A method for obtaining an equivalent resistance of a transformer winding and a related device

Abstract

The embodiment of the application discloses a kind of equivalent resistance acquisition methods of transformer winding and related equipment, by constructing the equivalent circuit model of transformer winding;And the turn of transformer winding is regarded as conductor unit, the conductor current density of equivalent circuit model is obtained under different frequency alternating current using finite element method;According to the conductor current density, alternating current and the cross-sectional area of conductor unit, the conductor equivalent resistance of transformer winding is obtained.The influence of frequency variation and current distribution on winding resistance is considered, the conductor current density of equivalent circuit model under different frequency alternating current is obtained in the application, and the corresponding conductor equivalent resistance is obtained based on the conductor current density, so that the conductor equivalent resistance error obtained under specific frequency is smaller.

Description

[0001] The present application relates to the field of winding analysis and testing, in particular to a method for obtaining equivalent resistance of transformer winding and related equipment.

[0002] As a key device in power system, transformer not only ensures efficient transmission and distribution of electricity, but also plays a positive role in the sustainable development of the whole society and economy, the improvement of people's living standards and social stability. The safe and stable operation of transformer winding, which is the key core component for realizing voltage and current transformation, energy distribution and transmission, is directly related to the reliable power supply of power system. However, due to the complex structure and long-term working state of transformer winding, combined with various factors such as long-term overload operation of transformer and complex working environment, the performance parameters of transformer winding will deteriorate, and even winding deformation, inter-turn short circuit and other faults will occur, causing transformer shutdown, leading to voltage loss of substation and regional large-area power failure, greatly reducing the reliability of power system, seriously affecting the normal power consumption of industrial production and public service facilities, causing serious economic losses and threatening the sustainable and healthy development of society. At the same time, winding fault may cause internal short circuit or partial discharge of transformer, thus aggravating the damage of transformer, and even causing fire or explosion, threatening the safety of personnel and property. In addition, winding fault may cause performance degradation of transformer, increase the load of power system, and further affect the stable operation of power system. Therefore, the performance parameters of transformer winding are of great significance to the operation of power system, and the monitoring, accurate calculation and comparative analysis of the equivalent resistance of transformer winding are particularly important.

[0003] The equivalent resistance parameter is an important index for evaluating the performance of transformer winding. The traditional equivalent resistance parameter calculation method often ignores the influence of frequency change on winding resistance and does not carefully consider the distribution of current, but gives the equivalent resistance based on the geometric size and electromagnetic characteristics of the conductor, resulting in a large error in the calculation result at a specific frequency.

[0004] Therefore, the present application provides a method for obtaining equivalent resistance of transformer winding and related equipment.

[0005] The specific technical scheme of the first embodiment of the present application is as follows: a method for obtaining equivalent resistance of transformer winding, the method comprising: constructing an equivalent circuit model of transformer winding; taking the turns of the transformer winding as a conductor unit, and obtaining the conductor current density of the equivalent circuit model under alternating current at different frequencies by using finite element method; and obtaining the conductor equivalent resistance of the transformer winding according to the conductor current density, the alternating current and the cross-sectional area of the conductor unit. ​​​

[0006] Preferably, the equivalent circuit model of the transformer winding is constructed according to the winding shape, size, material and connection mode of the transformer winding.

[0007] Preferably, the equivalent circuit model of the transformer winding is constructed according to the winding shape, size, material and connection mode of the transformer winding, including: modeling the transformer winding based on the winding shape, size, material and using electromagnetic field simulation software; simulating and analyzing the electromagnetic field distribution characteristics of the transformer winding by using the modeled model; extracting the simulation inductance and simulation capacitance of the transformer winding according to the electromagnetic field distribution characteristics, and correcting the simulation inductance according to the actual inductance of the transformer winding and correcting the simulation capacitance according to the actual capacitance of the transformer winding; constructing the equivalent circuit model by using the corrected simulation inductance, corrected simulation capacitance and connection mode of the winding.

