Oil-immersed transformer leakage magnetic vibration combined measuring device and method

Abstract

The application discloses an oil-immersed transformer leakage magnetic vibration combined measuring device and method, comprising a light source, a leakage magnetic vibration composite sensor, a leakage magnetic processing device, a vibration processing device and an optical fiber; the oil-immersed transformer leakage magnetic vibration composite sensing device and measuring method disclosed by the application firstly proposes a new method capable of simultaneously measuring the leakage magnetic signal and the vibration signal of the oil-immersed transformer; according to different frequencies, the leakage magnetic measurement result and the vibration measurement result can be obtained respectively, the composite sensing of the leakage magnetic and the vibration of the oil-immersed transformer can be realized, the leakage magnetic signal and the vibration signal of the oil-immersed transformer can be simultaneously measured, the winding state of the transformer can be better reflected, the practicability is good, and the online monitoring effect of the transformer winding deformation can be improved.

Description

Technical Field

[0001] This invention relates to the field of electrical measurement technology, and in particular to a combined measurement device and method for leakage flux and vibration of an oil-immersed transformer. Background Technology

[0002] Power transformers are the core main equipment of the power system, and their safe and stable operation is crucial to the stability and economy of the power system. Power transformer failures include a variety of factors, among which winding deformation is one of the main causes of power transformer failures. Timely and effective monitoring of winding deformation is the foundation for ensuring the safe and stable operation of power transformers.

[0003] Currently, the common monitoring methods for transformer winding deformation are mainly electrical measurement methods such as the short-circuit impedance method. These are primarily used for offline monitoring of transformer winding deformation and cannot monitor the winding status during transformer operation in real time. For example, the existing patent CN202110809146.0, which describes a vibration monitoring device for an oil-immersed transformer based on fiber optic sensing, uses the vibration on the iron core or winding to transmit to the connected insulating rod, and the vibration of the tank wall to another insulating rod. The two sensing sections of an oil-resistant single-core optical cable are tightly wound around the two insulating rods to transmit the vibration. This patent uses a traditional monitoring method and only achieves the effect of vibration monitoring; it cannot provide information on vibration amplitude, frequency, or leakage flux.

[0004] Existing research indicates that after transformer winding deformation occurs, the distribution of leakage flux signals and the transformer vibration signals change. Therefore, those skilled in the art are dedicated to developing a combined leakage flux and vibration measurement device and method for oil-immersed transformers. By studying the oil-immersed transformer leakage flux and vibration composite sensing device, simultaneous online measurement of transformer leakage flux and vibration can be achieved. Furthermore, based on the two characteristic parameters of leakage flux and vibration, transformer winding deformation can be monitored together, improving the monitoring effect of transformer winding deformation and overcoming the shortcomings of the aforementioned existing technologies. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is that the existing transformer winding deformation monitoring methods are mainly applied to offline monitoring of transformer winding deformation and cannot monitor the winding status during transformer operation in real time.

[0006] To achieve the above objectives, the first aspect of the present invention provides a combined measurement device for leakage flux and vibration of an oil-immersed transformer, comprising a light source, a leakage flux and vibration composite sensor, a leakage flux processing device, a vibration processing device, and an optical fiber; the optical fiber connects the various components; the light source is connected to the leakage flux and vibration composite sensor via the optical fiber; the leakage flux and vibration composite sensor is connected to the leakage flux processing device and the vibration processing device via the optical fiber.

[0007] Furthermore, the light source outputs linearly polarized light;

[0008] Furthermore, the leakage magnetic field vibration composite sensor includes a leakage magnetic field sensitive unit;

[0009] Furthermore, the leakage magnetic field vibration composite sensor includes a vibration-sensitive unit;

[0010] Furthermore, the leakage magnetic field vibration composite sensor includes a photodetector;

[0011] Furthermore, the leakage magnetic sensing unit includes a collimator, a polarizer, a magneto-optical material, and a photodetector;

[0012] Furthermore, the vibration-sensitive unit comprises a structure surrounded by multiple turns of optical fiber;

[0013] Furthermore, the leakage magnetic field sensing unit is connected to the vibration sensing unit via an optical fiber, and the signal output by the photodetector is transmitted to the leakage magnetic field processing device and the vibration processing device via a BNC line.

