Method and system for detecting short-circuit withstand capability of transformer, terminal, medium, and program

Abstract

Disclosed are a method and system for detecting the short-circuit withstand capability of a transformer, a terminal, a medium, and a program. The method comprises: acquiring transformer design parameters and operating conditions of a power system in which the transformer is located; on the basis of the transformer design parameters and the operating conditions of the power system in which the transformer is located, obtaining a maximum short-circuit through current value of a transformer winding; inputting the maximum short-circuit through current value of the transformer winding into a first preset calculation model, and obtaining a first stress value of each coil cake of the transformer winding; using a second preset mode to obtain a second stress value of each coil cake of the transformer winding, then using a third preset mode to obtain a second current value of the transformer winding; and finally obtaining a safety margin of the transformer to determine the short-circuit withstand capability of the transformer. According to the present invention, even when radial support is invalid, accurate detection of the short-circuit withstand capability of a transformer can still be implemented.

Description

Transformer short-circuit withstand capability testing methods, systems, terminals, media, and procedures. Technical Field

[0001] This invention relates to the field of transformer testing, and more particularly to a method, system, terminal, medium, and program for testing the short-circuit withstand capability of a transformer. Background Technology

[0002] The reliable operation of power transformers plays a crucial role in the safety and stability of the power system. When a near-circuit occurs outside the transformer, the enormous short-circuit electrodynamic force may damage the conductor insulation or structural components. In severe cases, it can lead to loosening, twisting, and deformation of the windings, or even the collapse or burnout of the entire winding, resulting in incalculable economic losses and social impact.

[0003] Currently, there are three main methods for testing the short-circuit withstand capability of power transformers: First, direct short-circuit testing of the transformer body is conducted, but the testing conditions and costs are extremely high, which is not conducive to widespread promotion and application; second, short-circuit testing is conducted through sampling, which reduces testing costs to some extent, but the coverage is limited and there are significant potential risks; third, transformer short-circuit withstand capability verification testing is performed, and the traditional method for verifying transformer short-circuit withstand capability is based on the effective radial support method.

[0004] However, in the actual design and manufacturing process of transformers, the windings themselves have a certain set gap, and the insulation material inevitably shrinks during the drying process. Therefore, in actual operation, the support bars used for radial support and insulation cannot play an effective supporting role. This leads to a large deviation in the results of the traditional short-circuit withstand capability verification method based on the effective radial support method. The accuracy of the transformer's short-circuit withstand capability judgment is not high, which poses a significant risk to the quality control of transformer equipment and the reliable operation of the power system. Summary of the Invention

[0005] This invention provides a method, system, terminal, medium, and program for testing the short-circuit withstand capability of transformers, in order to solve the technical problem that the results of the existing method for verifying and testing the effective short-circuit withstand capability based on radial support have large deviations.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a method, system, terminal, medium, and program for detecting the short-circuit withstand capability of a transformer, including:

[0007] Obtain the transformer design parameters and the operating status of the power system where the transformer is located;

[0008] Based on the transformer design parameters and the operating status of the power system where the transformer is located, the maximum through-short-circuit current value of the transformer winding is obtained;

[0009] The maximum through-short-circuit current value of the transformer winding is input into the first preset calculation model to obtain the first stress value of each coil of the transformer winding; wherein, the first preset calculation model is determined by the transformer design parameters;

[0010] Based on the transformer design parameters, the second stress value of each coil of the transformer winding is obtained using a second preset method;

[0011] The second current value of the transformer winding is obtained in a third preset manner based on the first stress value of each coil of the transformer winding and the second stress value of each coil of the transformer winding.

[0012] The safety margin of the transformer is obtained based on the second current value of the transformer winding and the maximum through short-circuit current value of the transformer winding.

[0013] The transformer's short-circuit withstand capability is determined based on the transformer's safety margin.