[0008] Preferably, the conductor current density of the equivalent circuit model under different frequencies of alternating current is obtained by using the finite element method, including: setting the boundary conditions of the current and voltage of the transformer winding; using finite element software to mesh the equivalent circuit model, dividing the transformer winding into a finite number of units; setting material properties for each unit; the material properties include electrical conductivity and magnetic permeability; constructing a finite element equation according to Maxwell's equations, the boundary conditions and the material properties of each unit; solving the finite element equation to obtain the conductor current density of each unit.

[0009] Preferably, the conductor equivalent resistance of the transformer winding is obtained according to the conductor current density, the alternating current and the cross-sectional area of the conductor unit, including: obtaining the conductor equivalent resistance according to the conductor current density, the alternating current, the cross-sectional area of the conductor unit and the electrical conductivity of the conductor in the field calculator.

[0010] Preferably, the conductor equivalent resistance is obtained by the following formula:

[0011] I 2 R eq =∫ S J 2 σ -1 dS

[0012] Where |I| is the effective value of the alternating current, R eq is the conductor equivalent resistance, S is the cross-sectional area of the conductor unit, J is the conductor current density, and σ is the electrical conductivity of the conductor.

[0013] Preferably, the effective value of the alternating current is obtained according to waveform data of the alternating current and a period length of the alternating current.

[0014] The specific technical scheme of the second embodiment of the application is as follows: an equivalent resistance acquisition system of a transformer winding, characterized in that the system comprises an equivalent model construction module, a conductor current density acquisition module, and a conductor equivalent resistance acquisition module; the equivalent model construction module is configured to construct an equivalent circuit model of the transformer winding; the conductor current density acquisition module is configured to take a winding turn of the transformer winding as a conductor unit, and acquire a conductor current density of the equivalent circuit model under alternating currents of different frequencies by using a finite element method; and the conductor equivalent resistance acquisition module is configured to acquire an equivalent resistance of a conductor of the transformer winding according to the conductor current density, the alternating current, and a cross-sectional area of the conductor unit.

[0015] The specific technical scheme of the third embodiment of the application is as follows: an equivalent resistance acquisition device of a transformer winding, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program, when executed by the processor, causes the processor to perform the steps of the method according to any one of the first embodiment of the application.

[0016] The specific technical scheme of the fourth embodiment of the application is as follows: a computer readable storage medium, which stores a computer program, and the computer program, when executed by a processor, causes the processor to perform the steps of the method according to any one of the first embodiment of the application.

[0017] The application has the following beneficial effects:

[0018] The application constructs an equivalent circuit model of a transformer winding, takes a winding turn of the transformer winding as a conductor unit, acquires a conductor current density of the equivalent circuit model under alternating currents of different frequencies by using a finite element method, and acquires an equivalent resistance of a conductor of the transformer winding according to the conductor current density, the alternating current, and a cross-sectional area of the conductor unit. The application considers the influence of frequency variation and current distribution on the winding resistance, acquires the conductor current density of the equivalent circuit model under alternating currents of different frequencies, and acquires the corresponding equivalent resistance of the conductor based on the conductor current density, so that the error of the acquired equivalent resistance of the conductor under a specific frequency is small. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0020] Figure 1 Flow chart of steps for a method for obtaining an equivalent resistance of a transformer winding;

[0021] Figure 2 Schematic diagram of an equivalent circuit model of a transformer winding;

[0022] Figure 3a Schematic diagram of current density distribution of a conductor at 1 kHz frequency;

[0023] Figure 3b Schematic diagram of current density distribution of a conductor at 100 kHz frequency;

[0024] Figure 3c Schematic diagram of current density distribution of a conductor at 600 kHz frequency;

[0025] Figure 3d Schematic diagram of current density distribution of a conductor at 1000 kHz frequency;

[0026] Figure 4 Schematic diagram of a system for obtaining an equivalent resistance of a transformer winding;

[0027] Figure 5 Internal structure diagram of a computer device;

[0028] The equivalent model construction module 201, the conductor current density obtaining module 202, and the conductor equivalent resistance obtaining module 203.

DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work fall within the scope of protection of the present application.

[0030] The terms "first", "second", and the like in the specification and claims of the present application and the drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or modules is not limited to the listed steps or modules, but can optionally include other steps or modules not listed, or can optionally include other steps or modules inherent to the process, method, product, or device.

[0031] Reference to an "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0032] Reference is made to Figure 1 , a flow chart of steps of a method for obtaining an equivalent resistance of a transformer winding in a first embodiment of the application, so that the equivalent resistance of the conductor obtained at a certain frequency has a small error, the method comprising:

[0033] Step 101, constructing an equivalent circuit model of the transformer winding;

[0034] Step 102, taking the turns of the transformer winding as a conductor unit, and obtaining the conductor current density of the equivalent circuit model under alternating current at different frequencies by using the finite element method;

[0035] Step 103, obtaining the equivalent resistance of the conductor of the transformer winding according to the conductor current density, the alternating current and the cross-sectional area of the conductor unit.

[0036] The method in the embodiment obtains the conductor current density of the equivalent circuit model under alternating current at different frequencies by constructing an equivalent circuit model of the transformer winding, taking the turns of the transformer winding as a conductor unit, and using the finite element method, and obtains the equivalent resistance of the conductor of the transformer winding based on the conductor current density, so that the equivalent resistance of the conductor obtained at a certain frequency has a small error.

[0037] Specifically, since the equivalent resistance parameter calculation and port response test analysis of the winding are mainly carried out at high frequencies, the influence of the skin effect and the proximity effect is significant, the current will be concentrated to the surface or the edge position of the cross section of the winding conductor as the frequency rises, thereby causing the current density in the conductor path to change, further affecting the winding resistance value. The schematic diagram of the equivalent circuit model of the transformer winding is shown in Figure 2 , the resistance in the equivalent circuit model of the transformer winding is divided into two parts, one part is the resistance in series with the inductance, representing the variable loss generated by the copper conductor in the winding; the other part is the conductance in parallel with the capacitance, representing the capacitive loss generated by the leakage current.

[0038] The turns of the winding are conductor units, and the current density distribution of the conductor at different frequencies is analyzed by two-dimensional finite element eddy current field analysis of ANSYS Maxwell. As shown in the conductor current density distribution diagrams shown in Figure 3a , Figure 3b 、 Figure 3c and Figure 3d , the distribution of the current density is greatly affected by the frequency. According to Figure 3a , at 1 kHz, the current density distribution has shown a trend of gradually concentrating from the center to the edge, but the overall difference is not large. According to Figure 3b , at 100 kHz, the current density is obviously distributed at the edge of the conductor cross section, with a maximum of 8.1715e+7 A / m2, and the current density in the central region is close to 0 A / m2. According to Figure 3c , when the frequency is greater than 600 kHz, the current density distribution is basically concentrated at the four corner edges of the conductor cross section, with a maximum of 4.0339e+8 A / m2, and the current density in the middle of the turn is 0 A / m2. According to Figure 3d , as the frequency increases, the winding is more significantly affected by the skin effect and proximity effect, and the current-carrying capacity of the conductor gradually decreases, resulting in an increase in the resistance value of the winding. Therefore, the calculation method for the resistance of the copper conductor includes the finite element method and the formula method. The finite element method is based on the calculation of the current density distribution in the conductor at different frequencies by the eddy current field, and then the equivalent resistance of the conductor is calculated by the field calculator.

[0039] In specific embodiments, the equivalent circuit model of the transformer winding is constructed, including: constructing the equivalent circuit model according to the winding shape, size, material and connection mode of the transformer winding.

