Finite element-based power transformer winding deformation frequency response test method without disassembling lead

Abstract

The invention relates to a finite element-based power transformer winding deformation frequency response test method without disassembling a lead, and belongs to the technical field of power transformer winding deformation detection. The problems of low efficiency, high safety risk and insufficient detection precision caused by the fact that a lead needs to be removed in a traditional frequency response test are solved. According to the technical scheme, the method comprises the steps that a transformer three-dimensional model is built in finite element simulation software, lead arrangement is designed, a winding deformation mode is set, capacitance and inductance parameters are obtained through electrostatic field and static magnetic field simulation, and feasibility of the method is verified by comparing wire-removing state parameter changes and wire-non-removing state parameter changes. The technical effects are that the detection efficiency and the operation safety are obviously improved, the diagnosis precision is ensured to meet the engineering requirements, the operation and maintenance resource consumption is reduced, and the development of the intelligent power grid maintenance technology is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of power transformer winding deformation detection, and relates to a finite element-based frequency response test method for power transformer winding deformation without removing leads. Background Art

[0002] Power transformers are core equipment in power grids. Winding deformation can cause insulation degradation and even short-circuit failures. Frequency response testing is an effective method for diagnosing winding deformation. Traditional frequency response testing requires the complete removal of high- and low-voltage leads, which has significant limitations. Removing leads requires the assistance of large equipment such as cranes, takes several hours, and involves working at height with live wires, posing a high risk of falling. Frequent disassembly and assembly can easily cause mechanical damage to bushing lead connectors, shortening equipment life. In intensive power grid maintenance scenarios, inefficient wiring removal can severely impact the execution of power outage plans.

[0003] Existing technologies attempt to solve the problem of lead removal, but focus on the field of dielectric loss testing: Han Xutao's team proposed a dielectric loss test method by applying pressure to the neutral point of the winding without removing the high-voltage lead. It was found that the capacitance value decreased slightly and the tangent value of the dielectric loss angle increased slightly when the two ends of the winding were not short-circuited. The reverse connection method was significantly affected by the cable and voltage transformer, while the positive connection method could eliminate interference; Chen Dengwei's team explored the feasibility of measuring the dielectric loss of transformer windings without removing the leads based on the parallel dielectric loss theory; Yang Xinchun's team compared the data of the reverse connection method with and without removing the leads, and combined with the positive connection method, proposed a solution for dielectric loss testing of 220kV transformers without removing the leads.

[0004] However, there are two major technical gaps in the above research: First, the dielectric loss tangent and capacitance values ​​measured without removing the leads lack a clear correlation model with the results of traditional lead removal, making it impossible to judge internal insulation defects or winding deformation based on this. Second, the frequency response method is the gold standard for diagnosing winding deformation, but its test technology without removing the leads is still blank. This is because removing the leads to conduct frequency response tests takes several hours, and existing research has not addressed the interference rules of the leads on the frequency response curve. As a result, this method has long relied on lead removal operations, seriously restricting maintenance efficiency.

[0005] To address the above-mentioned drawbacks, the present invention innovatively introduces finite element simulation into the field of frequency response testing, quantifies the influence of leads by establishing a three-dimensional model of the transformer, and breaks through the technical bottleneck of frequency response testing without removing leads. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a finite element-based method for testing the deformation frequency response of power transformer windings without removing the leads. The present invention constructs a finite element model of the power transformer windings using COMSOL simulation software that simulates coupled physical phenomena, sets the winding deformation mode and degree, and compares the various parameters (capacitance and inductance to ground) obtained by the non-removal of lead method with those obtained by the traditional removal method to verify the feasibility of the non-removal of lead method. This method is of great significance for improving the efficiency of power transformer power outage maintenance, so as to meet the demand of automatically completing the deformation frequency response test of the power transformer windings with only one wiring, shorten the test time, and eliminate safety hazards.