[0014] By obtaining the transformer's design parameters and the operating status of the power system in which the transformer is located, the maximum short-circuit current value of the transformer windings can be obtained. Based on the transformer's specific design parameters and the voltage, current, and impedance of the power system, the maximum short-circuit current value can be calculated, making the detection of the transformer's short-circuit withstand capability more accurate. Then, the obtained maximum short-circuit current value is input into the first preset calculation model, i.e., the finite element electromagnetic model, to obtain the first stress value of each coil of the transformer windings, improving calculation accuracy, reducing calculation errors, and increasing calculation efficiency. The second stress value of each coil of the transformer windings is obtained through a second preset method, which effectively detects the transformer's short-circuit withstand capability. The second current value is obtained through a third preset method, and then the transformer's safety margin is calculated. Whether the safety margin exceeds a first threshold is used to check if the transformer's short-circuit withstand capability is qualified. This allows for low-cost and high-efficiency assessment of the transformer's short-circuit withstand capability, thereby effectively reducing the risk of power system malfunctions.

[0015] As a preferred embodiment, the transformer design parameters include the transformer winding rated current and the transformer short-circuit impedance per unit value; the operating status of the power system in which the transformer is located includes the power grid system short-circuit impedance per unit value; the maximum through-short-circuit current value of the transformer winding is obtained through the following method:

[0016] Among them, I m I represents the maximum through-short-circuit current value of the transformer winding. N Z is the rated current of the transformer winding. T Z is the per-unit value of the transformer short-circuit impedance. S This represents the per-unit value of the short-circuit impedance of the power grid system.

[0017] By obtaining the maximum through-current value of the transformer winding under short-circuit conditions based on the per-unit short-circuit impedance of the power grid system, the rated current of the transformer winding, and the per-unit short-circuit impedance of the transformer, the short-circuit withstand capability of the transformer can be specifically analyzed according to specific conditions, thus improving the accuracy of the calculation.

[0018] As a preferred option, the transformer design parameters include core structure parameters, winding structure parameters based on the ineffectiveness of radial support, clamping structure parameters, and tank parameters; the first preset calculation model is a finite element electromagnetic model.

[0019] A finite element electromagnetic model is established based on the core structure parameters, the winding structure parameters based on the ineffective radial support, the clamping structure parameters, and the oil tank parameters.

[0020] The maximum through-short-circuit current value of the transformer winding is input into the finite element electromagnetic model to obtain the first stress value of each coil of the transformer winding.

[0021] Based on the transformer core structure parameters, the winding structure parameters due to ineffective radial support, the clamping structure parameters, and the tank parameters, a corresponding finite element electromagnetic model is established. This allows for accurate calculation of the first stress value using finite element computer software, reducing calculation time, improving work efficiency, and increasing the accuracy of the test results.

[0022] As a preferred embodiment, the transformer design parameters include the yield strength and thickness of the transformer conductors; the second stress value of each coil of the transformer winding is determined by the following method: σ l =(Aσ 0.2 +B)ln b eq +C

[0023] σ l σ represents the second stress value of each coil in the transformer winding. 0.2 b is the yield strength of the conductor. eq Where A is the thickness of the conductor, and B and C are preset coefficients.

[0024] This allows for more accurate calculation of the corresponding stress value based on the yield strength and thickness of the transformer conductor and a preset coefficient.

[0025] As a preferred embodiment, the preset coefficient A has a value range of 0.13-0.15; the preset coefficient B has a value range of 6-8; and the preset coefficient C has a value range of 12-15.

[0026] In this way, the preset coefficients are calculated within a certain numerical range, making the transformer's short-circuit withstand capability test more accurate.

[0027] As a preferred embodiment, the step of obtaining the second current value of the transformer winding in a third preset manner based on the first stress value and the second stress value of each coil of the transformer winding specifically involves:

[0028] Based on the first stress value and the second stress value of each coil of the transformer winding, the estimated range of the second current value is obtained.

[0029] The second current value is obtained based on the estimated range of the second current value and the second stress value of each coil of the transformer winding.

[0030] By using the range of the first stress value, the corresponding range of the current value can be obtained. Then, by using the first preset calculation model, the accurate current value can be obtained, reducing the user's calculation time and improving work efficiency.

[0031] As a preferred embodiment, the safety margin of the transformer is obtained based on the second current value of the transformer winding and the maximum through-short-circuit current value of the transformer winding, specifically as follows:

[0032] Where K is the safety margin, I2 is the second current value, and I m This represents the maximum through-short-circuit current value of the winding.

