Transformer direct-current bias vibration and noise evaluation method, system, equipment and medium

Abstract

The invention relates to the technical field of transformers, and discloses a transformer DC bias vibration and noise evaluation method, system and device and a medium, and the method comprises the steps: building a multi-physics field coupling analysis model comprising an electromagnetic field, structural mechanics and acoustics based on key parameters of a target transformer, and configuring an inter-field coupling relation in the model; constructing a field-circuit combined driving source of the target transformer under a direct current bias working condition, inputting the field-circuit combined driving source into the analysis model for transient electromagnetic structure coupling solution, obtaining a structure vibration response, converting the structure vibration response into a boundary condition through an inter-field coupling relationship, and inputting the structure vibration response into the analysis model for acoustic transient solution to obtain an acoustic response; obtaining harmonic distribution of the target transformer and a structural inherent frequency of the target transformer in a frequency domain to determine a modal harmonic overlap ratio, and determining a vibration and noise grading evaluation result of the target transformer in combination with a structural vibration response and an acoustic response; and the vibration and noise of the transformer are accurately evaluated by adopting a step-by-step coupling calculation strategy.

Description

Technical Field

[0001] This invention relates to the field of transformer technology, and in particular to a method, system, device and medium for assessing DC bias vibration and noise in transformers. Background Technology

[0002] Transformers are one of the key pieces of equipment in power transmission projects. Their safe and stable operation largely determines the reliability and power quality of the power system. However, existing transformers exhibit abnormal electromagnetic vibrations and noise during operation, especially under DC bias conditions. Traditional assessment methods for this phenomenon mainly rely on single-physical-field analysis, such as structural mechanics modal analysis or separate electromagnetic field calculations. This makes it difficult to accurately predict the vibration amplitude, frequency characteristics, and noise distribution of transformers under DC bias conditions, failing to meet the needs of high-precision operational assessment and risk warning.

[0003] Therefore, how to solve the problem that the vibration amplitude, frequency characteristics and noise distribution of transformers are difficult to predict accurately in the existing technology, and that it is difficult to meet the needs of high-precision operation assessment and risk warning, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a method, system, device, and medium for assessing DC bias vibration and noise in transformers, solving the problem that in the prior art, it is difficult to accurately predict the vibration amplitude, frequency characteristics, and noise distribution of transformers, and it is difficult to meet the needs of high-precision operation assessment and risk warning.

[0005] To address the aforementioned technical problems, this invention provides a method for evaluating DC bias vibration and noise in transformers, comprising: The key parameters of the target transformer are obtained, and a multiphysics coupling analysis model including electromagnetic field, structural mechanics and acoustics is constructed based on the key parameters. In the multiphysics coupling analysis model, the coupling relationship between fields is configured based on the energy transfer rules between the multiphysics fields; Obtain the harmonic distribution of the target transformer and its structural natural frequency in the frequency domain, and construct the field-circuit joint drive source of the target transformer under DC bias conditions; Under the DC bias condition, based on the field coupling relationship, the field-circuit joint driving source is input into the multi-physics field coupling analysis model to perform transient electromagnetic structure coupling solution, and the structural vibration response is obtained as the boundary condition input into the multi-physics field coupling analysis model to perform acoustic transient solution, and the acoustic response is obtained. The modal harmonic overlap of the target transformer is determined based on the natural frequency of the structure and the harmonic distribution. In combination with the structural vibration response and the acoustic response, the vibration and noise classification assessment results of the target transformer are determined.

[0006] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows: This system can comprehensively consider the interactions and influences between multiple physical fields during transformer operation to construct an electromagnetic-mechanical-acoustic coupled analysis model, reconstructing the entire process of vibration and noise "source-transmission-result," and solving the problem of inaccurate prediction by single-physical-field analysis. Based on the energy transfer rules between multiple physical fields, the system configures the inter-field coupling relationships, making the interactions between different physical fields in the model more consistent with actual physical laws, ensuring accurate energy exchange and information transmission between physical fields during simulation, and improving the reliability and accuracy of the model analysis results. Furthermore, by obtaining the harmonic distribution of the target transformer and its structural natural frequencies in the frequency domain, and constructing its field-circuit joint under DC bias conditions, the system can effectively address these issues. The driving source can more realistically simulate the transformer's operation under complex actual conditions, providing a basis for optimized design and operation. Employing a frequency-transient domain step-by-step coupling calculation strategy to efficiently solve multiphysics problems helps in-depth analysis of the transformer's dynamic characteristics under different physical fields and multiphysics coupling effects. By comprehensively considering the transformer's structural characteristics, excitation characteristics during operation, and actual vibration and noise responses, it can scientifically and objectively classify and evaluate the transformer's vibration and noise levels, providing clear and targeted guidance for transformer design optimization, operation and maintenance, and noise control, thus contributing to improved transformer operational reliability and environmental friendliness. Attached Figure Description

[0007] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. 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.

[0008] Figure 1 This is a flowchart of a method for evaluating DC bias vibration and noise of a transformer according to a certain embodiment of the present invention; Figure 2 This is a simplified sound field calculation model diagram provided in a certain embodiment of the present invention; Figure 3 This is a modal shape distribution diagram provided in a certain embodiment of the present invention; Figure 4 This is an excitation current diagram under different DC contents provided in a certain embodiment of the present invention; Figure 5This is a spectrum diagram of excitation current under different DC contents provided in a certain embodiment of the present invention; Figure 6 This is a force distribution characteristic diagram of the reactor core under different DC contents provided in a certain embodiment of the present invention; Figure 7 This is a force distribution characteristic diagram of the winding under different DC contents provided in a certain embodiment of the present invention; Figure 8 This is a diagram showing the deformation distribution characteristics of a reactor core under different DC contents according to a certain embodiment of the present invention; Figure 9 This is a diagram showing the deformation distribution characteristics of windings under different DC contents according to a certain embodiment of the present invention; Figure 10 This is a sound pressure level distribution diagram of a transformer with different DC contents provided in a certain embodiment of the present invention; Figure 11 This is a time-frequency distribution diagram of the sound pressure of a transformer under different DC contents provided in a certain embodiment of the present invention; Figure 12 This is a structural diagram of a transformer DC bias vibration and noise assessment system provided in a certain embodiment of the present invention; Figure 13 This is a structural diagram of an electronic device provided in a certain embodiment of the present invention; Figure label: Among them, 10 is the model building module; 20 is the relationship coupling module; 30 is the driver source building module; 40 is the model solving module; 50 is the result evaluation module; 5000 is the electronic equipment; 5001 is the processor; 5002 is the bus; 5003 is the memory; and 5004 is the transceiver. Detailed Implementation

[0009] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0010] In this invention description, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In this invention description, unless otherwise stated, "a plurality of" means two or more. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art will understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0011] In the description of this invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is merely for describing specific embodiments and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0012] In one embodiment, such as Figure 1 As shown, the first aspect of the present invention provides a method for evaluating DC bias vibration and noise in a transformer, comprising: S1. Obtain the key parameters of the target transformer and construct a multiphysics coupled analysis model including electromagnetic field, structural mechanics, and acoustics based on the key parameters. Specifically, sensors and other devices are used to collect the structural parameters, operating parameters, and material properties of the target transformer in real time as its key parameters. Among them, material properties include the relative permeability, Poisson's ratio, Young's modulus, sound velocity, and density of the windings, core, and transformer oil; structural parameters include the geometry of the core, winding arrangement, and tank structure; operating parameters include rated capacity, rated voltage, short-circuit impedance, connection group, and cooling method. Subsequently, these collected key parameters are preprocessed, such as cleaning, to improve data accuracy.