[0007] This paper studies the arrangement of leads and connection equipment for the windings on each side of a power transformer, explores their impact on the transformer itself, constructs a calculation model for testing power transformers without lead removal, and analyzes the impact of the leads and equipment on the frequency response winding deformation test results. The paper also studies the wiring method and result judgment method for transformer power outage tests without lead removal, conducts simulation tests, compares the test results with those with lead removal, verifies the validity of the test results, and develops a method for testing power transformers without lead removal.

[0008] This invention solves the problem of having to remove power transformer leads before conducting frequency response tests. It effectively reduces the number of maintenance personnel and the use of large-scale mechanical equipment, reduces the safety risks to personnel and equipment caused by removing and installing leads during power outage tests, shortens power outage test time, and improves the efficiency of planned power grid maintenance. It provides a strong guarantee for the safe, economical, and reliable operation of the power grid, achieving significant economic and social benefits. Due to the large number of power transformers, its market prospects are enormous.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A finite element-based method for testing the deformation frequency response of a power transformer winding without removing the leads comprises the following steps:

[0011] S1: In the finite element simulation software (COMSOL Multiphysics, COMSOL), a three-dimensional finite element model is constructed according to the structural parameters of the power transformer;

[0012] S2: designing a lead arrangement in the three-dimensional finite element model, and connecting the lead to at least one winding;

[0013] S3: Setting the deformation mode of the winding;

[0014] S4: Using the finite element simulation software, perform a frequency response test simulation without removing the leads to obtain capacitance and inductance parameters of the winding to ground;

[0015] S5: comparing the parameters obtained in the lead-not-removed state and the lead-completely-removed state, and determining the feasibility of the lead-not-removed method based on parameter changes;

[0016] Among them, S1, S2, S3, S4 and S5 are executed in sequence, and S4 depends on the model and settings built by S1 to S3, and S5 performs comparative analysis based on the output of S4.

[0017] Furthermore, in S1, constructing a three-dimensional finite element model includes:

[0018] Simplify the core into a cylinder or elliptical cylinder, and simplify the winding into a concentric cylindrical structure;

[0019] Among them, the core material is lossless soft iron in electrostatic field simulation, and low-carbon steel soft iron in static magnetic field simulation.

[0020] Furthermore, in S2, the lead wire is made of copper, and the lead wire is connected to the medium voltage winding and the high voltage winding;

[0021] Among them, the lead resistance is 1.72×10 -8 Ω·m, and the temperature coefficient of resistivity is 3.91×10 -3 / K.

[0022] Furthermore, in S3, the deformation mode is radial deformation, including multiple inward concavities, each of which has a depth of 15 mm.

[0023] Furthermore, in S4, an electrostatic field solver is used to obtain the ground capacitance parameters, and a static magnetic field solver is used to obtain the inductance parameters; wherein the frequency response test is performed within a frequency range of 10 kHz to 1 MHz.

[0024] Furthermore, in said S5, the parameter variation includes a relative variation of capacitance and a relative variation of inductance;

[0025] When the relative change in capacitance is less than 5% and the relative change in inductance is less than 2.06%, it is determined that the method of not removing the leads is feasible.

[0026] Furthermore, the relative capacitance change is calculated for the low voltage winding, the medium voltage winding, and the high voltage winding, respectively, as follows:

[0027] The relative change in capacitance of the low-voltage winding to ground shall not exceed 0.019%, the relative change in capacitance of the medium-voltage winding to ground shall not exceed 2.038%, and the relative change in capacitance of the high-voltage winding to ground shall not exceed 3.662%.

[0028] Furthermore, the inductance parameters are obtained within a frequency range of 10 kHz to 1 MHz, and the maximum relative change in inductance does not exceed 2.06%.

[0029] Furthermore, the method further comprises:

[0030] Based on the comparison results of S5, a parameter benchmark library without removing the leads is established for use in the automated detection system.

[0031] Furthermore, the automated detection system supports real-time comparison of historical data to locate deformation faults and is adapted to IoT terminals to achieve remote monitoring.

