Method for evaluating transformer winding deformation state based on monitoring axial magnetic flux leakage distribution

Abstract

The method for evaluating the deformation state of a transformer winding based on monitoring the axial magnetic flux leakage distribution comprises the following steps: establishing a three-dimensional simulation model of an actual transformer; obtaining a deformation position of the actual transformer, i.e., a position of the actual transformer winding where radial deformation is most likely to occur; simulating different degrees of winding radial deformation at the corresponding deformation position on the three-dimensional simulation model and performing simulation calculation to obtain simulated axial magnetic flux leakage distribution data of the three-dimensional simulation model when different degrees of winding radial deformation occur at the corresponding deformation position; setting a plurality of magnetic sensors along the axial direction of the winding at the deformation position of the actual transformer, and obtaining actual axial magnetic flux leakage distribution data at the deformation position of the actual transformer in the running state; and comparing the simulated axial magnetic flux leakage distribution data with the actual axial magnetic flux leakage distribution data to evaluate the deformation state of the winding of the actual transformer. The design can accurately evaluate the overall deformation state of the actual transformer by monitoring the axial magnetic flux leakage distribution at the deformation position of the actual transformer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer protection, in particular to a method for evaluating the deformation state of a transformer winding based on monitoring the axial leakage magnetic field distribution, and is particularly suitable for real-time monitoring and evaluation of the deformation state of a transformer winding. BACKGROUND

[0002] As a pivotal device in the power system, once a catastrophic failure occurs in a transformer, a major power accident is likely to occur, causing huge social and economic losses. Therefore, an online evaluation method for the state of a transformer will effectively prevent accidents and ensure the long-term safe operation of the power system.

[0003] Transformer winding deformation failure is one of the common failure types of transformers. The types of transformer winding deformation can be roughly divided into two types: axial deformation and radial deformation. In the case of axial deformation of the transformer winding, the winding will be compressed in the axial direction, and in severe cases, it will lead to the collapse of the winding. Due to the improvement of the manufacturing process of the transformer winding, the use of clamps at both ends of the transformer winding has greatly reduced the occurrence of transformer collapse. In addition, a large number of scholars have studied the influence of axial pre-tightening force on the axial stability of the transformer winding. By applying appropriate pre-tightening force, the axial stability of the winding is strengthened, and the axial deformation of the transformer is effectively protected. However, the radial deformation of the transformer winding is mainly the warping of the outer winding, and in severe cases, it will lead to broken strands. In the prior art, the axial deformation of the transformer winding has been effectively protected, and once the transformer has axial deformation, it must be accompanied by severe radial deformation, but the reverse is not necessarily true. Therefore, as long as the radial deformation state of the transformer is monitored, the overall deformation state of the winding can be evaluated.

[0004] In the conventional detection and evaluation of the deformation state of the transformer winding, the periodic inspection method is generally used, and offline detection is performed by using detection methods such as the frequency response method, the short-circuit impedance method, and the low-voltage pulse method. Then, the technical personnel evaluate the state according to the detection results. However, this traditional evaluation method requires offline detection, and cannot perform real-time monitoring and evaluation of the deformation state of the transformer winding. Therefore, how to achieve real-time monitoring and evaluation of the deformation state of the transformer winding is a technical problem that needs to be solved by technical personnel in the field. SUMMARY

[0005] The purpose of the present application is to overcome the problem that the deformation state of the transformer winding cannot be monitored and evaluated in real time without being offline in the prior art. A method for evaluating the deformation state of a transformer winding based on monitoring the axial leakage magnetic field distribution is provided.

[0006] To achieve the above purpose, the technical solution of the present application is as follows:

[0007] The method for evaluating the deformation state of a transformer winding based on monitoring the axial magnetic flux leakage distribution comprises the following steps:

[0008] S1. A three-dimensional simulation model of an actual transformer is established in finite element software according to the size and material parameters of the actual transformer;

[0009] S2. A deformation position of the actual transformer is obtained, which is the position of the winding of the actual transformer most prone to radial deformation under a short-circuit large current impact;

[0010] S3. Different degrees of radial deformation of the winding are simulated at the deformation position on the three-dimensional simulation model, and electromagnetic field simulation calculation is performed on the winding of the three-dimensional simulation model under the load of the normal operating current of the transformer, so as to obtain simulated axial magnetic flux leakage distribution data of the three-dimensional simulation model under different degrees of radial deformation of the winding at the corresponding deformation position;

[0011] S4. A plurality of magnetic sensors are arranged along the axial direction of the winding of the actual transformer at the deformation position of the actual transformer, and the actual transformer in a normal operating state is monitored by the magnetic sensors to obtain actual axial magnetic flux leakage distribution data of the actual transformer;

[0012] S5. The simulated axial magnetic flux leakage distribution data is compared with the actual axial magnetic flux leakage distribution data to evaluate the deformation state of the winding of the actual transformer.

[0013] The magnetic sensors are arranged close to the winding of the actual transformer, the number of the magnetic sensors is 8-10, and the magnetic sensors are arranged equidistantly along the axial direction of the winding of the actual transformer.

[0014] In the step S2, the deformation position of the actual transformer specifically comprises:

[0015] The three-dimensional simulation model is excited by a transformer in a field-circuit coupling manner in the simulation software to simulate the short-circuit operating condition of the transformer, and a "magnetic-solid" coupled field simulation calculation is performed on the three-dimensional simulation model, so that the deformation information of the winding in the three-dimensional simulation model is obtained through the "magnetic-solid" coupled field simulation calculation, and the position of the winding of the actual transformer most prone to radial deformation under a short-circuit large current impact is determined through the deformation information.

[0016] In the step S2, the three-dimensional simulation model is excited by a transformer in a field-circuit coupling manner in the simulation software specifically comprises:

[0017] The external short-circuit circuit of the transformer is simulated in the finite element software, the winding in the three-dimensional simulation model is connected with the external short-circuit circuit, a field-circuit coupling model is established according to the three-dimensional simulation model and the external short-circuit circuit, and the three-dimensional simulation model is excited by the transformer through the external short-circuit circuit.

[0018] The step S2, the transformer excitation is applied to the three-dimensional simulation model by the external short circuit circuit, specifically includes: the transformer excitation is applied to the transformer three-dimensional simulation model by the external short circuit circuit multiple times, and the time for applying the transformer excitation to the transformer three-dimensional simulation model each time is 0.2 seconds.