[0013] In one embodiment, constructing a multiphysics coupling analysis model encompassing electromagnetic fields, structural mechanics, and acoustics based on the key parameters includes: Based on the key parameters, a finite element dynamics model is adopted and the structural response of the target transformer is described in matrix form to obtain a structural mechanics subdomain model. Based on the key parameters, the Maxwell equations are discretized using the finite element method to obtain the electromagnetic field subdomain model; Based on the aforementioned key parameters, the sound field propagation of the target transformer is described by equations of motion, continuity, and state. Then, the Helmholtz equation is solved using the variable separation method to generate an acoustic subdomain model. The structural mechanics subdomain model, the electromagnetic field subdomain model, and the acoustic subdomain model are combined to obtain the multiphysics coupling analysis model.

[0014] Specifically, this invention establishes three sub-domain models—electromagnetic field, structural mechanics, and acoustics—based on the key parameters of the target transformer and integrates them into a multi-physics field coupled analysis model to cover the entire physical process of transformer vibration and noise.

[0015] This invention, based on key parameters such as structural parameters (core geometry, winding arrangement, tank structure) and material properties (Poisson's ratio, Young's modulus, density), constructs a structural mechanics subdomain using a finite element dynamics model. First, a 3D modeling tool (such as the CAD module in finite element software) is used to discretize the transformer's solid structure into a finite number of elements, forming a computational grid (e.g., windings, core, and tank). Based on the material density and element volume of each computational grid, an overall mass matrix is ​​assembled. Based on the Young's modulus and Poisson's ratio of each computational grid, an overall stiffness matrix is ​​assembled. A Rayleigh damping model is used to construct the overall damping matrix, with an interface reserved for coupling with the electromagnetic field to receive electromagnetic force loads. Finally, based on the formed data matrices and a finite element dynamics model, the structural response of the target transformer is described, resulting in a structural mechanics subdomain model, which is expressed by the following equation: Mu''+Cu'+Ku=Q(t) In the formula, u'', u', and u are the nodal acceleration vector (unit: m / s²), velocity vector (unit: m / s), and displacement vector (unit: m), respectively; M is the mass matrix (unit: kg); C is the damping matrix (unit: kg / s); K is the stiffness matrix (unit: N / m); Q(t) is the load vector (unit: N); and t is time (unit: s). It should also be noted that the calculation process of each matrix in the structural mechanics subdomain model construction can refer to the calculation of the corresponding matrix in existing technologies, and will not be elaborated upon here.

[0016] The geometric model of the electromagnetic field subdomain needs to focus on key electromagnetic components such as the core, windings, and transformer oil, ignoring redundant structures with non-electromagnetic effects (such as heat sinks) to ensure a balance between computational efficiency and accuracy. This involves extracting the geometric parameters of core components in the transformer, such as the core, windings, and oil gap; using 3D modeling tools to proportionally reconstruct these structures, forming a closed geometric domain of "core + windings + oil gap," and refining the mesh (e.g., 5mm element size) in areas with large magnetic field gradients (such as core corners and winding conductor surfaces), while using coarser meshes (e.g., 20mm element size) in areas with gentle magnetic fields, such as the oil gap. Simultaneously, the mesh continuity of the contact surface between the core and windings must be ensured (to avoid discrepancies at the coupling interface). Based on practical considerations, specific electromagnetic parameters are assigned to different components in the geometric model, such as relative permeability (determined by inputting hysteresis loop data for the core, preferably 0.98 for the windings, and preferably 1.75 for the transformer oil), and conductivity (preferably...). The preferred winding size is 5.8×10. 7 S / m), magnetostriction coefficient (input the magnetostriction curve of the silicon steel sheet, such as the maximum magnetostriction strain). To simulate the differences in electromagnetic characteristics of each component, circuit models for the high-voltage and low-voltage sides are constructed based on transformer connection groups (e.g., YNd11): the high-voltage side adopts a star connection with a neutral point grounded; the low-voltage side adopts a delta connection, with power supply (simulating grid voltage, including a 50Hz power frequency component + DC bias component), winding equivalent resistance (calculated based on conductor length and cross-section), and leakage reactance (temporarily estimated by circuit parameters, to be iteratively corrected later with field coupling). The conductor ends of the windings are connected to the nodes of the external circuit, defining the "current loading boundary": the high-voltage winding is connected to an AC power supply with DC bias (e.g., voltage 110kV, DC component K). dc =0.35 / 0.85 / 1.25), the low-voltage winding is defined as no-load or load according to the operating conditions (e.g., the low-voltage side is open when no-load), so that the current of the external circuit is input to the winding through the interface, driving the electromagnetic field subdomain to generate magnetic flux. The winding induced electromotive force calculated by the field domain is fed back to the circuit to correct the voltage distribution in the circuit, realizing the bidirectional coupling of "field driving the circuit, and the circuit reacting to the field", ensuring that the excitation source conforms to the actual operating conditions; the above geometric, material, and coupling relationships are transformed into a solvable finite element equation system using the finite element method. Its core is the low-frequency magnetic field simplification form of Maxwell's equations, that is, for the transformer power frequency (50Hz) and DC bias conditions, the magnetic field is mainly composed of constant magnetic field and eddy current magnetic field. The magnetic vector potential A method is used to simplify Maxwell's equations, and the geometric domain is divided into a finite number of elements. The control equations are discretized by the weighted residual method to obtain the matrix form to construct the electromagnetic field subdomain model, which is expressed by the following formula: K m ×A=I e In the formula, A is the magnetic vector potential (unit: Wb / m); μ is the magnetic permeability (unit: H / m); J is the current density (unit: A / m²); D is the displacement current (unit: A / m²); I e K is the current vector (unit: A); m Let be the system matrix (obtained by finite element discretization, with dimensions A·m / Wb), representing the coefficient matrix of the electromagnetic field.

[0017] Based on the acoustic material properties (sound velocity, density) and transformer geometry among the key parameters, the sound field propagation of the target transformer is described by the fundamental acoustic equations—the equation of motion describing the relationship between sound pressure and particle velocity, the continuity equation describing the conservation of mass, and the state equation describing the relationship between sound pressure and density increment. These equations are expressed as follows: In the formula, ρ Density increment (unit: kg / m³); v Particle velocity (unit: m / s); p Sound pressure level (unit: Pa); q Volumetric productivity of fluid (unit: 1 / s); c Speed ​​of sound (unit: m / s); s Entropy (unit: J / (kg·K)).

[0018] Combining the above three equations, we obtain the sound wave equation, which is expressed by the following formula: In the formula, ρ0 is the equilibrium density of the fluid (unit: kg / m³).

[0019] For frequency domain analysis, the variable separation method is used, with the following assumptions: p(x,y,z,t)=P(x,y,z)e jωt In the formula, P is the complex sound pressure amplitude (unit: Pa); ω is the angular frequency (unit: rad / s), used to describe the speed of sound wave oscillation.

