A Design Method for the Vibration Scaling Model of a Converter Transformer

Abstract

The present invention provides a design method for a vibration scaled model of a converter transformer, including: obtaining the frequency, current, voltage, resistance, and magnetic flux density of the scaled model based on the electromagnetic field parameter scaling criterion; obtaining the magnetostrictive force, Lorentz force, core acceleration, and winding acceleration of the scaled model based on the vibration parameter scaling criterion; constructing a three-dimensional multi-physics field coupling model of the converter transformer based on a finite element simulation platform, and performing similarity processing on the corresponding parameters of the three-dimensional multi-physics field coupling model of the converter transformer according to the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion to obtain the scaled model. Through the comparative analysis of the magnetic flux density distribution, stress distribution, deformation amount, and vibration time domain and frequency domain signals, it is proved that the model of the converter transformer corresponds to the similarity criterion in terms of electromagnetic field and structural mechanics before and after similarity, thus comprehensively verifying the correctness of the scaled model of the converter transformer.

Description

Technical Field

[0001] The invention belongs to the technical field of converter transformers, and particularly relates to a design method for a vibration scale model of a converter transformer. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] The converter transformer is one of the core devices of a high-voltage direct-current transmission system. Compared with an ordinary transformer, it is subjected to the combined action of alternating and direct-current voltages during operation. A large amount of DC bias current and high-order harmonics are contained in the load current of the converter transformer, making the electromagnetic force and the core resonance effect it bears more obvious. Coupled with the inherent magnetostrictive effect of the core material under an alternating magnetic field, the vibration of the core and winding is very complex. The vibration of the core and winding will be transmitted to the surface of the oil tank through the box structure, causing more complex vibration and noise of the entire converter transformer, thus threatening the safe operation of the converter transformer. People have been committed to the research on the vibration generation mechanism and vibration suppression of converter transformers, but they are still troubled by its changing test environment, complex electromagnetic field distribution, and complex vibration propagation process. There is still a debate about the main factors of the noise generation mechanism, and the vibration suppression effect is also difficult to meet the development needs of high-voltage direct-current transmission technology.

[0004] According to the similarity principle, scaling down the converter transformer proportionally to a size that can be accommodated in the laboratory to meet ideal test conditions is an effective measure to solve the problem of the complex test environment of large-capacity converter transformers.

[0005] However, among numerous current studies, there is no unified similarity method for the vibration suppression research of converter transformers, and there is also a lack of an effective method for verifying the accuracy of the similarity criteria of converter transformers. This greatly reduces the reliability of the scaled-down models of converter transformers. Most related studies use the consistency of electromagnetic fields and vibration spectra as the detection method for the correctness of scaled-down models. However, the prerequisite is that after the physical model is prepared, the electromagnetic fields and vibration signals need to be analyzed, making the model verification meaningless. At the same time, due to the limitations of detection technologies, it is difficult to perform stress analysis on the internal components of the physical proportional model. Therefore, the means for verifying the vibration characteristics of the proportional model have been limited to the analysis of vibration signals at external points of the model. The finite element simulation technology provides ideas for the analysis of such devices with complex internal structures and multi-field couplings. However, in current finite element model studies, electromagnetic field analysis is also mostly used as the verification method for scaled-down models, and the consistency of vibration characteristics before and after similarity is not taken as the core idea for verifying the vibration model of converter transformers. Existing scaled-down models do not have a unified scaling criterion for the vibration research of converter transformers; there is a lack of a relatively comprehensive prior method for the scaled-down vibration models of converter transformers. If the correctness of the scaling criterion can be determined before manufacturing the scaled-down model prototype, the efficiency and reliability of the experiment will be greatly improved. Summary of the Invention

[0006] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a design method for a scaled-down vibration model of a converter transformer. Based on the principle of ensuring that the response relationship between the input and vibration of the converter transformer remains unchanged before and after similarity, similarity criteria applicable to the vibration characteristics research of converter transformers are derived, and a converter transformer model and its scaled-down model are constructed.