[0040] Specifically, the winding can be wound in various forms, such as spiral, disc, cylinder, cross, etc. Different shapes of the winding will affect the inductance, capacitance and resistance of the winding. The size of the winding (such as diameter, length, number of turns, etc.) will affect its electrical performance. The increase in the number of turns will generally increase the inductance, while the change in the diameter and length of the winding will affect the resistance and capacitance. The electrical conductivity and magnetic permeability of the winding material will affect the resistance and inductance of the winding. Common winding materials include conductive materials such as copper and aluminum, and core materials (such as silicon steel sheets) to enhance magnetic permeability. The winding can be connected in series or parallel, which will affect the total resistance, total inductance and total capacitance of the circuit. When connected in series, the current of each winding is the same; when connected in parallel, the voltage at both ends of each winding is the same. In an ideal case, the transformer has no energy loss, and all the magnetic flux is perfectly coupled between the windings. At this time, the equivalent circuit model only includes an ideal transformer, and the number of turns ratio is n=N2 / N1, where N1 and N2 are the number of turns of the primary and secondary windings, respectively. In actual cases, the transformer has various non-ideal factors, such as resistance, inductance, capacitance and leakage magnetic flux.

[0041] The equivalent circuit model needs to include these non-ideal factors:

[0042] 1. Resistance: including the resistance of primary and secondary windings (Rp, Rs), and the parallel resistance that may exist (such as the equivalent resistance of core loss Rc).

[0043] 2. Inductance: including the self-inductance of primary and secondary windings (Llp, Lls), and the inductance due to mutual inductance.

[0044] 3. Capacitance: including the capacitance between windings (Cww), the distributed capacitance of primary and secondary windings (CDP, CDS).

[0045] 4. Leakage flux: simulated through leakage inductance (inductance in series with ideal self-inductance).

[0046] According to the shape, size, material of the winding and the connection mode of the winding, the equivalent circuit model is constructed, and the parameters of each element (such as resistance value, inductance value, capacitance value, etc.) and their connection mode are clearly marked. The equivalent circuit model is simulated and verified using circuit simulation software (such as Multisim, PSpice, etc.). By comparing the simulation results with the actual performance parameters of the transformer, the accuracy of the equivalent circuit model can be evaluated. According to the simulation results, the parameters in the equivalent circuit model are adjusted and optimized. Repeat the simulation and verification process until a satisfactory model precision is obtained.

[0047] In specific embodiments, the equivalent circuit model is constructed according to the shape, size, material of the winding and the connection mode of the winding, including: modeling the transformer winding based on the winding shape, size, material and using electromagnetic field simulation software; simulating and analyzing the electromagnetic field distribution characteristics of the transformer winding using the modeled model; extracting the simulation inductance and simulation capacitance of the transformer winding according to the electromagnetic field distribution characteristics, and correcting the simulation inductance according to the actual inductance of the transformer winding, and correcting the simulation capacitance according to the actual capacitance of the transformer winding; using the corrected simulation inductance, corrected simulation capacitance and connection mode of the winding to construct the equivalent circuit model.

[0048] Specifically, through simulation analysis and correction, the equivalent circuit model can more accurately reflect the electromagnetic characteristics of the transformer winding, including key parameters such as inductance and capacitance. Compared with direct measurement, using the corrected simulation values to construct the model can reduce errors caused by measurement errors, instrument accuracy and other factors. An accurate equivalent circuit model can provide strong support for the optimal design of transformers. By adjusting the parameters in the model, the performance under different design schemes can be predicted, and the optimal scheme can be selected. During the operation of the transformer, the equivalent circuit model can be used to evaluate its performance, including key indicators such as voltage fluctuation, current distribution, and loss. This helps to discover potential problems in a timely manner and make optimal adjustments.

[0049] In specific embodiments, the method of obtaining the conductor current density of the equivalent circuit model under alternating current at different frequencies includes setting the boundary conditions of the current and voltage of the transformer winding; using finite element software to mesh the equivalent circuit model, dividing the transformer winding into a finite number of units; setting material properties for each unit; the material properties include electrical conductivity and magnetic permeability; constructing a finite element equation according to Maxwell's equations, the boundary conditions and the material properties of each unit; solving the finite element equation to obtain the conductor current density of each unit.