[0020] Substituting the above variables into the acoustic wave equation yields the Helmholtz equation, also known as the acoustic subdomain model, which is expressed by the following equation: k=ω / a In the formula, k is the wave number (unit: rad / m); q0 is the external volume productivity amplitude acting on the fluid (unit: 1 / s). a The velocity of sound waves in a fluid (unit: m / s).

[0021] By organically combining the three subdomain models through physical coupling interfaces, a complete multiphysics coupling analysis model can be formed. The physical coupling interfaces include an electromagnetic-structural coupling interface: mapping the magnetostrictive force and Lorentz force obtained from electromagnetic field calculations to structural mesh nodes, adding the electromagnetic force as a volume force to the load term on the right side of the structural dynamics equations, and ensuring geometric consistency between the electromagnetic mesh and the structural mesh at the coupling interface; and a structural-acoustic coupling interface: mapping the vibration velocity of the structural surface to the acoustic boundary mesh, using the structural vibration velocity as the Neumann boundary condition of the acoustic subdomain, and considering the impedance characteristics of the fluid-structure interface.

[0022] This invention avoids the limitations of traditional single-physics field analysis by simultaneously considering the complete physical chain of electromagnetic excitation, structural response, and acoustic radiation. This enables the constructed model to accurately capture the complete energy conversion process from electromagnetic energy to mechanical energy and then to acoustic energy, ensuring the physical authenticity of the analysis results. The multi-physics field coupling model can fully consider the interaction effects between various physical fields. The modeling adopts a strategy of domain-based modeling and recombination, which can optimize the utilization of computational resources while ensuring accuracy.

[0023] S2. In the multiphysics coupling analysis model, the inter-field coupling relationship is configured based on the energy transfer rules between multiphysics fields; In one embodiment, step S2 includes: In the multiphysics coupling analysis model, the subdomains corresponding to the electromagnetic field, the structural mechanics and the acoustics are delineated to obtain the electromagnetic-structural coupling interface and the structural-acoustic coupling interface. Based on the electromagnetic structure coupling interface, the electromagnetic structure coupling relationship is configured according to the first energy transfer rule between the electromagnetic field and the structural mechanics. Based on the structural acoustic coupling interface, the structural acoustic coupling relationship is configured through the second energy transfer rule between the structural mechanics and the acoustics; The electromagnetic structural coupling relationship and the structural acoustic coupling relationship are combined to obtain the inter-field coupling relationship.

[0024] Specifically, for multiphysics coupling analysis models, it is necessary to define the interface ranges of the three major subdomains and clarify the coupling logic to ensure that the energy transfer from electromagnetic force to structural vibration to noise radiation conforms to physical laws. Geometric identification is used to identify the boundaries of each subdomain model, and the shared portions are extracted as coupling interfaces. For electromagnetic and structural mechanical fields, the shared geometric regions include the iron core and windings. In these regions, the electromagnetic force calculated by the electromagnetic field is transferred to the structural mechanical field as a load. Therefore, the shared geometric regions of electromagnetic and structural mechanical fields are the electromagnetic-structural coupling interfaces. For structural mechanical and acoustic fields, the shared boundaries include the outer surface of a transformer tank. On these boundaries, the vibration velocity or displacement calculated by the structural mechanical field is used as the boundary condition of the acoustic field. Therefore, the shared boundaries of structural mechanical and acoustic fields are the structural-acoustic coupling interfaces.

[0025] In the electromagnetic structure coupling interface, based on the first energy transfer rule between the electromagnetic field and structural mechanics—the electromagnetic field transfers energy to the structural mechanics field through electromagnetic forces (including magnetostrictive force and Lorentz force)—the magnetostrictive force and Lorentz force calculated by the electromagnetic field are transferred to the corresponding boundary nodes of the structural mechanics subdomain through the finite element interface. The energy transfer relationship corresponding to the external load driving the structural vibration to generate displacement and stress response is taken as the electromagnetic structure coupling relationship.

[0026] In the structural acoustic coupling interface, based on the second energy transfer rule between structural mechanics and acoustics—that the structural mechanical field transfers energy to the acoustic field through vibration—the vibration velocity / acceleration of the structural surface is directly applied as the boundary condition of the acoustic subdomain (such as the vibration velocity of the oil tank input to the sound field model, etc.) to the acoustic subdomain. This is used to calculate the energy transfer relationship corresponding to the sound field distribution as the structural acoustic coupling relationship.

[0027] Combining the above electromagnetic structural coupling relationship and structural acoustic coupling relationship forms a complete inter-field coupling relationship, which allows energy to be transferred from the electromagnetic field to the structural mechanical field, and then to the acoustic field, forming a complete coupling chain.

[0028] This invention ensures that the interactions between various physical fields strictly follow the laws of physical conservation by clearly defining the coupling interface and configuring physical energy transfer rules, thus avoiding physical inconsistencies introduced by the simplification of coupling relationships in traditional methods. The separate coupling interface design and clear energy transfer path effectively prevent energy "leakage" or non-physical reflection phenomena in numerical calculations. At the same time, based on the coupling relationship settings of the boundary division results, sequential driving and energy transfer between electromagnetic, mechanical, and acoustic multi-physics fields are realized, thereby ensuring the physical consistency of the calculation process and the traceability of the results.

[0029] S3. Obtain the harmonic distribution of the target transformer and its structural natural frequency in the frequency domain, and construct the field-circuit joint drive source of the target transformer under DC bias conditions. In one embodiment, step S3 includes: Configure frequency domain solution conditions to perform passive characteristic frequency solutions on the target transformer as a whole, core and winding respectively based on the structural mechanics subdomain model, and obtain the structural natural frequency of the target transformer in the frequency domain. The excitation current data of the target transformer is collected, and the spectrum analysis of the excitation current data is performed to obtain the harmonic distribution. The composite excitation source is constructed by combining the power frequency component and the DC bias component of the target transformer under the DC bias condition. The composite excitation source is coupled with the external equivalent circuit of the electromagnetic field subdomain model to form the field-circuit joint driving source.

[0030] Specifically, this invention selects a frequency domain analysis step (e.g., 0.01s), sets the solution frequency range (typically covering the main possible vibration frequencies of the transformer, preferably 0-1000Hz), and defines a convergence tolerance (preferably...). The maximum number of iterations is calculated. Based on the structural mechanics subdomain model, the passive characteristic frequency solution (i.e., only considering solid mechanical properties, without external load) is performed on the target transformer as a whole, core and winding respectively through modal analysis algorithm (such as subspace iteration method). The first few natural frequencies and mode shapes of each part are output so as to facilitate subsequent judgment on whether the harmonics coincide with the natural frequencies and cause resonance.

[0031] The time-domain data of the excitation current of the target transformer under DC bias conditions are obtained by experimental measurement or circuit simulation. The excitation current data is then subjected to Fast Fourier Transform (FFT) to obtain its frequency domain representation, i.e., harmonic distribution. The amplitude and phase of each harmonic are analyzed, and the excitation current is represented as the superposition of the power frequency component (fundamental 50Hz), harmonic components and DC bias components to construct a composite excitation source of power frequency + harmonic + DC.

