Transformer fault positioning method based on photoelectric conversion integrated device of laser Doppler velocity measurement system

Abstract

The invention belongs to the technical field of electrical equipment measurement, and particularly relates to a transformer fault positioning method based on a photoelectric conversion integrated device of a laser Doppler velocity measurement system. Building a transformer oil flow velocity analog simulation model based on a laser Doppler velocity measurement system photoelectric conversion integrated device; transformer flow velocity field distribution characteristics in different fault modes are analyzed, and an installation and arrangement strategy of flow velocity sensors in the transformer box wall is determined; fault codes are constructed according to sensor measurement data, and transformer fault positioning is realized based on the fault codes. The photoelectric conversion integrated device of the laser Doppler velocity measurement system comprises a laser, a first optical fiber coupler, an optical fiber circulator, a second optical fiber coupler and a photoelectric detector. Integrated optimization design is carried out according to an existing Doppler optical flow velocity sensor structure, the fault type can be quickly determined, the fault occurrence position can be positioned, and the reliability and accuracy of field application are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical equipment measurement, and in particular relates to a transformer fault locating method based on a photoelectric conversion integrated device of a laser Doppler speed measurement system. Background Art

[0002] In the existing technology, laser technology has been applied to various technical fields with its unique technical advantages, becoming a breakthrough method to solve traditional technical problems. The laser Doppler flowmeter has the following advantages: long service life, the continuous working time of the laser far exceeds the life of piezoelectric ceramics. In theory, the lower the working threshold current requirement of the laser for laser Doppler velocity measurement, the longer the life of the laser will be; high measurement accuracy, large velocity measurement value range, and high spatial resolution. The laser speed can reach 3×10 8 m / s, the frequency of light waves is at the terahertz level, which can undertake the measurement of high-speed object movement. The theoretical speed measurement range is close to the speed of light, and the accuracy can reach 0.001m / s. The detection range can centrally control the light beam to detect a very small range of points, so as to accurately detect the motion state of particles at one point; high sensitivity, the transmission speed of the laser is sufficient to monitor some high-speed scenes in real time, such as monitoring the movement of object explosion fragments or the motion state of high-speed moving objects; the information transmission channel uses high temperature and high pressure resistant optical fiber. The slender glass fiber is protected by plastic, and the optical fiber has the characteristics of easy installation, making it suitable for various complex environments.

[0003] Since the advent of laser Doppler velocimetry technology in 1964, various scientific research teams have built laser Doppler velocimetry systems using a combination of optical and electronic devices. With the rapid development of light sources, various optical passive devices, and photoelectric detection devices, the stability of laser Doppler velocimeters has been greatly improved. In addition, signal processing technology is not limited to the use of spectrum analyzers. Signal processing modules such as frequency trackers and counting processors have emerged, making the built system more and more complicated. The external photoelectric conversion circuit connection of the Doppler flow velocity optical sensor currently applicable is extremely complex, and the signal transmission efficiency and monitoring sensitivity depend on the parameter settings of each device in the circuit. The circuit connection debugging takes a lot of time in field applications, and the circuit is easily interfered by external environmental factors and is not suitable for field environments.

[0004] Therefore, there is an urgent need for a transformer fault location method based on the optoelectronic conversion integrated device of the laser Doppler velocity measurement system, and an integrated optimization design based on the existing Doppler optical flow velocity sensor structure to improve the reliability and accuracy of field applications. Summary of the invention

[0005] The object of the present invention is to provide a transformer fault location method based on a laser Doppler speed measurement system photoelectric conversion integrated device, which is characterized by comprising the following steps:

[0006] According to the actual internal situation of the transformer to be tested, a transformer oil flow velocity simulation model is built based on the photoelectric conversion integrated device of the laser Doppler velocity measurement system;

[0007] Analyze the distribution characteristics of transformer flow velocity field under different fault modes and determine the installation layout strategy of flow velocity sensors inside the transformer box wall;

[0008] The fault code is constructed according to the sensor measurement data, and the transformer fault location is realized based on the fault code.

[0009] The transformer oil flow velocity simulation model based on the laser Doppler velocity measurement system photoelectric conversion integrated device includes:

[0010] Use the laser Doppler velocimetry system photoelectric conversion integrated device to obtain the flow velocity information of the transformer oil inside the transformer; screen the tracer particles; select the transformer parameters; select the simulation model; and set the boundary conditions.