[0019] The step S3, the degree of the winding radial deformation is defined as follows:

[0020]

[0021] In the above formula, φ is the degree of winding radial deformation, φ≥0, ΔR2 is the maximum deformation displacement of the outer winding, and R2 is the radius of the outer winding.

[0022] The step S3 specifically includes:

[0023] S301, a threshold degree of winding radial deformation is set, and the threshold degree includes a first threshold degree φ1, a second threshold degree φ2, a third threshold degree φ3 and a fourth threshold degree φ4, wherein the φ1=0, and φ1<φ2<φ3<φ4;

[0024] S302, the degree of winding radial deformation at the corresponding deformation position on the three-dimensional simulation model is changed, so that the degree of winding radial deformation at the corresponding deformation position on the three-dimensional simulation model is φ1, φ2, φ3 and φ4, a normal working current of the transformer is loaded on the winding of the three-dimensional simulation model, electromagnetic field simulation calculation is performed on the three-dimensional simulation model, simulation axial magnetic flux leakage distribution data when the winding radial deformation at the corresponding deformation position on the three-dimensional simulation model occurs to the degree of φ1 is obtained, simulation axial magnetic flux leakage distribution data when the winding radial deformation at the corresponding deformation position on the three-dimensional simulation model occurs to the degree of φ2 is obtained, simulation axial magnetic flux leakage distribution data when the winding radial deformation at the corresponding deformation position on the three-dimensional simulation model occurs to the degree of φ3 is obtained, and simulation axial magnetic flux leakage distribution data when the winding radial deformation at the corresponding deformation position on the three-dimensional simulation model occurs to the degree of φ4 is obtained.

[0025] The step S5, the simulation axial magnetic flux leakage distribution data is compared with the actual axial magnetic flux leakage distribution data, and the winding deformation state of the actual transformer is evaluated, specifically including:

[0026] comparing the actual axial magnetic flux leakage distribution data with the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ1, the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ2, the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ3, and the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ4 at the corresponding deformation position of the three-dimensional simulation model, and obtaining the size relationship of the degree φ0 of the winding radial deformation at the deformation position of the actual transformer and the degrees of φ1, φ2, φ3 and φ4 according to the comparison result;

[0027] If φ0 = φ1, the winding deformation state of the actual transformer is no deformation.

[0028] If φ1 < φ0 ≤ φ2, the winding deformation state of the actual transformer is slight deformation.

[0029] If φ2 < φ0 ≤ φ3, the winding deformation state of the actual transformer is moderate deformation.

[0030] If φ3 < φ0 < φ4, the winding deformation state of the actual transformer is serious deformation.

[0031] comparing the actual axial magnetic flux leakage distribution data with the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ1, the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ2, the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ3, and the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ4 at the corresponding deformation position of the three-dimensional simulation model, and obtaining the size relationship of the degree φ0 of the winding radial deformation at the deformation position of the actual transformer and the degrees of φ1, φ2, φ3 and φ4 according to the comparison result specifically comprises:

[0032] S501, generating an actual axial magnetic flux leakage distribution curve according to the actual axial magnetic flux leakage distribution data;

[0033] S502, generating a first axial magnetic flux leakage distribution curve according to the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ1 at the corresponding deformation position of the three-dimensional simulation model;

[0034] generating a second axial magnetic flux leakage distribution curve according to the simulated axial magnetic flux leakage distribution data of the winding radial deformation of the degree of φ2 at the corresponding deformation position of the three-dimensional simulation model;

[0035] According to the simulated axial magnetic leakage distribution data of the winding radial deformation with a degree of φ3 at the corresponding deformation position on the three-dimensional simulation model, a third axial magnetic leakage distribution curve is generated;

[0036] According to the simulated axial magnetic leakage distribution data of the winding radial deformation with a degree of φ4 at the corresponding deformation position on the three-dimensional simulation model, a fourth axial magnetic leakage distribution curve is generated;

[0037] S503, compare the position relationship of the actual axial magnetic leakage distribution curve and the first axial magnetic leakage distribution curve, the second axial magnetic leakage distribution curve, the third axial magnetic leakage distribution curve and the fourth axial magnetic leakage distribution curve:

[0038] If the actual axial magnetic leakage distribution curve and the first axial magnetic leakage distribution curve are substantially coincident, then φ0=φ1;

[0039] If the actual axial magnetic leakage distribution curve is located between the first axial magnetic leakage distribution curve and the second axial magnetic leakage distribution curve or the actual axial magnetic leakage distribution curve and the second axial magnetic leakage distribution curve are substantially coincident, then φ1<φ0≤φ2;

[0040] If the actual axial magnetic leakage distribution curve is located between the second axial magnetic leakage distribution curve and the third axial magnetic leakage distribution curve or the actual axial magnetic leakage distribution curve and the third axial magnetic leakage distribution curve are substantially coincident, then φ2<φ0≤φ3;

[0041] If the actual axial magnetic leakage distribution curve is located between the third axial magnetic leakage distribution curve and the fourth axial magnetic leakage distribution curve, then φ3<φ0<φ4;

[0042] The φ2 is 3%, the φ3 is 5%, and the φ4 is 10%.

[0043] In the step S5, after evaluating the winding deformation state of the actual transformer, a maintenance decision is made according to the winding deformation state of the actual transformer:

[0044] If the winding deformation state of the actual transformer is moderate deformation, a risk warning is issued for the winding deformation state of the actual transformer;

[0045] If the winding deformation state of the actual transformer is severe deformation, the actual transformer is subjected to shutdown processing.