[0007] To achieve the above object, one or more embodiments of the present invention provide the following technical solutions:

[0008] In a first aspect, a design method for a scaled-down vibration model of a converter transformer is disclosed, including:

[0009] Obtaining the frequency, current, voltage, resistance, and magnetic flux density of the scaled-down model based on the electromagnetic field parameter scaling criterion;

[0010] Obtaining the magnetostrictive force, Lorentz force, core acceleration, and winding acceleration of the scaled-down model based on the vibration parameter scaling criterion;

[0011] Constructing a three-dimensional multi-physical-field coupling model of the converter transformer based on a finite element simulation platform, and performing similarity processing on the corresponding parameters of the three-dimensional multi-physical-field coupling model of the converter transformer according to the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion to obtain a scaled-down model.

[0012] In a further technical solution, the electromagnetic field parameter scaling criterion is specifically:

[0013] Table 1 Electromagnetic Field Parameter Scaling Criterion

[0014]

[0015] k is the scaling factor of the similarity criterion.

[0016] In a further technical solution, the vibration parameter scaling criterion is specifically:

[0017] Table 2 Vibration parameter scaling criteria

[0018]

[0019] k is the scaling factor of the similarity criterion.

[0020] According to a further technical solution, the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion select the magnetic flux density as a reference value, introduce a proportional factor of a similarity criterion, and the number of coil turns remains unchanged before and after scaling.

[0021] According to a further technical solution, the magnetic permeability, dielectric constant, electrical conductivity, magnetic permeability and resistivity of the scaled-down model core and winding materials are consistent with those of the original model.

[0022] As a further technical solution, in the process of constructing the multi-physics field coupled three-dimensional model of the converter transformer, the converter transformer structure is idealized, the fixture structure is ignored, and corresponding fixed constraints are imposed on the winding and the core as boundary conditions;

[0023] The field-circuit coupling method is applied to couple the magnetic field model with the external circuit, and the corresponding material properties are assigned to the core, winding and other domains respectively;

[0024] The Lorentz force is applied to the winding as a body load, a magnetostrictive module is added to the core domain, a voltage source excitation is added to each winding and its input and output ports are set.

[0025] A further technical solution is to perform three-dimensional symmetry on the longitudinal section of the core when analyzing the magnetic flux density distribution of the scaled model, so as to obtain a distribution diagram of the magnetic flux density modulus on the core surface. Different colors in the distribution diagram distinguish the magnetic flux density values ​​of different intensities at different locations on the core surface, and the arrows represent the direction and path of the magnetic flux.

[0026] In a second aspect, a design system for a converter transformer vibration scale model is disclosed, including: a server, wherein the server is configured to execute the following:

[0027] Based on the electromagnetic field parameter scaling criterion, the frequency, current, voltage, resistance and magnetic flux density of the scaled model are obtained;

[0028] Based on the vibration parameter scaling criterion, the magnetostrictive force, Lorentz force, core acceleration and winding acceleration of the scaled model are obtained;

[0029] Based on a finite element simulation platform, a three-dimensional multi-physical field coupling model of a converter transformer is constructed. The corresponding parameters of the three-dimensional multi-physical field coupling model of the converter transformer are processed for similarity according to the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion to obtain a scaled model.

[0030] The above one or more technical solutions have the following beneficial effects:

[0031] The present invention analyzes the magnetic flux density distribution, stress distribution, deformation amount and vibration characteristics before and after model similarity, and verifies the correctness of the similarity criterion.

[0032] Through the comparative analysis of the magnetic flux density distribution, stress distribution, deformation amount and vibration time-domain and frequency-domain signals, the present invention proves that the model of the converter transformer corresponds to the similarity criterion in terms of electromagnetic field and structural mechanics before and after model similarity, thus comprehensively verifying the correctness of the scaled model of the converter transformer. The comparison results show that the main vibration of the scaled model of the converter transformer is still the magnetostrictive effect of the iron core under the magnetic field, and the main frequency of the vibration signal is an even multiple of the excitation source. The above characteristics remain unchanged during the scaling process. The vibration scaled model of the converter transformer and its verification method have certain reference value for the research on the vibration characteristics of the converter transformer and its suppression, and for improving the operation reliability of the converter transformer.