[0050] Specifically, according to the actual operation of the transformer and the analysis requirements, the boundary condition type of current and voltage is determined. Common boundary conditions include current source, voltage source, ground, etc. A current source is set at the input or output end of the winding, specifying the size and direction of the current. If the analysis is of alternating current, the amplitude and phase of the current need to be specified. A voltage source or ground condition is set at the other end of the winding or a specific location. The voltage source can specify the size and phase of the voltage, while the ground condition means that the potential at this point is zero. The equivalent circuit model of the transformer is imported into the finite element software. In the finite element software, the winding is meshed. The density of the mesh should be reasonably selected according to the analysis accuracy and computing resources. The mesh can be appropriately densified in areas where the current density changes greatly, such as the end of the winding, the joint, etc. In the finite element software, the material type used by the winding is defined. This usually includes conductive materials such as copper and aluminum. According to the physical properties of the material, its electrical conductivity and magnetic permeability are set. These parameters will affect the current distribution and electromagnetic field distribution in the winding. In the finite element software, the electromagnetic field is selected as the physical field for analysis. This usually includes options such as electric field, magnetic field, or electromagnetic field coupling analysis. According to Maxwell's equations, boundary conditions, and the material properties of each element, the finite element equations are constructed. These equations will describe the electromagnetic field distribution and current density distribution in the winding. In the finite element software, the solver type and solving parameters are set. This includes selecting an iterative solver or a direct solver, and setting convergence criteria and the number of iterations, etc. The solver is run to solve the finite element equations. This usually requires a certain amount of computing time and resources, depending on the complexity of the model and the density of the mesh. After the solution is complete, the conductor current density results are extracted from the finite element software. This can be achieved by viewing the results file or using post-processing tools. The results are usually presented in the form of graphs or data tables, which can visually show the current density distribution in the winding.

[0051] In specific embodiments, the obtaining the conductor equivalent resistance of the transformer winding according to the conductor current density, the alternating current, and the cross-sectional area of the conductor unit comprises: obtaining the conductor equivalent resistance according to the conductor current density, the alternating current, the cross-sectional area of the conductor unit, and the conductor conductivity in a field calculator. Specifically, by considering the conductor current density, cross-sectional area, and conductivity, the local resistance of each unit of the conductor can be accurately calculated. This method is more reflective of the internal resistance distribution of the conductor than the traditional overall resistance calculation method. The field calculator can usually handle complex geometries and boundary conditions. Therefore, this method can be applied to conductors with complex geometries without the need for simplification or approximation.

[0052] In specific embodiments, the conductor equivalent resistance is obtained using the following formula:

[0053] I 2 Req =∫ S J 2 σ -1 dS

[0054] Where |I| is the effective value of the alternating current, R eq Let S be the equivalent resistance of the conductor, S be the cross-sectional area of ​​the conductor unit, J be the current density of the conductor, and σ be the conductivity of the conductor.

[0055] In a specific embodiment, the effective value of the alternating current is obtained based on the waveform data and the period length of the alternating current. Specifically, the waveform data of the alternating current, including the instantaneous values ​​of the current changing over time, is obtained through measurement or simulation. The period length of the alternating current, i.e., the time required for a complete waveform, is determined based on the waveform data. Each instantaneous value in the waveform data is squared to obtain a sequence of squared instantaneous values. The sequence of squared instantaneous values ​​is integrated over one period (or summed and divided by the period length) to obtain the average value of the squared instantaneous values. The square root of the average value of the squared instantaneous values ​​is then taken to obtain the effective value of the alternating current.

[0056] In a specific embodiment, the existing technical solution is to obtain the equivalent resistance using a formula method. Specifically, the formula method does not take into account the distribution of current in detail, but rather gives the expression for solving the equivalent resistance based on the geometric dimensions and electromagnetic properties of the conductor, as shown below:

[0057]

[0058] Where, n z d represents the number of turns in a coil unit. b h is the diameter of the winding coil. a and h r Here, λ represents the axial height and radial width of the coil, f represents the frequency of the excitation signal, μ represents the conductor's permeability, and σ represents the conductor's conductivity.