[0011] The screening of tracer particles comprises: using a followability function to calculate particle followability F;

[0012] The following function is:

[0013]

[0014] Where a, b, and c are:

[0015]

[0016] ω is the angular frequency of light pulsation, μ is the viscosity coefficient, d p is the particle diameter, ρ p is the particle density, ρ f is the fluid density.

[0017] The method of using the laser Doppler velocity measurement system photoelectric conversion integrated device to obtain the flow velocity information of the transformer oil inside the transformer includes:

[0018] The laser (1-1) emits laser light, which enters the first optical fiber coupler (1-2) along the optical fiber, is then emitted to the external collimator via the optical fiber circulator (1-3), and finally enters the interior of the transformer;

[0019] Transformer oil is provided inside the transformer, and tracer particles are provided in the transformer oil; after the laser enters the transformer, the tracer particles in the transformer oil emit scattered light after being irradiated by the laser;

[0020] After the scattered light enters the collimator and returns to the optical fiber circulator (1-3), it directly enters the second optical fiber coupler (1-4) and reaches the photoelectric detector (1-5);

[0021] The photoelectric detector (1-5) converts the flow velocity information carried by the received scattered light signal into an electrical signal output;

[0022] The electrical signal is digitally processed to obtain flow rate information of transformer oil inside the transformer.

[0023] The analysis of the transformer flow velocity field distribution characteristics under different fault modes and determination of the installation layout strategy of the flow velocity sensor inside the transformer tank wall include:

[0024] Based on the transformer oil flow velocity simulation model, simulation experiments were carried out on the normal operation of the transformer and various fault modes of the transformer. The positions where the oil velocity changes more obviously under various fault conditions were analyzed and compared, and flow velocity sensors were set there to determine the installation layout strategy of the flow velocity sensors inside the transformer box wall.

[0025] The method of constructing a fault code according to the sensor measurement data and locating the transformer fault based on the fault code includes:

[0026] Determine whether a fault occurs based on the sensor measurement data;

[0027] When a fault occurs, a fault probability score is calculated for each sensor location based on the sensor measurement data;

[0028] The fault probability integrals of all positions are concatenated into a fault code;

[0029] The sensor position represented by the digit with the highest fault possibility score in the fault code is determined as the fault location, thereby locating the transformer fault.

[0030] The method of judging whether a fault occurs based on the sensor measurement data includes: an oil pillow flow rate sensor needs to be installed in the oil pillow connecting pipe. If the flow rate obtained by the oil pillow flow rate sensor continues to rise and exceeds the normal flow rate of the transformer oil, it is judged that a fault occurs in the transformer to be tested.

[0031] The calculation of the fault likelihood score includes:

[0032] Read the flow rate value of the flow rate sensor measurement point;

[0033] When the flow rate value is lower than x0, the index is set to 0;

[0034] When the flow rate value is between x0 and x1, let the index be 1;

[0035] When the flow rate monitoring value is between x1 and x2, let the index be 2;

[0036] When the flow rate value is greater than x2, let the index be 3.

[0037] The indicators corresponding to the flow rates measured by the various sensors form a number in sequence, and the number is a fault possibility score for the measuring point.

[0038] Another object of the present invention is to disclose a photoelectric conversion integrated device of a laser Doppler speed measurement system, characterized in that it comprises: a laser, a first optical fiber coupler, an optical fiber circulator, a second optical fiber coupler, and a photoelectric detector;

[0039] The laser output end is connected to the first fiber coupler input end, the first fiber coupler output port is connected to the fiber circulator port 1, the fiber circulator port 2 is connected to the external collimator, and the fiber circulator port 3 is connected to the second fiber coupler; the second fiber coupler output port is connected to the photodetector input port, and the photodetector output port will output the electrical signal to the outside through the circuit line.

[0040] Furthermore, the external power supply powers the laser and the photodetector simultaneously.

