the power transformer, and is used to utilize alternating electromagnetic field induction to acquire energy, and utilize the rectifier circuit and the energy storage module to convert alternating current into direct current and store energy.

[0015] As a further improvement of the present invention, the shell of the system is a copper shielding shell.

[0016] As a further improvement of the present invention, the shell of the system is in a fishbone shape, a communication optical fiber is arranged on the shell part located on one side of the fishbone trunk, the leakage magnetic sensor is located on the protruding part of the fishbone, and the protruding part of the fishbone is attached to the transformer winding.

[0017] The present invention also provides a multi-channel magnetic leakage measurement method for intrusive monitoring of power transformers, comprising:

[0018] Obtaining a leakage magnetic signal of the transformer according to each measuring point arranged on the wall of the transformer oil tank, wherein the measuring points are respectively located between two magnetic shields on the wall of the transformer oil tank, and the number of the measuring points is greater than or equal to 2;

[0019] The magnetic leakage signals at each measuring point are collected, processed and uploaded synchronously, and real-time fault monitoring is performed according to the phase difference changes of the magnetic leakage signals at different measuring points.

[0020] The beneficial effects of the present invention are as follows: a multi-channel magnetic leakage measurement system for intrusive monitoring of power transformers of the present invention has a plurality of sensors separately arranged inside the transformer, and the plurality of magnetic leakage sensors can be arranged at different heights inside the power transformer to monitor transformer winding faults occurring at different positions, and a channel signal acquisition module is used to collect multi-channel corresponding magnetic leakage signals, and different magnetic leakage sensors are used to measure the change in the magnetic leakage phase difference to locate the fault, thereby solving the problem of multi-point measurement of transformer magnetic leakage and integration.

[0021] Furthermore, the magnetic flux leakage sensor of the system adopts a high-precision one-dimensional lateral Hall probe, which improves the measurement accuracy and can reach 0.1mT accuracy.

[0022] Furthermore, the system also includes a channel signal amplification module to ensure the acquisition capability of the small magnetic leakage signal inside the power transformer and obtain an undistorted magnetic leakage signal.

[0023] Furthermore, the signal transmission method of the present invention adopts an optical signal transmission method, and further includes a photoelectric conversion module. Optical fiber communication is resistant to electromagnetic interference, has good transmission quality, strong adaptability and long life, and can solve the electromagnetic interference problem inside the power transformer.

[0024] Furthermore, the energy taking and storage module utilizes the equipotentially arranged power taking modules to solve the power supply problem of the active sensors arranged inside the power transformer and the subsequent signal processing and signal conversion circuits, and at the same time facilitates the integrated application of the present invention inside the power transformer; the rectifier circuit and the energy storage module solve the power supply fluctuation problem when the transformer operation mode changes, and meet the needs of the present invention for continuous online monitoring of transformer leakage.

[0025] Furthermore, the system housing adopts a copper shielding housing to solve the compatibility problem between the measurement system and transformer oil and alternating electromagnetic fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 Schematic diagram of the structure of a magnetic flux leakage measurement system for online monitoring of a power transformer in an embodiment of the present invention;

[0028] Figure 2 is a front view of a magnetic flux leakage measurement system for online monitoring of a power transformer in an embodiment of the present invention;

[0029] Figure 3 is a top view of a magnetic flux leakage measurement system for online monitoring of a power transformer in an embodiment of the present invention;

[0030] Figure 4 It is a schematic diagram of the location of the magnetic flux leakage sensor in the embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The present invention provides a leakage magnetic field measurement method and system for online monitoring of power transformers, the system comprising:

[0033] N magnetic leakage sensors, each of which is disposed at a measuring point on the wall of the transformer oil tank, for obtaining a magnetic leakage signal in the transformer, and each of which is located between two magnetic shields on the wall of the transformer oil tank; wherein N≥2;

[0034] The channel signal acquisition module is electrically connected to each leakage magnetic sensor and is used to collect the leakage magnetic signal of each measuring point, process the collected leakage magnetic signal and upload it synchronously, and locate the fault according to the phase difference change of the leakage magnetic signal at different measuring points.

