Multi-scale Simulation Modeling Method for Transformer Vibration Noise

Abstract

A multi-scale simulation modeling method for transformer vibration noise is disclosed. In the method, transformer parameters are collected to establish a two-dimensional axisymmetric model of the winding and a three-dimensional finite element model of the iron core and the oil tank. The two-dimensional axisymmetric model and the three-dimensional finite element model are used to construct a vibration coupling model including the iron core and the winding via a shared boundary. The sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model is extracted. After coordinate transformation, the sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model is mapped to the sound pressure on the sound pressure contour surface in the three-dimensional model. Based on the sound pressure on the sound pressure contour surface in the three-dimensional model, the magnetostriction of the iron core is simulated and calculated to obtain the time-domain calculation result of the magnetostriction. The time-domain calculation result of the magnetostriction is subjected to a fast Fourier transform to obtain the iron core deformation displacement distribution at different frequencies. The frequency response analysis of the two-dimensional axisymmetric model and the three-dimensional finite element model is carried out to calculate the winding vibration and the sound pressure distribution in the oil caused by the vibration of the iron core transmitted to the winding.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and particularly to a multi-scale simulation modeling method for transformer vibration noise. Background Art

[0002] Power transformers are key equipment for power transmission and distribution in the power grid, and are widely distributed in energy-rich areas and densely populated areas. With the increase in transmission voltage levels and transmission power, especially the influx of a large number of harmonics, transformers are correspondingly subjected to the driving force generated by harmonics, resulting in vibrations and noises with rich frequency contents. Field test results show that harmonic currents can cause the vibration acceleration of transformers to exceed 10 m / s 2 , the sound power increases by 1 - 24 dB, and the overall sound power level exceeds 100 dB(A), making it difficult for the substation boundary noise to meet the day-night sound pressure level requirements for Class I and Class II areas specified in GB12348 - 2008. On the other hand, mechanical defects such as loosening, wear, and fatigue will occur in the internal structure of transformers under the influence of long-term severe vibrations, affecting the operation reliability. Therefore, whether from the perspective of meeting environmental protection requirements or from the perspective of improving equipment design levels and operation safety, in-depth understanding of the vibration characteristics and noise distribution of transformers is of great significance for designing low-noise transformers and improving the service characteristics of transformers.

[0003] In the prior art, usually an empirical formula based on statistics is used to determine the radiated sound pressure level of a transformer according to the capacity, core working magnetic flux density, and size of the transformer, or a finite element model is used to simulate and calculate the no-load and load noises of the transformer. When using the finite element method, most researchers directly simplify the winding into a cylindrical model as shown in Figure 1 to study its modal characteristics and vibration responses. However, the cylindrical model greatly increases the overall stiffness of the winding, and the vibration of the core is transmitted to the winding disks, causing the disks to vibrate and radiate sound pressure outward. Since the cylindrical winding does not conform to the actual structure of the disk winding, its natural frequency is higher than that of the real winding, and the radiation surface area is smaller than that of the real winding, so it is not representative.

[0004] The axial structure of the winding is composed of insulating materials and coil laminations. The axial structure composed of "soft materials" and "hard coils" makes the axial modal frequency of the winding relatively low, and it is easy to approach the excitation frequency of the electromagnetic force and resonate. Since the 1960s, the mass-spring-damping model of winding axial vibration has been widely used. In this model, the winding disks are regarded as rigid bodies, with the same vibration acceleration at each part of the disks, and the pads between the disks are regarded as parallel springs and dampers. A two-dimensional finite element model can be used to simulate the dynamic characteristics of the above-mentioned winding, and combined with magnetic field simulation to calculate the vibration responses of each disk and the sound pressure distribution in the oil.

[0005] The above information disclosed in the background section is only used to enhance the understanding of the background of the present invention, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0006] The object of the present invention is to provide a multi-scale simulation modeling method for transformer vibration noise to achieve accurate analysis of transformer vibration noise.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A multi-scale simulation modeling method for transformer vibration noise of the present invention includes:

[0009] Collect transformer parameters to establish a two-dimensional axisymmetric model of the winding and a three-dimensional finite element model of the iron core and the oil tank. The two-dimensional axisymmetric model and the three-dimensional finite element model are constructed into a vibration coupling model including the iron core and the winding via a shared boundary. Among them, the two-dimensional axisymmetric model of the winding includes the iron core, high-voltage winding discs, low-voltage winding discs, regulating winding discs, spacers, and the sound pressure contour surface outside the winding. The three-dimensional finite element model of the iron core and the oil tank includes the iron core contour surface, clamping piece contour surface, and sound pressure contour surface. The transformer parameters include the geometric parameters of the iron core, winding, and oil tank, as well as sound pressure data;