[0041] The beneficial effects of the present invention are:

[0042] The photoelectric conversion part of the laser Doppler velocimetry system is integrated to reduce its size, reduce the distance between components that is wasted in the normal system construction, and greatly improve its portability; the optical path designed based on the reference light model can measure the transformer oil flow rate inside a large power transformer with high precision; the transformer simulation model is used to design the best solution for the distributed layout of sensors, which makes it faster to judge when a fault occurs; based on the simulation results, the flow velocity difference characteristics for judging various faults are obtained and the encoding design is performed according to the sensor measurement results at the layout points, which can judge a large number of different faults, not only determine the fault type but also locate the fault location, which is convenient for subsequent maintenance of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of a transformer fault location method based on a laser Doppler speed measurement system photoelectric conversion integrated device of the present invention;

[0044] Figure 2 A schematic diagram of a sensor deployment strategy and a fault identification and location method flow chart of an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the structure of a photoelectric conversion integrated device of a laser Doppler velocity measurement system according to an embodiment of the present invention;

[0046] In the figure, 1-1: laser, 1-2: first fiber coupler, 1-3: fiber circulator, 1-4: second fiber coupler, 1-5: photodetector. DETAILED DESCRIPTION

[0047] The present invention provides a transformer fault locating method based on a laser Doppler velocity measurement system photoelectric conversion integrated device, and the present invention is further described in detail below in conjunction with the accompanying drawings.

[0048] like Figure 1 The embodiment of the present invention shown discloses a transformer fault location method based on a laser Doppler speed measurement system photoelectric conversion integrated device, comprising:

[0049] According to the actual internal situation of the transformer to be tested, a transformer oil flow velocity simulation model is built based on the photoelectric conversion integrated device of the laser Doppler velocity measurement system;

[0050] Analyze the distribution characteristics of transformer flow velocity field under different fault modes and determine the installation layout strategy of flow velocity sensors inside the transformer box wall;

[0051] The fault code is constructed according to the sensor measurement data, and the transformer fault location is realized based on the fault code.

[0052] In this embodiment, the transformer fault location method based on the optoelectronic conversion integrated device of the laser Doppler velocity measurement system improves the complex external measurement circuit of the existing Doppler optical flow velocity sensor, making it more suitable for field application; after simulating the transformer, it is found that the position where the transformer oil flow velocity inside the transformer changes significantly during a fault is formed, and a targeted flow velocity sensor layout strategy is formed to provide a criterion for fault discovery and identification; the measurement data of each sensor is divided to form a transformer internal arc fault identification and location method based on the encoding result, thereby improving the recognition rate of arc faults.

[0053] The photoelectric conversion integrated device of the laser Doppler speed measurement system comprises: a laser 1-1, a first optical fiber coupler 1-2, an optical fiber circulator 1-3, a second optical fiber coupler 1-4, and a photoelectric detector 1-5;

[0054] The output end of the laser 1-1 is connected to the input end of the first fiber coupler 1-2, the output port of the first fiber coupler 1-2 is connected to the port 1 of the fiber circulator 1-3, the port 2 of the fiber circulator 1-3 is connected to the external collimator, and the port 3 of the fiber circulator 1-3 is connected to the second fiber coupler 1-4; the output port of the second fiber coupler 1-4 is connected to the input port of the photodetector 1-5, and the output port of the photodetector 1-5 will output the electrical signal to the outside through the circuit line.

[0055] The laser Doppler velocity measurement system photoelectric conversion integrated device is used for a transformer fault locating method based on the laser Doppler velocity measurement system photoelectric conversion integrated device disclosed by the present invention.

[0056] In this embodiment, the photoelectric conversion integrated device of the laser Doppler speed measurement system overcomes the following defects existing in the photoelectric conversion part of the laser Doppler speed measurement system in the prior art:

[0057] In the prior art, it is necessary to assemble and combine various components to measure the flow rate, which is very troublesome to assemble and measure. Not only do the photodetector and laser need to be powered separately, which occupies a large space, but the gain of the photodetector needs to be adjusted separately during use to adapt to the actual transformer operating conditions.

