Transformer transportation impact damage assessment method based on damage response surface model

Abstract

The invention provides a transformer transportation impact damage assessment method based on a damage response surface model. According to the method, refined impact excitation is constructed, and impact simulation is carried out on a finite element model of the transformer by utilizing the impact excitation. In the simulation process, the vibration response of the finite element model is collected, the damage conditions of different parts of the finite element model are subjected to harmonic response analysis, and damage point data of the part which is damaged first is selected to construct a damage response surface model. And multi-modal influence factors of impact acceleration and impact frequency are introduced into the damage response surface model, so that the damage response surface model can accurately describe the boundary of damage of the transformer under impact. By using the damage response surface model, the damage risk in the transformer transportation process can be accurately and effectively evaluated.

Description

Technical Field

[0001] This invention relates to the field of impact damage assessment, and more specifically to a method for assessing transformer transportation impact damage based on a damage response surface model. Background Technology

[0002] Vibration and shock during transformer transportation can damage the internal structure of the transformer equipment. To effectively reduce transportation risks, the industry widely adopts transportation monitoring and vibration analysis technologies to assess the stress condition of the equipment. Existing technologies mainly record impact vibration data through sensors and combine it with specific preset thresholds for a rough qualitative assessment. However, this coarse assessment method fails to fully consider the comprehensive impact of key factors such as the transformer's structural characteristics, impact duration, frequency components, and impact energy on equipment damage, thus its accuracy is not high. Summary of the Invention

[0003] Purpose of the invention: The present invention aims to propose a method for assessing transformer transportation impact damage based on a damage response surface model, so as to at least partially overcome the deficiencies of the prior art.

[0004] Summary of the Invention: To achieve the above objectives, the present invention proposes the following technical solution: A method for assessing transformer transportation impact damage based on a damage response surface model, the method comprising the following steps: Construct a finite element model of the transformer; An impact load was applied to the finite element model, and the vibration response of the finite element model was collected. The vibration response is analyzed to obtain the maximum equivalent stress of different components of the finite element model under the impact load, and the damage point of the component is determined based on the yield strength of the component material. The impact load corresponding to the damage point of the component that is damaged first is used as input, and the corresponding maximum equivalent stress is used as output to construct a damage response surface model. The real-time impact loads experienced by the target transformer during transportation are collected, and the maximum equivalent stress of the target transformer under the real-time impact loads is calculated using the damage response surface model. Based on the calculated maximum equivalent stress and the preset stress threshold, it is determined whether the target transformer is at risk of damage under the real-time impact load.

[0005] In one alternative embodiment, the transformer components include an iron core, windings, positioning blocks, and lead wire assembly.

[0006] In one optional implementation, an impact load is applied to the finite element model, and the vibration response of the finite element model is acquired, specifically including: The impact load is decomposed into impact acceleration and impact frequency in three orthogonal directions: X, Y, and Z. The maximum equivalent stress of each component in the finite element model under the corresponding impact acceleration and impact frequency is measured.

[0007] Specifically, the vibration response is analyzed to obtain the maximum equivalent stress of different components in the finite element model under the impact load, and the damage points of the components are determined based on the yield strength of the component materials. This includes: For the aforementioned components, the relationship curves between impact frequency and equivalent stress under different impact accelerations in the X, Y, and Z directions are constructed respectively; The frequency band in the relationship curve between the impact frequency and the equivalent stress, where the equivalent stress is greater than the yield strength of the component material, is determined as the damage frequency band of the component under the corresponding impact acceleration. The damage frequency band is then sampled to obtain the damage point of the component.

[0008] Specifically, the expression for the damage response surface model is: ; ; ; Where R1 represents the response factor in the Y direction, which is the equivalent stress of the most vulnerable component under Y-direction impact acceleration and impact frequency excitation. Let Y be the impact acceleration. R1 represents the impact frequency in the Y direction; R2 represents the response factor in the Z direction, which is the equivalent stress of the most vulnerable component under Z-direction impact acceleration and impact frequency excitation. Let Z be the impact acceleration. RZ represents the impact frequency in the Z direction; RX represents the response factor in the X direction, which is the equivalent stress of the most vulnerable component under X-direction impact acceleration and impact frequency excitation. Let X be the impact acceleration in the X direction. Let X be the impact frequency in the X direction.