[0010] Extract the average axial displacement at the upper end and the average axial displacement at the lower end of the high-voltage winding discs, low-voltage winding discs, and regulating winding discs of the two-dimensional axisymmetric model as the shared boundary conditions of the three-dimensional finite element model. Extract the sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model. After coordinate transformation, the sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model is mapped to the sound pressure on the sound pressure contour surface in the three-dimensional model;

[0011] Based on the sound pressure on the sound pressure contour surface in the three-dimensional model, simulate and calculate the magnetostriction of the iron core to obtain the time-domain calculation result of magnetostriction. The control equation of magnetostriction is:

[0012]

[0013] where ε me is the free strain, λ s is the saturation magnetostriction coefficient, M is the magnetization intensity vector, dev is the tensor operator. Perform a fast Fourier transform on the time-domain calculation result of magnetostriction to obtain the iron core deformation displacement distribution at different frequencies;

[0014] Extract the 100Hz multiple frequency component of the iron core deformation displacement based on the iron core deformation displacement distribution and apply it to the iron core of the three-dimensional model. Perform frequency response analysis on the two-dimensional axisymmetric model and the three-dimensional finite element model, and calculate the winding vibration and the sound pressure distribution in the oil caused by the vibration of the iron core transmitted to the winding.

[0015] In the multi-scale simulation modeling method of transformer vibration and noise, in the vibration coupling model, the mechanical connection between the iron core and the winding is the parallel connection of two springs.

[0016] In the multi-scale simulation modeling method of transformer vibration and noise, the average axial displacement at the upper end or the average axial displacement at the lower end is where L i is the radial width of the winding, and w is the displacement of a point on the winding boundary.

[0017] In the above technical solution, the multi-scale simulation modeling method of transformer vibration and noise provided by the present invention has the following beneficial effects: The multi-scale simulation modeling method of transformer vibration and noise described in the present invention uses a two-dimensional axisymmetric model to characterize winding vibration and a three-dimensional finite element model to characterize iron core vibration. The mechanical connection between the iron core and the winding is regarded as the parallel connection of two springs, sharing the boundary, so as to construct a vibration coupling model including the iron core and the winding, and realize the accurate analysis of transformer vibration and noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings.

[0019] Figure 1 It is a schematic diagram of the two-dimensional model of the multi-scale simulation modeling method of transformer vibration and noise in the present invention;

[0020] Figure 2 It is a schematic diagram of the three-dimensional model of the multi-scale simulation modeling method of transformer vibration and noise in the present invention;

[0021] Figure 3 It is a radial structure diagram of the winding of the multi-scale simulation modeling method of transformer vibration and noise in the present invention;

[0022] Figures 4(a) to 4(b) It is a schematic diagram of the time-domain waveform of the displacement generated by magnetostriction at a point in the A, B, and C columns of the iron core of the multi-scale simulation modeling method of transformer vibration and noise in the present invention;

[0023] Figures 5(a) to 5(c) It is a schematic diagram of the displacements at 100 Hz, 200 Hz, and 300 Hz caused by magnetostriction of the iron core in the multi-scale simulation modeling method of transformer vibration and noise in the present invention;

[0024] Figures 6(a) to 6(c)Schematic diagram of winding vibration displacement caused by the vibration of the iron core at different frequencies in the multi-scale simulation modeling method of transformer vibration noise in the present invention;

[0025] Figures 7(a) to 7(c) Schematic diagram of sound pressure generated in oil by the winding vibration caused by the vibration of the iron core at different frequencies in the multi-scale simulation modeling method of transformer vibration noise in the present invention;

[0026] Figures 8(a) to 8(b) The sound pressure mapped from the sound pressure contour surface of the two-dimensional axisymmetric model to the sound pressure contour surface of the three-dimensional model. Detailed implementation manners

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the appendices Figures 1 to 8(b) is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0032] In the present invention, unless otherwise clearly specified and defined, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0034] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. As Figures 1 to 8(b) shown, a multi-scale simulation modeling method for transformer vibration noise includes

[0035] collecting transformer parameters to establish a two-dimensional axisymmetric model of the winding and a three-dimensional finite element model of the iron core and the oil tank, and constructing a vibration coupling model including the iron core and the winding through a shared boundary by the two-dimensional axisymmetric model and the three-dimensional finite element model. Among them, the two-dimensional axisymmetric model of the winding includes the iron core, high-voltage winding disks, low-voltage winding disks, regulating winding disks, spacers, and a sound pressure contour surface outside the winding, and the three-dimensional finite element model of the iron core and the oil tank includes an iron core contour surface, a clamping piece contour surface, and a sound pressure contour surface. The transformer parameters include the geometric parameters of the iron core, the winding, and the oil tank, as well as sound pressure data.