[0058] like Figure 3 As shown, the laser Doppler speed measurement system optoelectronic conversion integrated device disclosed in the present invention is used to implement the transformer fault locating method disclosed in the present invention, the laser 1-1, the first optical fiber coupler 1-2, the optical fiber circulator 1-3, the second optical fiber coupler 1-4, and the photodetector 1-5 are encapsulated in the optoelectronic conversion module, the external power supply simultaneously powers the laser 1-1 and the photodetector 1-5, the output end of the laser 1-1 is connected to the input end of the first optical fiber coupler 1-2, the output port of the first optical fiber coupler 1-2 is connected to the port 1 of the optical fiber circulator 1-3, the port 2 of the optical fiber circulator 1-3 is connected to the external collimator, the port 3 of the optical fiber circulator 1-3 is connected to the second optical fiber coupler 1-4; the output port of the second optical fiber coupler 1-4 is connected to the input port of the photodetector 1-5, and the output port of the photodetector 1-5 outputs the electrical signal to the outside through the circuit line.

[0059] In a preferred embodiment, an external power supply simultaneously powers the laser 1-1 and the photodetector 1-5, integrating the power supply lines for the laser 1-1 and the photodetector 1-5, eliminating the need for separate power supplies and reducing the sensor's requirements for external power.

[0060] In the prior art, the gain adjustment of the photoelectric detectors 1-5 requires close-range adjustment. In a preferred embodiment, a gain knob is provided outside the photoelectric module to achieve long-range change of the gain of the photoelectric detectors 1-5.

[0061] The use of the laser Doppler velocity measurement system photoelectric conversion integrated device disclosed in the present invention makes the entire module small in size and does not require a construction and layout process, making it more convenient to use. Packaging the components into modules also avoids the erosion of the components and circuits by the external environment, reduces interference in signal transmission, and ensures the measurement accuracy of the system and stability during operation.

[0062] like Figure 2As shown, a transformer fault location method based on a laser Doppler velocity measurement system photoelectric conversion integrated device disclosed in this embodiment is based on the actual internal situation of the transformer where the sensor needs to be installed, a transformer oil flow velocity simulation model is built, the transformer flow velocity field distribution characteristics under different fault modes are analyzed, and the installation and layout strategy of the flow velocity sensor inside the transformer box wall is clarified. Combined with the actual transformer structure size, according to the flow velocity characteristics of the flow velocity sensor arrangement points under different faults, a coding identification and location method for transformer internal faults is formed.

[0063] The implementation methods of each step are described in detail below:

[0064] The transformer oil flow velocity simulation model based on the laser Doppler velocity measurement system photoelectric conversion integrated device includes:

[0065] Use the laser Doppler velocimetry system photoelectric conversion integrated device to obtain the flow velocity information of the transformer oil inside the transformer; screen the tracer particles; select the transformer parameters; select the simulation model; and set the boundary conditions.

[0066] In this embodiment, the factors affecting the followability of particles in the fluid include the particle diameter, viscosity coefficient, density of the fluid, and density ratio of the particle to the fluid. The screening of tracer particles includes: using a followability function to calculate the particle followability F;

[0067] The following function is:

[0068]

[0069] Where a, b, and c are:

[0070]

[0071] ω is the angular frequency of light pulsation, μ is the viscosity coefficient, d p is the particle diameter, ρ p is the particle density, ρ f is the fluid density.

[0072] The F calculated based on the followability function can reflect the followability of the particles. The closer F is to 1, the better the followability of the particles, and the more it can reflect the velocity of the fluid.

[0073] Those skilled in the art should be aware that transformer parameters, simulation models and boundary conditions are selected according to the specific working environment, which are not specifically limited in this embodiment.

[0074] The method of using the laser Doppler velocity measurement system photoelectric conversion integrated device to obtain the flow velocity information of the transformer oil inside the transformer includes:

[0075] The laser 1-1 emits laser light, which enters the first fiber coupler 1-2 along the optical fiber, and then is emitted to the external collimator through the fiber circulator 1-3, and finally enters the transformer;

[0076] Transformer oil is provided inside the transformer, and tracer particles are provided in the transformer oil; after the laser enters the transformer, the tracer particles in the transformer oil emit scattered light after being irradiated by the laser;

[0077] After the scattered light enters the collimator and returns to the optical fiber circulator 1-3, it directly enters the second optical fiber coupler 1-4 and reaches the photodetector 1-5;

[0078] The photoelectric detectors 1-5 convert the flow velocity information carried by the received scattered light signals into electrical signal outputs;

[0079] The electrical signal is digitally processed to obtain flow rate information of transformer oil inside the transformer.