[0046] Compared with the prior art, the beneficial effects of the present application are:

[0047] 1、The method for evaluating the deformation state of the transformer winding based on monitoring the axial magnetic flux leakage distribution in the application ignores the deformation of other areas of the simulated transformer winding, simulates different degrees of winding radial deformation at the corresponding deformation position on the simulated transformer, obtains simulated axial magnetic flux leakage distribution data when the three-dimensional simulation model at the corresponding deformation position occurs different degrees of winding radial deformation, sets magnetic sensors according to the deformation position of the actual transformer, and obtains actual axial magnetic flux leakage distribution data of the actual transformer in the running state through the magnetic sensors. The winding radial deformation degree at the deformation position of the actual transformer can be monitored by comparing the simulated axial magnetic flux leakage distribution data with the actual axial magnetic flux leakage distribution data, and the overall deformation state of the winding can be evaluated. Moreover, the axial distribution data of the magnetic flux leakage field of the actual transformer is collected in real time through the magnetic sensors in the running state of the transformer, so that the transformer can be monitored online, and the purpose of real-time evaluation of the winding state of the transformer is achieved. Therefore, the axial distribution data of the magnetic flux leakage field of the actual transformer is collected in real time through the magnetic sensors in the design, and the winding deformation state of the transformer in the running state can be monitored online and evaluated in real time.

[0048] 2、The method for evaluating the deformation state of the transformer winding based on monitoring the axial magnetic flux leakage distribution in the application applies transformer excitation to the three-dimensional simulation model of the transformer in a field-circuit coupling manner in the simulation software. The field-circuit coupling manner of applying transformer excitation can more truly simulate the current change process of the transformer under short-circuit working conditions, restore the complex short-circuit running conditions of the transformer, and perform "magnetic-solid" coupled field simulation calculation on the three-dimensional simulation model of the transformer. According to the real stress-strain curve of the winding material, the plastic deformation process of the transformer winding under the action of the radial electric force can be calculated and simulated. Moreover, since there are circuit protection devices in the actual transformer circuit, the circuit protection devices will cut off the circuit in time when the transformer occurs short-circuit large current impact. Therefore, the transformer excitation is applied to the three-dimensional simulation model of the transformer for multiple times, and the time of applying the transformer excitation each time is set to 0.2 seconds. The plastic deformation process of the transformer winding under repeated and multiple short-circuit large current impacts can be truly restored, and the deformation position of the actual transformer can be accurately positioned. Therefore, the three-dimensional simulation model of the transformer is repeatedly and multiple times excited in a short time in the field-circuit coupling manner in the design, the complex short-circuit running conditions of the transformer and the plastic deformation process of the transformer winding can be truly restored, and the deformation position of the actual transformer can be accurately positioned.

[0049] 3、The method for evaluating the winding deformation state of a transformer based on monitoring the axial magnetic flux leakage distribution, when collecting the actual axial magnetic flux leakage distribution data, first obtains the position of the winding of the actual transformer that is most prone to radial deformation under a short-circuit large current impact, i.e., the deformation position, then sets a monitoring point at the deformation position and arranges a magnetic sensor, since the deformation position is the position of the winding of the entire transformer that is most prone to radial deformation, the axial magnetic flux leakage at this position is more obviously affected by the radial deformation of the winding, arranging a magnetic sensor at this position and detecting the axial magnetic flux leakage is more sensitive and more accurate, and only arranging a magnetic sensor along the axial direction of the winding at the deformation position, the radial deformation of the winding of the transformer can be accurately monitored through fewer sensors and less data collection, and then the winding deformation state of the actual transformer can be evaluated. Therefore, in the design, the monitoring point is set according to the deformation position of the actual transformer, which is more sensitive and more accurate, and in the method, only a few sensors need to be arranged and less data need to be collected to accurately monitor the radial deformation of the winding of the transformer, and then the winding deformation state of the entire transformer can be evaluated. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is a flowchart of the method for evaluating the winding deformation state of a transformer.

[0051] Figure 2 is a schematic diagram of a transformer short-circuit current simulated by simulation.

[0052] Figure 3 is a schematic diagram of an excitation circuit.

[0053] Figure 4 is a schematic diagram of a three-dimensional simulation model of a transformer.

[0054] Figure 5 is a schematic diagram of the radial deformation of the winding of a three-dimensional simulation model of a transformer.

[0055] Figure 6 is a schematic diagram of the arrangement position of a magnetic sensor.

[0056] Figure 7 is a schematic diagram of evaluating the winding deformation state according to the monitoring data.

[0057] Figure 8 is a schematic diagram of a device for collecting actual axial magnetic flux leakage distribution data.

[0058] In the figure: actual transformer 1, three-dimensional simulation model 2, magnetic sensor 3. DETAILED DESCRIPTION

[0059] The application will be further described in detail in combination with the description of the drawings and the specific embodiments.

[0060] Referring toFigures 1 to 8 The method for evaluating the deformation state of a transformer winding based on monitoring the axial magnetic flux leakage distribution, the evaluation method comprising:

[0061] S1. According to the size and material parameters of the actual transformer 1, a three-dimensional simulation model 2 of the actual transformer 1 is established in COMSOL finite element software.

[0062] The three-dimensional simulation model 2 is as shown in Figure 4 The actual transformer 1 is a dry-type three-phase transformer. In the COMSOL finite element simulation software, the transformer model is built according to the structure and size parameters of the actual transformer 1, and the transformer model is set according to the material parameters of each part of the actual transformer 1, thereby obtaining the transformer three-dimensional simulation model 2. Among the material parameters of each part of the actual transformer 1, the stress-strain curve of the actual transformer winding material is included.

[0063] S2. Obtain the deformation position of the actual transformer 1, which is the position of the winding of the actual transformer 1 most prone to radial deformation under short-circuit high-current impact.

[0064] The deformation position of the actual transformer 1 can also be obtained in actual operation according to the operation and fault conditions of the transformer, or through the three-dimensional simulation model 2. The deformation position of the actual transformer 1 obtained through the three-dimensional simulation model 2 specifically includes:

[0065] The three-dimensional simulation model 2 is excited in the field-circuit coupling manner in the simulation software to simulate the short-circuit operation condition of the transformer, and the “magnetic-solid” coupling field simulation calculation is performed on the three-dimensional simulation model 2. The deformation information of the winding in the three-dimensional simulation model 2 under the short-circuit high-current impact is obtained through the “magnetic-solid” coupling field simulation calculation, and the position of the winding of the actual transformer 1 most prone to radial deformation under the short-circuit high-current impact is determined through the deformation information.

[0066] When the three-dimensional simulation model 2 is excited, the winding coil in the three-dimensional simulation model can be directly loaded with current for excitation, or the three-dimensional simulation model 2 can be excited in the field-circuit coupling manner. When the winding coil in the three-dimensional simulation model is directly excited by the current, the size of the current loaded on the winding coil in the transformer three-dimensional simulation model can be a specific numerical value or a function value that changes with time.