[0009] Specifically, the real-time impact loads experienced by the target transformer during transportation are collected, and the maximum equivalent stress of the target transformer under the real-time impact loads is calculated using the damage response surface model. This includes: The real-time impact load of the target transformer collected is decomposed into impact acceleration and impact frequency in the X, Y, and Z directions; Substituting the impact acceleration and impact frequency into the damage response surface model in the corresponding direction, the maximum equivalent stress of the target transformer in the corresponding direction is obtained.

[0010] Specifically, based on the calculated maximum equivalent stress and the preset stress threshold, it is determined whether the target transformer is at risk of damage under the real-time impact load, including: The calculated maximum equivalent stress of the target transformer in the X, Y, and Z directions under the real-time impact load is compared with the preset stress threshold in the corresponding direction. If it is greater than the stress threshold, the target transformer is determined to be at risk of damage. The preset stress threshold in the X, Y, and Z directions is set based on the yield strength of the component most prone to damage in the corresponding direction.

[0011] Beneficial effects: Compared with the prior art, the transformer transportation impact damage assessment method based on the damage response surface model proposed in this invention has the following beneficial effects: This method constructs a refined impact excitation and uses it to simulate the impact on a finite element model of a transformer. During the simulation, the vibration response of the finite element model is collected, and harmonic response analysis is performed on the damage of different components. The damage point data of the component that fails first are selected to construct a damage response surface model. Furthermore, multimodal influence factors of impact acceleration and impact frequency are introduced into the damage response surface model, enabling it to accurately describe the boundary of transformer damage under impact.

[0012] Using the damage response surface model described above, the damage risk during transformer transportation can be accurately and effectively assessed. Attached Figure Description

[0013] Figure 1 This is a schematic flowchart of a transformer transportation impact damage assessment method based on a damage response surface model, as described in an embodiment.

[0014] Figure 2 The curves show the equivalent stress of the core, winding, positioning block, and lead wire device involved in the embodiment under an impact acceleration of 2g in the X direction as a function of impact frequency.

[0015] Figure 3 The curves show the equivalent stress of the core, winding, positioning block, and lead wire device involved in the embodiment under an impact acceleration of 2g in the Y direction as a function of impact frequency.

[0016] Figure 4 The curves show the equivalent stress of the core, winding, positioning block, and lead wire device involved in the embodiment under an impact acceleration of 2g in the Z direction as a function of impact frequency.

[0017] Figure 5 This is a schematic diagram of the damage response surface model in the Y direction involved in the embodiment.

[0018] Figure 6This is a schematic diagram of the damage response surface model in the Z direction involved in the embodiment.

[0019] Figure 7 This is a schematic diagram of the damage response surface model in the X direction involved in the embodiment. Detailed Implementation

[0020] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. However, it should be understood that the present invention can be implemented in various forms. The exemplary and non-limiting embodiments shown in the drawings and described below are not intended to limit the invention to the specific embodiments illustrated.

[0021] It should be understood that, where technically feasible, the technical features listed above for different embodiments can be combined with each other to form other embodiments within the scope of this invention. Furthermore, the specific examples and embodiments described in this invention are non-limiting, and corresponding modifications can be made to the structures, steps, and order described above without departing from the protection scope of this invention.

[0022] Please refer to Figure 1 , Figure 1 A flowchart illustrating a transformer transportation impact damage assessment method based on a damage response surface model is shown. Figure 1 As shown, the method includes steps S100 to S108.

[0023] S100: Construct the finite element model of the transformer.

[0024] The following will illustrate the construction process of the finite element model of a transformer using a specific embodiment, including: (1) Simplification of geometric model Shell and thin-walled structure simplification: This is primarily achieved through Hypermesh mid-surface extraction, simplifying thin-walled components (such as transformer shells, bushing risers, top covers, and plate stiffeners) into shell models. Actual thicknesses are then assigned in ANSYS DesignModeler. During the simplification process, for components requiring connection, operations such as merging mid-surfaces and face-to-face cutting are performed to achieve common node connections.