[0032] The beneficial effects of the present invention are:

[0033] 1. Significantly improve transformer detection efficiency and safety

[0034] Traditional frequency response testing relies on removing leads, a time-consuming process involving live wire work at height, a high risk of falls, and potential mechanical damage to bushing joints. This method pre-builds a three-dimensional transformer model using finite element simulation software, eliminating the need for physical lead removal and enabling multiple tests with a single connection. This method significantly shortens testing time, completely eliminates the safety hazards associated with lead removal, and ensures safe and efficient maintenance operations.

[0035] 2. Ensure that the detection accuracy meets the requirements of engineering applications

[0036] In the background art, the parameter variation patterns without removing the leads are unclear, making it difficult to reliably diagnose winding deformation. The present invention accurately simulates the influence of the leads based on simulation software, obtains the ground capacitance and inductance parameters through electrostatic field and static magnetic field solvers, and compares the wire removal status data. Verification shows that the parameter deviation obtained by the method without removing the leads is completely within the engineering allowable error range and can be directly used for deformation diagnosis, solving the defect of insufficient accuracy of traditional methods. In the specific implementation, the deformation setting and potential distribution comparison confirm the parameter consistency.

[0037] 3. Reduce operation and maintenance costs and resource consumption

[0038] Traditional methods require the collaboration of multiple personnel and the assistance of large machinery, consume significant resources, and can accelerate equipment wear. This invention replaces physical disassembly and assembly with a simulation model, reducing labor and avoiding the negative impact of frequent operation on equipment life. Furthermore, the single-wiring design reduces material loss, making it suitable for high-density power grid maintenance scenarios and improving overall operational efficiency. This cost optimization is supported by the lead design and model meshing.

[0039] 4. Promote the implementation of intelligent diagnostic technology

[0040] Background technology lacks intelligent support for non-wired frequency response testing. This invention establishes a parameter benchmark library based on simulation results, providing core data support for automated detection systems. This method supports real-time comparison of historical data for rapid fault location and adapts to the Internet of Things for remote monitoring, improving the efficiency of planned grid maintenance and laying the foundation for the development of smart substations. Comparison of inductor parameters serves as the verification basis for this intelligent application.

[0041] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0043] Figure 1 Simplified model diagram for power transformer;

[0044] Figure 2 It is the BH curve of the core material;

[0045] Figure 3 This is the design drawing of the winding lead;

[0046] Figure 4 This is a simulation model diagram of a power transformer with access leads;

[0047] Figure 5 This is the mesh decomposition diagram of the power transformer model without removing the leads;

[0048] Figure 6 Selection of winding deformation mode and position;

[0049] Figure 7 The potential distribution diagram of the two wire removal methods on the low-voltage side;

[0050] Figure 8 The potential distribution diagram of the two wire removal methods on the medium voltage side;

[0051] Figure 9 The potential distribution diagram of the two wire removal methods on the high-voltage side;

[0052] Figure 10 The figure compares the inductance of the left and right phase windings within 100kHz-1MHz with the leads intact and with all the leads removed. DETAILED DESCRIPTION

[0053] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0054] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0055] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0056] (1) Construction of finite element model of power transformer

[0057] In COMSOL simulation software, a three-dimensional physical model was constructed based on the main structural parameters of a single-phase double-column transformer model ZZDFPZ-509400 / 500. The main parameters are shown in Table 1. According to the actual transformer structure, the center column and side yoke of the model are simplified into cylinders and elliptical cylinders. The core is composed of multiple silicon steel sheets stacked together. The three windings on the low, medium and high voltage sides are simplified from the inside to the outside into concentric cylindrical structures, surrounding the center column. Due to the limited computational load of the computer, too many components will lead to slow meshing. Some components that have little impact on the results are omitted, such as insulating pads and oil channels, as well as bolts, screws, clamps and other components. The model is shown in the figure below. Figure 1 shown.