[0032] In finite element method (FEM) software, an external circuit model of the transformer is constructed, including components such as voltage sources (or current sources), resistors, and inductors, and their parameters are set. A composite excitation source is assigned to the power supply in the external circuit (for example, a current source represents the magnetizing current, and its waveform is described by the composite excitation source). By associating the winding nodes in the circuit with the corresponding winding domains in the electromagnetic model, the external circuit is connected to the electromagnetic field subdomain model, enabling the transfer of current and voltage. In this way, the current in the circuit is applied as excitation to the windings of the electromagnetic field model, and the induced voltage on the windings is fed back to the circuit, forming a bidirectional coupled field-circuit joint driving source (if a voltage source excitation is used, then voltage is used as excitation and current as feedback).

[0033] This invention can accurately identify the natural frequencies of a transformer structure by solving for passive characteristic frequencies, thereby avoiding resonance in subsequent analysis and improving the operational reliability of the transformer. By analyzing the excitation current through spectrum, it can obtain the harmonic distribution including DC bias components, construct a composite excitation source, and more realistically simulate actual DC bias conditions, improving simulation accuracy. By using a field-circuit combined drive source, the external circuit is coupled with the electromagnetic field model, which can simultaneously consider the interaction between the circuit and the magnetic circuit, and calculate the electromagnetic field more accurately, thus providing accurate excitation for subsequent vibration and noise analysis.

[0034] S4. Under the DC bias condition, based on the field coupling relationship, the field-circuit joint driving source is input into the multi-physics field coupling analysis model to perform transient electromagnetic structure coupling solution, and the structural vibration response is used as the boundary condition input into the multi-physics field coupling analysis model to perform acoustic transient solution, and the acoustic response is obtained. In one embodiment, under the DC bias condition, based on the inter-field coupling relationship, the joint field-circuit driving source is input into the multi-physics coupling analysis model for transient electromagnetic structure coupling solution to obtain the structural vibration response, including: Under the DC bias condition, transient solution conditions are configured to input the field-circuit joint driving source into the electromagnetic field subdomain model for transient solution, and the electromagnetic force distribution over time is obtained as the electromagnetic field response. The electromagnetic field response is converted into a load through the electromagnetic structure coupling relationship, and the load is input into the structural mechanics subdomain model for transient solution based on the transient solution conditions to obtain the stress, displacement and acceleration that change with time as the vibration response of the structure. Based on a preset vibration criterion, it is determined whether the structural vibration response converges. If so, the electromagnetic field response and the structural vibration response are output as transient electromagnetic-structural coupling solution results. Otherwise, the transient solution conditions are adjusted once, and the solution process for the electromagnetic field subdomain model and the structural mechanics subdomain model are iteratively executed based on the adjusted transient solution conditions.

[0035] Specifically, under DC bias conditions, the excitation current of the target transformer is acquired, and the time step is determined based on the highest frequency component of the excitation current. Typically, at least 20 points are taken within one cycle, usually 1 / 100 to 1 / 200 of the power frequency cycle, such as 0.01s. The total time is configured to cover at least several power frequency cycles to ensure the transient process reaches stability, thus configuring the transient solution conditions. Subsequently, the field-circuit combined driving source is input as simulation conditions into the electromagnetic field subdomain model for transient solution, obtaining the electromagnetic force distribution over time as the electromagnetic field response. The time-varying current of "power frequency AC + DC bias" in the field-circuit joint drive source is used as the current in the winding, and this current is substituted into the electromagnetic field subdomain model as the excitation of the electromagnetic field. The solution is obtained iteratively according to the time step. Since the relationship between magnetic flux density B and magnetic vector potential A is... Then, by using the gradient operator of the finite element element, the nodal magnetic vector potential is transformed into a three-dimensional vector of magnetic flux density within the element, and the magnetic flux density distribution B(t) that varies with time is obtained. The Lorentz force is the force experienced by a current-carrying conductor in a magnetic field. It applies to windings (current-carrying components). At each time step, the winding current density (calculated from the excitation current and conductor cross-section) and magnetic flux density distribution B(t) of the winding unit are obtained. The cross product of the current density J×B(t) for each unit is calculated to obtain the unit Lorentz force density. The Lorentz force density of the entire winding is obtained by integrating the unit Lorentz force density, and its spatial distribution is output. Magnetostrictive force is the internal stress generated in the core material due to changes in magnetic flux density. At each time step, the magnetic flux density amplitude B(t) of the core unit is extracted. The magnetostrictive strain tensor is calculated based on the magnetostrictive strain-magnetic flux density relationship of the material (obtained by fitting material experimental data). The obtained magnetostrictive strain tensor is multiplied by the elastic coefficient matrix of the core material to obtain the stress tensor of the core unit. The stress tensor is then converted into magnetostrictive force density (the product of the stress tensor and the area is taken as the total force of the unit, and the total force of the unit is divided by the unit volume to obtain the total magnetostrictive force of the unit). Integrating the magnetostrictive force density yields the overall magnetostrictive force of the core, and its spatial distribution is output. Finally, the Lorentz force (winding) and magnetostrictive force (core) are discretized into finite element units to obtain the force vector (including magnitude and direction) of each unit at each time step. The calculation results of all time steps are integrated to obtain the electromagnetic force distribution over time, which is then output as the electromagnetic field response.

[0036] Based on the electromagnetic-structural coupling relationship, the electromagnetic force calculated in the electromagnetic field subdomain is transformed into the nodal load vector of the structural mechanics model. This vector is then mapped to the corresponding nodes of the structural mechanics subdomain using a shared mesh or interpolation method. The vector is then input into the structural mechanics subdomain model and solved using a direct integration method (such as the Newmark-β method) to obtain the displacement, velocity, and acceleration at each time step. Based on the calculated displacement results, the stress is derived using geometric equations and Hooke's law. Finally, a complete time-varying dataset of "displacement-velocity-acceleration-stress" is output as the structural vibration response.

[0037] Based on a preset vibration criterion (such as displacement change) If the stress fluctuation is less than 5%, the structural vibration response is judged to converge. If it does, the electromagnetic field response and the structural vibration response are output as the transient electromagnetic-structural coupling solution results. Otherwise, the transient solution conditions are adjusted once (e.g., the time step is reduced to one-third of the original, or the adjustment amount can be determined based on experiments or experience). The solution process of the electromagnetic field subdomain model and the structural mechanics subdomain model are iteratively executed based on the adjusted transient solution conditions until the final structural vibration response converges.

[0038] This invention, through transient solution, can fully capture the dynamic evolution of electromagnetic force and structural response under DC bias conditions, accurately reflecting the time-varying characteristics of nonlinear phenomena such as magnetic saturation and eddy current effects, and avoiding transient impacts and transition processes that may be missed in steady-state analysis. Employing a sequential coupling strategy ensures that the force density calculated from the electromagnetic field is accurately transferred to the structural field, fully considering the spatial non-uniformity and temporal variation characteristics of the force distribution, thus improving the physical realism of vibration response prediction. Through preset vibration criteria and an automatic adjustment mechanism, the numerical stability and reliability of the solution process are ensured, effectively addressing the common convergence difficulties in nonlinear coupled systems.