[0033] The advantages of the additional aspects of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0035] Figure 1 Simplified model for the embodiment of the present invention;

[0036] Figure 2 Magnetic flux density distribution diagram;

[0037] Figure 3 Iron core stress distribution diagram;

[0038] Figure 4 Winding stress distribution diagram;

[0039] Figure 5 Overall stress distribution diagram;

[0040] Figure 6 Winding displacement diagram;

[0041] Figure 7 Iron core displacement diagram;

[0042] Figure 8 Vibration signal diagram of similar front and rear points 1

[0043] Figure 9 Vibration signal diagram of similar front and rear points 2 Detailed implementation manners

[0044] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0045] It should be noted that the terms used herein are only for describing the specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention.

[0046] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0047] Embodiment 1

[0048] This embodiment discloses a design method for a vibration scaled model of a converter transformer, including:

[0049] Obtaining the frequency, current, voltage, resistance and magnetic flux density of the scaled model based on the electromagnetic field parameter scaling criterion;

[0050] Obtaining the magnetostrictive force, Lorentz force, core acceleration and winding acceleration of the scaled model based on the vibration parameter scaling criterion;

[0051] Constructing a three-dimensional multi-physics coupling model of the converter transformer based on a finite element simulation platform, and performing similarity processing on the corresponding parameters of the three-dimensional multi-physics coupling model of the converter transformer according to the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion to obtain the scaled model.

[0052] Regarding the electromagnetic field parameter scaling criterion: According to the similarity theory, the similarity criterion can be derived from the differential equation describing the same physical process without solving the equation. In order to better restore the vibration characteristics of the converter transformer, more sufficient consideration should be given to the selection of the reference value of the similarity criterion. The core magnetic flux density is one of the main indicators considered in the design of the converter transformer. The magnitude of the magnetic flux density affects the working characteristics and vibration characteristics of the core, and its selection should be in the linear region of the B-H curve. Based on the operating characteristics of the converter transformer, the core material generally works between the magnetic flux densities of 1.5 - 1.8 T. To ensure the normal working performance of the core and restore the vibration characteristics of the core, the present invention selects the magnetic flux density B as the reference value for the similarity criterion. Introducing the scale factor k of the similarity criterion, the length l, width w, and height h of the converter transformer are respectively reduced to l' = kl, w' = kw, h' = kh, and the area S is reduced to S' = k 2S. The number of turns N of the coil should remain unchanged before and after scaling. Then, the number of turns n per unit length after scaling is n' = k -1 n. The frequency is inversely proportional to the square of the skin depth. The skin depth δ is reduced to δ' = kδ. Therefore, the frequency of the converter transformer after scaling is f' = k -2 f.

[0053] The electromagnetic field state of the converter transformer under normal operating conditions can be described by the following equations:

[0054]

[0055]

[0056]

[0057]

[0058] J = σE (5)

[0059] B = μH (6)

[0060] In the formula, B is the magnetic induction intensity, H is the magnetic field intensity, E is the electric field intensity, D is the electric displacement vector, J is the current density, σ is the conductivity, μ is the magnetic permeability, ε is the permittivity, ρ is the charge density, and S is the area.

[0061] Based on Maxwell's equations and similarity theory, assuming that the magnetic field density B remains unchanged, according to the integral form of Ampere's law ∫Bdl = μ 0 NI, it can be known that I' = kI. According to R = ρl / S, and the scaling criteria for l and S, the resistance after scaling is R' = k -1 R, where ρ is the resistivity. Since U = IR, according to the scaling criteria for I and R, the voltage is reduced to U' = U. According to G = I / U, the conductance after scaling is G' = kG. According to G / σ = C / ε, C' = kC is obtained. According to L = U / 2πfI, and the scaling criteria for U, I, and f, the inductance is reduced to L' = kL. The similarity criteria for the main electromagnetic field parameters are listed in Table 1. The above criteria are used to determine the corresponding relationship of the electromagnetic field parameters of the converter transformer before and after scaling.