[0058] Table 1 Main parameters of transformer

[0059] name Numerical name Numerical Transformer model ZZDFPZ-509400 / 500 Rated capacity (MVA) 509.4 Link group label YNy Rated frequency (Hz) 50 Short circuit voltage (%) 21 No-load current (%) 0.15 Load loss (kW) 1315 No-load loss (kW) 209 Core diameter (mm) 700 Iron window height (mm) 2595 Low voltage winding inner diameter (mm) 737 Low voltage winding outer diameter (mm) 801 Medium voltage winding inner diameter (mm) 899 Low voltage winding outer diameter (mm) 1065 High voltage winding inner diameter (mm) 1167 High voltage winding outer diameter (mm) 1330 Low voltage winding height (mm) 1315 Medium voltage winding height (mm) 1615 High voltage winding height (mm) 1795 Low voltage winding turns 7 Medium voltage winding turns 611 High voltage winding turns 179

[0060] The finite element analysis method is used to simulate the model, and the simplified model of the power transformer established above is used to simulate the electrostatic field and the static magnetic field. The three windings of the power transformer model all use the copper material provided by the software. When calculating the capacitance in the electrostatic field, the material model selected for the core is lossless soft iron; when calculating the inductance in the static magnetic field, the material selected is low-carbon steel soft iron. The BH curves of the two core materials are shown as follows: Figure 2 The specific parameter settings are shown in Table 2.

[0061] Table 2 Material related parameters

[0062] Material Conductivity (MS / m) Relative dielectric constant Relative magnetic permeability Copper(winding) 59.98 1 1 Lossless soft iron (electric field core) 0 1 / Low carbon steel soft iron (magnetic field core) 10.15 1 500

[0063] (2) Lead design and layout

[0064] The lead wire is an important channel for connecting the winding of the power transformer with the external circuit. It can safely transmit the current in the winding to the bushing or the outlet terminal to achieve connection with the external power grid. At the same time, the lead wire is wrapped with an insulating bushing to prevent discharge, avoid local discharge breakdown failure, and ensure the long-term and safe operation of the transformer. The lead wires of the power transformer windings are mostly preferably made of oxygen-free copper, which has low cost, good conductivity, low resistance, strong current carrying capacity, and strong anti-oxidation and anti-corrosion capabilities. In the present invention, copper is selected as the material of the lead wire, and the material parameter setting is consistent with the winding. The design of the lead wire is as follows: Figure 3 shown.

[0065] Since the leads connected to the low voltage side are relatively easy to disconnect, this section chooses to connect the leads to the medium and high voltage windings of the left and right phases without considering the leads on the low voltage side. The volume of the leads connected to the medium voltage side is 1.188×107mm 3 , with a surface area of ​​4.894×105mm 2 The volume of the lead connected to the high voltage side is 2.307×109mm 3 , with a surface area of ​​3.127×107mm 2 The other parameters of the high and medium voltage side leads are equal, and the resistivity is 1.72×10 -8 Ω·m, and the temperature coefficient of resistivity is 3.91×10 -3 / K, the simulation reference temperature is room temperature of 298K. The power transformer model with lead wires is as follows Figure 4 shown.

[0066] (3) Analysis of the influence of the lead-free method on the deformation of power transformer windings

[0067] By comparing the capacitance and inductance parameters of the winding deformation after the lead wires are not removed and the lead wires on the high and medium voltage sides are completely removed, the influence characteristics of the lead wire removal method are analyzed to verify the feasibility of this method. The mesh division of the power transformer lead wire removal model is also refined, and the specific unit data is the same as when the lead wires are not connected. In the refined mesh division of the lead wire removal model, the entire model has a total of 294,238 units, and the average unit quality reaches 0.1878. Figure 5 shown.

