Transformer cushion block pre-tightening force prediction method, system and equipment based on finite element analysis and medium

Abstract

The invention relates to the technical field of power dispatching, and discloses a transformer cushion block pretightening force prediction method, system and device based on finite element analysis and a medium, and the method comprises the steps: adding corresponding constraints through an axial equivalent spring model of a transformer, and constructing a power transformer simulation model; obtaining current recording data of the transformer substation, and obtaining the distribution of short-circuit impact force borne by each winding cushion block in combination with the electromagnetic field calculation model; and the reduction of the winding height is analyzed through the plastic deformation of the structure field and is converted into the reduction degree of the pre-tightening force, and the pre-tightening force of the low cushion block is pre-warned. The method analyzes and predicts the change of the pre-tightening force of the cushion block in the transformer through mathematical calculation, only needs a substation to provide short-circuit current recording data of the current transformer, does not need additional detection equipment, has the characteristic of long-term stable work, can also realize an early warning function for the overlarge decrease degree of the pre-tightening force of the winding, and improves the reliability of the transformer. And a theoretical basis is provided for maintenance of the transformer.

Description

Technical Field

[0001] This invention relates to the field of power dispatching technology, and in particular to a method, system, equipment and medium for predicting the preload of transformer pads based on finite element analysis. Background Technology

[0002] During transformer assembly, in order to ensure that the spacers between the windings can provide support, a preload is applied to the pressure plate at the top of the winding. The purpose is to ensure that there is sufficient friction between the spacers and the windings, so that the spacers can constrain the deformation of the windings and prevent the spacers from rotating or shifting.

[0003] When a short circuit occurs, the pad, as an insulating component made of fiber paper, is prone to plastic deformation under the impact force of the short circuit, which causes the axial height of the winding to decrease. This results in a decrease in the preload of the pad, which in turn leads to increased winding vibration and operating noise, and also increases the risk of axial instability of the winding.

[0004] Existing preload detection technologies mostly rely on external sensors for online detection. However, these pressure sensors are expensive, and high-precision devices are difficult to adapt to long-term detection work. How to reduce the cost of preload detection while meeting the needs of long-term continuous operation in transformer testing is an urgent technical problem to be solved. Summary of the Invention

[0005] In view of the aforementioned existing problems, this invention is proposed. Therefore, this invention provides a transformer pad preload prediction method based on finite element analysis to solve the problem of high cost in traditional preload detection.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a method for predicting the preload of transformer pads based on finite element analysis, comprising:

[0008] A power transformer simulation model is constructed by adding corresponding constraints to the axial equivalent spring model of the transformer.

[0009] Based on the power transformer simulation model, substation current recording data is obtained, and combined with the electromagnetic field calculation model, the distribution of short-circuit impact force on each winding pad is obtained.

[0010] Based on the distribution of short-circuit impact force, the decrease in winding height is analyzed by plastic deformation of the structural field and converted into the degree of preload decrease, so as to provide early warning of the preload of the low pad block.

[0011] As a preferred embodiment of the transformer pad preload prediction method based on finite element analysis described in this invention, the construction of a power transformer simulation model includes:

[0012] For unpredictable windings, the windings are modeled using a cylindrical model. For windings with predicted pad preload, the windings are modeled using a combination of circular rings with the same number of turns and square uniformly distributed pads.

[0013] Set the bottom of the model as a fixed constraint, set the contact between the winding and the pad as a binding constraint, and set the pressure plate pressure as a pre-compressed spring element through an axial equivalent spring model.

[0014] As a preferred embodiment of the transformer pad preload prediction method based on finite element analysis described in this invention, obtaining substation current recording data includes:

[0015] A current transformer is connected to the high-voltage winding side of the transformer. A recording threshold and a detection time are set. When the current in the transformer exceeds the recording threshold, recording is performed according to the set recording time period to obtain the substation current recording data.

[0016] As a preferred embodiment of the transformer pad preload prediction method based on finite element analysis described in this invention, the distribution of short-circuit impact force on each winding pad includes:

[0017] The current recording data is converted into the short-circuit current of the winding for which the preload needs to be predicted, based on the turns ratio of the current transformer and the turns ratio of the transformer.