[0025] Simplified internal connecting components: The shell model is also created using mid-surface extraction, ensuring that it shares nodes with the outer shell. For components with regular shapes and large thicknesses (such as parts of the outer shell, iron core, and certain connecting blocks), solid models are retained.

[0026] (2) Material properties and component assembly The engineering data module in ANSYS Workbench precisely defines the physical parameters of various materials used in the model, including oxygen-free copper, insulating cardboard, silicon steel, low-alloy steel, aluminum alloys, and laminated wood. These parameters cover density, Young's modulus, Poisson's ratio, yield strength, and tensile strength, among others.

[0027] (3) Component connection settings and mesh generation The connection method of each component in the model is crucial. Shell model components generated through mid-surface extraction are automatically connected via shared nodes. For components requiring physical contact, such as insulating pads, upper and lower connection structures, housing covers, windings, cores, and pipelines, this embodiment employs "bonded connections." Bonded connections set appropriate contact tolerances based on component type and thickness to ensure effective load transfer.

[0028] To achieve a balance between computational efficiency and result accuracy, a hybrid mesh strategy was adopted when constructing the finite element model, and the mesh size was adjusted according to the component type and geometric features. The size parameters are shown in Table 1.

[0029] Table 1 ; (4) Boundary conditions and load application The boundary conditions and loads in this embodiment are set as follows: Fixed supports: The four horizontal plates on both sides of the box are set as fixed supports, and all their degrees of freedom are constrained.

[0030] Gravity load: A standard downward force of Earth's gravity (9.8066 m / s²) is applied to simulate the effect of the structure's self-weight.

[0031] S102: Apply impact load to the finite element model and collect the vibration response of the finite element model.

[0032] In terms of impact load simulation, considering the diversity and complexity of external impacts in actual transportation, the impact load can be decomposed into impact accelerations with certain impact frequencies in three orthogonal directions: X, Y, and Z. The maximum equivalent stress of each component in the finite element model at the corresponding impact acceleration and impact frequency is then measured. The Y direction is the vertical direction, the X direction is the horizontal direction parallel to the long side of the transformer, and the Z direction is the horizontal direction parallel to the short side of the transformer.

[0033] Given that the industry-standard empirical impact threshold is 3g, this embodiment sets the impact acceleration amplitude parameter within the range of 0g to 3g, discretizing it in 0.5g increments to cover impact scenarios of varying intensities. Furthermore, to explore the equipment's response under extreme conditions, supplementary analysis of 4g and 5g extreme impact conditions can be performed. The impact frequency can be set according to requirements; this embodiment does not impose any limitations on this.

[0034] S104: Analyze the vibration response to obtain the maximum equivalent stress of different components in the finite element model under impact load, and determine the damage point of the component based on the yield strength of the component material.

[0035] At each set impact amplitude, the maximum equivalent stress of key internal components (including core, winding, positioning block and lead wire device) will be calculated and output, and compared with the yield strength of the corresponding material to evaluate its structural integrity.

[0036] For the continuous vibration conditions during transportation, this embodiment uses a harmonic response analysis method for evaluation. Based on historical transportation data and the inherent frequency distribution characteristics of the equipment, the frequency sweep range is set to a sinusoidal excitation from 0 Hz to 30 Hz, aiming to accurately capture the key resonant response.

[0037] To ensure the accuracy of the harmonic response analysis (using the modal superposition method), a thorough modal analysis is necessary. Following the commonly adopted 1.5-fold rule in engineering practice, the upper limit of the calculation frequency for the modal analysis must cover at least 45Hz to ensure that all effective modes that significantly contribute to the structural response are included, thereby improving the reliability of the harmonic response analysis. Table 2 shows the harmonic response analysis results described in this embodiment, displaying the resonant frequency values ​​for the first 7 and 55th orders.