[0068] Since the three-dimensional model established in this paper does not include components such as insulation pads and coils, this section mainly studies the radial deformation of the winding, that is, the winding is concave inward at 8 points, the deformation degree is the full deformation of the winding (collectively referred to as radial deformation), and the concave depth of each point is 15mm. Figure 6 shown.

[0069] The AC / DC module based on COMSOL Multiphysics 6.3a uses the electrostatic field solver to simulate and analyze the radially deformed low-voltage winding. The medium-voltage winding and the high-voltage winding are grounded. Figure 7 Table 3 shows the potential distribution cloud diagrams of the two methods when the power transformer winding undergoes radial deformation, and Table 4 shows the corresponding ground capacitance parameter values.

[0070] Table 3 Capacitance to ground of two wire removal methods on the low voltage side

[0071]

[0072]

[0073] As can be seen from the above figure and table, when simulating on the low-voltage side, the difference in potential distribution between the two lead removal methods is negligible. Furthermore, the capacitance-to-ground values ​​for the two methods are very similar: 1558.1pF for the lead-in-place method and 1557.8pF for the traditional lead-in-place method. The relative difference between the two is only 0.019%. This indicates that when measuring the capacitance-to-ground of radially deformed windings on the low-voltage side, whether or not the lead is removed has little impact on the results. The lead-in-place method can replace the traditional lead-in-place method for testing.

[0074] Then the capacitance of the deformed winding on the medium voltage side is simulated and analyzed. The low voltage winding and the high voltage winding are grounded. Figure 8 Table 4 shows the capacitance parameter values ​​of the medium voltage winding to ground.

[0075] Table 4 Capacitance to ground of two wire removal methods on the medium voltage side

[0076] Parameters / Methods Do not remove the lead Complete lead removal Relative change (%) Medium voltage winding to ground capacitance (pF) 4240.4 4154 2.038％

[0077] As can be seen from the above figure and table, when simulating the medium-voltage side, the potential distributions for the two lead removal methods differ slightly compared to those for the low-voltage winding, but the overall change is not significant. For capacitance to ground, the value measured using the method without lead removal is 4240.4pF for the medium-voltage winding, while the value measured after complete lead removal is 4154pF. The relative change is 2.038%, which is still within the error range (5%). This indicates that even if there is a slight difference between the two methods when measuring capacitance to ground for radially deformed medium-voltage windings, maintaining lead removal can still meet inspection and maintenance requirements, given the labor and time costs.

[0078] Finally, the capacitance of the high voltage side winding to ground is simulated and analyzed, and the low voltage winding and the medium voltage winding are grounded. Figure 9 Table 5 shows the capacitance parameter values ​​of the high voltage winding to ground.

[0079] Table 5 Capacitance to ground of two methods of removing wires on the high-voltage side

[0080] Parameters / Methods Do not remove the lead Complete lead removal Relative change (%) High voltage winding to ground capacitance (pF) 1507.2 1452 3.662％

[0081] From the high-voltage side simulation in the figure above, it can be observed that the potential of the iron posts surrounding the winding increases synchronously, while the potential distributions for the two lead removal methods remain similar, making them difficult to distinguish with the naked eye. Regarding the ground capacitance, the value measured for the high-voltage winding using the unremoved lead method was 1507.2pF, while the value measured after complete lead removal was 1452pF, a relative change of 3.662%. The largest change occurred in the low, medium, and high deformation windings, likely due to the influence of the iron posts. However, this error remains within the specified error range and has no impact on actual testing. This demonstrates that when measuring the ground capacitance of a radially deformed high-voltage winding, it is possible to meet testing and maintenance requirements without removing the leads.

[0082] Based on the AC / DC module of COMSOL Multiphysics 6.3a, the static magnetic field solver is used to simulate and analyze the inductance of power transformers with and without leads removed in the range of 10kHz-1MHz. This section specifically lists the 10 inductance parameters of the left and right phase windings in this range, as follows: Figure 10 As shown in Tables 6 and 7.