[0033] This allows for a more accurate expression of the safety margin, reducing errors caused by simulation and calculation.

[0034] As a preferred embodiment, determining the transformer's short-circuit withstand capability based on the transformer's safety margin specifically involves:

[0035] When the safety margin of the transformer is greater than the first threshold, the transformer's short-circuit withstand capability is qualified.

[0036] When the safety margin of the transformer is less than the first threshold, the transformer's short-circuit withstand capability is unqualified.

[0037] Thus, the higher the safety margin of a transformer, the stronger its short-circuit withstand capability and the higher its safety factor. Representing the safety margin in numerical form provides users with a more intuitive understanding.

[0038] This invention also provides a transformer short-circuit withstand capability detection system, comprising: an acquisition module, a first calculation module, a second calculation module, a third calculation module, a fourth calculation module, a fifth calculation module, and a judgment module;

[0039] The acquisition module is used to acquire the transformer design parameters and the operating status of the power system where the transformer is located;

[0040] The first calculation module is used to obtain the maximum through-short-circuit current value of the transformer winding based on the transformer design parameters and the operating status of the power system where the transformer is located;

[0041] The second calculation module is used to input the maximum through-short-circuit current value of the transformer winding into the first preset calculation model to obtain the first stress value of each coil of the transformer winding; wherein, the first preset calculation model is determined by the transformer design parameters;

[0042] The third calculation module is used to obtain the second stress value of each coil of the transformer winding according to the transformer design parameters and a second preset method.

[0043] The fourth calculation module is used to obtain the second current value of the transformer winding in a third preset manner based on the first stress value and the second stress value of each coil of the transformer winding.

[0044] The fifth calculation module is used to obtain the safety margin of the transformer based on the second current value of the transformer winding and the maximum through short-circuit current value of the transformer winding;

[0045] The judgment module is used to determine the transformer's short-circuit withstand capability based on the transformer's safety margin.

[0046] This method involves acquiring transformer design parameters and the operating status of the power system in which the transformer is located through an acquisition module. The first calculation module obtains the maximum short-circuit current value of the transformer windings. Based on the transformer's specific design parameters and the voltage, current, and impedance of the power system, the maximum short-circuit current value can be calculated, making the short-circuit withstand capability test more accurate. Then, the second calculation module inputs the obtained maximum short-circuit current value into the first preset calculation model, i.e., the finite element electromagnetic model, to obtain the first stress value of each coil of the transformer windings. This improves calculation accuracy, reduces calculation errors, and increases calculation efficiency. The third calculation module obtains the second stress value of each coil of the transformer windings, effectively testing the transformer's short-circuit withstand capability. The fourth calculation module obtains the second current value, and the fifth calculation module calculates the transformer's safety margin. Finally, a judgment module determines whether the safety margin exceeds a first threshold, checking if the transformer's short-circuit withstand capability is qualified. This allows for low-cost and high-efficiency assessment of the transformer's short-circuit withstand capability, effectively reducing the risk of power system malfunctions.

[0047] This invention also provides a terminal device, characterized in that it includes a processor, a memory, and a computer program stored in the memory and running on the memory, wherein the processor executes the computer program to implement any of the steps of the transformer short-circuit withstand capability detection method as described in this invention.

[0048] This invention also provides a computer-readable storage medium storing a computer program thereon, characterized in that, when the computer program is executed by the processor, it implements any of the steps of the transformer short-circuit withstand capability detection method as described in this invention.

[0049] This invention also provides a computer program product, including a computer program, characterized in that when the computer program is executed by a processor, it implements any of the steps of the transformer short-circuit withstand capability detection method described in this invention. Attached Figure Description

[0050] Figure 1: A flowchart illustrating an embodiment of a transformer short-circuit withstand capability testing method provided by the present invention;

[0051] Figure 2: A schematic diagram of an embodiment of a transformer short-circuit withstand capability detection system provided by the present invention;

[0052] Figure 3: A numerical curve of radial critical stress based on ineffective radial support, representing an embodiment of a transformer short-circuit withstand capability testing method provided by the present invention.

[0053] Figure 4: A diagram showing the critical state of a transformer winding after being subjected to a short-circuit current, according to an embodiment of the transformer short-circuit withstand capability detection method provided by the present invention.