[0038] Table 2 ; Before performing harmonic response analysis, the impact load is decomposed into impact components (impact acceleration excitation with a certain impact frequency) in three orthogonal directions, namely X, Y, and Z, and the vibration response of the finite element model in the X, Y, and Z directions is collected.

[0039] In harmonic response analysis, for the core, winding, positioning block, and lead wire assembly, the equivalent stress of each component under impact load is analyzed in the X, Y, and Z directions, respectively, constructing the relationship curves between impact frequency and equivalent stress under different impact accelerations in the X, Y, and Z directions. The frequency band where the equivalent stress is greater than the yield strength of the component material is defined as the damage frequency band. Sampling this damage frequency band yields the damage points of the component. The damage points are represented as... This indicates the impact acceleration corresponding to the damage to the component. This indicates the impact frequency at which a component is damaged.

[0040] The following example illustrates step S104 using the analysis process of vibration response under 2g acceleration.

[0041] Please refer to Figures 2 to 4 . Figure 2 The curves showing the equivalent stress of the core, winding, positioning block, and lead wire assembly under an impact acceleration of 2g in the X direction as a function of impact frequency are shown. Figure 3 The curves showing the equivalent stress of the core, winding, positioning block, and lead wire assembly under a 2g impact acceleration in the Y direction as a function of impact frequency are presented. Figure 4 The curves showing the equivalent stress of the core, winding, positioning block, and lead wire assembly under a 2g impact acceleration in the Z direction as a function of impact frequency are presented.

[0042] exist Figures 2 to 4 The diagram also shows the yield strength of the core, windings, locating blocks, and lead wire assembly. When the equivalent stress of a component exceeds its yield strength, it indicates that the component is damaged. Figures 2 to 4 In this context, the frequency band in which the equivalent stress of a component is greater than the yield strength of the component material is defined as the damage frequency band of that component.

[0043] S106: Using the impact load corresponding to the damage point of the component that is damaged first as input and the corresponding maximum equivalent stress as output, construct a damage response surface model.

[0044] Depend on Figures 2 to 4 As can be seen, under an impact acceleration of 2g, as the impact frequency increases, the components that are damaged first in the X, Y, and Z directions are shown in Table 3.

[0045] Table 3 ; To support the subsequent establishment of the damage response surface model, the analysis results of the most vulnerable components in each direction are parameterized. Specifically, the parameters of the damage points of the components that fail first in each direction are extracted, namely the impact acceleration amplitude, impact frequency, and corresponding maximum equivalent stress value of the damage points, and these are organized into a structured data table as parameters for constructing the damage response surface model.

[0046] Specifically, the Design-Expert software can be used to fit a damage response surface model based on the input parameters.

[0047] Taking the Y direction as an example, the structured parameters of the impact acceleration amplitude, impact frequency, and maximum equivalent stress value of the damage point of the first damaged positioning block in the Y direction are input into the Design-Expert software. The Design-Expert software is then used to fit a damage response surface model in the Y direction with the impact acceleration amplitude and impact frequency as input and the maximum equivalent stress value as output.

[0048] Similarly, damage response surface models in the X and Z directions are fitted.

[0049] After fitting, the expression for the damage response surface model is as follows: ; ; ; Where R1 represents the response factor in the Y direction, which is the equivalent stress of the component (locating block) most easily damaged under impact acceleration and impact frequency excitation in the Y direction. Let Y be the impact acceleration. R1 represents the impact frequency in the Y direction; R2 represents the response factor in the Z direction, which is the equivalent stress of the most vulnerable component (lead assembly) under impact acceleration and impact frequency excitation in the Z direction. Let Z be the impact acceleration. R3 represents the impact frequency in the Z direction; R3 represents the response factor in the X direction, which is the equivalent stress of the most vulnerable component (winding) under impact acceleration and impact frequency excitation in the X direction. Let X be the impact acceleration in the X direction. Let X be the impact frequency in the X direction.

[0050] Please refer to Figures 5 to 7 , Figure 5 The figure shows a schematic diagram of the damage response surface model in the Y direction. Figure 6 The figure shows a schematic diagram of the damage response surface model in the Z direction. Figure 7 The figure shows a schematic diagram of the damage response surface model in the X direction.