[0039] In one embodiment, the step of inputting the acoustic transient solution as boundary condition into the multiphysics coupling analysis model to obtain the acoustic response includes: The structural vibration response is transformed into the boundary conditions through the structural acoustic coupling relationship. Based on the transient solution conditions, the boundary conditions are input into the acoustic subdomain model for acoustic transient solution to obtain the sound pressure time history and spatial distribution as the acoustic response. Based on a preset noise criterion, it is determined whether the acoustic response has converged. If so, the acoustic response is output as the acoustic transient solution result. Otherwise, the transient solution conditions are adjusted a second time, and the solution process of the acoustic subdomain model is iteratively executed based on the adjusted transient solution conditions.

[0040] Specifically, this invention, based on the electromagnetic structure coupling relationship, applies the nodal normal displacement (or normal velocity) of the structural mechanical field at the coupling interface as acoustic field boundary conditions to the corresponding boundaries of the acoustic subdomain. Simultaneously, because the transformer radiated sound field is a "closed external sound field," two types of boundaries need to be set (closed boundary: tank surface; infinite boundary: hemispherical domain boundary). Based on the time step and total time in the transient solution conditions, the boundary conditions are input into the acoustic subdomain model for acoustic transient solution: the boundary conditions corresponding to the displacement are input into the element strain-displacement matrix composed of the shape function derivatives to obtain the single... Element strain; since the relationship between element stress and strain satisfies Hooke's law, the element stress can be calculated for each time step; calculate the stress, velocity, and acceleration for all time steps (velocity can be directly solved using the Newmark method) to obtain the spatial distribution: output the displacement cloud map and stress cloud map of the core / winding (by time step), mark the location of the maximum displacement / stress (such as the winding end, core corner) and the sound pressure time history curve: extract the displacement time history (such as the winding center node) and acceleration time history (such as the oil tank surface node) of key nodes, and output the obtained spatial distribution and sound pressure time history curve as the acoustic response.

[0041] The acoustic response is judged to converge based on a preset noise criterion (e.g., sound pressure distribution fluctuation < 3dB). If convergence is achieved, the acoustic response is output as the acoustic transient solution result. Otherwise, the transient solution conditions are adjusted a second time (if no adjustment has been made, the second adjustment here is a round of adjustment to the transient solution conditions; if an adjustment has been made, it is adjusted again on the basis of the first adjustment, and the adjustment amount can be determined based on experiments or expert experience). The solution process of the acoustic subdomain model is iteratively executed based on the transient solution conditions after the second adjustment until the final acoustic response converges.

[0042] This invention utilizes structural acoustic coupling, treating structural vibration response as the boundary condition for acoustic solutions, to achieve a complete transmission path analysis from vibration to noise, ensuring the continuity of the physical process. Employing transient acoustic solutions, it captures details of sound pressure changes over time and the spatial distribution of the sound field, thus more accurately assessing the transformer's noise level. By pre-setting noise criteria and iterative adjustments, it ensures the convergence of the acoustic solutions, improving the reliability and stability of the results. Automatic convergence detection and adjustment reduce manual intervention and improve analysis efficiency. The frequency-transient domain step-by-step coupling calculation strategy employed in this invention efficiently solves multiphysics problems, facilitating in-depth analysis of the dynamic characteristics of transformers under different physical fields and multiphysics coupling effects.

[0043] S5. Determine the modal harmonic overlap of the target transformer based on the natural frequency of the structure and the harmonic distribution, and combine the vibration response of the structure and the acoustic response to determine the vibration and noise classification assessment results of the target transformer. In one embodiment, step S5 includes: The overlap of the structure's natural frequency and the harmonic distribution is determined using the frequency tolerance method to obtain the modal harmonic overlap of the target transformer. The severity of vibration is graded based on the structural vibration response to obtain a first grading result, and the severity of noise is graded based on the acoustic response to obtain a second grading result. The modal harmonic overlap, the first classification result, and the second classification result are combined to obtain the vibration and noise classification evaluation result of the target transformer.

[0044] Specifically, this invention employs a frequency tolerance method, comparing the difference between harmonic frequencies and the structure's natural frequencies to determine the presence of resonance risk. Based on engineering experience, a tolerance threshold Δf = 5Hz is set (covering the frequency calculation error range, which can be adjusted within the range of 1-10Hz depending on the transformer type and accuracy requirements). The difference between each frequency in the harmonic distribution and the structure's natural frequency is calculated one by one. If the difference is ≤ 5Hz, it is determined as "overlapping"; otherwise, it is "not overlapping". The degree of overlap is determined based on the number of overlaps (0 times = low, 1 time = medium, 2 times and above = high). The higher the degree of overlap, the greater the risk of resonance.

[0045] The maximum displacement and maximum stress are extracted from the transient electromagnetic structure coupling solution and compared with a vibration grading standard based on engineering specifications and equipment characteristics to obtain the first grading result characterizing the severity of vibration; the vibration grading standard is: mild (maximum displacement < And the maximum stress < ), moderate ( Maximum displacement and Maximum stress ) and severe (maximum displacement > And the maximum stress > The maximum sound pressure level in the acoustic response is extracted and compared with the noise grading standard to obtain a second grading result characterizing the severity of the noise. The noise grading standard is mild (maximum sound pressure level < 60 dB), moderate (60 dB < maximum sound pressure level < 70 dB), and severe (maximum sound pressure level > 70 dB).

[0046] Based on the single classification results of vibration and noise, the results are corrected by combining the modal harmonic overlap level (if the overlap is "high", the classification result is upgraded by one level; if it is "medium", the classification result remains unchanged; if it is "low", the classification result is downgraded by one level). Finally, the corrected first and second classification results are used as the vibration and noise classification assessment results of the target transformer. For example, if the first classification result is "medium", the second classification result is "low", and the overlap level is "high", then the final vibration and noise classification assessment results include a vibration risk level of high risk and a noise risk level of medium risk.

[0047] This invention integrates multi-field data from electromagnetics, structural mechanics, and acoustics to overcome the shortcomings of traditional single-physical-field analysis in failing to correlate the risk of "modal-harmonic" resonance, making vibration and noise assessment results more consistent with actual operating conditions. The calculation of modal harmonic overlap can directly pinpoint the core cause of increased vibration and noise (resonance), providing a clear direction for transformer structure optimization and operation monitoring. The use of standardized frequency tolerance methods and grading rules ensures a unified assessment process under different DC bias conditions, and the results are comparable and reproducible.

[0048] To verify the effectiveness and accuracy of this invention, the structure and operating characteristics of a 110kV transformer during operation are shown in Table 1. A physical model of the 110kV transformer was then established using a finite element simulation platform. Table 1. Operating Parameters of 110kV Transformer The sound field is represented as a hemisphere with a diameter of 16m. The core and the wrapped portion are chosen as the solid mechanics domain, and the hemispherical air domain is chosen as the sound field domain. This is to calculate the interface coupling between solid mechanics and the sound field. The simplified sound field calculation model is as follows: Figure 2 As shown in the figure. The mesh was refined and meshed, and the study was set up as a coil geometry analysis and transient, with geometric nonlinearity applied. After completing the model structure and solver configuration, the electromagnetic and mechanical properties of the 110kV transformer were settled, and the calculation results were used as boundary conditions for the external acoustic calculations of the model. The material parameters of each part of the model are shown in the table below: Table 2 Model Parameter Configuration Table To elucidate the contribution of each component to the transformer's harmonic resonance effect in more detail, the modal vibration analysis of the 110kV transformer is divided into three parts: the core, windings, and tank, before proceeding with the active coupling solution. Considering only solid mechanics, the characteristic frequencies of the transformer are solved under passive conditions. The first four different natural frequencies of the transformer as a whole, the core, and the windings are shown in Table 3, and the corresponding mode shapes are shown in... Figure 3 As shown, in Figure 3 middle, Figure 3 (a) Figure 3 (b) Figure 3 (c) Figure 3 (d) shows the modal distribution diagrams of the transformer as a whole, the core, and the windings at the first, second, third, and fourth natural frequencies, respectively. The performance of each mode is interleaved with the vibration frequency corresponding to the added harmonic excitation.