[0018] Using the short-circuit current as an excitation, the electromagnetic force distribution of each turn of the winding is calculated through electromagnetic field transient analysis.

[0019] The beneficial effect of this preferred solution is that by using transient electromagnetic field analysis to calculate the electromagnetic force distribution of each turn of the winding, it provides accurate load input for structural analysis. Ignoring the influence of non-conductive parts simplifies the calculation and improves the analysis efficiency.

[0020] As a preferred embodiment of the transformer pad preload prediction method based on finite element analysis described in this invention, the decrease in winding height is analyzed through plastic deformation analysis of the structural field and converted into the degree of preload decrease, including:

[0021] By applying the corresponding short-circuit impact electromagnetic force to the power transformer simulation model and setting a nonlinear stress-strain curve, the plastic deformation of the pad block and the change of elastic modulus are simulated.

[0022] A pressure detection label is set at the end of the pressure plate to obtain the detection results. The preload loss caused by the current short circuit impact can be obtained by the pressure test difference before and after the short circuit.

[0023] As a preferred embodiment of the transformer pad preload prediction method based on finite element analysis described in this invention, the method for providing early warning of low pad preload includes:

[0024] Based on the preload loss, a preload attenuation curve after a short-circuit impact is generated;

[0025] If the preload curve falls below the set warning threshold, a warning message will be generated to remind staff to reload the transformer preload.

[0026] The beneficial effect of this preferred solution is that by dynamically updating the preload decay curve, it is possible to achieve real-time monitoring of the transformer preload status. The threshold warning can promptly remind maintenance personnel to take measures to avoid equipment damage due to insufficient preload.

[0027] As a preferred embodiment of the transformer pad preload prediction method based on finite element analysis described in this invention, the generation of the preload attenuation curve for short-circuit impact includes:

[0028] The initial axial preload is obtained based on the transformer data, and the initial preload is calculated based on the number of transformer pads and the bearing area, which serves as the starting point of the preload decay curve.

[0029] The preload loss obtained through transient structural analysis is used to update the preload curve after each short-circuit impact.

[0030] Secondly, the present invention provides a transformer pad preload prediction system based on finite element analysis, comprising:

[0031] The module is used to build a power transformer simulation model by adding corresponding constraints through the axial equivalent spring model of the transformer.

[0032] The calculation module is used to obtain substation current recording data based on the power transformer simulation model, and combine it with the electromagnetic field calculation model to obtain the distribution of short-circuit impact force on each winding pad.

[0033] The early warning module is used to analyze the decrease in winding height based on the distribution of short-circuit impact force and plastic deformation of the structural field, and convert it into the degree of preload decrease to provide early warning for the preload of the low pad block.

[0034] Thirdly, the present invention provides a computer device, comprising:

[0035] Memory and processor;

[0036] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the transformer pad preload prediction method based on finite element analysis.

[0037] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the transformer pad preload prediction method based on finite element analysis.

[0038] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention proposes a transformer pad preload prediction method based on finite element analysis. It analyzes and predicts changes in the preload of pads in the transformer through mathematical calculations. It only requires the substation to provide short-circuit current recording data from the current transformer, without the need for additional detection equipment, and also features long-term stable operation. Furthermore, by setting a corresponding preload threshold, it can also achieve an early warning function for excessive reduction in winding preload by comparing the existing preload with the threshold, providing a theoretical basis for determining whether the transformer needs maintenance. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the overall process of the transformer pad preload prediction method based on finite element analysis according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the equivalent spring model of a power transformer for the transformer pad preload prediction method based on finite element analysis according to an embodiment of the present invention.

[0042] Figure 3 This is a schematic diagram of a power transformer structural field simulation model of the transformer pad preload prediction method based on finite element analysis according to an embodiment of the present invention.

[0043] Figure 4 This is a schematic diagram of the current transformer waveform recording of the transformer pad preload prediction method based on finite element analysis according to an embodiment of the present invention.

[0044] Figure 5 This is a schematic diagram of the electromagnetic field calculation results of the transformer pad preload prediction method based on finite element analysis according to an embodiment of the present invention.