[0080] In this embodiment, as the photoelectric conversion part of the laser Doppler velocity measurement system, a power supply is used to power the laser 1-1 and the photodetector 1-5 in the system. After the power is turned on and the switch is turned on, the laser 1-1 emits a laser. The laser enters the first fiber coupler 1-2 along the optical fiber, and then the laser is emitted to the external collimator through the fiber circulator 1-3, and then enters the oil inside the transformer. After being irradiated by the laser, the tracer particles in the oil will emit scattered light. The scattered light carries the flow rate information and enters the collimator and returns to the fiber circulator 1-3, and then directly enters the second fiber coupler 1-4 to the photodetector 1-5. The photodetector 1-5 converts the flow rate information carried by the received scattered light signal into an electrical signal for output. After processing in the photodetector 1-5, the electrical signal is output to the outside. It only needs to perform digital signal processing on the electrical signal to obtain the optical frequency shift generated by the light after being scattered by the tracer particles in the transformer oil, and then obtain the flow rate inside the transformer.

[0081] The laser Doppler velocity measurement system photoelectric conversion integrated device is used to obtain the electrical signal change corresponding to the flow velocity of the transformer oil inside the transformer, and the corresponding relationship between the electrical signal and the flow velocity is obtained through laboratory calibration results to calculate the flow velocity information in the actual transformer, which is not specifically limited in this embodiment.

[0082] The analysis of the transformer flow velocity field distribution characteristics under different fault modes and determination of the installation layout strategy of the flow velocity sensor inside the transformer tank wall include:

[0083] Based on the transformer oil flow velocity simulation model, simulation experiments were carried out on the normal operation of the transformer and various fault modes of the transformer. The positions where the oil velocity changes more obviously under various fault conditions were analyzed and compared, and flow velocity sensors were set there to determine the installation layout strategy of the flow velocity sensors inside the transformer box wall.

[0084] In this embodiment, by studying the distribution characteristics of the transformer flow velocity field under different fault modes, the layout strategy with the best fault monitoring effect is obtained. After the transformer is modeled, simulation experiments are carried out on the normal operation of the transformer and various fault modes of the transformer, and the positions where the oil velocity changes more obviously under various fault conditions are analyzed and compared, and flow velocity sensors are set there. When a fault occurs, the closer to the fault, the greater the measured flow velocity amplitude, thereby locating the fault position.

[0085] The method of constructing a fault code according to the sensor measurement data and locating the transformer fault based on the fault code includes:

[0086] Determine whether a fault occurs based on the sensor measurement data;

[0087] When a fault occurs, a fault probability score is calculated for each sensor location based on the sensor measurement data;

[0088] The fault probability integrals of all positions are concatenated into a fault code;

[0089] The sensor position represented by the digit with the highest fault possibility score in the fault code is determined as the fault location, thereby locating the transformer fault.

[0090] The method of judging whether a fault occurs based on the sensor measurement data includes: an oil pillow flow rate sensor needs to be installed in the oil pillow connecting pipe. If the flow rate obtained by the oil pillow flow rate sensor continues to rise and exceeds the normal flow rate of the transformer oil, it is judged that a fault occurs in the transformer to be tested.

[0091] In this embodiment, the fault will continue to exist, and the flow rate will continue to increase where the fault exists. Those skilled in the art should know that the corresponding normal flow rate threshold of the transformer oil is set according to the specific working environment, and no specific limitation is made in this embodiment.

[0092] In this embodiment, a flow rate sensor needs to be installed in the oil pillow connecting pipe. The flow rate at this position will continue to increase when a fault occurs, which can distinguish transformer faults from normal oil flow inside the transformer.

[0093] After that, the flow rate signals at each preset flow rate sensor under each fault are analyzed, and different indicators corresponding to different flow rate values ​​of each sensor within a range can be defined:

[0094] The calculation of the fault likelihood score includes:

[0095] Read the flow rate value of the flow rate sensor measurement point;

[0096] When the flow rate value is lower than x0, the index is set to 0;

[0097] When the flow rate value is between x0 and x1, let the index be 1;

[0098] When the flow rate monitoring value is between x1 and x2, let the index be 2;

[0099] When the flow rate value is greater than x2, let the index be 3.

[0100] The indicators corresponding to the flow rates measured by the various sensors form a number in sequence, and the number is a fault possibility score for the measuring point.