[0049] Table 3 Natural Frequency Distribution Excitation current under different DC contents, such as Figure 4 As shown, Figure 4 (a) Figure 4 (b) Figure 4 (c) Figure 4 (d) represents K dc The excitation current plots at 0.00, 0.35, 0.85, and 1.25°C show the effect of DC bias on the excitation characteristics of a 110kV transformer. The bias voltage causes the positive half-cycle area of ​​the core excitation to continuously increase, while the negative half-cycle area continues to decrease, gradually exhibiting a sharp peak waveform that is no longer symmetrical. Fast Fourier decomposition of the excitation current time-domain data is performed to observe the changes in harmonic components under DC bias. The excitation current spectrum under different DC contents is shown below. Figure 5 As shown. Based on the distribution data displayed in red bars, it is easy to see that before the DC component is applied, the harmonic components generated during the excitation process are basically odd harmonics. When K dc When the harmonic distortion reaches 0.85, a large-scale uniform component is generated during the excitation process. This reflects the accelerated saturation process of the silicon steel sheet under the influence of the DC component, and the transformer's operating point rapidly moves upward on the hysteresis loop. Simultaneously, according to the modal distribution data in Table 3, the increase in the uniform harmonic component increases the possibility of resonance with the fourth natural frequency of the core and the second natural frequency of the winding, which will be one explanation for the intensified vibration group noise. With K... dc As K increases, the magnetic flux density tends to increase. dc When the value is increased to 0.85, the magnetic flux of the iron core gradually saturates, and the rate of increase in magnetic flux density slows down. Table 4 lists the electromagnetic and vibration characteristics of a 110kV transformer under various DC components.

[0050] Table 4 Electromagnetic and Vibration Noise Characteristic Parameters Force distribution characteristics of the reactor core under different DC contents, such as Figure 6 As shown, Figure 6 (a) Figure 6 (b) Figure 6 (c) Figure 6 (d) represents K dcThe force distribution characteristics of the core at 0.00, 0.35, 0.85, and 1.25 are shown. Meanwhile, the main contribution of DC bias to the core stress distribution is on the main columns, which is closely related to the flow direction of the magnetic flux loop. The 110kV transformer is a three-phase, three-winding transformer. Sinusoidal alternating current with the same amplitude and a 120° phase difference flows through the windings on the main and side columns. The magnetic field generated by each winding on the core column needs to pass through the main column. Therefore, when the DC component enters, the magnetic flux density on the main column increases the fastest, leading to a more significant change in stress distribution. Secondly, the number of stress points on the side columns increases, especially at the connection between the three core columns and the upper and lower yokes, exhibiting very strong stress. Overall, the maximum stress on the core increases with the increase of the DC component, and reaches a certain level at K... dc The maximum growth rate is reached at a value of 0.85, with a maximum value of 5.42 × 10. 5 N / m 2 Increased to 2.35 × 10 6 N / m 2 The stress then continues to increase, but at a slower rate. This is because at this point, the core is close to the saturation point of the magnetization curve, and the stress in the core is positively correlated with the voltage U and the magnetic flux density B.

[0051] Ignoring phase difference, the stress distribution characteristics of the high-voltage and low-voltage windings on the three columns are not significantly different. Therefore, taking the B-phase winding as an example, the stress distribution characteristics of the high-voltage and low-voltage winding coils are compared as the DC component increases. The force distribution characteristics of the windings under different DC contents are shown in the figure below. Figure 7 As shown, Figure 7 (a) Figure 7 (b) Figure 7 (c) Figure 7 (d) represents K dc Force distribution characteristic diagrams of the winding at values ​​of 0.00, 0.35, 0.85, and 1.25 are obtained. At the same time point and observation direction, the distribution of stress points on the winding surface exhibits two different states. When no DC power supply is applied, the stress points on the front of the winding are concentrated along the central axis of symmetry. The maximum stress value appears at 1.03 × 10⁻⁶ for every 90° clockwise rotation along the z-axis. 5 N / m 2 Place, such as Figure 7 As shown in (a). When K dc When the values ​​are 0.35, 0.85, and 1.25, respectively, the stress points of the winding are almost distributed across all surface finite element points within the visible light range. The range of stress intensity points gradually increases, with the maximum stress value increasing to 5.13 × 10⁻⁶. 5 N / m 2 8.24×10 5 N / mm 2 and 2.19×10 6 N / m2 .

[0052] Core deformation distribution characteristics under different DC contents, such as Figure 8 As shown, Figure 8 (a) Figure 8 (b) Figure 8 (c) Figure 8 (d) represents K dc The deformation distribution characteristics of the reactor core at DC bias values ​​of 0.00, 0.35, 0.85, and 1.25 are shown, illustrating the deformation distribution characteristics of the core during DC bias. Silicon steel has relatively high hardness, and the stress direction of widely used oriented silicon steel sheets is relatively stable; therefore, the morphological deformation distribution of the core does not change significantly. However, the DC component has a very significant impact on the core deformation amplitude, starting from 1.29 × 10⁻⁶. -8 m(K) dc =0.00) changed to 3.07×10 -7 m(K) dc =1.25). DC bias has a significant impact on the distribution of winding deformation. Similarly, taking the A-phase winding as an example, the deformation characteristics of the winding under DC bias were compared. The deformation distribution characteristics of the winding under different DC contents are as follows: Figure 9 As shown, Figure 9 (a) Figure 9 (b) Figure 9 (c) Figure 9 (d) represents K dc The deformation distribution characteristics of the winding are shown at values ​​of 0.00, 0.35, 0.85, and 1.25. Without a DC bias, the maximum displacement of the winding is 1.15 × 10⁻⁶. -7 m, similar to the stress distribution of the winding, shows that the displacement points are concentrated in the middle of the winding, exhibiting an overall inward compression state. When K dc When the values ​​are increased to 0.35, 0.85, and 1.25, the maximum displacement of the winding increases to 3.37 × 10⁻⁶. -7 m, 6.26×10 -7 m and 8.34×10 -7 m, the distribution range of points with larger displacements increases, even in K dc At 1.25, it covers almost the entire surface of the high-voltage winding. This is related to the frequency range of the excitation harmonics flowing through the winding. In the field-circuit coupling stage of the winding model in this application, the windings are set as a series of tangled circuit connections at the ends, and the intermediate windings are set as a series of continuous circuit connections. Under the action of DC bias, the frequency range of the current harmonics on the winding changes from odd harmonics to odd plus even harmonics, which greatly increases the stress time on each winding and increases the overall stress surface of the winding.