[0045] Figure 6 This is a schematic diagram of the preload decay curve of the transformer pad preload prediction method based on finite element analysis according to an embodiment of the present invention. Detailed Implementation

[0046] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0047] Example 1

[0048] Reference Figures 1-3 As an embodiment of the present invention, a method for predicting the preload of transformer pads based on finite element analysis is provided, such as... Figure 1 As shown, it includes:

[0049] S101, by adding corresponding constraints through the axial equivalent spring model of the transformer, a simulation model of the power transformer is constructed;

[0050] S102, based on the power transformer simulation model, obtain the substation current recording data, and combine it with the electromagnetic field calculation model to obtain the distribution of short-circuit impact force on each winding pad;

[0051] S103, based on the distribution of short-circuit impact force, analyzes the decrease in winding height through the plastic deformation of the structural field and converts it into the degree of preload decrease, thus providing an early warning for the preload of the low pad block.

[0052] It should be noted that this invention applies corresponding constraints to the axial equivalent spring model of the transformer to construct a corresponding transformer model. Then, by combining the waveform data of the current transformer in the substation with the electromagnetic field calculation model, the distribution of short-circuit impact force on each winding pad is obtained. The decrease in winding height is analyzed by the plastic deformation of the structural field, and it is converted into the degree of preload decrease based on the elastic modulus of the pressure plate, thereby realizing the early warning function of low pad preload.

[0053] In a preferred embodiment, constructing a power transformer simulation model includes:

[0054] For unpredictable windings, the windings are modeled using a cylindrical model; for windings with predicted pad preload, the windings are modeled using a combination of circular rings with the same number of turns and square uniformly distributed pads.

[0055] Set the bottom of the model as a fixed constraint, set the contact between the winding and the pad as a binding constraint, and set the pressure plate pressure as a pre-compressed spring element through an axial equivalent spring model.

[0056] In this embodiment, for non-predictable windings, a cylindrical model is used to simulate the windings; for windings whose pad preload needs to be predicted, a model is created using a combination of circular rings with the same number of turns and square, evenly distributed pads; for the bottom of the model, considering the weight of the winding itself, it is set as a fixed constraint; for the contact between the winding and the pad, considering that the pad should have a constraint effect on the winding before the preload completely fails, it is set as a binding constraint; for the displacement of the pad, considering the radial friction, only axial deformation and displacement of the pad are allowed; for the pressure plate, an axial equivalent spring model is used, assuming it to be a pre-compressed spring.

[0057] Specifically, such as Figure 2 As shown, for a normally constrained power transformer, its axial deformation can be controlled by means of... Figure 2 The axial equivalent spring model of the transformer is used for calculation. The positions of the upper and lower pressure plates of the transformer are fixed, corresponding to the upper and lower fixed planes in the figure, k B Expressed as the elastic modulus within the elastic range of the pressure plate, k1 to k n The elastic modulus of each spacer between windings, m1 to m n These are the winding coils of each gate coil.

[0058] Before the transformer receives any short-circuit impact, the height of each component is at the normal value. At the same time, the top pressure plate is pre-compressed to a certain extent to provide pre-tightening force. As the short-circuit impact proceeds, the height of each pad between the windings gradually decreases, which reduces the pre-compression degree of the pressure plate. This leads to a decrease in the overall pre-tightening force of the equivalent spring model. When the pressure plate compression degree approaches 0, the upper pressure plate constraint almost fails, and huge vibrations will occur at the upper end of the winding, posing a risk of instability.

[0059] like Figure 3 As shown, a simulation model of a power transformer is constructed. To reduce the amount of calculation of the structural field, a local model is selected to replace the overall winding. A fixed constraint is applied at the bottom of the winding, i.e., point A, to simulate the transformer's self-weight. At both sides of the winding, i.e., point B, the supporting effect of the pads and struts is simulated. Finally, a pre-compressed spring is applied to the top of the winding to simulate the pressure plate that provides preload.

[0060] It should be noted that by establishing an accurate transformer simulation model, the mechanical behavior of the windings can be simulated, especially the distribution and changes of the preload. The use of an axial equivalent elastic modulus model simplifies the analysis of complex structures and improves computational efficiency. The setting of constraints ensures the consistency between the model and actual physical behavior.

[0061] In an alternative implementation, preload prediction can also be achieved through full three-dimensional finite element modeling, directly establishing a complete three-dimensional model of the transformer winding, including all components such as pressure plates and integral blocks, for more accurate mechanical analysis, but the computational load is large.