[0035] Among them, the sensing end of the leakage magnetic sensor includes a one-dimensional transverse Hall probe and a constant current source circuit, and the processing end includes a signal processing module. The constant current source circuit is used to provide a constant current for the Hall probe; the interior of the Hall probe includes a semiconductor, and the carriers in the semiconductor are subjected to the Lorentz force in the leakage magnetic field, causing the motion trajectory to deviate; the signal processing module obtains the leakage magnetic signal according to the output voltage between two electrodes perpendicular to the current direction.

[0036] The channel signal acquisition module includes a detection and conditioning module and an analog-to-digital conversion module which are unidirectionally connected in sequence. The input side of the detection and conditioning module is connected to the output side of the processing end of each leakage magnetic sensor, and is used to synchronously collect the leakage magnetic signal of each measuring point, and transmit each leakage magnetic signal to the analog-to-digital conversion module for conversion between analog signals and digital signals.

[0037] In addition, the system also includes a channel signal amplification module, the input side of the channel signal amplification module is electrically connected to the leakage magnetic sensor, and the output side is connected to the input side of the channel signal acquisition module, which is used to amplify and process the acquired leakage magnetic signals. The channel signal amplification module includes a channel signal conditioning circuit and a channel signal amplification circuit connected in sequence; the channel signal conditioning circuit is connected to the output ends of multiple leakage magnetic sensors using multiple multi-core cables, and is used to eliminate the DC bias of the output voltage of the leakage magnetic sensor; the channel signal amplification circuit is used to collect the output signal of the channel signal conditioning circuit and perform lossless amplification processing.

[0038] In addition, the system also includes a communication optical fiber and a photoelectric conversion module. The input side of the photoelectric conversion module is connected to the output side of the channel signal acquisition module, and the output side is connected to the communication optical fiber. The photoelectric conversion module is used to include an ARM core board and a photoelectric conversion chip connected in sequence. The ARM core board is connected to the output side of the channel acquisition module, and is also connected to the photoelectric conversion chip through a PCB circuit. It is used to transcode the multi-channel leakage magnetic signals sampled by the channel signal acquisition module into pulse code modulation information, and use the photoelectric conversion chip to convert them into optical signals for transmission through the communication optical fiber.

[0039] The power supply of the system is completed by an energy acquisition and storage module, which includes an energy acquisition coil, a rectifier circuit and an energy storage module; the energy acquisition coil is arranged inside the power transformer, and is used to utilize alternating electromagnetic field induction to acquire energy, and utilizes the rectifier circuit and energy storage module to convert alternating current into direct current and store energy.

[0040] Furthermore, the system shell adopts a copper shielding shell. The shell is fishbone-shaped, and a communication optical fiber is arranged on the shell part located on one side of the fishbone trunk. The magnetic flux leakage sensor is located on the protruding part of the fishbone trunk, and the protruding part is attached to the transformer winding.

[0041] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, wherein the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0042] Embodiment 1:

[0043] like Figures 1 to 4 A multi-channel magnetic leakage measurement system for intrusive monitoring of power transformers is shown, which mainly includes N magnetic leakage sensors and a channel signal acquisition module. Each magnetic leakage sensor is located at a measuring point of the transformer, wherein the measuring points are located between two magnetic shields on the wall of the transformer oil tank and close to the transformer winding. The magnetic leakage sensor at each measuring point obtains the magnetic leakage signal of the transformer and transmits the respective magnetic leakage signal to the channel signal acquisition module. Wherein N≥2, the number of magnetic leakage sensors in this embodiment ranges from 2 to 10, and the number of magnetic leakage sensors can be adjusted according to actual conditions. The corresponding number of measuring points in this embodiment is approximately between 2 and 10, and the number of magnetic leakage sensors corresponds to the number of measuring points, or the number of measuring points is greater than or equal to the number of magnetic leakage sensors.