[0014] Furthermore, the leakage magnetic field processing device includes a data acquisition card and an FPGA, wherein the data acquisition card is used to acquire signals, and the FPGA has a built-in analysis program to process the signals to obtain leakage magnetic field data.

[0015] Furthermore, the vibration processing device includes a data acquisition card and an FPGA, wherein the data acquisition card is used to acquire signals, and the FPGA has a built-in analysis program to process the signals to obtain vibration data;

[0016] Furthermore, the 50Hz component of the output light intensity of the leakage magnetic field vibration composite sensor is only related to the measured leakage magnetic field;

[0017] Furthermore, the leakage magnetic vibration composite sensor can perform a fast Fourier transform on the output light intensity to obtain the amplitude P0 of the 0Hz component and the amplitude of the 50Hz component.

[0018] Furthermore, the leakage magnetic vibration sensor performs a fast Fourier transform on the linearly polarized light emitted by the light source to obtain the light intensity amplitude at different frequencies, which are caused by the magnetic field and vibration.

[0019] In a specific embodiment of the present invention, the leakage magnetic frequency of the transformer is 50Hz, and the minimum vibration frequency of the transformer is 100Hz, and the two are independent of each other.

[0020] The second aspect of this invention provides a method for combined leakage flux and vibration measurement of an oil-immersed transformer using a combined leakage flux and vibration measurement device, comprising the following steps:

[0021] Step 1: Sensor placement;

[0022] Step 2, composite measurement;

[0023] Step 3, signal processing;

[0024] Furthermore, in step 1, the sensor is arranged such that the leakage flux processing device and the vibration processing device are connected to the leakage flux vibration composite sensor by optical fiber, and the optical fiber between the light source and the leakage flux vibration composite sensor is not suspended in the transformer oil when it is wired inside the transformer.

[0025] Furthermore, in step 2, the composite measurement involves processing the received optical signal using a leakage magnetic field vibration composite sensor when the transformer is running, to obtain the signal amplitude with frequencies equal to the leakage magnetic field signal frequency and the vibration signal frequency.

[0026] Furthermore, in step 2, the leakage magnetic vibration composite sensor performs a fast Fourier transform on the output light intensity to obtain the amplitude P0 of the 0Hz component and the amplitude P of the 50Hz component. 50 They are respectively:

[0027]

[0028] In the formula,

[0029] I0 is the light intensity after passing through the polarizer on the light source side under vibration-free conditions;

[0030] V is the Field constant of the magneto-optical crystal;

[0031] L is the length of the optical signal transmitted in the magneto-optical crystal. When a through-type structure is used, L is the length of the magneto-optical crystal. When a reflective structure is used, L is generally twice the length of the magneto-optical crystal.

[0032] B represents the magnetic field measurement result;

[0033] The amplitudes of the two components are directly divided to obtain a value that is independent of light intensity and only related to the leakage magnetic field. This compensates for the influence of vibration interference on the sensor's leakage magnetic field measurement results. The leakage magnetic field measurement results obtained using the signal cross-comparison method are as follows:

[0034]

[0035] Further, in step 2, the leakage magnetic field vibration sensor performs a fast Fourier transform on the linearly polarized light emitted from the light source to obtain the light intensity amplitude at different frequencies, which is caused by the magnetic field and vibration, and is expressed as follows:

[0036]

[0037] In the formula,

[0038] ω is the frequency of the vibration;

[0039] θ is the phase of the vibration;

[0040] I represents the initial light intensity, which needs to be removed from the cross component to eliminate the light intensity change caused by leakage magnetic field variation;

[0041] The ω corresponds to the transformer leakage magnetic frequency: an integer multiple of 50Hz, such as 100Hz, 150Hz, etc.;

[0042] In addition, ω0 will contain some signals at integer multiples of 100Hz. The corresponding interference needs to be subtracted from the corresponding frequency components to obtain the vibration signal.