[0062] In a preferred embodiment, acquiring substation current recording data includes:

[0063] A current transformer is connected to the high-voltage winding side of the transformer. A recording threshold and a detection time are set. When the current in the transformer exceeds the recording threshold, recording is performed according to the set recording time period to obtain the substation current recording data.

[0064] In this embodiment, the waveform recording threshold can be twice the rated current, and the detection time can be set according to the actual time requirements. The set waveform recording period can be at least 1 second. When the current in the transformer exceeds the waveform recording threshold, waveform recording begins and stops after at least 1 second, which can accurately capture the transient characteristics of the short-circuit current.

[0065] In a preferred embodiment, the distribution of short-circuit impact force on each winding pad includes:

[0066] The current recording data is converted into the short-circuit current of the winding for which the preload needs to be predicted, based on the turns ratio of the current transformer and the turns ratio of the transformer.

[0067] Using the short-circuit current as an excitation, the electromagnetic force distribution of each turn of the winding is calculated through transient electromagnetic field analysis.

[0068] In this embodiment, the recorded waveform data is multiplied by the turns ratio of the current transformer and the turns ratio of the transformer to convert it into the short-circuit current of the winding for which the preload needs to be predicted. This current is used as an excitation, and the electromagnetic force distribution of each turn of the winding is calculated through electromagnetic field transient analysis (finite element analysis). To simplify the difficulty of finite element analysis, the influence of non-conductive components such as pads and pressure plates is not considered in the electromagnetic field calculation.

[0069] It should be noted that by performing transient electromagnetic field analysis, the electromagnetic force distribution of each turn of the winding is calculated, providing accurate load input for structural analysis. Ignoring the influence of non-conductive parts simplifies the calculation and improves analysis efficiency.

[0070] In one alternative implementation, the short-circuit impact electromagnetic force can be analyzed using the Biot-Savart law, calculating the magnetic field distribution of a single-turn conductor, integrating to obtain the overall winding force, introducing empirical coefficients to improve accuracy, and enabling rapid estimation, but the spatial magnetic field inhomogeneity needs to be ignored.

[0071] In a preferred embodiment, the decrease in winding height is analyzed by plastic deformation analysis of the structural field and converted into the degree of preload reduction, including:

[0072] By applying the corresponding short-circuit impact electromagnetic force to the power transformer simulation model and setting a nonlinear stress-strain curve, the plastic deformation of the pad block and the change of elastic modulus are simulated.

[0073] A pressure detection label is set at the end of the pressure plate to obtain the detection results. The preload loss caused by the current short circuit impact can be obtained by the pressure test difference before and after the short circuit.

[0074] In this embodiment, the axial equivalent spring model composed of the pressure plate, winding, and pad is constrained, and a corresponding short-circuit impact electromagnetic force is applied to it. Based on the obtained electromagnetic force distribution of each turn of the winding, the plastic deformation of the pad and the change of elastic modulus are simulated by setting a nonlinear stress-strain curve. A pressure detection label is set at the pressure plate end, and the difference between the detection results before and after the short circuit is the magnitude of the preload loss caused by the short-circuit impact.

[0075] In one alternative implementation, the transient structural analysis of the axial equivalent elastic modulus model can be achieved using the discrete element method, which discretizes the entire material into spherical particles, defines the contact stiffness and friction coefficient, converts the electromagnetic force into the contact force between the particles, and simulates fracture or permanent deformation through a particle bonding model.

[0076] In a preferred embodiment, providing an early warning for the low pad preload includes:

[0077] Based on the preload loss, a preload attenuation curve after a short-circuit impact is generated;

[0078] If the preload curve falls below the set warning threshold, a warning message will be generated to remind staff to reload the transformer with preload.

[0079] In a preferred embodiment, generating the preload decay curve for short-circuit impact includes:

[0080] The initial axial preload is obtained from the transformer data, and the initial preload is calculated based on the number of transformer pads and the bearing area, which serves as the starting point of the preload decay curve.

[0081] The preload loss obtained through transient structural analysis is used to update the preload curve after each short-circuit impact.