[0062] Table 1 Scaling criteria for electromagnetic field parameters

[0063]

[0064] Scaling criteria for vibration parameters:

[0065] Starting from the parameters directly related to vibration, similarity analysis is carried out on them to ensure that the vibration characteristics of the model are consistent before and after similarity. According to previous studies, the vibration of the converter transformer mainly originates from the iron core and winding. Therefore, in order to equivalent the vibration intensity and distribution of the iron core column and winding, it is necessary to scale down the mass matrix M and the stiffness coefficient matrix K in proportion, and then the natural frequency of the structure remains almost unchanged, theoretically continuing the mode and vibration shape of the converter transformer. The permeability, permittivity, conductivity σ, permeability μ, and resistivity ρ of the iron core and winding materials are consistent with the original model.

[0066] The finite element dynamic equation of the winding and iron core structure is:

[0067]

[0068] where and are the node acceleration vector and the node velocity vector, M is the mass matrix of the model, C is the damping matrix of the model, K is the stiffness matrix, and Q(t) is the load vector.

[0069] The magnetostrictions of the magnetic material in the parallel and perpendicular directions are respectively:

[0070] ε p =αB 2 (8)

[0071] ε v =-νε p (9)

[0072] where α is the material coefficient and v is the Poisson's ratio. According to the relationship between the applied voltage and the magnetic flux density:

[0073]

[0074] it can be known that the magnetostrictive force F c on the node is proportional to the square U 2 of the applied voltage. Since the voltage remains unchanged before and after similarity, the magnetostrictive force on the iron core after similarity should be F c ' = F c .

[0075] Under the alternating magnetic field generated by the alternating current in the winding, the winding will be subjected to the radial electrodynamic force F x and the axial electrodynamic force F z generated by the axial and radial leakage magnetic fluxes:

[0076] F x =iB zt ·2πr (11)

[0077] F z =iBxt ·2πr (12)

[0078] Then the resultant electromagnetic force F of the two l is as follows:

[0079]

[0080] where r is the winding radius, i t is the winding current, B t is the leakage flux density, and I is the effective current value. It can be seen that the force on the winding is related to the current i, the leakage magnetic field density B t and the winding radius r. Since i' = ki, B' = B, and r' = kr, after similarity, the force on the winding F l ' = k 2 F l .

[0081] The acceleration a of the iron core vibration caused by magnetostriction under the action of voltage u c is as follows:

[0082]

[0083] where ε s is the saturation magnetostriction coefficient of the silicon steel sheet, ω is the angular frequency of the voltage source, B s is the saturation magnetic induction intensity of the iron core, l 1 is the length of the silicon steel sheet, and A is the area of the silicon steel sheet. After model similarity, ε s and u remain unchanged, A' = k 2 A, B s ' = B s , so after model similarity, the acceleration a of the iron core vibration c ' = k -3 a c .

[0084] Equivalent the winding vibration to a mass-spring-damping system, then the differential equation of the winding vibration displacement x under the action of the Lorentz force F l is as follows:

[0085]

[0086] where m is the mass matrix, s is the stiffness matrix, and c is the damping matrix. Assuming the initial state is zero, the vibration acceleration is solved as:

[0087]

[0088] where is a constant related to the parameters of the transformer itself under the initial conditions. It can be seen that the vibration acceleration of the winding is proportional to I 2 , so after model similarity, the vibration acceleration of the winding should be a l' = k 2 a l The vibration parameters before and after model similarity are listed in Table 2, and the corresponding relationship of the vibration parameters of the converter transformer before and after scaling is determined by using the above criteria.