[0043] Furthermore, in step 3, the signal processing involves the signal amplitude with frequencies of leakage flux signal frequency and vibration signal frequency, and then the final leakage flux measurement result and vibration measurement result are obtained through leakage flux processing device and vibration processing device, thereby realizing the composite measurement of leakage flux and vibration of oil-immersed transformer.

[0044] By adopting the above scheme, the oil-immersed transformer leakage flux vibration composite sensing device and measurement method disclosed in this invention have the following advantages:

[0045] (1) This invention proposes a new method for simultaneously measuring leakage magnetic field and vibration signal of oil-immersed transformer. According to different frequencies, leakage magnetic field measurement results and vibration measurement results can be obtained separately to realize composite sensing of leakage magnetic field and vibration of oil-immersed transformer. It can realize simultaneous measurement of leakage magnetic field and vibration signal of oil-immersed transformer, which can better reflect the state of transformer winding. It has good practicality and is conducive to improving the online monitoring effect of transformer winding deformation.

[0046] (2) The present invention uses the characteristic frequency ratio method to eliminate the influence of light source disturbance on the measurement results, thereby improving the accuracy of the results;

[0047] In summary, the oil-immersed transformer leakage flux and vibration composite sensing device and measurement method disclosed in this invention proposes a novel method for simultaneously measuring leakage flux and vibration signals of oil-immersed transformers. Based on different frequencies, leakage flux measurement results and vibration measurement results can be obtained separately, achieving composite sensing of leakage flux and vibration in oil-immersed transformers. This allows for simultaneous measurement of leakage flux and vibration signals, better reflecting the transformer winding state, and offers good practicality. It also improves the online monitoring effect of transformer winding deformation. Furthermore, the use of the characteristic frequency ratio method eliminates the influence of light source disturbance on the measurement results, improving the accuracy of the results.

[0048] The following will further explain the concept, specific technical solution and technical effects of the present invention in conjunction with specific embodiments, so as to fully understand the purpose, features and effects of the present invention. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of a combined measurement device for leakage flux and vibration of an oil-immersed transformer according to the present invention;

[0050] Figure 2 This is a waveform diagram of the signal amplitude of Embodiment 1 of the present invention;

[0051] In the diagram, 1 is the light source; 2 is the magnetic flux leakage vibration composite sensor; 3 is the magnetic flux leakage processing device; 4 is the vibration processing device; and 5 is the optical fiber. Detailed Implementation

[0052] The following describes several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, which are described exemplarily, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0053] If there are experimental methods that do not specify the conditions, they are usually carried out according to the standard conditions, such as the relevant instructions or manuals.

[0054] The present invention discloses a combined measurement device for leakage flux and vibration of an oil-immersed transformer, comprising a light source 1, a leakage flux and vibration composite sensor 2, a leakage flux processing device 3, a vibration processing device 4, and an optical fiber 5; the optical fiber 5 connects the various parts; the light source 1 is connected to the leakage flux and vibration composite sensor 2 through the optical fiber 5; the leakage flux and vibration composite sensor 2 is connected to the leakage flux processing device 3 and the vibration processing device 4 through the optical fiber 5.

[0055] The light source 1 outputs linearly polarized light;

[0056] The magnetic flux leakage vibration composite sensor includes a magnetic flux leakage sensing unit;

[0057] The leakage magnetic field vibration composite sensor includes a vibration-sensitive unit;

[0058] The leakage magnetic field vibration composite sensor includes a photodetector;

[0059] The leakage magnetic sensing unit includes a collimator, a polarizer, and a magneto-optical material;

[0060] The vibration-sensitive unit is made of multiple turns of optical fiber 5.