[0101] In this embodiment, the specific values ​​of x0, x1 and x2 need to be determined according to the specific conditions of each transformer and are not specifically limited in this embodiment.

[0102] In this embodiment, when the flow rate value at the flow rate sensor measurement point is lower than x0, the index is set to 0; when the flow rate value is between x0 and x1, the index is set to 1; when the flow rate monitoring value is between x1 and x2, the index is set to 2; when the flow rate value is greater than x2, the index is set to 3. The indicators corresponding to the flow rates measured by each sensor form a number in sequence, and arc discharge and normal operation have different codes respectively. The severity of the arc inside the transformer and the fault location are determined according to the code.

[0103] In order to verify the effectiveness of the transformer fault location method based on the laser Doppler speed measurement system photoelectric conversion integrated device disclosed in the present invention, the following verification experiment was carried out.

[0104] Taking the 110kV oil-immersed three-phase transformer as an example, in the simulation model, when an arc discharge fault occurs between the turns of phases A and B in the transformer, the flow velocity at the oil pillow connecting pipe is (0, x0), the flow velocity at phase A is (x1, x2), the flow velocity at phase B is (x1, x2), and the flow velocity at phase C is (x0, x1), and the fault code is 0221. In the case of an arc discharge fault between the turns of phases A and B in the transformer, the flow velocity at the oil pillow connecting pipe is x*, which is (0, x0); the flow velocity at phase A is x A *, at (x1,x2); the velocity of phase B is x B *, at (x1,x2); the flow rate of phase C is x C *, at (x0, x1), the fault code is 0221, which is consistent with the characteristics of the simulation model.

[0105] In the simulation model, when the transformer A phase lead overheats, the flow velocity at the oil pillow connecting pipe is at (0, x0), the flow velocity at phase A is greater than x2, the flow velocity at phase B is at (x1, x2), and the flow velocity at phase C is at (x0, x1), and the fault code is 0321. When conducting the overheat simulation test of the transformer internal A phase winding lead fault, when the transformer A phase winding lead overheats, the flow velocity at the oil pillow connecting pipe is x*, which is at (0, x0); the flow velocity at phase A is x A *, greater than x2; the flow rate of phase B is x B *, at (x1,x2); the flow rate of phase C is x C *, at (x0, x1), the fault code is 0321, which is consistent with the characteristics of the simulation model.

[0106] In summary, by using a transformer fault locating method based on a laser Doppler velocity measurement system photoelectric conversion integrated device and a laser Doppler velocity measurement system photoelectric conversion integrated device disclosed in the present invention, the complex external measurement circuit of the existing Doppler optical flow velocity sensor is improved, making it more suitable for field application; after simulating the transformer, the position where the transformer oil flow velocity inside the transformer changes significantly during a fault is found, and a targeted flow velocity sensor layout strategy is formed to provide a criterion for fault discovery and identification; the measurement data of each sensor is divided to form a transformer internal arc fault identification and locating method based on the encoding result, thereby improving the recognition rate of arc faults.

Claims

1. A transformer fault location method based on a laser Doppler speed measurement system photoelectric conversion integrated device, characterized in that: The steps include: According to the actual internal situation of the transformer to be tested, a transformer oil flow velocity simulation model is built based on the photoelectric conversion integrated device of the laser Doppler velocity measurement system; Analyze the distribution characteristics of transformer flow velocity field under different fault modes and determine the installation layout strategy of flow velocity sensors inside the transformer box wall; The fault code is constructed according to the sensor measurement data, and the transformer fault location is realized based on the fault code.

2. The transformer fault location method based on the laser Doppler speed measurement system photoelectric conversion integrated device according to claim 1 is characterized in that: The transformer oil flow velocity simulation model based on the laser Doppler velocity measurement system photoelectric conversion integrated device includes: Use the laser Doppler velocimetry system photoelectric conversion integrated device to obtain the flow velocity information of the transformer oil inside the transformer; screen the tracer particles; select the transformer parameters; select the simulation model; and set the boundary conditions.

3. The transformer fault location method based on the laser Doppler speed measurement system photoelectric conversion integrated device according to claim 2 is characterized in that: The screening of tracer particles comprises: using a followability function to calculate particle followability F; The following function is: Where a, b, and c are: ω is the angular frequency of light pulsation, μ is the viscosity coefficient, d p is the particle diameter, ρ p is the particle density, ρ f is the fluid density.