[0036] Extract the average axial displacements at the upper ends and lower ends of the high-voltage winding disks, low-voltage winding disks, and regulating winding disks of the two-dimensional axisymmetric model as the shared boundary conditions of the three-dimensional finite element model. Extract the sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model. After coordinate transformation, the sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model is mapped to the sound pressure on the sound pressure contour surface in the three-dimensional model.

[0037] Based on the sound pressure on the sound pressure contour surface in the three-dimensional model, simulate the magnetostriction of the iron core to obtain the time-domain calculation results of magnetostriction. The control equation of magnetostriction is:

[0038]

[0039] where ε me is the free strain, λ s is the saturation magnetostriction coefficient, M is the magnetization intensity vector, dev is the tensor operator. Perform a fast Fourier transform on the time-domain calculation results of magnetostriction to obtain the distribution of the iron core deformation displacement at different frequencies. Further, the magnetization intensity vector is calculated in the finite element and has three components: Mx, My, and Mz. When approaching saturation, the modulus of the magnetization vector M approaches the saturation magnetization intensity Ms.

[0040] Extract the 100Hz multiple-frequency component of the iron core deformation displacement based on the iron core deformation displacement distribution and apply it to the iron core of the three-dimensional model. Perform frequency response analysis on the two-dimensional axisymmetric model and the three-dimensional finite element model to calculate the winding vibration and the sound pressure distribution in the oil caused by the vibration of the iron core transmitted to the winding.

[0041] In the multi-scale simulation modeling method for transformer vibration and noise described above, in the vibration coupling model, the mechanical connection between the iron core and the winding is the parallel connection of two springs.

[0042] In the multi-scale simulation modeling method for transformer vibration and noise described above, the average axial displacement at the upper end or the lower end is where Li is the radial width of the winding and w is the displacement of a point on the winding boundary.

[0043] In one embodiment, the multi-scale calculation model for transformer vibration and noise includes an axisymmetric model representing the winding magnetic field and structural dynamics, a three-dimensional model representing the iron core magnetic field and dynamics, and a three-dimensional dynamics and acoustic model of the oil tank. By sharing the boundary conditions of the two-dimensional and three-dimensional models at different scales, jointly solve the two-dimensional winding model with the iron core three-dimensional model in units of winding disks to calculate the sound field near the winding in units of winding disks, so as to accurately solve the vibration and noise of the transformer.

[0044] In one embodiment, a two-dimensional axisymmetric model of the transformer winding is established based on the transformer core and winding parameters, and a three-dimensional finite element model of the core and the oil tank. The established models are as shown in Figure 1 and Figure 2 shown. Figure 1 is the established transformer winding model, including the core, high, low, regulating winding discs, spacers, and the external transformer oil area. Figure 2 is the three-dimensional model of the core, clamping parts, sound pressure contour surface, and sound pressure.

[0045] Extract Figure 1 the average axial displacements W of the upper and lower ends of the high, low, and regulating windings in 上 / 下 , denoted as the shared boundary condition, which can be specifically expressed as:

[0046]

[0047] where Li is the radial width of the winding, and w is the displacement of a point on the winding boundary.

[0048] Extract Figure 1 the average axial displacements W of the upper and lower ends in 上 / 下 and add them to the upper and lower shared boundaries of the three-dimensional model. The upper shared boundary is the lower bottom surface of component 1-12, and the lower shared boundary is the upper bottom surface of component 13-24.

[0049] Extract Figure 1 the sound pressure on the sound pressure contour surface outside the winding in

[0050]

[0051] denoted as p(r, z), where (r, z) is the coordinate of a point in the two-dimensional axisymmetric (cylindrical coordinate system). Perform a coordinate transformation on p(r, z): A , 0), (a B , 0), and (a C , 0). After the coordinate transformation, the sound pressure contour of the two-dimensional winding is mapped onto the cylinder in the three-dimensional model. According to the phase difference existing in the vibration of the three-phase windings, when mapping the sound pressure contour surface in the two-dimensional model to the three-dimensional model, it is necessary to correct the phases of each phase of ABC. The correction method is as follows:

[0052]

[0053] where p A , p B and p C are respectively the sound pressures at the center positions of (a A, 0), (a B , 0) and (a C , 0) on the sound pressure contour surface of the sound pressure.

[0054] The spacer in the two-dimensional axisymmetric model means that the spacer is the entire ring, and the contact area between the spacer and the winding disk in the winding is increased as shown in Figure 2 . Therefore, the Young's modulus and density of the spacer need to be corrected according to the actual number and width of the spacers. The correction coefficient is:

[0055]

[0056] Among them, N and A are the number and area of the circumferential spacers of the winding respectively, r1 and r2 are the outer diameter and inner diameter of the winding respectively, and the Young's modulus and density of the spacers in the two-dimensional model are set to be 1 / k times of the true values. The true elastic modulus of the spacer is:

[0057]

[0058] Among them, a = 830 MPa, b = 1.432, σ is the pressing force of the winding, and the value range is 2.0 MPa - 3.0 MPa.