[0061] The magnetic flux leakage sensing unit is connected to the vibration sensing unit through optical fiber 5. The signal output by the photodetector is transmitted to the magnetic flux leakage processing device 3 and the vibration processing device 4 through the BNC line.

[0062] The leakage magnetic field processing device 3 includes a data acquisition card and an FPGA. The data acquisition card is used to acquire signals, and the FPGA has a built-in analysis program to process the signals to obtain leakage magnetic field data.

[0063] The vibration processing device 4 includes a data acquisition card and an FPGA. The data acquisition card is used to acquire signals, and the FPGA has a built-in analysis program to process the signals to obtain vibration data.

[0064] The 50Hz component of the output light intensity of the leakage magnetic field vibration composite sensor 2 is only related to the measured leakage magnetic field.

[0065] The leakage magnetic vibration composite sensor 2 can perform a fast Fourier transform on the output light intensity to obtain the amplitude P0 of the 0Hz component and the amplitude of the 50Hz component.

[0066] The leakage magnetic field vibration composite sensor 2 performs a fast Fourier transform on the linearly polarized light emitted by the light source 1 to obtain the light intensity amplitude at different frequencies, which are caused by the magnetic field and vibration.

[0067] The transformer leakage magnetic frequency is 50Hz, and the transformer vibration frequency is at least 100Hz, and the two are independent of each other.

[0068] Example 1: Monitoring of oil-immersed transformers using a combined leakage flux and vibration measurement device of the present invention.

[0069] Step 1, Sensor Arrangement; The sensor arrangement is to connect the leakage magnetic flux processing device and the vibration processing device to the leakage magnetic flux vibration composite sensor with optical fibers, and to ensure that the optical fiber between the light source and the leakage magnetic flux vibration composite sensor is not suspended in the transformer oil when it is wired inside the transformer.

[0070] Step 2, Composite Measurement; The composite measurement involves processing the received optical signal using a leakage magnetic field vibration composite sensor when the transformer is running, to obtain the signal amplitude with frequencies equal to the leakage magnetic field signal frequency and the vibration signal frequency.

[0071] The magnetic flux leakage vibration composite sensor performs a fast Fourier transform on the output light intensity to obtain the amplitude P0 of the 0Hz component and the amplitude P of the 50Hz component. 50 They are respectively:

[0072]

[0073] In the formula,

[0074] I0 is the light intensity after passing through the polarizer on the light source side under vibration-free conditions;

[0075] V is the Field constant of the magneto-optical crystal;

[0076] L is the length of the optical signal transmitted in the magneto-optical crystal. When a through-type structure is used, L is the length of the magneto-optical crystal. When a reflective structure is used, L is generally twice the length of the magneto-optical crystal.

[0077] B represents the magnetic field measurement result;

[0078] The amplitudes of the two components are directly divided to obtain a value that is independent of light intensity and only related to the leakage magnetic field. This compensates for the influence of vibration interference on the sensor's leakage magnetic field measurement results. The leakage magnetic field measurement results obtained using the signal cross-comparison method are as follows:

[0079]

[0080] The leakage magnetic field vibration sensor performs a fast Fourier transform on the linearly polarized light emitted from the light source to obtain the light intensity amplitude at different frequencies, which is caused by the magnetic field and vibration, and is expressed as follows:

[0081]

[0082] In the formula,

[0083] ω is the frequency of the vibration;

[0084] θ is the phase of the vibration;

[0085] I represents the initial light intensity, which needs to be removed from the cross component to eliminate the light intensity change caused by leakage magnetic field variation;

[0086] The ω corresponds to the transformer leakage magnetic frequency: an integer multiple of 50Hz, such as 100Hz, 150Hz, etc.;

[0087] In addition, ω0 will contain some signals at integer multiples of 100Hz. The corresponding interference needs to be subtracted from the corresponding frequency components to obtain the vibration signal.