[0067] In actual transformer 1 normal operation, its current is stable sinusoidal alternating current, and when the transformer circuit occurs short circuit, the current in the winding coil is no longer stable, at this time the short circuit current in the winding coil will first appear peak, then gradually flat and stable and show steady state. Direct to the winding coil in the three-dimensional simulation model to apply current is difficult to restore the actual transformer short circuit current change process, therefore, in order to truly simulate the transformer short circuit when the complex operation condition, in the simulation software with field-circuit coupling way to transformer three-dimensional simulation model 2 to apply excitation, through simulation of transformer short circuit current as shown in Figure 2 .

[0068] In the simulation software with field-circuit coupling way to three-dimensional simulation model 2 to apply transformer excitation specifically includes:

[0069] In COMSOL finite element software in the form of nodes to simulate external short circuit, the external short circuit, that is, the external equivalent circuit of the transformer under external short circuit condition, the external short circuit circuit contains the external excitation under the transformer short circuit operation condition, the winding in the three-dimensional simulation model 2 is connected with the external short circuit circuit as circuit element, using COMSOL limit element software in the electric field interface and magnetic field interface, according to three-dimensional simulation model 2 and external short circuit circuit to establish field-circuit coupling model, and in COMSOL finite element software to set the excitation of transformer winding coil as external UvsI or IvsU, that is, the three-dimensional simulation model 2 can be excited by external short circuit circuit. As shown in Figure 3 The winding in the three-dimensional simulation model 2 is connected with the external short circuit circuit, and the secondary side of the winding in the three-dimensional simulation model 2 is short-circuited to simulate the transformer short circuit operation condition.

[0070] Because the actual transformer is subjected to short circuit current impact, the circuit protection device will cut off the circuit to protect the line and equipment. In order to truly simulate the actual transformer 1 in the process of short circuit current impact winding gradually occurs amplitude deformation, in the simulation software with field-circuit coupling way to transformer three-dimensional simulation model 2 to apply excitation, multiple times to transformer three-dimensional simulation model 2 to apply transformer excitation, each time to transformer three-dimensional simulation model 2 to apply transformer excitation time is 0.2 seconds.

[0071] Since the radial electromagnetic force suffered by the transformer winding is closely related to the axial leakage magnetic density, in the process of the three-dimensional simulation model 2 suffering from short-circuit impact, the "magnetic-solid" coupling field simulation calculation is performed by using the COMSOL finite element software, so as to obtain the electromagnetic force suffered by each part of the winding of the three-dimensional simulation model 2. According to the electromagnetic force suffered by each part of the winding of the three-dimensional simulation model 2 and the stress-strain curve of the winding material, the deformation information of the winding of the three-dimensional simulation model 2 is obtained. Through the deformation information, the position of the winding of the three-dimensional simulation model 2 with the largest radial deformation degree under the short-circuit large current impact is obtained. The position corresponding to the position of the winding of the three-dimensional simulation model 2 with the largest radial deformation degree under the short-circuit large current impact on the actual transformer 1 is the position of the winding of the actual transformer 1 most prone to radial deformation under the short-circuit large current impact, that is, the deformation position of the actual transformer 1. As shown in Figure 5 , the deformation position of the actual transformer 1 is a region on the winding thereof.

[0072] Each time the "magnetic-solid" coupling field simulation calculation is performed on the three-dimensional simulation model 2 under the short-circuit operation condition, the COMSOL finite element software first calculates the electromagnetic force suffered by the winding in the magnetic field, and then the obtained electromagnetic force is used as the load applied to the winding structure module for subsequent calculation, so as to obtain the winding deformation information of the three-dimensional simulation model 2. Since the excitation time of the three-dimensional simulation model 2 is 0.2 seconds each time, in the calculation process, the calculation function equation of the load applied to the winding structure module is as follows:

[0073] F V =f*in1(t)

[0074]

[0075] In the above formula, F V is the load applied to the winding structure module, f is the electromagnetic force, and in1(t) is a time function.

[0076] Since the actual transformer 1 is a dry-type three-phase transformer, through simulation calculation, it is known that the middle phase is more prone to deformation relative to the left and right two phases, and the deformation position is located in the middle phase winding, as shown in Figure 5 , the region of the middle phase winding located in the core window is the deformation position of the dry-type three-phase transformer.

[0077] S3, simulate different degrees of winding radial deformation at the corresponding deformation position on the three-dimensional simulation model 2, and load the normal working current of the transformer on the winding of the three-dimensional simulation model 2 and perform electromagnetic field simulation calculation, so as to obtain the simulated axial leakage magnetic distribution data of the three-dimensional simulation model 2 when the winding radial deformation at the corresponding deformation position occurs in different degrees.

[0078] When simulating different degrees of radial deformation of the winding at the corresponding deformation positions on the 3D simulation model 2, the deformation at other positions of the winding in the 3D simulation model 2 is ignored, that is, no deformation is set at other positions of the winding in the 3D simulation model 2.

[0079] In step S3, the degree of radial deformation of the winding is defined as follows:

[0080]

[0081] In the above formula, φ is the degree of radial deformation of the winding, φ≥0, ΔR2 is the maximum deformation displacement of the outer winding, and R2 is the radius of the outer winding.

[0082] When φ = 0%, there is no radial deformation at the corresponding deformation position on the three-dimensional simulation model 2. The radial deformation of the winding with a degree of 0% is simulated at the corresponding deformation position on the three-dimensional simulation model 2 and simulation calculation is performed to obtain the simulated axial leakage magnetic field distribution data of the three-dimensional simulation model 2 when the winding has no deformation.

[0083] After obtaining the simulated axial leakage magnetic field distribution data of the three-dimensional simulation model 2 when different degrees of radial deformation of the winding occur at the corresponding deformation positions, a simulated axial leakage magnetic field distribution database can be established based on the obtained data, which is convenient for extracting the simulated axial leakage magnetic field distribution data when evaluating the winding deformation state of the actual transformer 1.

[0084] S4. Multiple magnetic sensors 3 are arranged at intervals along the axial direction of the winding of the actual transformer 1 at the deformation position of the actual transformer 1. The actual transformer 1 under normal operation is monitored by the magnetic sensors 3 to obtain the actual axial leakage magnetic distribution data of the actual transformer 1.