4. The transformer fault location method based on the laser Doppler velocity measurement system photoelectric conversion integrated device according to claim 2 is characterized in that: The method of using the laser Doppler velocity measurement system photoelectric conversion integrated device to obtain the flow velocity information of the transformer oil inside the transformer includes: The laser (1-1) emits laser light, which enters the first optical fiber coupler (1-2) along the optical fiber, is then emitted to the external collimator via the optical fiber circulator (1-3), and finally enters the interior of the transformer; Transformer oil is provided inside the transformer, and tracer particles are provided in the transformer oil; after the laser enters the transformer, the tracer particles in the transformer oil emit scattered light after being irradiated by the laser; After the scattered light enters the collimator and returns to the optical fiber circulator (1-3), it directly enters the second optical fiber coupler (1-4) and reaches the photoelectric detector (1-5); The photoelectric detector (1-5) converts the flow velocity information carried by the received scattered light signal into an electrical signal output; The electrical signal is digitally processed to obtain flow rate information of transformer oil inside the transformer.

5. The transformer fault location method based on the laser Doppler speed measurement system photoelectric conversion integrated device according to claim 1 is characterized in that: The analysis of the transformer flow velocity field distribution characteristics under different fault modes and the determination of the installation layout strategy of the flow velocity sensor inside the transformer box wall include: Based on the transformer oil flow velocity simulation model, simulation experiments were carried out on the normal operation of the transformer and various fault modes of the transformer. The positions where the oil velocity changes more obviously under various fault conditions were analyzed and compared, and flow velocity sensors were set there to determine the installation layout strategy of the flow velocity sensors inside the transformer box wall.

6. The transformer fault location method based on the laser Doppler velocity measurement system photoelectric conversion integrated device according to claim 1 is characterized in that: The method of constructing a fault code according to the sensor measurement data and locating the transformer fault based on the fault code includes: Determine whether a fault occurs based on the sensor measurement data; When a fault occurs, a fault probability score is calculated for each sensor location based on the sensor measurement data; The fault probability integrals of all positions are concatenated into a fault code; The sensor position represented by the digit with the highest fault possibility score in the fault code is determined as the fault location, thereby locating the transformer fault.

7. The transformer fault location method based on the laser Doppler velocity measurement system photoelectric conversion integrated device according to claim 6 is characterized in that: The method of judging whether a fault occurs based on the sensor measurement data includes: an oil pillow flow rate sensor needs to be installed in the oil pillow connecting pipe. If the flow rate obtained by the oil pillow flow rate sensor continues to rise and exceeds the normal flow rate of the transformer oil, it is judged that a fault occurs in the transformer to be tested.

8. The transformer fault location method based on the laser Doppler velocity measurement system photoelectric conversion integrated device according to claim 6 is characterized in that: The calculation of the fault likelihood score includes: Read the flow rate value of the flow rate sensor measurement point; When the flow rate value is lower than x0, the index is set to 0; When the flow rate value is between x0 and x1, let the index be 1; When the flow rate monitoring value is between x1 and x2, let the index be 2; When the flow rate value is greater than x2, let the index be 3. The indicators corresponding to the flow rates measured by the various sensors form a number in sequence, and the number is a fault possibility score for the measuring point.

9. A photoelectric conversion integrated device for a laser Doppler velocity measurement system, characterized in that: include: Laser (1-1), first optical fiber coupler (1-2), optical fiber circulator (1-3), second optical fiber coupler (1-4), photoelectric detector (1-5); The output end of the laser (1-1) is connected to the input end of the first optical fiber coupler (1-2), the output port of the first optical fiber coupler (1-2) is connected to port 1 of the optical fiber circulator (1-3), port 2 of the optical fiber circulator (1-3) is connected to an external collimator, and port 3 of the optical fiber circulator (1-3) is connected to the second optical fiber coupler (1-4); the output port of the second optical fiber coupler (1-4) is connected to the input port of the photodetector (1-5), and the output port of the photodetector (1-5) outputs an electrical signal to the outside through a circuit line.

10. The photoelectric conversion integrated device of the laser Doppler velocity measurement system according to claim 9, characterized in that: The external power supply simultaneously supplies power to the laser (1-1) and the photodetector (1-5).

Images