[0051] To verify the accuracy of the damage response surface model described above, this embodiment also provides the following verification data.

[0052] Taking the X direction as an example, select The data was input into the Design-Expert software for simulated impact testing in the X direction. The equivalent stress prediction results from the Design-Expert software were: Predicted Mean = 90.5879, Predicted Median = 90.5278, and the standard deviation of the prediction (Std Dev) was 2.69481. The corresponding 95% confidence interval (CI for Mean) was [89.5722, 91.621], and the corresponding 99% prediction interval (TI for 99% Pop) was [82.7466, 99.4605].

[0053] For comparison, the above prediction conditions ( Independent numerical verification was performed. The verification method was as follows: numerical simulation was performed on this specific combination of factors using ANSYS software, and the corresponding numerical verification results of the response variable R3 were obtained. The R3 value obtained by ANSYS simulation was 90.883 MPa.

[0054] The numerical verification results from ANSYS were compared with the Predicted Mean (90.5879) or Predicted Mean (90.5278) predicted by the Design-Expert model. It can be concluded that the ANSYS results are very close to the model predictions, indicating that the established response surface model has extremely high accuracy and reliability, and can effectively replace time-consuming and labor-intensive numerical simulations or actual experiments.

[0055] S108: Collect the real-time impact load on the target transformer during transportation, and use the damage response surface model to calculate the maximum equivalent stress of the target transformer under the real-time impact load.

[0056] The real-time impact load of the target transformer is decomposed into impact acceleration and impact frequency in the X, Y, and Z directions; the impact acceleration and impact frequency are substituted into the damage response surface model in the corresponding direction to obtain the maximum equivalent stress of the target transformer in the corresponding direction.

[0057] In practice, in order to monitor the impact on the transformer during transportation, sensors should be installed on the shoulder of the bridge vehicle connecting the transformer to monitor the overall impact and the force in different directions.

[0058] The sensor can be a triaxial accelerometer, which can collect and record the impact acceleration, impact duration, and specific direction (X, Y, Z) of the impact event in real time.

[0059] S110: Based on the calculated maximum equivalent stress and the preset stress threshold, determine whether the target transformer is at risk of damage under real-time impact load.

[0060] The maximum equivalent stress of the target transformer in the X, Y, and Z directions under real-time impact load is calculated and compared with the preset stress threshold in the corresponding direction. If it is greater than the corresponding stress threshold, the target transformer is determined to be at risk of damage. The preset stress threshold in the X, Y, and Z directions is set based on the yield strength of the component most prone to damage in the corresponding direction.

[0061] shock event By substituting a point into the damage response surface model in the corresponding direction, the maximum equivalent stress that it may generate can be quickly predicted. .

[0062] Define a preset stress threshold This stress threshold is determined based on the allowable stress of the most vulnerable component material in each direction, as shown in Table 4.

[0063] Table 4 ; The results for each direction are as follows: ;

[0064] if If the maximum equivalent stress from the recorded impact event is within the structural tolerance range, the transformer structure is deemed safe.

[0065] if If the impact exceeds the preset allowable stress threshold, an alarm will be triggered. This means that the maximum equivalent stress generated by the impact at the critical location exceeds the preset allowable stress threshold. This is not directly equivalent to "the transformer is damaged," but it is a strong warning signal indicating that an abnormal impact event has occurred that may cause hidden damage.

[0066] The above describes the transformer transportation impact damage assessment method based on the damage response surface model as described in this embodiment. The damage response surface model constructed by this method can predict damage under any impact conditions. Maximum equivalent stress By As a response variable, it is no longer a simple safety or alarm signal, but rather three-dimensional data representing the structural stress level under different impact combinations. This method can provide richer quantitative information to assist damage assessors in making more accurate judgments.