[0054] The reference numerals in the accompanying drawings are as follows: 100, acquisition module; 200, first calculation module; 300, second calculation module; 400, third calculation module; 500, fourth calculation module; 600, fifth calculation module; 700, judgment module. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Example 1

[0057] Please refer to Figure 1, which is a flowchart illustrating an embodiment of a transformer short-circuit withstand capability testing method provided by the present invention, including steps S1 to S7, the specific steps of which are as follows:

[0058] Step S1: Obtain the transformer design parameters and the operating status of the power system where the transformer is located;

[0059] In this embodiment, by obtaining the transformer design parameters and the operating status of the power system in which the transformer is located, specific parameters of a specific transformer can be analyzed in detail, improving the accuracy of short-circuit withstand capability detection. Combined with the operating status of the power system in which the transformer is located, this provides a realistic basis for the accuracy of short-circuit withstand capability detection, ensuring that the calculation results are targeted and have practical significance.

[0060] In one specific embodiment, taking a transformer of model SSZ-40000 / 110 as an example, the transformer has a rated voltage of 121 / 40.5 / 10.5kV, a connection group of YNyn0d11, a short-circuit impedance of HV-MV: 9.75%, a winding arrangement of LV-MV-HV-TV, a yield strength of 90MPa for the medium-voltage winding, a wire gauge of 2.24*12.5mm for the medium-voltage winding, a reactance height of 1280mm for the medium-voltage winding, and 20 support bars for the medium-voltage winding.

[0061] Step S2: Based on the transformer design parameters and the operating status of the power system where the transformer is located, obtain the maximum through-short-circuit current value of the transformer winding;

[0062] In this embodiment, the transformer design parameters include the transformer winding rated current and the transformer short-circuit impedance per unit value; the operating status of the power system where the transformer is located includes the power grid system short-circuit impedance per unit value; the maximum through-short-circuit current value of the transformer winding is obtained through the following method:

[0063] Among them, I m I represents the maximum through-short-circuit current value of the transformer winding. N Z is the rated current of the transformer winding. T Z is the per-unit value of the transformer short-circuit impedance. S This represents the per-unit value of the short-circuit impedance of the power grid system.

[0064] Furthermore, different types of transformers have different short-circuit conditions. For two-winding transformers, the short-circuit condition is high-voltage to low-voltage; for three-winding transformers, the short-circuit conditions are divided into four types: high-voltage to low-voltage, high-voltage to medium-voltage, medium-voltage to low-voltage, and high-voltage + medium-voltage to low-voltage. The maximum through-short-circuit current value of the transformer will also be different for different conditions.

[0065] In one specific embodiment, the maximum through-short-circuit current of the transformer winding is 5.6kA.

[0066] By obtaining the maximum through-current value of the transformer winding under short-circuit conditions based on the per-unit short-circuit impedance of the power grid system, the rated current of the transformer winding, and the per-unit short-circuit impedance of the transformer, the short-circuit withstand capability of the transformer can be specifically analyzed according to specific conditions, thus improving the accuracy of the calculation.

[0067] Step S3: Input the maximum through-short-circuit current value of the transformer winding into the first preset calculation model to obtain the first stress value of each coil of the transformer winding; wherein, the first preset calculation model is determined by the transformer design parameters;

[0068] In this embodiment, the transformer design parameters include core structure parameters, winding structure parameters based on ineffective radial support, clamping structure parameters, and tank parameters; the first preset calculation model is a finite element electromagnetic model.

[0069] A finite element electromagnetic model is established based on the core structure parameters, the winding structure parameters based on the ineffective radial support, the clamping structure parameters, and the oil tank parameters.

[0070] The maximum through-short-circuit current value of the transformer winding is input into the finite element electromagnetic model to obtain the first stress value of each coil of the transformer winding.