[0053] The sound pressure level distribution of transformers with different DC contents is as follows: Figure 10As shown, Figure 10 (a) Figure 10 (b) Figure 10 (c) Figure 10 (d) represents K dc Sound pressure level distribution diagrams of the transformer at values ​​of 0.00, 0.35, 0.85, and 1.25 are shown, illustrating the sound field distribution characteristics of the 110kV transformer under the influence of different DC components. Since the distribution patterns of sound pressure and sound pressure level are consistent, and the conversion relationship between sound pressure and sound pressure level on amplitude is fixed, the sound pressure distribution characteristics are not discussed separately. Based on... Figure 10 As can be seen, after considering DC bias, the sound pressure level amplitude of the 110kV transformer increases from 58.2dB to 73.6dB, with the most significant increase occurring at K0.85. dc Simultaneously, under the influence of DC bias, the acoustic field distribution of the 110kV transformer changes from initial vertical stratification to horizontal-vertical partitioning; the higher the DC content, the more pronounced the partitioning area. This is due to the change in harmonic distribution caused by DC bias, and the increase in harmonic components makes the three-dimensional distribution of noise more widespread at the finite element point in the acoustic field. In other words, at the same finite element point and at the same time, the richness of different dimensional components of noise increases. This undoubtedly enhances the noise radiation efficiency, and coupled with the contribution of the DC component to the amplitude of the excitation source, ultimately leads to a maximum possible increase in noise of 10dB during actual operation of the 110kV transformer.

[0054] The time-frequency distribution of sound pressure in transformers with different DC contents is as follows: Figure 11 As shown, Figure 11 (a) Figure 11 (b) are K respectively dc The time-frequency distribution diagrams of the transformer's sound pressure at 0.00 and 0.85 are taken, which describe the sound pressure at K... dc =0 and K dc The time-frequency distribution of sound pressure at the top of the converter transformer when the bias is 0.85. Comparing the two figures, it can be seen that under the influence of DC bias, the overall harmonic content of the noise signal increases sharply, and the sound pressure amplitude increases by nearly two times. By comparing the frequency domain distribution of the sound pressure signal, it can be seen that the sound pressure content increases in the frequency range of multiples of 50Hz, and the dominant frequency shifts from 100Hz to 300Hz, reflecting the shift in the overall vibration noise radiation energy, which is closely related to the change in the frequency domain distribution of the excitation harmonics.

[0055] It should be noted that although the steps in the flowchart above are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order requirement for the execution of these steps, and they can be executed in other orders.

[0056] In another embodiment, such as Figure 12 As shown, a second aspect of the present invention provides a transformer DC bias vibration and noise assessment system, comprising: The model building module 10 is used to obtain the key parameters of the target transformer and build a multi-physics coupling analysis model containing electromagnetic field, structural mechanics and acoustics based on the key parameters. The relationship coupling module 20 is used to configure the inter-field coupling relationship based on the energy transfer rules between the multi-physics fields in the multi-physics field coupling analysis model; The drive source construction module 30 is used to obtain the harmonic distribution of the target transformer and its structural natural frequency in the frequency domain, and to construct the field-circuit joint drive source of the target transformer under DC bias conditions. The model solving module 40 is used to input the field-circuit joint driving source into the multi-physics coupling analysis model for transient electromagnetic structure coupling solution under the DC bias condition, based on the inter-field coupling relationship, to obtain the structural vibration response, which is then used as a boundary condition to input into the multi-physics coupling analysis model for acoustic transient solution to obtain the acoustic response. The result evaluation module 50 is used to determine the modal harmonic overlap of the target transformer based on the natural frequency of the structure and the harmonic distribution, so as to combine the vibration response of the structure and the acoustic response to determine the vibration and noise classification evaluation result of the target transformer.

[0057] It should be noted that each module in the aforementioned transformer DC bias vibration and noise assessment system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module. For specific limitations regarding the transformer DC bias vibration and noise assessment system, please refer to the limitations of the transformer DC bias vibration and noise assessment method described above; both have the same function and role, and will not be repeated here.

[0058] A third aspect of the present invention provides an electronic device comprising: A processor, a memory, and a bus; the bus for connecting the processor and the memory; the memory for storing operation instructions; the processor for executing instructions by invoking the operation instructions to cause the processor to perform operations corresponding to a transformer DC bias vibration and noise assessment method as shown in the first aspect of the present invention.

[0059] In one alternative embodiment, an electronic device is provided, such as Figure 13 As shown, Figure 13The illustrated electronic device 5000 includes a processor 5001 and a memory 5003. The processor 5001 and the memory 5003 are connected, for example, via a bus 5002. Optionally, the electronic device 5000 may also include a transceiver 5004. It should be noted that in practical applications, the transceiver 5004 is not limited to one type, and the structure of this electronic device 5000 does not constitute a limitation on the embodiments of the present invention.

[0060] Processor 5001 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, transistor logic device, hardware component, or any combination thereof. It may implement or execute the various exemplary logic blocks, modules, and circuits described in connection with this disclosure. Processor 5001 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0061] Bus 5002 may include a path for transmitting information between the aforementioned components. Bus 5002 may be a PCI bus or an EISA bus, etc. Bus 5002 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 13 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0062] The memory 5003 may be a ROM or other type of static storage device capable of storing static information and instructions, RAM or other type of dynamic storage device capable of storing information and instructions, or it may be an EEPROM, CD-ROM or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.

[0063] The memory 5003 is used to store application code that executes the present invention, and its execution is controlled by the processor 5001. The processor 5001 is used to execute the application code stored in the memory 5003 to implement the content shown in any of the foregoing method embodiments.

[0064] Among them, electronic devices include, but are not limited to: mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), and in-vehicle terminals (such as in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers.

[0065] The fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements a transformer DC bias vibration and noise assessment method as shown in the first aspect of the present invention.

[0066] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program that, when run on a computer, enables the computer to execute the corresponding content in the foregoing method embodiments.

[0067] Furthermore, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0068] In summary, this invention relates to the field of transformer technology and discloses a method, system, device, and medium for assessing DC bias vibration and noise in transformers. It constructs a multi-physics coupled analysis model encompassing electromagnetic fields, structural mechanics, and acoustics based on key parameters of the target transformer, and configures the inter-field coupling relationships within the model. A field-circuit joint driving source for the target transformer under DC bias conditions is constructed and input into the analysis model for transient electromagnetic-structural coupling solution. The resulting structural vibration response is then transformed into boundary conditions via inter-field coupling relationships and input into the analysis model for transient acoustic solution, yielding the acoustic response. The harmonic distribution of the target transformer and its natural structural frequencies in the frequency domain are obtained to determine the modal harmonic overlap. The vibration and noise classification assessment results for the target transformer are determined by combining the structural vibration response and acoustic response. A step-by-step coupling calculation strategy is employed to achieve accurate assessment of the transformer's vibration and noise.