[0085] The magnetic sensor 3 is positioned close to the winding of the actual transformer 1. There are 8-10 magnetic sensors 3, which are equally spaced along the axial direction of the winding of the actual transformer 1.

[0086] like Figure 6 As shown, multiple magnetic sensors 3 are spaced apart along the axial direction of the windings of the actual transformer 1 to monitor the actual transformer 1 under normal operating conditions. When arranging the magnetic sensors 3, the number and spacing of the magnetic sensors 3 can be set according to the height of the actual transformer windings to accurately measure the axial leakage magnetic field distribution data of the transformer windings.

[0087] The magnetic sensor 3 is arranged close to the winding of the actual transformer 1, and the number of the magnetic sensor 3 is 8-10, and the 8-10 magnetic sensors 3 are arranged equidistantly along the axial direction of the winding of the actual transformer 1. When arranging the magnetic sensor 3, one magnetic sensor 3 is arranged at the middle position of the winding and close to the two ends of the winding, and all the magnetic sensors 3 are arranged symmetrically along the axial direction of the winding. In this way, the actual axial leakage magnetic field distribution data at the deformation position of the actual transformer 1 can be accurately monitored.

[0088] As shown in Figure 6 the deformation position of the dry-type three-phase transformer is the area where the middle-phase winding is located in the middle of the core window. In order to arrange the magnetic sensor 3 at the deformation position of the dry-type three-phase transformer, the magnetic sensor 3 is arranged in the core window of the transformer core, and the number of the magnetic sensor 3 is 9. The 9 magnetic sensors 3 are arranged equidistantly along the axial direction of the middle-phase winding.

[0089] The magnetic sensor 3 is a Hall magnetic sensor. As shown in Figure 8 When collecting the actual axial leakage magnetic field distribution data, the axial leakage magnetic field data collected by each magnetic sensor 3 is recorded by the data acquisition card, and all the recorded axial leakage magnetic field data is uploaded to the upper computer in real time through the wireless transmission module. After the upper computer processes the axial leakage magnetic field data collected by all the magnetic sensors 3, the axial leakage magnetic field distribution data, i.e. the actual axial leakage magnetic field distribution data, is obtained.

[0090] When evaluating the winding deformation state of the actual transformer 1, the winding deformation state of the actual transformer 1 is divided into no deformation, slight deformation, moderate deformation and severe deformation. When the winding deformation state of the actual transformer 1 is no deformation, the degree of the winding radial deformation at the deformation position of the actual transformer 1 is 0%. When the winding deformation state of the actual transformer 1 is slight deformation, the degree of the winding radial deformation at the deformation position of the actual transformer 1 is greater than 0% but not more than 3%. When the winding deformation state of the actual transformer 1 is moderate deformation, the degree of the winding radial deformation at the deformation position of the actual transformer 1 is greater than 3% but not more than 5%. When the winding deformation state of the actual transformer 1 is severe deformation, the degree of the winding radial deformation at the deformation position of the actual transformer 1 is greater than 5%.

[0091] Therefore, in step S3, the threshold degree of the winding radial deformation is set, which includes a first threshold degree φ1, a second threshold degree φ2, a third threshold degree φ3 and a fourth threshold degree φ4, the φ1=0, the φ2=3%, the φ3=5% and the φ4=10%.

[0092] The degree of radial deformation of the winding at the corresponding deformation position on the 3D simulation model 2 is changed to 0%, 3%, 5%, and 10%. At the same time, the normal operating current of the transformer is applied to the winding of the 3D simulation model 2, and electromagnetic field simulation calculations are performed on the 3D simulation model 2. The simulated axial leakage magnetic flux distribution data when the degree of radial deformation of the winding at the corresponding deformation position on the 3D simulation model 2 is 0%, 3%, 5%, and 10% is obtained.

[0093] In step S5, comparing the simulated axial leakage flux distribution data with the actual axial leakage flux distribution data to evaluate the winding deformation state of the actual transformer 1 specifically includes:

[0094] S501. Generate the actual axial flux leakage distribution curve based on the actual axial flux leakage distribution data;

[0095] S502. Based on the simulated axial leakage magnetic field distribution data of the winding radial deformation with a degree of 0 at the corresponding deformation position on the three-dimensional simulation model 2, generate the first axial leakage magnetic field distribution curve.

[0096] Based on the simulated axial leakage magnetic field distribution data of the winding radial deformation with a degree of 3% at the corresponding deformation position on the three-dimensional simulation model 2, a second axial leakage magnetic field distribution curve is generated.

[0097] Based on the simulated axial leakage magnetic field distribution data of the winding radial deformation of 5% at the corresponding deformation position on the three-dimensional simulation model 2, a third axial leakage magnetic field distribution curve is generated.

[0098] Based on the simulated axial leakage magnetic field distribution data of the winding radial deformation of 10% at the corresponding deformation position on the three-dimensional simulation model 2, a fourth axial leakage magnetic field distribution curve is generated.

[0099] S505, such as Figure 7 As shown, the actual axial leakage magnetic flux distribution curve is compared with the first axial leakage magnetic flux distribution curve, the second axial leakage magnetic flux distribution curve, and the third axial leakage magnetic flux distribution curve. If the actual axial leakage magnetic flux distribution curve basically coincides with the first axial leakage magnetic flux distribution curve, then φ0=0. At this time, the winding deformation state of the actual transformer 1 is evaluated as no deformation.

[0100] If the actual axial magnetic flux leakage distribution curve is located between the first axial magnetic flux leakage distribution curve and the second axial magnetic flux leakage distribution curve or the actual axial magnetic flux leakage distribution curve is substantially coincident with the second axial magnetic flux leakage distribution curve, 0 < φ0 ≤ 3%, at this time, the winding deformation state of the actual transformer 1 is slight deformation;

[0101] If the actual axial magnetic flux leakage distribution curve is located between the second axial magnetic flux leakage distribution curve and the third axial magnetic flux leakage distribution curve or the actual axial magnetic flux leakage distribution curve is substantially coincident with the third axial magnetic flux leakage distribution curve, 3% < φ0 ≤ 5%, at this time, the winding deformation state of the actual transformer 1 is moderate deformation;

[0102] If the actual axial magnetic flux leakage distribution curve is located between the third axial magnetic flux leakage distribution curve and the fourth axial magnetic flux leakage distribution curve, 5% < φ0 < 10%, at this time, the winding deformation state of the actual transformer 1 is severe deformation.