[0088] Step 3, Signal Processing; The signal processing involves the amplitude of the signal with frequencies of leakage flux signal and vibration signal, and then the final leakage flux measurement result and vibration measurement result are obtained through leakage flux processing device and vibration processing device, thereby realizing the composite measurement of leakage flux and vibration of oil-immersed transformer;

[0089] like Figure 2 As shown,

[0090] After processing the acquired waveforms, the measured leakage magnetic flux was found to be 26.38 mT, the vibration frequency was 100 Hz, and the amplitude was 2.5 m / s². 2 ;

[0091] This indicates that when monitoring an oil-immersed transformer using the combined leakage flux and vibration measurement device of Example 1, the leakage flux signal and vibration signal of the oil-immersed transformer can be measured online simultaneously.

[0092] Comparative Example 2: Measuring the vibration of an oil-immersed transformer using a patented fiber optic sensing device.

[0093] The vibration monitoring is performed using the existing patent CN202110809146.0, which describes a vibration monitoring device for an oil-immersed transformer in a power grid based on fiber optic sensing.

[0094] Step 1: The two lasers emit lasers into the input ports of the two circulators respectively;

[0095] Step 2: The two laser beams enter the two ends of the oil-resistant single-core optical cable through the middle ports of the two circulators respectively;

[0096] Step 3: The root forms two optical signals that run in opposite directions;

[0097] Step 4: The optical characteristics of the two optical signals change as they pass through the two sensing segments respectively;

[0098] Step 5: The light enters the photodetector through the output ports of the two circulators respectively;

[0099] Step 6: Convert the optical signal into an electrical signal using a photodetector and transmit it to a computer for data analysis to determine whether any abnormal vibration has occurred.

[0100] Vibration result: Vibration occurred, and the vibration was located on the winding side;

[0101] This indicates that when monitoring an oil-immersed transformer using the traditional electrical measurement method in Comparative Example 2, the results show two optical signals, allowing monitoring based on only two parts: first, comparing the characteristics of the two optical signals to determine if abnormal vibration exists; second, determining whether the vibration is in the core, winding, or tank based on the time difference of the vibration signals. Therefore, the existing patent CN202110809146.0, "A Vibration Monitoring Device for an Oil-Immersed Transformer Based on Fiber Optic Sensing," cannot provide vibration amplitude, frequency, or leakage flux information.

[0102] Experimental Example 3: Compare the results of Example 1 and Comparative Example 2;

[0103] It can be seen that when monitoring the same device, the oil-immersed transformer leakage flux and vibration composite sensing device and measurement method of Example 1 has a transmission optical path structure, which can obtain leakage flux measurement results and vibration measurement results according to different frequencies, and realize the simultaneous online measurement of leakage flux signal and vibration signal of oil-immersed transformer; the vibration monitoring device of power grid oil-immersed transformer based on fiber optic sensing of Comparative Example 2 has a reflection optical path structure, which can only monitor vibration signal. Compared with Comparative Example 2, Example 1 not only uses the characteristic frequency ratio method to eliminate the influence of light source disturbance on the measurement results, but also uses the leakage flux / vibration signal processing methods included in the leakage flux processing unit and vibration processing unit, including Fourier calculation, characteristic frequency analysis, leakage flux amplitude and vibration frequency and amplitude calculation, etc., to make the obtained results more accurate, the online monitoring effect better, and the practicality better.

[0104] In summary, the present invention provides a novel method for simultaneously measuring the leakage flux and vibration signals of an oil-immersed transformer. This method allows for the simultaneous measurement of leakage flux and vibration signals of the transformer at different frequencies, enabling composite sensing of leakage flux and vibration in the oil-immersed transformer. Furthermore, the characteristic frequency ratio method is used to eliminate the influence of light source disturbances on the measurement results, thus better reflecting the transformer winding condition. This invention is highly practical and beneficial for improving the online monitoring effect of transformer winding deformation.

[0105] Other embodiments of the present invention provide oil-immersed transformer leakage magnetic field vibration composite sensing devices with similar beneficial effects as described above.