[0071] In one specific embodiment, a finite element electromagnetic model is established based on the core structure parameters, the winding structure parameters based on the ineffective radial support, the clamping structure parameters, and the tank parameters. The leakage flux magnitude B at different positions of the winding is calculated using finite element electromagnetic software. The electrodynamic force F of the non-continuous coil can be obtained using the Lorentz force formula. Then, based on the winding conductor cross-sectional parameters, the stress value of each coil of the transformer winding is calculated using material mechanics formulas. Considering the transmission characteristics of the electrodynamic force of the coil, the average leakage flux is used for verification during the calculation. That is, the electrodynamic force and stress used for verification are the average electrodynamic force and average stress values ​​of different coils. Finally, the first stress value of 61.2 MPa for each coil of the transformer winding is calculated.

[0072] Based on the transformer core structure parameters, the winding structure parameters due to ineffective radial support, the clamping structure parameters, and the tank parameters, a corresponding finite element electromagnetic model is established. This allows for accurate calculation of the first stress value using finite element computer software, reducing calculation time, improving work efficiency, and increasing the accuracy of the test results.

[0073] Step S4: Based on the transformer design parameters, obtain the second stress value of each coil of the transformer winding using the second preset method;

[0074] Please refer to Figure 3, which shows a numerical curve of radial critical stress based on ineffective radial support, representing an embodiment of the transformer short-circuit withstand capability testing method provided by this invention. In this embodiment, the transformer design parameters include the yield strength and thickness of the transformer conductors. The second stress value of each coil of the transformer winding is determined by the following method: σ l =(Aσ 0.2 +B)ln beq +C

[0075] σ l σ represents the second stress value of each coil in the transformer winding. 0.2 b is the yield strength of the conductor. eq Where A is the thickness of the conductor, and B and C are preset coefficients.

[0076] In one specific embodiment, the preset coefficient A has a value range of 0.13-0.15; the preset coefficient B has a value range of 6-8; and the preset coefficient C has a value range of 12-15.

[0077] In one specific embodiment, the second stress value is 26.3-32.3 MPa.

[0078] In this way, the preset coefficients are calculated within a certain numerical range, making the transformer's short-circuit withstand capability test more accurate.

[0079] Step S5: Based on the first stress value of each coil of the transformer winding and the second stress value of each coil of the transformer winding, obtain the second current value of the transformer winding in a third preset manner.

[0080] In this embodiment, the step of obtaining the second current value of the transformer winding in a third preset manner based on the first stress value and the second stress value of each coil of the transformer winding specifically involves:

[0081] Based on the first stress value and the second stress value of each coil of the transformer winding, the estimated range of the second current value is obtained.

[0082] The second current value is obtained based on the estimated range of the second current value and the second stress value of each coil of the transformer winding.

[0083] In one specific embodiment, the estimated range of the second current value is first obtained based on the first stress value and the second stress value of each coil of the transformer winding. Then, two values ​​within the estimated range of the second current value are randomly selected and substituted into the first preset calculation model to obtain the corresponding stress value. The magnitude of the corresponding stress value is compared with the second stress value, and the corresponding stress value is continuously obtained by using an iterative method. Finally, when the corresponding stress value is equal to the second stress value, the second current value is determined.

[0084] In one specific embodiment, the second current value is a withstand current value of 3.7-4.1kA, and the second stress value is a radial critical stress value of 26.3-32.3MPa.

[0085] By using the range of the first stress value, the corresponding range of the current value can be obtained. Then, by using the first preset calculation model, the accurate current value can be obtained, reducing the user's calculation time and improving work efficiency.

[0086] Step S6: Obtain the safety margin of the transformer based on the second current value of the transformer winding and the maximum through short-circuit current value of the transformer winding;

[0087] In one specific embodiment, the step of obtaining the transformer's safety margin based on the second current value of the transformer winding and the maximum through-short-circuit current value of the transformer winding specifically involves:

[0088] Where K is the safety margin, I2 is the second current value, and I m This represents the maximum through-short-circuit current value of the winding.

[0089] In one specific embodiment, the safety margin is 0.66-0.73. The safety margin value is reflected by the ratio of current values, which can obtain more accurate evaluation data. This can more accurately express the safety margin and reduce the errors caused by simulation and calculation.

[0090] Step S7: Determine the transformer's short-circuit withstand capability based on the transformer's safety margin;

[0091] In this embodiment, determining the transformer's short-circuit withstand capability based on the transformer's safety margin specifically involves:

[0092] When the safety margin of the transformer is greater than the first threshold, the transformer's short-circuit withstand capability is qualified.