[0103] As shown in Figure 7 The actual axial magnetic flux leakage distribution curve and the first axial magnetic flux leakage distribution curve, the second axial magnetic flux leakage distribution curve and the third axial magnetic flux leakage distribution curve are all axial magnetic flux leakage distribution curves along the axial direction of the winding. Generally, the amplitude deformation degree of the winding at the deformation position of the actual transformer 1 does not exceed 10%, therefore, the winding deformation state of the actual transformer 1 can be accurately evaluated by comparing the axial magnetic flux leakage distribution curves.

[0104] In the step S5, after evaluating the winding deformation state of the actual transformer 1, a maintenance decision is made according to the winding deformation state of the actual transformer 1:

[0105] If the winding deformation state of the actual transformer 1 is no deformation or slight deformation, the actual transformer 1 in the normal operation state is continuously monitored by the magnetic sensor 3;

[0106] If the winding deformation state of the actual transformer 1 is moderate deformation, a risk warning is issued for the winding deformation state of the actual transformer 1;

[0107] If the winding deformation state of the actual transformer 1 is severe deformation, the actual transformer 1 is stopped.

[0108] As shown in Figure 7 In the monitoring of the axial magnetic flux leakage distribution of the dry-type three-phase transformer, if the position of the actual axial magnetic flux leakage distribution curve is between the second axial magnetic flux leakage distribution curve and the third axial magnetic flux leakage distribution curve, at this time, the winding deformation state of the actual transformer 1 is evaluated as moderate deformation, and a risk warning is issued for the winding deformation state of the actual transformer 1.

[0109] The principle of the present application is explained as follows:

[0110] The radial direction is the radial direction of the winding, the radial deformation of the transformer winding is the deformation of the transformer winding in the radial direction.

[0111] The axial leakage magnetic field is a component of the leakage magnetic field in the axial direction of the transformer winding; the axial leakage magnetic field distribution data is distribution data of the axial leakage magnetic field; the simulated axial leakage magnetic field distribution data is simulated axial leakage magnetic field distribution data obtained by simulation calculation; the actual axial leakage magnetic field distribution data is actual axial leakage magnetic field distribution data measured by a sensor.

[0112] Embodiment 1:

[0113] The method for evaluating the deformation state of the transformer winding based on monitoring the axial leakage magnetic field distribution comprises:

[0114] S1. According to the size and material parameters of the actual transformer 1, a three-dimensional simulation model 2 of the actual transformer 1 is established in a finite element software;

[0115] S2. The deformation position of the actual transformer 1 is obtained, which is the position of the winding of the actual transformer 1 most prone to radial deformation under short-circuit high-current impact;

[0116] S3. Different degrees of winding radial deformation are simulated at the corresponding deformation position on the three-dimensional simulation model 2, and electromagnetic field simulation calculation is performed on the winding of the three-dimensional simulation model 2 by loading the normal operating current of the transformer, to obtain simulated axial leakage magnetic field distribution data of the three-dimensional simulation model 2 when different degrees of winding radial deformation occur at the corresponding deformation position;

[0117] S4. A plurality of magnetic sensors 3 are arranged at intervals along the axial direction of the winding of the actual transformer 1 at the deformation position of the actual transformer 1, and the actual transformer 1 in a normal operating state is monitored by the magnetic sensors 3 to obtain actual axial leakage magnetic field distribution data of the actual transformer 1;

[0118] The magnetic sensors 3 are arranged close to the winding of the actual transformer 1, the number of the magnetic sensors 3 is 8-10, and the magnetic sensors 3 are arranged at equal intervals along the axial direction of the winding of the actual transformer 1.

[0119] S5. The simulated axial leakage magnetic field distribution data is compared with the actual axial leakage magnetic field distribution data to evaluate the deformation state of the winding of the actual transformer 1.

[0120] Embodiment 2:

[0121] Embodiment 2 is basically the same as Embodiment 1, and the difference is that:

[0122] In the step S2, the deformation position of the actual transformer 1 specifically comprises:

[0123] The three-dimensional simulation model 2 is subjected to transformer excitation in a field-circuit coupling manner in simulation software to simulate a short-circuit operation condition of the transformer, and a magnetic-solid coupling field simulation calculation is performed on the three-dimensional simulation model 2 to obtain deformation information of the winding in the three-dimensional simulation model 2, and the deformation information is used to determine a position of the winding in the actual transformer 1 which is most prone to radial deformation under a short-circuit large current impact.

[0124] In the step S2, the transformer excitation is applied to the three-dimensional simulation model 2 in a field-circuit coupling manner in simulation software, and specifically includes the following steps.

[0125] In the step S2, the transformer excitation is applied to the three-dimensional simulation model 2 in a field-circuit coupling manner in simulation software, and specifically includes the following steps.

[0126] In the step S2, the transformer excitation is applied to the three-dimensional simulation model 2 in a field-circuit coupling manner in simulation software, and specifically includes the following steps.

[0127] Embodiment 3:

[0128] Embodiment 3 is basically the same as Embodiment 2, and the difference is that:

[0129] In the step S3, the degree of the winding radial deformation is defined as follows.

[0130]

[0131] In the above formula, φ is the degree of the winding radial deformation, φ≥0, ΔR2 is the maximum deformation displacement of the outer winding, and R2 is the radius of the outer winding.

[0132] The step S3 specifically includes the following steps.

[0133] S301, a threshold degree of winding radial deformation is set, and the threshold degree includes a first threshold degree φ1, a second threshold degree φ2, a third threshold degree φ3 and a fourth threshold degree φ4, and the φ1=0, and φ1<φ2<φ3<φ4.

[0134] S302, change the degree of the winding radial deformation at the corresponding deformation position on the three-dimensional simulation model 2, so that the degree of the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 is φ1, φ2, φ3 and φ4, load the normal working current of the transformer on the winding of the three-dimensional simulation model 2, perform electromagnetic field simulation calculation on the three-dimensional simulation model 2, obtain the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ1, obtain the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ2, obtain the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ3, and obtain the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ4.