[0106] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A combined measurement device for leakage flux and vibration of an oil-immersed transformer, characterized in that, It includes a light source (1), a magnetic flux leakage vibration composite sensor (2), a magnetic flux leakage processing device (3), a vibration processing device (4), and an optical fiber (5); the optical fiber (5) connects the various parts; the light source (1) is connected to the magnetic flux leakage vibration composite sensor (2) through the optical fiber (5); the magnetic flux leakage vibration composite sensor (2) is connected to the magnetic flux leakage processing device (3) and the vibration processing device (4) through the optical fiber (5); When the transformer is running, the received optical signal is processed by the leakage magnetic field vibration composite sensor (2) to obtain the signal amplitude with frequencies equal to the leakage magnetic field signal frequency and the vibration signal frequency; the leakage magnetic field vibration composite sensor (2) performs a fast Fourier transform on the output light intensity to obtain the amplitude P0 of the 0Hz component and the amplitude P of the 50Hz component. 50 They are respectively: P0=0.5I0A 2 ； P 50 =0.5I0A2sin(2VLB); In the formula, I0 is the light intensity after passing through the polarizer on the side of the light source (1) under vibration-free conditions; V is the Feld constant of the magneto-optical crystal; L is the length of the optical signal transmitted in the magneto-optical crystal. When a through-type structure is used, L is the length of the magneto-optical crystal. When a reflective structure is used, L is twice the length of the magneto-optical crystal; B is the magnetic field measurement result. The amplitudes of the two components are directly divided to obtain a value that is independent of light intensity and only related to the leakage magnetic field. The leakage magnetic field measurement results obtained by the signal cross-comparison method are as follows: N=P 50 / P0=sin(2BVL) B = arcsinN / 2VL; The leakage magnetic field vibration composite sensor (2) performs a fast Fourier transform on the linearly polarized light emitted by the light source (1) to obtain the light intensity amplitude at different frequencies, which is caused by the magnetic field and vibration, and is expressed as follows: P=1 / 2I0[A2+A1cos(ωt+θ)]·[1+A3cos(ωpt)]; In the formula, ω is the frequency of vibration; θ is the phase of vibration; ωp corresponds to the transformer leakage magnetic frequency: an integer multiple of 50Hz; in addition, ω and ωp will contain some signals at integer multiples of 100Hz, and the corresponding interference needs to be subtracted from the corresponding frequency components to obtain the vibration signal. The light source (1) outputs linearly polarized light; the leakage magnetic vibration composite sensor (2) includes a leakage magnetic sensing unit, a vibration sensing unit, and a photodetector.

2. The combined measurement device for leakage flux and vibration of oil-immersed transformers as described in claim 1, characterized in that, The leakage magnetic sensing unit includes a collimator, a polarizer, and a magneto-optical material; The vibration-sensitive unit is made of multiple turns of optical fiber (5) wrapped around it; The leakage magnetic field sensing unit is connected to the vibration sensing unit through an optical fiber (5). The signal output by the photodetector is transmitted to the leakage magnetic field processing device (3) and the vibration processing device (4) through the BNC line.

3. The combined measurement device for leakage flux and vibration of oil-immersed transformers as described in claim 1, characterized in that, The leakage magnetic field processing device (3) includes a data acquisition card and an FPGA. The data acquisition card is used to acquire signals, and the FPGA has a built-in analysis program to process the signals to obtain leakage magnetic field data. The vibration processing device (4) includes a data acquisition card and an FPGA. The data acquisition card is used to acquire signals, and the FPGA has a built-in analysis program to process the signals to obtain vibration data. The 50Hz component of the output light intensity of the leakage magnetic field vibration composite sensor (2) is only related to the measured leakage magnetic field; The leakage magnetic vibration composite sensor (2) can perform a fast Fourier transform on the output light intensity to obtain the amplitude P0 of the 0Hz component and the amplitude of the 50Hz component. The leakage magnetic field vibration composite sensor (2) performs a fast Fourier transform on the linearly polarized light emitted by the light source (1) to obtain the light intensity amplitude at different frequencies caused by the magnetic field and vibration.