[0069] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0070] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A method for evaluating DC bias vibration and noise in transformers, characterized in that, include: The key parameters of the target transformer are obtained, and a multiphysics coupling analysis model including electromagnetic field, structural mechanics and acoustics is constructed based on the key parameters. In the multiphysics coupling analysis model, the coupling relationship between fields is configured based on the energy transfer rules between the multiphysics fields; Obtain the harmonic distribution of the target transformer and its structural natural frequency in the frequency domain, and construct the field-circuit joint drive source of the target transformer under DC bias conditions; Under the DC bias condition, based on the field coupling relationship, the field-circuit joint driving source is input into the multi-physics field coupling analysis model to perform transient electromagnetic structure coupling solution, and the structural vibration response is obtained as the boundary condition input into the multi-physics field coupling analysis model to perform acoustic transient solution, and the acoustic response is obtained. The modal harmonic overlap of the target transformer is determined based on the natural frequency of the structure and the harmonic distribution. In combination with the structural vibration response and the acoustic response, the vibration and noise classification assessment results of the target transformer are determined.

2. The method for evaluating DC bias vibration and noise of a transformer according to claim 1, characterized in that, The construction of a multiphysics coupled analysis model based on the key parameters, including electromagnetic fields, structural mechanics, and acoustics, includes: Based on the key parameters, a finite element dynamics model is adopted and the structural response of the target transformer is described in matrix form to obtain a structural mechanics subdomain model. Based on the key parameters, the Maxwell equations are discretized using the finite element method to obtain the electromagnetic field subdomain model; Based on the aforementioned key parameters, the sound field propagation of the target transformer is described by equations of motion, continuity, and state. Then, the Helmholtz equation is solved using the variable separation method to generate an acoustic subdomain model. The structural mechanics subdomain model, the electromagnetic field subdomain model, and the acoustic subdomain model are combined to obtain the multiphysics coupling analysis model.

3. The method for evaluating DC bias vibration and noise of a transformer according to claim 2, characterized in that, In the multiphysics coupling analysis model, configuring the inter-field coupling relationship based on the energy transfer rules between multiphysics fields includes: In the multiphysics coupling analysis model, the subdomains corresponding to the electromagnetic field, the structural mechanics and the acoustics are delineated to obtain the electromagnetic-structural coupling interface and the structural-acoustic coupling interface. Based on the electromagnetic structure coupling interface, the electromagnetic structure coupling relationship is configured according to the first energy transfer rule between the electromagnetic field and the structural mechanics. Based on the structural acoustic coupling interface, the structural acoustic coupling relationship is configured through the second energy transfer rule between the structural mechanics and the acoustics; The electromagnetic structural coupling relationship and the structural acoustic coupling relationship are combined to obtain the inter-field coupling relationship.

4. The method for evaluating DC bias vibration and noise of a transformer according to claim 2, characterized in that, The process of obtaining the harmonic distribution of the target transformer and its structural natural frequencies in the frequency domain, and constructing a combined field-circuit drive source for the target transformer under DC bias conditions, includes: Configure frequency domain solution conditions to perform passive characteristic frequency solutions on the target transformer as a whole, core and winding respectively based on the structural mechanics subdomain model, and obtain the structural natural frequency of the target transformer in the frequency domain. The excitation current data of the target transformer is collected, and the spectrum analysis of the excitation current data is performed to obtain the harmonic distribution. The composite excitation source is constructed by combining the power frequency component and the DC bias component of the target transformer under the DC bias condition. The composite excitation source is coupled with the external equivalent circuit of the electromagnetic field subdomain model to form the field-circuit joint driving source.

5. The method for evaluating DC bias vibration and noise of a transformer according to claim 3, characterized in that, Under the DC bias condition, based on the inter-field coupling relationship, the field-circuit joint driving source is input into the multi-physics field coupling analysis model for transient electromagnetic structure coupling solution to obtain the structural vibration response, including: Under the DC bias condition, transient solution conditions are configured to input the field-circuit joint driving source into the electromagnetic field subdomain model for transient solution, and the electromagnetic force distribution over time is obtained as the electromagnetic field response. The electromagnetic field response is converted into a load through the electromagnetic structure coupling relationship, and the load is input into the structural mechanics subdomain model for transient solution based on the transient solution conditions to obtain the stress, displacement and acceleration that change with time as the vibration response of the structure. Based on a preset vibration criterion, it is determined whether the structural vibration response converges. If so, the electromagnetic field response and the structural vibration response are output as transient electromagnetic-structural coupling solution results. Otherwise, the transient solution conditions are adjusted once, and the solution process for the electromagnetic field subdomain model and the structural mechanics subdomain model are iteratively executed based on the adjusted transient solution conditions.

6. The method for evaluating DC bias vibration and noise of a transformer according to claim 5, characterized in that, The process of inputting boundary conditions into the multiphysics coupling analysis model to perform acoustic transient solution and obtain acoustic response includes: The structural vibration response is transformed into the boundary conditions through the structural acoustic coupling relationship. Based on the transient solution conditions, the boundary conditions are input into the acoustic subdomain model for acoustic transient solution to obtain the sound pressure time history and spatial distribution as the acoustic response. Based on a preset noise criterion, it is determined whether the acoustic response has converged. If so, the acoustic response is output as the acoustic transient solution result. Otherwise, the transient solution conditions are adjusted a second time, and the solution process of the acoustic subdomain model is iteratively executed based on the adjusted transient solution conditions.

7. The method for evaluating DC bias vibration and noise of a transformer according to claim 1, characterized in that, The step of determining the modal harmonic overlap of the target transformer based on the structure's natural frequency and harmonic distribution, and combining the structure's vibration response and acoustic response to determine the vibration and noise classification assessment results for the target transformer, includes: The overlap of the structure's natural frequency and the harmonic distribution is determined using the frequency tolerance method to obtain the modal harmonic overlap of the target transformer. The severity of vibration is graded based on the structural vibration response to obtain a first grading result, and the severity of noise is graded based on the acoustic response to obtain a second grading result. The modal harmonic overlap, the first classification result, and the second classification result are combined to obtain the vibration and noise classification evaluation result of the target transformer.

8. A transformer DC bias vibration and noise assessment system, characterized in that, include: The model building module is used to obtain the key parameters of the target transformer and build a multi-physics coupling analysis model containing electromagnetic field, structural mechanics and acoustics based on the key parameters. The relationship coupling module is used to configure the inter-field coupling relationship based on the energy transfer rules between multiple physics fields in the multi-physics field coupling analysis model. The drive source construction module is used to obtain the harmonic distribution of the target transformer and its structural natural frequency in the frequency domain, and to construct the field-circuit joint drive source of the target transformer under DC bias conditions. The model solving module is used to input the field-circuit joint driving source into the multi-physics coupling analysis model for transient electromagnetic structure coupling solution under the DC bias condition, based on the field coupling relationship, to obtain the structural vibration response, which is then used as a boundary condition to input into the multi-physics coupling analysis model for acoustic transient solution to obtain the acoustic response. The result evaluation module is used to determine the modal harmonic overlap of the target transformer based on the structure's natural frequency and the harmonic distribution, so as to combine the structure's vibration response and the acoustic response to determine the vibration and noise classification evaluation result of the target transformer.

9. An electronic device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the transformer DC bias vibration and noise assessment method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein when the device containing the computer-readable storage medium executes the computer program, it implements the transformer DC bias vibration and noise assessment method as described in any one of claims 1 to 7.

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