[0082] In this embodiment, the initial axial preload is obtained based on the transformer's nameplate value. The initial preload (pressure divided by the bearing area) is calculated based on the number of pads and the bearing area, and this is used as the starting point of the attenuation curve. The preload curve is updated based on the preload loss obtained after each short-circuit impact, obtained through the transient structural analysis in the previous step. When the preload curve falls below the user-set warning threshold (5%), the operator is alerted to reload the transformer with preload.

[0083] It should be noted that by dynamically updating the preload decay curve, real-time monitoring of the transformer preload status can be achieved, and threshold warnings can promptly remind maintenance personnel to take measures to avoid equipment damage due to insufficient preload.

[0084] This invention proposes a method for predicting transformer pad preload based on finite element analysis. It analyzes and predicts changes in the preload of pads in a transformer through mathematical calculations. It only requires short-circuit current recording data from the current transformer provided by the substation, without the need for additional detection equipment, and features long-term stable operation. Furthermore, by setting appropriate preload thresholds, it can also provide an early warning function for excessive reduction in winding preload by comparing the existing preload with the threshold, providing a theoretical basis for determining whether the transformer requires maintenance.

[0085] The above is a schematic scheme of a transformer pad preload prediction method based on finite element analysis according to this embodiment. It should be noted that the technical solution of this transformer pad preload prediction system based on finite element analysis belongs to the same concept as the above-described transformer pad preload prediction method based on finite element analysis. Details not described in detail in the technical solution of the transformer pad preload prediction system based on finite element analysis in this embodiment can be found in the description of the above-described transformer pad preload prediction method based on finite element analysis.

[0086] Example 2

[0087] This embodiment provides a transformer pad preload prediction system based on finite element analysis, including:

[0088] The module is used to build a power transformer simulation model by adding corresponding constraints through the axial equivalent spring model of the transformer.

[0089] The calculation module is used to obtain substation current recording data based on the power transformer simulation model, and combine it with the electromagnetic field calculation model to obtain the distribution of short-circuit impact force on each winding pad;

[0090] The early warning module is used to analyze the decrease in winding height based on the distribution of short-circuit impact force and plastic deformation of the structural field, and convert it into the degree of preload decrease to provide early warning for the preload of the low pad block.

[0091] This embodiment also provides a computer device applicable to the prediction of transformer pad preload force based on finite element analysis, including:

[0092] The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement the transformer pad preload prediction method based on finite element analysis as proposed in the above embodiments.

[0093] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the transformer pad preload prediction method based on finite element analysis as proposed in the above embodiments.

[0094] The storage medium proposed in this embodiment and the method for predicting the preload of transformer pads based on finite element analysis proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0095] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0096] Example 3

[0097] Reference Figures 4-6 As an embodiment of the present invention, a method for predicting the preload of transformer pads based on finite element analysis is provided. To verify its beneficial effects, it is scientifically demonstrated through economic benefit calculations and simulation experiments.

[0098] After constructing the power transformer simulation model, as follows Figure 4 As shown, the instrument transformer activates its waveform recording function after the short-circuit current exceeds the threshold, and stops recording after allowing sufficient time for troubleshooting, thus ensuring that all short-circuit current peak values ​​are captured. In this embodiment, the instrument transformer ratio is 600, and the high-low voltage ratio of the transformer winding is 5.7. Therefore, the three short-circuit current peak values ​​experienced by phase A in this short circuit can be calculated to be 29070A, 29028A, and 27907A, respectively.

[0099] See Figure 5 The electromagnetic field module calculation results are obtained, and a response function is constructed based on the recorded waveform data. Finite element simulation calculations of the electromagnetic field are then performed, and the results are as follows: Figure 5 As shown, electromagnetic field calculations were performed with phase A subjected to a current of 29070A as excitation. The maximum magnetic field value was 3.906T, and the maximum short-circuit electromotive force value was 6.09e8N / m3. Both maximum and minimum values ​​were located near the main open circuit at the winding end.

[0100] See Figure 6A preload decay curve was generated. For transformers with high natural frequencies, the size of the time step has little impact on the results. Here, 1 second is taken as the time step, and three short-circuit impacts are performed using 29070A, 29028A, and 27907A. After three short-circuit impacts, the preload decreased from the initial downward direction of 9940N to 7988N, that is, the stress on the pad decreased from 3MPa to 2.4MPa. In the figure, the preload is negative, which represents the downward direction. The curve gradually increases with the number of short-circuit impacts, indicating that the preload gradually decreases with the number of short-circuit impacts.