[0044] Among them, the sensing end of the leakage magnetic sensor includes a one-dimensional transverse Hall probe and a constant current source circuit, and the processing end includes a signal processing module. The constant current source circuit located at the sensing end is used to provide a continuous and constant current for the Hall probe; the Hall probe includes a semiconductor inside, and the carriers in the semiconductor are subjected to the Lorentz force in the leakage magnetic field, causing the motion trajectory to shift and forming an additional electric field perpendicular to the current and magnetic field plane, until the Lorentz force and the electric field force on the carriers finally reach a state of equilibrium, and the signal processing module calculates the leakage magnetic signal based on the output voltage between the two electrodes perpendicular to the current direction. The Hall probe used in this embodiment has high precision in measuring the magnetic field, and can achieve an accuracy of 0.1mT when measuring inside the power transformer, and multiple leakage magnetic sensors can be arranged at different heights inside the power transformer to monitor transformer winding faults occurring at different locations.

[0045] The channel signal acquisition module includes a detection and conditioning module and an analog-to-digital conversion module which are connected in sequence in a unidirectional manner, wherein the input side of the detection and conditioning module is connected to the processing end output side of each magnetic leakage sensor, and is used to synchronously collect the magnetic leakage signals of each measuring point, and transmit each magnetic leakage signal to the analog-to-digital conversion module for conversion between analog signals and digital signals. The magnetic leakage results obtained by synchronous acquisition and processing are used by the channel signal acquisition module, and the changes in the magnetic leakage phase difference are measured by different magnetic leakage sensors to locate the fault.

[0046] Since the leakage magnetic signal is relatively small and prone to distortion, the system is also equipped with a channel signal amplification module. The input side of the channel signal amplification module is electrically connected to the leakage magnetic sensor, and the output side is connected to the input side of the channel signal acquisition module, so as to amplify and process the obtained leakage magnetic signals.

[0047] Specifically, the channel signal amplification module includes a channel signal conditioning circuit and a channel signal amplification circuit connected in sequence. The channel signal conditioning circuit is connected to multiple leakage magnetic sensor output terminals using multiple multi-core cables to eliminate the DC bias of the leakage magnetic sensor output voltage; the channel signal amplification circuit is used to collect the output signal of the channel signal conditioning circuit and perform lossless amplification processing. The channel signal amplification module ensures the acquisition capability of the leakage magnetic small signal inside the power transformer, thereby obtaining an undistorted leakage magnetic signal.

[0048] In order to solve the electromagnetic interference problem during the transmission of leakage magnetic data inside the power transformer, the system also includes a communication optical fiber and a photoelectric conversion module. The input side of the photoelectric conversion module is connected to the output side of the channel signal acquisition module, and the output side is connected to the communication optical fiber. Further, the photoelectric conversion module is used to include an ARM core board and a photoelectric conversion chip connected in sequence. The ARM core board is connected to the output side of the channel acquisition module, and is also connected to the photoelectric conversion chip through a PCB circuit, for transcoding the multi-channel leakage magnetic signals sampled by the channel signal acquisition module into pulse code modulation information, and using the photoelectric conversion chip to convert it into an optical signal for transmission through the communication optical fiber. Optical fiber communication is used to resist electromagnetic interference and has good transmission quality, which effectively solves the electromagnetic interference problem inside the power transformer. At the same time, the communication optical fiber also has the advantages of strong adaptability and long life.

[0049] In addition, the power supply of the system is completed by the energy acquisition and storage module. The energy acquisition and storage module includes an energy acquisition coil, a rectifier circuit and an energy storage module. The energy acquisition coil is arranged inside the power transformer, and is used to utilize the alternating electromagnetic field to inductively acquire energy, and utilize the rectifier circuit and the energy storage module to convert the alternating current into direct current and store energy. The use of equipotentially arranged energy acquisition modules solves the power supply problem of the active sensors arranged inside the power transformer and the subsequent signal processing and signal conversion circuits, and also facilitates the integrated application of the system inside the power transformer; the rectifier and energy storage modules solve the problem of power supply fluctuations when the transformer operation mode changes, and meet the needs of continuous online monitoring of transformer leakage magnetic field in this embodiment.