[0059] Figure 1 and Figure 2 The material parameters of each region in

[0060]

[0061] are shown in Table 1. Among them, the magnetization intensity M curve in the non-linear BH of the iron core adopts the form of the Langevin function: s , H is the magnetic field strength.

[0062] Table 1 Material parameters of each region

[0063]

[0064] When using the above model for the vibration and noise simulation calculation of the transformer, first, the field-circuit coupling method is used to jointly calculate the 100 ms time-domain variation law of the magnetostriction of the iron core by structural mechanics. The control equation of the magnetostriction is:

[0065]

[0066] Among them, ε me is the free strain, λ s is the saturation magnetostriction coefficient, M is the magnetization intensity vector. dev is the tensor operator.

[0067] For Figures 4(a) to 4(b)Perform a fast Fourier transform on the time-domain calculation results of magnetostriction shown, to obtain the core deformation displacement distributions at different frequencies, as Figures 5(a) to 5(c) shown.

[0068] Extract the 100Hz, 200Hz and other 100Hz multiple frequency components of the core displacement, and apply the core displacement to the core of the three-dimensional model as Figure 2 shown. Conduct a frequency response analysis on the three-dimensional and two-dimensional winding axisymmetric models, and calculate the winding vibration and the sound pressure distribution in oil caused by the core vibration transmitted to the winding, as shown in Figures 6(a) to 6(c) and Figures 7(a) to 7(c) shown respectively.

[0069] Map the sound pressure contour surface calculated by the two-dimensional axisymmetric model into the three-dimensional model. The sound pressure contour surface in the three-dimensional model forms a sound pressure in the transformer tank as the equivalent sound source of the winding, transmitting vibration.

[0070] Finally, it should be noted that: the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0071] Some exemplary embodiments of the present invention have been described above only by way of illustration. Undoubtedly, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the protection scope of the claims of the present invention.

Claims

1. A multi-scale simulation modeling method for transformer vibration noise, characterized in that, It includes the following steps: Collect transformer parameters to establish a two-dimensional axisymmetric model of the winding and a three-dimensional finite element model of the iron core and the oil tank. The two-dimensional axisymmetric model and the three-dimensional finite element model are constructed into a vibration coupling model including the iron core and the winding through a shared boundary. Among them, the two-dimensional axisymmetric model of the winding includes the iron core, high-voltage winding disks, low-voltage winding disks, regulating winding disks, spacers, and the sound pressure contour surface outside the winding. The three-dimensional finite element model of the iron core and the oil tank includes the iron core contour surface, clamping piece contour surface, and sound pressure contour surface. The transformer parameters include the geometric parameters of the iron core, winding, and oil tank, as well as sound pressure data; Extract the average axial displacements of the upper ends and lower ends of the high-voltage winding disks, low-voltage winding disks, and regulating winding disks of the two-dimensional axisymmetric model as the shared boundary conditions of the three-dimensional finite element model. Extract the sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model. After coordinate transformation, the sound pressure on the sound pressure contour surface of the two-dimensional axisymmetric model is mapped to the sound pressure on the sound pressure contour surface in the three-dimensional model; Based on the sound pressure on the sound pressure contour surface in the three-dimensional model, simulate and calculate the magnetostriction of the iron core to obtain the time-domain calculation result of the magnetostriction. The control equation of the magnetostriction is: where ε me is the free strain, λ s is the saturation magnetostriction coefficient, M is the magnetization intensity vector, dev is the tensor operator, and the time-domain calculation result of magnetostriction is subjected to a fast Fourier transform to obtain the core deformation displacement distribution at different frequencies; Based on the iron core deformation displacement distribution, extract the 100Hz frequency doubling component of the iron core deformation displacement and apply it to the iron core of the three-dimensional model. Perform frequency response analysis on the two-dimensional axisymmetric model and the three-dimensional finite element model, and calculate the winding vibration caused by the vibration of the iron core transmitted to the winding and the sound pressure distribution in the oil.

2. A multi-scale simulation modeling method for transformer vibration noise according to claim 1, characterized in that, In the vibration coupling model, the mechanical connection between the iron core and the winding is the parallel connection of two springs.

3. A multi-scale simulation modeling method for transformer vibration noise according to claim 1, characterized in that, The average axial displacement of the upper end or the average axial displacement of the lower end is where L i is the radial width of the winding, and w is the displacement of a point on the winding boundary.

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