[0093] When the safety margin of the transformer is less than the first threshold, the transformer's short-circuit withstand capability is unqualified.

[0094] In one specific embodiment, when the safety margin value is greater than 1.0, it indicates that the transformer's short-circuit withstand capability is qualified; when the safety margin value is less than 1.0, it indicates that the transformer's short-circuit withstand capability is unqualified.

[0095] Please refer to Figure 4, which is a critical state diagram of a transformer winding after being subjected to a short-circuit current, according to an embodiment of the transformer short-circuit withstand capability detection method provided by the present invention. In this embodiment, the safety margin value is 0.66-0.73, which is much lower than the first threshold of 1.0, so the transformer is determined to have insufficient short-circuit withstand capability.

[0096] By obtaining the transformer's design parameters and the operating status of the power system in which the transformer is located, the maximum short-circuit current value of the transformer windings can be obtained. Based on the transformer's specific design parameters and the voltage, current, and impedance of the power system, the maximum short-circuit current value can be calculated, making the detection of the transformer's short-circuit withstand capability more accurate. Then, the obtained maximum short-circuit current value is input into the first preset calculation model, i.e., the finite element electromagnetic model, to obtain the first stress value of each coil of the transformer windings, improving calculation accuracy, reducing calculation errors, and increasing calculation efficiency. The second stress value of each coil of the transformer windings is obtained through a second preset method, which effectively detects the transformer's short-circuit withstand capability. The second current value is obtained through a third preset method, and then the transformer's safety margin is calculated. Whether the safety margin exceeds a first threshold is used to check if the transformer's short-circuit withstand capability is qualified. This allows for low-cost and high-efficiency assessment of the transformer's short-circuit withstand capability, thereby effectively reducing the risk of power system malfunctions.

[0097] Example 2

[0098] Please refer to Figure 2, which is a structural schematic diagram of an embodiment of a transformer short-circuit withstand capability detection system provided by the present invention, including: an acquisition module 100, a first calculation module 200, a second calculation module 300, a third calculation module 400, a fourth calculation module 500, a fifth calculation module 600, and a judgment module 700.

[0099] The acquisition module 100 is used to acquire the transformer design parameters and the operating status of the power system where the transformer is located;

[0100] In this embodiment, the transformer design parameters and the operating status of the power system where the transformer is located are obtained by the acquisition module 100. This allows for specific analysis of the specific parameters of a particular transformer, improving the accuracy of short-circuit withstand capability detection. Combined with the operating status of the power system where the transformer is located, this provides a realistic basis for the accuracy of short-circuit withstand capability detection, ensuring that the calculation results are targeted and have practical significance.

[0101] In one specific embodiment, taking a transformer of model SSZ-40000 / 110 as an example, the transformer has a rated voltage of 121 / 40.5 / 10.5kV, a connection group of YNyn0d11, a short-circuit impedance of HV-MV: 9.75%, a winding arrangement of LV-MV-HV-TV, a yield strength of 90MPa for the medium-voltage winding, a wire gauge of 2.24*12.5mm for the medium-voltage winding, a reactance height of 1280mm for the medium-voltage winding, and 20 support bars for the medium-voltage winding.

[0102] The first calculation module 200 is used to obtain the maximum through-short-circuit current value of the transformer winding based on the transformer design parameters and the operating status of the power system where the transformer is located;

[0103] In this embodiment, the transformer design parameters include the transformer winding rated current and the transformer short-circuit impedance per unit value; the operating status of the power system where the transformer is located includes the power grid system short-circuit impedance per unit value; the maximum through-short-circuit current value of the transformer winding is obtained in the first calculation module 200 in the following way:

[0104] Among them, I m I represents the maximum through-short-circuit current value of the transformer winding. N Z is the rated current of the transformer winding. T Z is the per-unit value of the transformer short-circuit impedance. S This represents the per-unit value of the short-circuit impedance of the power grid system.

[0105] Furthermore, different types of transformers have different short-circuit conditions. For two-winding transformers, the short-circuit condition is high-voltage to low-voltage; for three-winding transformers, the short-circuit conditions are divided into four types: high-voltage to low-voltage, high-voltage to medium-voltage, medium-voltage to low-voltage, and high-voltage + medium-voltage to low-voltage. The maximum through-short-circuit current value of the transformer will also be different for different conditions.