[0050] The system uses a copper shielding shell to integrate the above-mentioned magnetic flux leakage sensor, channel signal amplification module, channel signal acquisition module and photoelectric conversion module. Figure 2 , Figure 3As shown, the copper shielding shell is located between the two copper shields of the power transformer and is arranged at the same potential as the transformer shell. Since a magnetic shielding fixing clamp is arranged between the two power transformer shields, the front shape of the copper shielding shell is set to a fishbone shape, the trunk is located between the magnetic shielding fixing clamps on both sides, and the width is less than or equal to the space size between the magnetic shielding fixing clamps on both sides. The branch part is located at the interval between the two magnetic shielding fixing clamps on one side, and is arranged in a concave-convex manner with the interval position. The trunk part located at the branch part is provided with a protruding part at the top view position, and the width of the protruding part is the same as that of the trunk, and the protruding part is attached to the transformer winding, and the leakage magnetic sensor is arranged at the protruding part. The shell part located on one side of the fishbone trunk is provided with a communication optical fiber. Specifically, in this embodiment, the maximum width is w1, which is 20-60mm, and the height of this part is l1, which is 30-100mm; the minimum width is w2, which is 10-20mm, and the height of this part is l2, which is 100-200mm; the copper shielding shell is "convex" when viewed from above, and its overall height is H1, which is 20-40mm in this embodiment, and the height of the protruding part is H2, which is 5-15mm in this embodiment. The leakage magnetic sensor is arranged in the protruding part, and the channel signal amplification module, the channel signal acquisition module and the photoelectric conversion module are arranged at the rear part close to the transformer box wall, that is, at the branch part containing the trunk. The overall thickness of the shielding shell is d, and d in this embodiment is 0.5mm-2mm. The compatibility of copper and transformer oil has been widely verified, and the use of a copper shielding shell meets the long-term use requirements of the entire sensor system inside the power transformer. The leakage magnetic sensor is arranged in the protruding part to be as close to the transformer winding as possible, and more abundant leakage magnetic information can be measured. In order to be arranged in the gap between two adjacent magnetic shields, the shielding shell adopts a fishbone shape, which can avoid the magnetic shielding fixing frame and reserve sufficient lateral width for the multi-channel signal amplification module, the multi-channel acquisition module and the photoelectric conversion module.

[0051] The system is connected to the host computer processing platform through communication optical fiber, which is also covered with a copper shielding shell inside the power transformer until it is led out of the transformer through the flange. The host computer processing platform includes a host based on an ARM chip, which includes functions such as amplitude analysis, phase comparison, and spectrum analysis. It can identify and classify the leakage magnetic data collected by the leakage magnetic sensor inside the power transformer and perform online monitoring of the power transformer.

[0052] Example 2

[0053] In this embodiment, a multi-channel magnetic flux leakage measurement method for intrusive monitoring of a power transformer is implemented based on the multi-channel magnetic flux leakage measurement system for intrusive monitoring of a power transformer in Embodiment 1, and includes:

[0054] The transformer leakage magnetic signal is obtained according to each measuring point arranged on the transformer oil tank wall, wherein the measuring points are respectively located between two magnetic shields on the transformer oil tank wall, wherein the number of measuring points is greater than or equal to 2, and in actual situations, the number of measuring points can be between 2 and 10;

[0055] The magnetic leakage signals at each measuring point are collected, processed and uploaded synchronously, and real-time fault monitoring is performed according to the phase difference changes of the magnetic leakage signals at different measuring points.

[0056] The specific components and corresponding principles in the implementation process of this embodiment have been described in the leakage magnetic field measurement system for online monitoring of power transformers in Example 1, and will not be further elaborated here.