[0059]

[0060] Table 1: Conductor resistance values ​​at frequency points

[0061] Table 1 is a comparison of the copper conductor resistance parameters calculated at the main frequency points using the finite element method and the formula method, where HV is the high-voltage winding, MV is the medium-voltage winding, and LV is the low-voltage winding. From the table, it can be seen that the finite element method and the formula method have high consistency in calculating the resistance parameters in the medium and high frequency bands. The conductor resistance increases with the increase of frequency, and the MV winding has a resistance of 0.549Ω at 1MHz calculated by the finite element method. The LV winding maintains a small value throughout the frequency band, with a resistance of 0.150Ω and 0.147Ω at 1MHz calculated by the finite element method and the formula method, respectively. Therefore, the equivalent resistance value obtained by the finite element method is more accurate when testing and calculating the equivalent resistance of the transformer winding.

[0062] In specific embodiments, referring to Figure 4 , the structure of a system for obtaining the equivalent resistance of a transformer winding in the second embodiment of the present application is shown in the figure. The system includes an equivalent model construction module 201, a conductor current density acquisition module 202, and a conductor equivalent resistance acquisition module 203. The equivalent model construction module 201 is used to construct an equivalent circuit model of the transformer winding. The conductor current density acquisition module 202 is used to take the turns of the transformer winding as a conductor unit and acquire the conductor current density of the equivalent circuit model under different frequencies of alternating current using the finite element method. The conductor equivalent resistance acquisition module 203 is used to obtain the conductor equivalent resistance of the transformer winding according to the conductor current density, the alternating current, and the cross-sectional area of the conductor unit. The system in this embodiment constructs an equivalent circuit model of the transformer winding, takes the turns of the transformer winding as a conductor unit, acquires the conductor current density of the equivalent circuit model under different frequencies of alternating current using the finite element method, and obtains the conductor equivalent resistance of the transformer winding according to the conductor current density, the alternating current, and the cross-sectional area of the conductor unit. The influence of frequency variation and current distribution on the winding resistance is considered, the conductor current density of the equivalent circuit model under different frequencies of alternating current is acquired, and the corresponding conductor equivalent resistance is obtained based on the conductor current density, so that the error of the obtained conductor equivalent resistance under a specific frequency is small.

[0063] In specific embodiments, the third embodiment of the present application provides a device for obtaining the equivalent resistance of a transformer winding, which includes a memory and a processor. The memory stores a computer program, and the computer program is executed by the processor to make the processor execute the steps of the method described in any one of the first embodiments of the present application. The device in this embodiment considers the influence of frequency variation and current distribution on the winding resistance, acquires the conductor current density of the equivalent circuit model under different frequencies of alternating current, and obtains the corresponding conductor equivalent resistance based on the conductor current density, so that the error of the obtained conductor equivalent resistance under a specific frequency is small.

[0064] In specific embodiments, the fourth embodiment of the present application provides a computer readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method according to any one of the first embodiments of the present application. The storage medium in the present embodiment takes into account the influence of frequency change and current distribution on winding resistance, and the present application obtains the conductor current density of the equivalent circuit model under alternating current at different frequencies, and obtains the corresponding conductor equivalent resistance based on the conductor current density, so that the error of the obtained conductor equivalent resistance at a specific frequency is small.

[0065] Figure 5 An internal structure diagram of a computer device in an embodiment is shown. The computer device can be a terminal or a server. Please refer to Figure 5 The computer device includes a processor, a memory and the like connected through a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system, and can also store a computer program, which, when executed by the processor, can enable the processor to implement the method in the present embodiment. The internal memory can also store a computer program, which, when executed by the processor, can enable the processor to execute the method in the present embodiment. Those skilled in the art can understand that Figure 5 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0066] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

[0067] The above is only the preferred embodiment of the present application, and is not a limitation on other forms of the present application. Any skilled person in the art can make changes or modifications to the equivalent embodiments applied to other fields by using the disclosed technical content, but any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution content of the present application, and in accordance with the technical essence of the present application, still belongs to the protection scope of the technical solution of the present application.