[0106] In one specific embodiment, the maximum through-short-circuit current of the transformer winding is 5.6kA.

[0107] In this way, by using the first calculation module 200 to obtain the maximum through current value of the transformer winding under short-circuit conditions based on the per-unit value of the short-circuit impedance of the power grid system, the rated current of the transformer winding, and the per-unit value of the transformer short-circuit impedance, the transformer winding can be subjected to a specific analysis of its short-circuit withstand capability according to specific conditions, thereby improving the accuracy of the calculation.

[0108] The second calculation module 300 is used to input the maximum through-short-circuit current value of the transformer winding into the first preset calculation model to obtain the first stress value of each coil of the transformer winding; wherein, the first preset calculation model is determined by the transformer design parameters;

[0109] In this embodiment, the transformer design parameters include core structure parameters, winding structure parameters based on ineffective radial support, clamping structure parameters, and tank parameters; the first preset calculation model is a finite element electromagnetic model.

[0110] A finite element electromagnetic model is established based on the core structure parameters, the winding structure parameters based on the ineffective radial support, the clamping structure parameters, and the oil tank parameters.

[0111] The maximum through-short-circuit current value of the transformer winding is input into the finite element electromagnetic model to obtain the first stress value of each coil of the transformer winding.

[0112] In one specific embodiment, a finite element electromagnetic model is established based on the core structure parameters, the winding structure parameters based on the ineffective radial support, the clamping structure parameters, and the tank parameters. The leakage flux magnitude B at different positions of the winding is calculated using finite element electromagnetic software. The electrodynamic force F of the non-continuous coil can be obtained using the Lorentz force formula. Then, based on the winding conductor cross-sectional parameters, the stress value of each coil of the transformer winding is calculated using material mechanics formulas. Considering the transmission characteristics of the electrodynamic force of the coil, the average leakage flux is used for verification during the calculation. That is, the electrodynamic force and stress used for verification are the average electrodynamic force and average stress values ​​of different coils. Finally, the first stress value of 61.2 MPa for each coil of the transformer winding is calculated.

[0113] In this way, in the second calculation module 300, a corresponding finite element electromagnetic model is established based on the transformer core structure parameters, the winding structure parameters based on the ineffective radial support, the clamping structure parameters, and the tank parameters. It can accurately calculate the first stress value by relying on finite element computer software, reducing calculation time, improving work efficiency, and improving the accuracy of detection results.

[0114] The third calculation module 400 is used to obtain the second stress value of each coil of the transformer winding according to the transformer design parameters and a second preset method.

[0115] Please refer to Figure 3, which shows the radial critical stress numerical curve based on radial support ineffectiveness provided by the present invention. In this embodiment, the transformer design parameters include the yield strength and thickness of the transformer conductors; the second stress value of each coil of the transformer winding is determined by the following method: σ l =(Aσ 0.2 +B)ln b eq +C

[0116] σ l σ represents the second stress value of each coil in the transformer winding. 0.2 b is the yield strength of the conductor. eq Where A is the thickness of the conductor, and B and C are preset coefficients.

[0117] In one specific embodiment, the preset coefficient A has a value range of 0.13-0.15; the preset coefficient B has a value range of 6-8; and the preset coefficient C has a value range of 12-15.

[0118] In one specific embodiment, the second stress value is 26.3-32.3 MPa.

[0119] In this way, the third calculation module 400 performs corresponding calculations on the preset coefficients within a certain numerical range, making the transformer's short-circuit withstand capability detection more accurate.

[0120] The fourth calculation module 500 is used to obtain the second current value of the transformer winding in a third preset manner based on the first stress value of each coil of the transformer winding and the second stress value of each coil of the transformer winding.

[0121] In this embodiment, the step of obtaining the second current value of the transformer winding in a third preset manner based on the first stress value and the second stress value of each coil of the transformer winding specifically involves:

[0122] Based on the first stress value and the second stress value of each coil of the transformer winding, the estimated range of the second current value is obtained.

[0123] The second current value is obtained based on the estimated range of the second current value and the second stress value of each coil of the transformer winding.