[0101] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for predicting the preload force of transformer pads based on finite element analysis, characterized in that, include: A power transformer simulation model is constructed by adding corresponding constraints to the axial equivalent spring model of the transformer. Based on the power transformer simulation model, substation current recording data is obtained, and combined with the electromagnetic field calculation model, the distribution of short-circuit impact force on each winding pad is obtained. Based on the distribution of short-circuit impact force, the decrease in winding height is analyzed by plastic deformation of the structural field and converted into the degree of preload decrease, so as to provide early warning of the preload of the low pad block.

2. The method for predicting the preload of transformer pads based on finite element analysis as described in claim 1, characterized in that, Constructing a power transformer simulation model includes: For unpredictable windings, the windings are modeled using a cylindrical model. For windings with predicted pad preload, the windings are modeled using a combination of circular rings with the same number of turns and square uniformly distributed pads. Set the bottom of the model as a fixed constraint, set the contact between the winding and the pad as a binding constraint, and set the pressure plate pressure as a pre-compressed spring element through an axial equivalent spring model.

3. A method for predicting the preload of transformer pads based on finite element analysis as described in claim 1 or 2, characterized in that, Obtaining substation current recording data includes: A current transformer is connected to the high-voltage winding side of the transformer. A recording threshold and a detection time are set. When the current in the transformer exceeds the recording threshold, recording is performed according to the set recording time period to obtain the substation current recording data.

4. The method for predicting the preload of transformer pads based on finite element analysis as described in claim 3, characterized in that, The distribution of short-circuit impact force on each winding pad includes: The current recording data is converted into the short-circuit current of the winding for which the preload needs to be predicted, based on the turns ratio of the current transformer and the turns ratio of the transformer. Using the short-circuit current as an excitation, the electromagnetic force distribution of each turn of the winding is calculated through electromagnetic field transient analysis.

5. The method for predicting the preload of transformer pads based on finite element analysis as described in claim 1, characterized in that, The decrease in winding height is analyzed through plastic deformation analysis of the structural field and converted into the degree of preload reduction, including: By applying the corresponding short-circuit impact electromagnetic force to the power transformer simulation model and setting a nonlinear stress-strain curve, the plastic deformation of the pad block and the change of elastic modulus are simulated. A pressure detection label is set at the end of the pressure plate to obtain the detection results. The preload loss caused by the current short circuit impact can be obtained by the pressure test difference before and after the short circuit.

6. The method for predicting the preload of transformer pads based on finite element analysis as described in claim 5, characterized in that, Early warning of low pad preload includes: Based on the preload loss, a preload attenuation curve after a short-circuit impact is generated; If the preload curve falls below the set warning threshold, a warning message will be generated to remind staff to reload the transformer with preload.

7. The method for predicting the preload of transformer pads based on finite element analysis as described in claim 6, characterized in that, The preload decay curve for generating short-circuit impact includes: The initial axial preload is obtained based on the transformer data, and the initial preload is calculated based on the number of transformer pads and the bearing area, which serves as the starting point of the preload decay curve. The preload loss obtained through transient structural analysis is used to update the preload curve after each short-circuit impact.

8. A transformer pad preload prediction system based on finite element analysis, employing the transformer pad preload prediction method based on finite element analysis as described in any one of claims 1 to 7, characterized in that, include: The module is used to build a power transformer simulation model by adding corresponding constraints through the axial equivalent spring model of the transformer. The calculation module is used to obtain substation current recording data based on the power transformer simulation model, and combine it with the electromagnetic field calculation model to obtain the distribution of short-circuit impact force on each winding pad. The early warning module is used to analyze the decrease in winding height based on the distribution of short-circuit impact force and plastic deformation of the structural field, and convert it into the degree of preload decrease to provide early warning for the preload of the low pad block.

9. A computer device, characterized in that, include: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the transformer pad preload prediction method based on finite element analysis as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores computer-executable instructions, which, when executed by a processor, implement the steps of the transformer pad preload prediction method based on finite element analysis as described in any one of claims 1 to 7.

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