4. The combined measurement device for leakage flux and vibration of an oil-immersed transformer as described in claim 1, characterized in that, The transformer leakage magnetic frequency is 50Hz, and the transformer vibration frequency is at least 100Hz; the two are independent of each other.

5. The combined measurement device for leakage flux and vibration of an oil-immersed transformer as described in claim 1, characterized in that, Based on the different frequencies of the leakage magnetic signal and the vibration signal, the leakage magnetic signal and the vibration signal are measured simultaneously.

6. A method for applying the combined measurement device for leakage flux and vibration of an oil-immersed transformer as described in claim 1, characterized in that, Includes the following steps, Step 1: Sensor placement; Step 2, composite measurement; Step 3, signal processing; In step 2, the composite measurement involves processing the received optical signal using a leakage magnetic field vibration composite sensor (2) when the transformer is running to obtain the signal amplitude with frequencies equal to the leakage magnetic field signal frequency and the vibration signal frequency; the leakage magnetic field vibration composite sensor (2) performs a fast Fourier transform on the output light intensity to obtain the amplitude P0 of the 0Hz component and the amplitude P of the 50Hz component. 50 They are respectively: P0=0.5I0A 2； P 50 =0.5I0A2sin(2VLB); In the formula, I0 is the light intensity after passing through the polarizer on the side of the light source (1) under vibration-free conditions; V is the Feld constant of the magneto-optical crystal; L is the length of the optical signal transmitted in the magneto-optical crystal. When a through-type structure is used, L is the length of the magneto-optical crystal. When a reflective structure is used, L is twice the length of the magneto-optical crystal; B is the magnetic field measurement result. The amplitudes of the two components are directly divided to obtain a value that is independent of light intensity and only related to the leakage magnetic field. The leakage magnetic field measurement results obtained by the signal cross-comparison method are as follows: N=P 50 / P0=sin(2BVL) B = arcsinN / 2VL; The leakage magnetic field vibration composite sensor (2) performs a fast Fourier transform on the linearly polarized light emitted by the light source (1) to obtain the light intensity amplitude at different frequencies, which is caused by the magnetic field and vibration, and is expressed as follows: P=1 / 2I0[A2+A1cos(ωt+θ)]·[1+A3cos(ωpt)]; In the formula, ω is the frequency of vibration; θ is the phase of vibration; ωp corresponds to the transformer leakage magnetic frequency: an integer multiple of 50Hz; in addition, ω and ωp will contain some signals at integer multiples of 100Hz, and the corresponding interference needs to be subtracted from the corresponding frequency components to obtain the vibration signal. The light source (1) outputs linearly polarized light; the leakage magnetic vibration composite sensor (2) includes a leakage magnetic sensing unit, a vibration sensing unit, and a photodetector.

7. The method of the combined measurement device for leakage flux and vibration of an oil-immersed transformer as described in claim 6, characterized in that, In step 1, The sensor is arranged such that the leakage magnetic flux processing device (3) and the vibration processing device (4) are connected to the leakage magnetic flux vibration composite sensor (2) by optical fiber, and the optical fiber (5) between the light source (1) and the leakage magnetic flux vibration composite sensor (2) is not suspended in the transformer oil when it is wired inside the transformer.

8. The method of the combined measurement device for leakage flux and vibration of an oil-immersed transformer as described in claim 6, characterized in that, In step 3 The signal processing is the signal amplitude with frequencies of leakage magnetic signal frequency and vibration signal frequency. Then, the leakage magnetic signal processing device (3) and vibration processing device (4) are used to obtain the final leakage magnetic signal measurement result and vibration measurement result, thereby realizing the composite measurement of leakage magnetic signal and vibration of oil-immersed transformer.

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