[0089] Table 2 Scaling Criteria for Vibration Parameters

[0090]

[0091] Converter Transformer Physical Model:

[0092] Based on the finite element simulation platform, taking the 500 kV converter transformer as an example, a three-dimensional model of the multi-physical field coupling of the converter transformer was constructed. Considering the symmetric physical structure of the converter transformer, the model was divided into four completely symmetric parts, and only one part was studied to reduce the computational workload. The effect of the simplified model is as Figure 1 shown.

[0093] During the modeling process, the structure of the converter transformer was idealized, structures such as fixtures were ignored, and corresponding fixed constraints were applied to the windings and iron cores as boundary conditions. The magnetic field model was coupled with the external circuit by applying the field-circuit coupling method. Corresponding material properties were assigned to the iron core, windings and other domains respectively. The Lorentz force was applied to the windings as a body load, and a magnetostriction module was added to the iron core domain. Voltage source excitations were added to each winding and their input and output ports were set. The parameter settings of the model are shown in Table 3. In order to obtain more accurate calculation results, the tolerance was set to 0.1, the mesh element size was set to super-refinement, the number of degrees of freedom for solution was increased to 610654, and the solution time was 1928 s. The calculation results include the magnetic flux density distribution, stress distribution, deformation amount, and acceleration of each part of the converter transformer, which are convenient for the vibration mode analysis of the converter transformer.

[0094] Table 3 Model Parameter Configuration

[0095]

[0096] Converter transformer scale model: According to the previous analysis of the similarity principle of the converter transformer, the corresponding parameters of the physical model of the converter transformer are processed for similarity. The similarity coefficient k = 0.1 is selected. Accordingly, the voltage remains unchanged after similarity, the resistance increases to 10 times the original, the frequency increases to 100 times the original, the current is reduced to 0.1 times the original, the inductance and capacitance increase to 10 times the original. The operating parameters of the physical model of the converter transformer after similarity are listed in Table 4. It should be noted additionally that after the frequency increases to 100 times the original, the operations related to time need to be corrected. Set the output time in the transient study step, and reduce both the output time length and the step size to 1 / 100 of the original. The grid cell size is also set to super refinement, the tolerance is set to 0.1, the number of degrees of freedom for solution is 610654, and the solution time is 2102 s. This paper aims to conduct a study on the scale model for the vibration analysis and suppression of the converter transformer. Therefore, the focus of the scale model verification lies in the consistency analysis of the vibration conditions before and after model similarity. The following conducts a comparative analysis of the magnetic flux density distribution, stress distribution, and vibration signals of the converter transformer models before and after similarity.

[0097] Table 4 Operating parameters

[0098]

[0099] Results and discussion:

[0100] Magnetic flux density distribution: The longitudinal section of the iron core is made three-dimensional symmetric to obtain the distribution map of the magnetic flux density modulus on the iron core surface, as Figure 2 shown. Different colors distinguish the magnetic flux density values of different intensities at various parts of the iron core surface, and the arrows represent the direction and path of the magnetic flux. It can be seen from the figure that the distribution of the magnetic induction intensity, the direction of the magnetic flux, and the magnetic flux path on the main magnetic circuit of the converter transformer before and after similarity are basically the same. The strong magnetic flux density points on the iron core are all distributed at the corners and junctions of the iron core. The magnetic flux density modulus thresholds of the models before and after similarity remain the same, both around 1.5 T, which is consistent with the magnetic field similarity condition in the similarity criterion.

[0101] Analysis of the force on the iron core: After making the iron core domain and the winding domain three-dimensional symmetric respectively, the models of the entire iron core domain and the winding domain are obtained. The model of the entire converter transformer domain is obtained in the same way. Since the frequency increases to 100 times the original after similarity, according to the relationship between frequency and time, the time point of the model after similarity corresponds to 0.01 times the time point of the original model. All the following time points selected for the time-domain diagrams are based on this.