[0067] For example: when a shock event When the stress falls between a certain stress contour line, assessors can not only determine whether the impact is safe, but also intuitively understand how close the generated stress level is to the allowable stress threshold, or the specific degree to which it exceeds the threshold. For example, if the response surface model predicts... for Assessors can definitively determine if stress exceeds the 20% threshold, providing more quantifiable information about the extent of damage than a simple "risk exists." This quantitative data helps in deciding the priority and depth of subsequent inspections and whether immediate intervention is necessary, leading to a more instructive damage assessment.

[0068] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent application should be determined by the appended claims.

Claims

1. A method for assessing transformer transportation impact damage based on a damage response surface model, characterized in that, The method includes the following steps: Construct a finite element model of the transformer; An impact load was applied to the finite element model, and the vibration response of the finite element model was collected. The vibration response is analyzed to obtain the maximum equivalent stress of different components of the finite element model under the impact load, and the damage point of the component is determined based on the yield strength of the component material. The impact load corresponding to the damage point of the component that is damaged first is used as input, and the corresponding maximum equivalent stress is used as output to construct a damage response surface model. The real-time impact loads experienced by the target transformer during transportation are collected, and the maximum equivalent stress of the target transformer under the real-time impact loads is calculated using the damage response surface model. Based on the calculated maximum equivalent stress and the preset stress threshold, it is determined whether the target transformer is at risk of damage under the real-time impact load.

2. The method according to claim 1, characterized in that, The transformer's components include an iron core, windings, positioning blocks, and lead wire assembly.

3. The method according to claim 1, characterized in that, Applying an impact load to the finite element model and acquiring its vibration response specifically includes: The impact load is decomposed into impact acceleration and impact frequency in three orthogonal directions: X, Y, and Z. The maximum equivalent stress of each component in the finite element model under the corresponding impact acceleration and impact frequency is measured.

4. The method according to claim 3, characterized in that, The vibration response is analyzed to obtain the maximum equivalent stress of different components in the finite element model under the impact load, and the damage points of the components are determined based on the yield strength of the component materials. Specifically, this includes: For the aforementioned components, the relationship curves between impact frequency and equivalent stress under different impact accelerations in the X, Y, and Z directions are constructed respectively; The frequency band in the relationship curve between the impact frequency and the equivalent stress, where the equivalent stress is greater than the yield strength of the component material, is determined as the damage frequency band of the component under the corresponding impact acceleration. The damage frequency band is then sampled to obtain the damage point of the component.

5. The method according to claim 4, characterized in that, The expression for the damage response surface model is: ； ； ； Where R1 represents the response factor in the Y direction, which is the equivalent stress of the most vulnerable component under Y-direction impact acceleration and impact frequency excitation. Let Y be the impact acceleration. R1 represents the impact frequency in the Y direction; R2 represents the response factor in the Z direction, which is the equivalent stress of the most vulnerable component under impact acceleration and impact frequency excitation in the Z direction. Let Z be the impact acceleration. RZ represents the impact frequency in the Z direction; RX represents the response factor in the X direction, which is the equivalent stress of the most vulnerable component under X-direction impact acceleration and impact frequency excitation. Let X be the impact acceleration in the X direction. Let X be the impact frequency in the X direction.

6. The method according to claim 5, characterized in that, The real-time impact load on the target transformer during transportation is collected, and the maximum equivalent stress of the target transformer under the real-time impact load is calculated using the damage response surface model. Specifically, this includes: The real-time impact load of the target transformer collected is decomposed into impact acceleration and impact frequency in the X, Y, and Z directions; Substituting the impact acceleration and impact frequency into the damage response surface model in the corresponding direction, the maximum equivalent stress of the target transformer in the corresponding direction is obtained.

7. The method according to claim 6, characterized in that, Based on the calculated maximum equivalent stress and the preset stress threshold, determine whether the target transformer is at risk of damage under the real-time impact load, specifically including: The calculated maximum equivalent stress of the target transformer in the X, Y, and Z directions under the real-time impact load is compared with the preset stress threshold in the corresponding direction. If it is greater than the stress threshold, the target transformer is determined to be at risk of damage. The preset stress threshold in the X, Y, and Z directions is set based on the yield strength of the component most prone to damage in the corresponding direction.

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