[0135] The step S5 of comparing the simulated axial magnetic flux leakage distribution data with the actual axial magnetic flux leakage distribution data to evaluate the winding deformation state of the actual transformer 1 specifically includes:

[0136] The actual axial magnetic flux leakage distribution data is compared with the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ1, the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ2, the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ3, and the simulated axial magnetic flux leakage distribution data when the winding hoop deformation at the corresponding deformation position on the three-dimensional simulation model 2 occurs to the degree of φ4, and the size relationship between the degree φ0 of the winding hoop deformation at the deformation position of the actual transformer 1 and φ1, φ2, φ3 and φ4 is obtained according to the comparison result;

[0137] If φ0 = φ1, the winding deformation state of the actual transformer 1 is no deformation;

[0138] If φ1 < φ0 ≤ φ2, the winding deformation state of the actual transformer 1 is slight deformation;

[0139] If φ2 < φ0 ≤ φ3, the winding deformation state of the actual transformer 1 is moderate deformation;

[0140] If φ3 < φ0 < φ4, the winding deformation state of the actual transformer 1 is serious deformation.

[0141] The actual axial magnetic flux leakage distribution data is compared with the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ1, the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ2, the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ3, and the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ4, and the size relationship between the degree φ0 of the winding radial deformation at the deformation position of the actual transformer 1 and the degrees φ1, φ2, φ3, and φ4 is obtained according to the comparison result, specifically including:

[0142] S501, generating an actual axial magnetic flux leakage distribution curve according to the actual axial magnetic flux leakage distribution data;

[0143] S502, generating a first axial magnetic flux leakage distribution curve according to the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ1;

[0144] generating a second axial magnetic flux leakage distribution curve according to the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ2;

[0145] generating a third axial magnetic flux leakage distribution curve according to the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ3;

[0146] generating a fourth axial magnetic flux leakage distribution curve according to the simulated axial magnetic flux leakage distribution data when the winding radial deformation occurs at the corresponding deformation position on the three-dimensional simulation model 2 with a degree of φ4;

[0147] S503, comparing the position relationship of the actual axial magnetic flux leakage distribution curve and the first axial magnetic flux leakage distribution curve, the second axial magnetic flux leakage distribution curve, the third axial magnetic flux leakage distribution curve, and the fourth axial magnetic flux leakage distribution curve:

[0148] if the actual axial magnetic flux leakage distribution curve and the first axial magnetic flux leakage distribution curve are substantially coincident, then φ0=φ1;

[0149] if the actual axial magnetic flux leakage distribution curve is located between the first axial magnetic flux leakage distribution curve and the second axial magnetic flux leakage distribution curve or the actual axial magnetic flux leakage distribution curve and the second axial magnetic flux leakage distribution curve are substantially coincident, then φ1<φ0≤φ2;

[0150] if the actual axial magnetic flux leakage distribution curve is located between the second axial magnetic flux leakage distribution curve and the third axial magnetic flux leakage distribution curve or the actual axial magnetic flux leakage distribution curve and the third axial magnetic flux leakage distribution curve are substantially coincident, then φ2<φ0≤φ3;

[0151] If the actual axial magnetic flux leakage distribution curve is located between the third axial magnetic flux leakage distribution curve and the fourth axial magnetic flux leakage distribution curve, then φ3< φ0< φ4;

[0152] The φ2=3%, the φ3=5%, and the φ4=10%.

[0153] In the step S5, after evaluating the winding deformation state of the actual transformer 1, a maintenance decision is made according to the winding deformation state of the actual transformer 1:

[0154] If the winding deformation state of the actual transformer 1 is moderate deformation, a risk warning is issued for the winding deformation state of the actual transformer 1;

[0155] If the winding deformation state of the actual transformer 1 is severe deformation, the actual transformer 1 is subjected to shutdown processing.

[0156] The above merely describes preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments, but any equivalent modification or change made by those skilled in the art according to the disclosed content of the present application shall fall within the protection scope recorded in the claims.

Claims

1. A method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution, characterized in that: The evaluation method includes: S1. Based on the dimensions and material parameters of the actual transformer (1), a three-dimensional simulation model (2) of the actual transformer (1) is established in the finite element software. S2. Obtain the deformation position of the actual transformer (1), which is the position where the winding of the actual transformer (1) is most likely to undergo radial deformation under the impact of short-circuit high current. S3. Simulate different degrees of radial deformation of the winding at the corresponding deformation position on the three-dimensional simulation model (2), and apply the normal operating current of the transformer to the winding of the three-dimensional simulation model (2) to perform electromagnetic field simulation calculation, and obtain the simulated axial leakage magnetic field distribution data when different degrees of radial deformation of the winding occur at the corresponding deformation position on the three-dimensional simulation model (2). S4. Multiple magnetic sensors (3) are arranged at intervals along the axial direction of the winding of the actual transformer (1) at the deformation position of the actual transformer (1). The actual transformer (1) under normal operation is monitored by the magnetic sensors (3) to obtain the actual axial leakage magnetic distribution data of the actual transformer (1). S5. Compare the simulated axial leakage flux distribution data with the actual axial leakage flux distribution data to evaluate the winding deformation state of the actual transformer (1). In step S2, obtaining the deformation position of the actual transformer (1) specifically includes: In the simulation software, transformer excitation is applied to the three-dimensional simulation model (2) in the field-circuit coupling manner to simulate the short-circuit operation condition of the transformer. At the same time, the three-dimensional simulation model (2) is subjected to "magnetic-solid" coupled field simulation calculation. The deformation information of the winding in the three-dimensional simulation model (2) is obtained through the "magnetic-solid" coupled field simulation calculation. The deformation information is used to determine the position where the actual transformer (1) is most likely to undergo radial deformation under the impact of short-circuit large current.

2. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 1, characterized in that: The magnetic sensor (3) is set close to the winding of the actual transformer (1). There are 8-10 magnetic sensors (3). The magnetic sensors (3) are set at equal intervals along the axial direction of the winding of the actual transformer (1).

3. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 2, characterized in that: In step S2, applying transformer excitation to the three-dimensional simulation model (2) in the simulation software using a field-circuit coupling method specifically includes: The external short-circuit circuit of the transformer is simulated in the finite element software. The winding in the three-dimensional simulation model (2) is connected to the external short-circuit circuit. A field-circuit coupling model is established based on the three-dimensional simulation model (2) and the external short-circuit circuit. Transformer excitation is applied to the three-dimensional simulation model (2) through the external short-circuit circuit.

4. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 3, characterized in that: In step S2, applying transformer excitation to the three-dimensional simulation model (2) through an external short-circuit circuit specifically includes: applying transformer excitation to the three-dimensional simulation model (2) of the transformer multiple times through an external short-circuit circuit, with each application of transformer excitation to the three-dimensional simulation model (2) of the transformer lasting for 0.2 seconds.

5. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 1, characterized in that: In step S3, the degree of radial deformation of the winding is defined as follows: ； In the above formula, The degree of radial deformation of the winding, ≥0, This represents the maximum deformation displacement of the outer winding. The radius of the outer winding.

6. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 5, characterized in that: Step S3 specifically includes: S301. Set a threshold level for the radial deformation of the winding, wherein the threshold level includes: a first threshold level.

1. Second threshold level 2. Third threshold level 3 and fourth threshold levels 4, the aforementioned 1=0, and 1 < 2< 3< 4; S302. Change the degree of radial deformation of the winding at the corresponding deformation position on the three-dimensional simulation model (2), so that the degree of radial deformation of the winding at the corresponding deformation position on the three-dimensional simulation model (2) is...

1.

2. 3 and 4. Simultaneously, the normal operating current of the transformer is applied to the winding of the three-dimensional simulation model (2), and electromagnetic field simulation calculations are performed on the three-dimensional simulation model (2) to obtain the degree of occurrence at the corresponding deformation position on the three-dimensional simulation model (2). Simulated axial leakage flux distribution data during the radial deformation of winding 1, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are obtained. Simulated axial leakage flux distribution data during the radial deformation of winding 2, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are obtained. Simulated axial leakage flux distribution data during the radial deformation of winding 3, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are obtained. Simulated axial leakage flux distribution data during the radial deformation of the winding of 4.

7. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 6, characterized in that: Step S5, comparing the simulated axial leakage flux distribution data with the actual axial leakage flux distribution data to evaluate the winding deformation state of the actual transformer (1), specifically includes: The actual axial leakage magnetic flux distribution data is compared with the degree of deformation at the corresponding deformation location on the three-dimensional simulation model (2). The simulated axial leakage flux distribution data of winding 1 during radial deformation, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are as follows: The simulated axial leakage flux distribution data during the radial deformation of winding 2, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are as follows: The simulated axial leakage flux distribution data of the winding during radial deformation of 3, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are as follows: The simulated axial leakage flux distribution data of winding 4 during radial deformation were compared, and the degree of radial deformation of the winding at the deformation location of the actual transformer (1) was obtained based on the comparison results. 0 and 1.

2.

3.

4. Size relationship; like 0= 1. Then the actual winding deformation state of the transformer (1) is no deformation; like 1 < 0≤ 2. The actual winding deformation state of the transformer (1) is slight deformation; like 2< 0≤ 3. The actual winding deformation state of transformer (1) is moderate deformation; like 3< 0 < 4. The actual winding deformation state of transformer (1) is severe deformation.

8. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 7, characterized in that: The actual axial leakage magnetic flux distribution data is compared with the corresponding deformation location on the three-dimensional simulation model (2) to determine the degree of deformation. The simulated axial leakage flux distribution data of winding 1 during radial deformation, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are as follows: The simulated axial leakage flux distribution data during the radial deformation of winding 2, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are as follows: The simulated axial leakage flux distribution data of the winding during radial deformation of 3, and the degree of occurrence at the corresponding deformation location on the three-dimensional simulation model (2) are as follows: The simulated axial leakage flux distribution data of winding 4 during radial deformation were compared, and the degree of radial deformation of the winding at the deformation location of the actual transformer (1) was obtained based on the comparison results. 0 and 1.

2.

3. The specific size relationships of 4 include: S501. Generate the actual axial flux leakage distribution curve based on the actual axial flux leakage distribution data; S502, Based on the degree of deformation at the corresponding deformation location on the three-dimensional simulation model (2), Simulated axial leakage flux distribution data during the radial deformation of the winding of 1 is used to generate the first axial leakage flux distribution curve; According to the degree of deformation at the corresponding deformation location on the three-dimensional simulation model (2), The simulated axial leakage flux distribution data of the winding during the radial deformation of 2 are used to generate the second axial leakage flux distribution curve; According to the degree of deformation at the corresponding deformation location on the three-dimensional simulation model (2), The simulated axial leakage flux distribution data of the winding under radial deformation of 3 are used to generate the third axial leakage flux distribution curve; According to the degree of deformation at the corresponding deformation location on the three-dimensional simulation model (2), The simulated axial leakage flux distribution data of the winding during the radial deformation of the 4th winding are used to generate the fourth axial leakage flux distribution curve. S503. Compare the positional relationship between the actual axial flux leakage distribution curve and the first, second, third, and fourth axial flux leakage distribution curves: If the actual axial leakage magnetic flux distribution curve basically coincides with the first axial leakage magnetic flux distribution curve, then 0= 1; If the actual axial magnetic flux leakage distribution curve is located between the first and second axial magnetic flux leakage distribution curves, or if the actual axial magnetic flux leakage distribution curve and the second axial magnetic flux leakage distribution curve substantially coincide, then 1 < 0≤ 2; If the actual axial magnetic flux leakage distribution curve is located between the second and third axial magnetic flux leakage distribution curves, or if the actual axial magnetic flux leakage distribution curve and the third axial magnetic flux leakage distribution curve basically coincide, then 2< 0≤ 3; If the actual axial leakage magnetic flux distribution curve lies between the third and fourth axial leakage magnetic flux distribution curves, then 3< 0 < 4; The 2=3%, the stated 3=5%, the stated 4 = 10%.

9. The method for evaluating the deformation state of transformer windings based on monitoring axial leakage flux distribution according to claim 8, characterized in that: In step S5, after assessing the winding deformation state of the actual transformer (1), a maintenance decision is made based on the winding deformation state of the actual transformer (1): If the winding deformation state of the actual transformer (1) is moderate, a risk warning is issued for the winding deformation state of the actual transformer (1). If the winding deformation state of the actual transformer (1) is severe deformation, then the actual transformer (1) shall be shut down.

Images