[0102] Figure 3Shows the stress distribution of the converter transformer core. The arrows represent the direction of the stress, and the color shade reflects the magnitude of the stress on the core. It can be clearly seen from the figure that the stress distributions of the core before and after similarity are basically the same, indicating that the stress application points and their directions on the core surface remain unchanged before and after similarity. The main stress areas of the core before and after similarity are basically the same, both located in the magnetic flux circuit, and the four most obvious stress points are all at the core corners, which corresponds to the previous magnetic flux density analysis. The stress amplitude on the core before similarity is 3.54×10 7 Pa, and the stress amplitude on the core after similarity is 3.98×10 7 Pa. They are of the same order of magnitude, which corresponds to the unchanged input voltage of the converter transformer before and after similarity. The relationship curve between the magnetostrictive length and the magnetic flux density can be approximately expressed as a quadratic relationship. According to the formula it can be known that the magnetostrictive force on the core is proportional to the square of the voltage. Therefore, the stress magnitude and distribution shown in the figure are all reasonable.

[0103] Analysis of the winding stress: Figure 4 Shows the stress distribution of the converter transformer winding. It can be seen that the stress application points, stress directions, and stress distributions of the winding remain the same before and after similarity. The stress amplitude on the winding before similarity is 237 Pa, and the stress amplitude on the winding after similarity is 2.78 Pa. The two show an approximate k 2 relationship, which is consistent with the analysis of the electrodynamic force calculation formula 13 for the winding. Since the winding material has a relatively low hardness, its stress change with current depends not only on the electromagnetic force but also on the vibration of the core and other parts and the periodic change of the electric field. There is a certain error between the numerical changes before and after similarity and the expected proportional relationship, but in terms of the order of magnitude, the corresponding relationship is maintained.

[0104] Analysis of the overall stress of the model: Figure 5 Shows the overall stress condition of the converter transformer. It can be seen from the figure that the stress application points, stress directions, and surface stress distributions on the surface are basically the same before and after similarity. It can be seen that the stress amplitude on the whole converter transformer is very close to that of the core, while the stress on the winding is not obvious in the overall stress distribution. Compared with the stress on the core, the difference in their order of magnitude is relatively large. As previously analyzed, the overall vibration of the converter transformer is dominated by the core stress, that is, the main factor affecting the vibration of the converter transformer is the magnetostrictive effect of the core.

[0105] Analysis of the deformation of the winding and the core: As Figure 6 shown, the deformation positions, deformation trends, and deformation quantity distributions of the winding before and after similarity remain the same. The deformation quantity amplitude of the winding before similarity is 8.19×10 -10 m, and the deformation quantity amplitude of the winding after similarity is 9.16×10 -12 m. The difference between the two is about k 2times. The deformation of the winding mainly comes from the electromagnetic force generated by the current and leakage magnetic flux, and its variation law is generally consistent with the similar process of the current.

[0106] Figure 7 It characterizes the deformation of the core of the converter transformer. The deformation positions, deformation trends and deformation quantity distributions of the core before and after similarity are consistent, and the deformation quantity thresholds before and after similarity are consistent in magnitude. With the continuous progress of the transformer production process, the gap between the core silicon steel sheets becomes smaller, and the electromagnetic force between the laminations can be ignored. Therefore, the deformation of the core mainly comes from the magnetostrictive effect under the magnetic field, which is proportional to the square of the voltage. In summary, the displacement law of the vibration scaling model of the converter transformer before and after similarity is verified.

[0107] Vibration signal analysis: To more accurately verify the correctness of the model, a point is taken on the surface of the core and the winding respectively, named point 1 and point 2, and their vibration signals are extracted, as Figure 8 shown.