Claims

1. A method of obtaining an equivalent resistance of a transformer winding, characterized by, The method comprises: constructing an equivalent circuit model of a transformer winding; taking turns of the transformer winding as conductor units, and obtaining conductor current density of the equivalent circuit model under alternating currents of different frequencies by using a finite element method; obtaining conductor equivalent resistance of the transformer winding according to the conductor current density, the alternating current and cross-sectional area of the conductor units; the step of obtaining the conductor current density of the equivalent circuit model under alternating currents of different frequencies by using the finite element method comprises: setting boundary conditions of current and voltage of the transformer winding; dividing the equivalent circuit model into a finite number of units by using a finite element software to divide the transformer winding; setting material properties for each unit, wherein the material properties comprise electrical conductivity and magnetic permeability; constructing a finite element equation according to Maxwell's equations, the boundary conditions and the material properties of each unit; solving the finite element equation to obtain conductor current density of each unit; the conductor equivalent resistance is obtained by using the following formula: |I| 2 R eq =∫ S |J| 2 σ -1 dS where |I| is the effective value of the alternating current, R eq is the equivalent resistance of the conductor, S is the cross-sectional area of the conductor unit, J is the current density of the conductor, and σ is the conductivity of the conductor.

2. The method of claim 1, wherein the step of obtaining the equivalent resistance of the transformer winding is performed by: the step of constructing the equivalent circuit model of the transformer winding comprises: constructing the equivalent circuit model according to winding shape, size, material and connection mode of the transformer winding.

3. The method of claim 2, wherein the step of obtaining the equivalent resistance of the transformer winding is performed by: the step of constructing the equivalent circuit model according to winding shape, size, material and connection mode of the transformer winding comprises: modeling the transformer winding based on the winding shape, the size, the material and by using an electromagnetic field simulation software; simulating and analyzing electromagnetic field distribution characteristics of the transformer winding by using the modeled model; extracting simulation inductance and simulation capacitance of the transformer winding according to the electromagnetic field distribution characteristics, and correcting the simulation inductance according to actual inductance of the transformer winding and correcting the simulation capacitance according to actual capacitance of the transformer winding; constructing the equivalent circuit model by using the corrected simulation inductance, the corrected simulation capacitance and the connection mode of the winding.

4. The method of claim 1, wherein the step of obtaining the equivalent resistance of the transformer winding is performed by: the step of obtaining the conductor equivalent resistance of the transformer winding according to the conductor current density, the alternating current and the cross-sectional area of the conductor units comprises: obtaining the conductor equivalent resistance according to the conductor current density, the alternating current, the cross-sectional area of the conductor units and conductor conductivity in a field calculator.

5. The method of claim 1, wherein the step of obtaining the equivalent resistance of the transformer winding is performed by a method comprising: obtaining the effective value of the alternating current according to waveform data of the alternating current and cycle length of the alternating current.

6. A system for obtaining an equivalent resistance of a transformer winding, applied to the method for obtaining an equivalent resistance of a transformer winding according to claim 1, characterized by The system comprises an equivalent model construction module, a conductor current density obtaining module and a conductor equivalent resistance obtaining module; the equivalent model construction module is configured to construct an equivalent circuit model of a transformer winding; the conductor current density obtaining module is configured to take turns of the transformer winding as conductor units, and obtain conductor current density of the equivalent circuit model under alternating currents of different frequencies by using a finite element method; the conductor equivalent resistance obtaining module is configured to obtain conductor equivalent resistance of the transformer winding according to the conductor current density, the alternating current and cross-sectional area of the conductor units.

7. An equivalent resistance acquisition device of a transformer winding, comprising a memory and a processor, characterized in that, The memory stores a computer program which, when executed by the processor, causes the processor to perform the steps of the method of any one of claims 1 to 5.

8. A computer readable storage medium storing a computer program, characterized in that, The computer program, when executed by the processor, causes the processor to perform the steps of the method of any one of claims 1 to 5.

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