[0083] Table 6 Left-phase three-winding inductance parameters (nH) and relative changes (%)

[0084]

[0085] Table 7 Right phase three-winding inductance parameters (nH) and relative changes (%)

[0086]

[0087] From the data in the above table and figure, it can be concluded that whether to remove the lead has the least influence on the inductance of the two-phase medium-voltage winding, and the maximum difference is only 0.36%. When the method of not removing the lead is applied to the high-voltage winding of the left phase, the change is slightly larger, and the data difference reaches 2.06%, the data accuracy is slightly lower, but it is still applicable. It can be found that the inductance and capacitance data measured by the method of not removing the lead are slightly larger than those measured by the method of removing all leads, which may be related to the parameters of the lead itself. Overall, it is completely feasible to use the method of not removing the lead to detect and test the radial deformation fault of the power transformer winding.

[0088] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the technical solutions, which should be covered in the scope of the claims of the present application.

Claims

1. A finite element-based method for testing the deformation frequency response of power transformer windings without removing leads, characterized by: The following steps are involved: S1: In the finite element simulation software COMSOL, a three-dimensional finite element model is constructed based on the structural parameters of the power transformer; S2: designing a lead arrangement in the three-dimensional finite element model, and connecting the lead to at least one winding; S3: Setting the deformation mode of the winding; S4: Using the finite element simulation software, perform a frequency response test simulation without removing the leads to obtain capacitance and inductance parameters of the winding to ground; S5: comparing the parameters obtained in the lead-not-removed state and the lead-completely-removed state, and determining the feasibility of the lead-not-removed method based on parameter changes; Among them, S1, S2, S3, S4 and S5 are executed in sequence, and S4 depends on the model and settings built by S1 to S3, and S5 performs comparative analysis based on the output of S4.

2. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 1 is characterized in that: In S1, constructing a three-dimensional finite element model includes: Simplify the core into a cylinder or elliptical cylinder, and simplify the winding into a concentric cylindrical structure; Among them, the core material is lossless soft iron in electrostatic field simulation, and low-carbon steel soft iron in static magnetic field simulation.

3. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 1 is characterized in that: In S2, the lead wire is made of copper and is connected to the medium voltage winding and the high voltage winding; Among them, the lead resistance is 1.72×10 -8 Ω·m, and the temperature coefficient of resistivity is 3.91×10 -3 / K.

4. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 1 is characterized in that: In the above-mentioned S3, the deformation mode is radial deformation, including multiple inward concavities, and the depth of the incavities at each point is 15 mm.

5. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 1 is characterized in that: In S4, an electrostatic field solver is used to obtain the ground capacitance parameters, and a static magnetic field solver is used to obtain the inductance parameters; wherein the frequency response test is performed within a frequency range of 10 kHz to 1 MHz.

6. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 1 is characterized in that: In said S5, the parameter variation includes the relative variation of capacitance and the relative variation of inductance; When the relative change in capacitance is less than 5% and the relative change in inductance is less than 2.06%, it is determined that the method of not removing the leads is feasible.

7. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 6, characterized in that: The relative capacitance change is calculated for the low voltage winding, the medium voltage winding, and the high voltage winding, respectively, as follows: The relative change in capacitance of the low-voltage winding to ground shall not exceed 0.019%, the relative change in capacitance of the medium-voltage winding to ground shall not exceed 2.038%, and the relative change in capacitance of the high-voltage winding to ground shall not exceed 3.662%.

8. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 5 is characterized in that: The inductance parameters are obtained within a frequency range of 10 kHz to 1 MHz, and the maximum relative inductance variation does not exceed 2.06%.

9. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 1, characterized in that: The method further comprises: Based on the comparison results of S5, a parameter benchmark library without removing the leads is established for use in the automated detection system.

10. The finite element-based frequency response test method for power transformer winding deformation without lead removal according to claim 9, characterized in that: The automated detection system supports real-time comparison of historical data to locate deformation faults and is adapted to IoT terminals to achieve remote monitoring.

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