[0108] Figure 8 In (a) and (d), the vibration acceleration frequency spectra at point 1 before and after similarity are shown respectively. It can be seen that the maximum peak values of the vibration acceleration before and after similarity are distributed at 100 Hz and 10,000 Hz respectively, which corresponds to a double relationship with the respective excitation source frequency values. The difference is that the maximum peak value of the core vibration acceleration after similarity is 228.39 m / s 2 , which is k 2 times that of the maximum peak value of the vibration acceleration before similarity, which is 0.19 m / s -3 , and this is consistent with the analysis of formula 14. Figure 8 In (b) and (e), the stress-time curves at point 1 before and after similarity are shown respectively. The waveforms of the two are almost the same, and the peak values of the curves are consistent in magnitude. Figure 8 In (c) and (f), the magnetostrictive contributions at point 1 before and after similarity are shown respectively. It can be seen that the magnetostrictive force-time waveforms at this point before and after similarity are consistent, and the peak values of the two also differ by k 2 times. It should be noted that the magnetostrictive contribution at point 1 is close to the stress value at this point before and after similarity. That is to say, before and after the model similarity, the stress on the core depends on its magnetostrictive effect under the magnetic field.

[0109] Figure 9 shows the vibration signal analysis diagram at the winding signal extraction point 2. Figure 9 In (a) and (d), the vibration acceleration frequency spectra at point 2 before and after similarity are shown respectively. The maximum peak values of the vibration acceleration before and after similarity are also distributed at 100 Hz and 10,000 Hz respectively, and the amplitude of the winding deformation before similarity is 3.51×10 -2 m, and the amplitude of the winding deformation after similarity is 3.5×10- 4 m, the vibration amplitudes differ by approximately k 2 times, which is consistent with the analysis of Equation 16. Figure 9 In (b) and (e) in [reference], they respectively correspond to the stress change curves at point 2 before and after similarity. The waveforms of the two are almost the same, and the peak values differ by approximately k 2 times. Figure 9 In (c) and (f) in [reference], they respectively characterize the Lorentz force contributions at point 2 before and after similarity. The waveforms of the two are almost the same, and the peak values differ by k 2 times, which is consistent with the stress distribution of the winding.

[0110] Vibration signal restoration:

[0111] As analyzed above, the magnitude of the magnetic flux density of the model remains unchanged before and after similarity, the overall stress of the iron core and the converter transformer remains unchanged, the winding stress differs by k 2 times, the vibration acceleration of the iron core differs by k -3 times, and the vibration acceleration of the winding differs by k 2 times. When a scaled-down model prototype is established based on this scaled-down model and its vibration analysis is carried out, multiplying the signal measured by the scaled-down model prototype by the corresponding coefficient can restore the signal value of the actual converter transformer, that is, ensuring the principle that the response relationship between the input and vibration of the converter transformer remains unchanged before and after similarity.

[0112] Example 2

[0113] The purpose of this example is to provide a computing device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the above method are implemented.

[0114] Example 3

[0115] The purpose of this example is to provide a computer-readable storage medium.

[0116] A computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the steps of the above method are executed.

[0117] Example 4

[0118] The purpose of this example is to provide a design system for a vibration scaled-down model of a converter transformer, characterized by including: a server, and the server is configured to execute the following:

[0119] Obtain the frequency, current, voltage, resistance, and magnetic flux density of the scaled-down model based on the electromagnetic field parameter scaling criterion;

[0120] Obtain the magnetostrictive force, Lorentz force, iron core acceleration, and winding acceleration of the scaled-down model based on the vibration parameter scaling criterion;

[0121] A three-dimensional model of the multi-physical field coupling of a converter transformer is constructed based on a finite element simulation platform. The corresponding parameters of the three-dimensional model of the multi-physical field coupling of the converter transformer are processed for similarity according to the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion to obtain a scaled model.

[0122] In the devices of the above-mentioned second, third, and fourth embodiments, the various steps involved correspond to those of the first method embodiment. For the specific implementation manners, reference may be made to the relevant description part of the first embodiment. The term "computer-readable storage medium" should be understood to include a single medium or multiple media including one or more instruction sets; it should also be understood to include any medium that can store, encode, or carry an instruction set for execution by a processor and cause the processor to execute any method in the present invention.