[0057] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers, characterized in that: include: N magnetic flux leakage sensors, each of which is disposed at a measuring point on the wall of the transformer oil tank, for obtaining a magnetic flux leakage signal in the transformer, and each of which is located between two magnetic shields on the wall of the transformer oil tank, wherein N≥2; The channel signal acquisition module is electrically connected to each leakage magnetic sensor and is used to collect the leakage magnetic signal of each measuring point, process the collected leakage magnetic signal and upload it synchronously, and perform real-time fault monitoring according to the phase difference change of the leakage magnetic signal at different measuring points.

2. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to claim 1 is characterized in that: The sensing end of the magnetic flux leakage sensor includes a one-dimensional transverse Hall probe and a constant current source circuit, and the processing end includes a signal processing module. The constant current source circuit is used to provide a constant current for the Hall probe. The Hall probe includes a semiconductor inside, and the carriers in the semiconductor are subjected to the Lorentz force in the leakage magnetic field, causing the motion trajectory to deviate. The signal processing module obtains the magnetic flux leakage signal according to the output voltage between two electrodes perpendicular to the current direction.

3. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to claim 2, characterized in that: The channel signal acquisition module includes a detection and conditioning module and an analog-to-digital conversion module which are unidirectionally connected in sequence. The input side of the detection and conditioning module is connected to the output side of the processing end of each leakage magnetic sensor, and is used to synchronously collect the leakage magnetic signal of each measuring point, and transmit each leakage magnetic signal to the analog-to-digital conversion module for conversion between analog signals and digital signals.

4. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to claim 1, characterized in that: The system also includes a channel signal amplifying module, the input side of which is electrically connected to the magnetic flux leakage sensor, and the output side is connected to the input side of the channel signal acquisition module, for amplifying the acquired magnetic flux leakage signals.

5. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to claim 4, characterized in that: The channel signal amplification module includes a channel signal conditioning circuit and a channel signal amplification circuit connected in sequence; the channel signal conditioning circuit is connected to multiple leakage magnetic sensor output ends using multiple multi-core cables to eliminate the DC bias of the leakage magnetic sensor output voltage; the channel signal amplification circuit is used to collect the output signal of the channel signal conditioning circuit and perform lossless amplification processing.

6. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to claim 3, characterized in that: The system also includes a communication optical fiber and a photoelectric conversion module. The input side of the photoelectric conversion module is connected to the output side of the channel signal acquisition module, and the output side is connected to the communication optical fiber. The photoelectric conversion module is used to include an ARM core board and a photoelectric conversion chip connected in sequence. The ARM core board is connected to the output side of the channel acquisition module and is also connected to the photoelectric conversion chip through a PCB circuit. It is used to transcode the multi-channel leakage magnetic signals sampled by the channel signal acquisition module into pulse code modulation information, and use the photoelectric conversion chip to convert them into optical signals for transmission through the communication optical fiber.

7. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to claim 1, characterized in that: The power supply of the system is completed by an energy acquisition and storage module, which includes an energy acquisition coil, a rectifier circuit and an energy storage module; the energy acquisition coil is arranged inside the power transformer, and is used to utilize alternating electromagnetic field induction to acquire energy, and utilizes the rectifier circuit and energy storage module to convert alternating current into direct current and store energy.

8. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to any one of claims 1 to 6, characterized in that: The housing of the system adopts a copper shielding housing.

9. The multi-channel magnetic flux leakage measurement system for intrusive monitoring of power transformers according to claim 8, characterized in that: The shell of the system is in a fishbone shape, a communication optical fiber is arranged on the shell part located on one side of the fishbone trunk, and the magnetic flux leakage sensor is located on the protruding part of the fishbone trunk, and the protruding part is attached to the transformer winding.

10. A multi-channel magnetic leakage measurement method for intrusive monitoring of power transformers, characterized in that: include: Obtaining a leakage magnetic signal of the transformer according to each measuring point arranged on the wall of the transformer oil tank, wherein the measuring points are respectively located between two magnetic shields on the wall of the transformer oil tank, and the number of the measuring points is greater than or equal to 2; The magnetic leakage signals at each measuring point are collected, processed and uploaded synchronously, and real-time fault monitoring is performed according to the phase difference changes of the magnetic leakage signals at different measuring points.

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