[0123] Those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general-purpose computer device. Optionally, they can be implemented by program codes executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be separately fabricated into individual integrated circuit modules, or multiple modules or steps among them can be fabricated into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0124] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made without creative efforts by those skilled in the art are still within the protection scope of the present invention.

Claims

1. A design method for a vibration scaled-down model of a converter transformer, characterized in that, it includes: Obtaining the frequency, current, voltage, resistance, and magnetic flux density of the scaled-down model based on the electromagnetic field parameter scaling criterion; The specific electromagnetic field parameter scaling criterion is: Table 1 Electromagnetic Field Parameter Scaling Criterion k The scale factor for the similarity criterion; Obtaining the magnetostrictive force, Lorentz force, core acceleration, and winding acceleration of the scaled-down model based on the vibration parameter scaling criterion; The specific vibration parameter scaling criterion is: Table 2 Vibration Parameter Scaling Criterion k The scale factor for the similarity criterion; Constructing a three-dimensional multi-physics field coupling model of the converter transformer based on the finite element simulation platform, and performing similarity processing on the corresponding parameters of the three-dimensional multi-physics field coupling model of the converter transformer according to the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion to obtain the scaled-down model.

2. The design method for a vibration scaled-down model of a converter transformer according to claim 1, characterized in that, The electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion select the magnetic flux density as the reference value, introduce the scale factor of the similarity criterion, and the number of turns of the coil remains unchanged before and after scaling.

3. The design method for a vibration scaled-down model of a converter transformer according to claim 1, characterized in that, The magnetic permeability, permittivity, conductivity, magnetic permeability, and resistivity of the core and winding materials of the scaled-down model are consistent with those of the original model.

4. The design method for a vibration scaled-down model of a converter transformer according to claim 1, characterized in that, During the process of constructing the three-dimensional multi-physics field coupling model of the converter transformer, the structure of the converter transformer is idealized, the fixture structure is ignored, and corresponding fixed constraints are applied to the winding and the core as boundary conditions; Applying the field-circuit coupling method to couple the magnetic field model with the external circuit, and assigning corresponding material properties to the core, winding, and other domains respectively; Taking the Lorentz force as the body load and applying it to the winding, adding a magnetostrictive module to the core domain, adding voltage source excitation to each winding, and setting its input and output ports.

5. The design method for a vibration scaled-down model of a converter transformer according to claim 1, characterized in that, When analyzing the magnetic flux density distribution of the scaled-down model, the longitudinal section of the core is made three-dimensional symmetric, so as to obtain the magnetic flux density modulus distribution diagram on the core surface. Different colors in the distribution diagram distinguish the different intensities of the magnetic flux density at each place on the core surface, and the arrows represent the direction and path of the magnetic flux.

6. A design system for a vibration scaled-down model of a converter transformer, characterized in that, it includes: A server, and the server is configured to perform the following: Obtaining the frequency, current, voltage, resistance, and magnetic flux density of the scaled-down model based on the electromagnetic field parameter scaling criterion; The specific electromagnetic field parameter scaling criterion is: Table 1 Electromagnetic Field Parameter Scaling Criterion k The scale factor for the similarity criterion; Obtaining the magnetostrictive force, Lorentz force, core acceleration, and winding acceleration of the scaled-down model based on the vibration parameter scaling criterion; The specific vibration parameter scaling criterion is: Table 2 Vibration Parameter Scaling Criterion k The scale factor for the similarity criterion; Constructing a three-dimensional multi-physics field coupling model of the converter transformer based on the finite element simulation platform, and performing similarity processing on the corresponding parameters of the three-dimensional multi-physics field coupling model of the converter transformer according to the electromagnetic field parameter scaling criterion and the vibration parameter scaling criterion to obtain the scaled-down model.

7. A computing device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, when the processor executes the program, the steps of the method according to any one of claims 1-5 above are implemented.

8. A computer-readable storage medium, on which a computer program is stored, wherein, when the program is executed by a processor, the steps of the method according to any one of claims 1-5 above are executed.

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