[0124] In one specific embodiment, the estimated range of the second current value is first obtained based on the first stress value and the second stress value of each coil of the transformer winding. Then, two values ​​within the estimated range of the second current value are randomly selected and substituted into the first preset calculation model to obtain the corresponding stress value. The magnitude of the corresponding stress value is compared with the second stress value, and the corresponding stress value is continuously obtained by using an iterative method. Finally, when the corresponding stress value is equal to the second stress value, the second current value is determined.

[0125] In one specific embodiment, the second current value is a withstand current value of 3.7-4.1kA, and the second stress value is a radial critical stress value of 26.3-32.3MPa.

[0126] In this way, the range of the first stress value is obtained through the fourth calculation module 500, and the corresponding range of the current value is obtained accordingly. Then, the accurate current value is obtained through the first preset calculation model, which reduces the user's calculation time and improves work efficiency.

[0127] The fifth calculation module 600 is used to obtain the safety margin of the transformer based on the second current value of the transformer winding and the maximum through short-circuit current value of the transformer winding.

[0128] In one specific embodiment, the step of obtaining the transformer's safety margin based on the second current value of the transformer winding and the maximum through-short-circuit current value of the transformer winding specifically involves:

[0129] Where K is the safety margin, I2 is the second current value, and I mThis represents the maximum through-short-circuit current value of the winding.

[0130] In one specific embodiment, the safety margin is obtained as 0.66-0.73 by the fifth calculation module 600. The safety margin value is reflected by the ratio of current values, which can obtain more accurate evaluation data. This can more accurately express the safety margin and reduce the errors caused by simulation and calculation.

[0131] The judgment module 700 is used to determine the short-circuit withstand capability of the transformer based on the safety margin of the transformer;

[0132] In this embodiment, determining the transformer's short-circuit withstand capability based on the transformer's safety margin specifically involves:

[0133] When the safety margin of the transformer is greater than the first threshold, the transformer's short-circuit withstand capability is qualified.

[0134] When the safety margin of the transformer is less than the first threshold, the transformer's short-circuit withstand capability is unqualified.

[0135] In one specific embodiment, when the safety margin value is greater than 1.0, it indicates that the transformer's short-circuit withstand capability is qualified; when the safety margin value is less than 1.0, it indicates that the transformer's short-circuit withstand capability is unqualified.

[0136] Please refer to Figure 4, which is a critical state diagram of a transformer winding after being subjected to a short-circuit current, according to an embodiment of the transformer short-circuit withstand capability detection method provided by the present invention. In this embodiment, the safety margin value is 0.66-0.73, which is much lower than the first threshold of 1.0, so the transformer is determined to have insufficient short-circuit withstand capability.

[0137] By acquiring transformer design parameters and the operating status of the power system in which the transformer is located through module 100, and obtaining the maximum short-circuit current value of the transformer winding through the first calculation module 200, the maximum short-circuit current value of the transformer can be calculated based on the specific design parameters of the transformer and the voltage, current and impedance of the power system in which the transformer is located, making the detection of the transformer's short-circuit withstand capability more accurate. Then, the second calculation module 300 inputs the obtained maximum short-circuit current value of the transformer winding into the first preset calculation model, that is, the finite element electromagnetic model, to obtain the first stress value of each coil of the corresponding transformer winding, which improves the calculation accuracy, reduces the calculation error and improves the calculation efficiency. The third calculation module 400 obtains the second stress value of each coil of the transformer winding, which can effectively detect the transformer's short-circuit withstand capability. The fourth calculation module 500 obtains the second current value, and then the fifth calculation module 600 obtains the safety margin of the transformer. Finally, the judgment module 700 determines whether the safety margin exceeds the first threshold, and detects whether the transformer's short-circuit withstand capability is qualified. This can achieve low-cost and high-efficiency judgment of the transformer's short-circuit withstand capability, thereby effectively reducing the risk of power system operation failure.

[0138] Example 3

[0139] This invention also provides a terminal device, including a processor, a memory, and a computer program stored in the memory and running on the memory. When the processor executes the computer program, it implements any of the steps of the transformer short-circuit withstand capability detection method described in this invention.

[0140] Example 4

[0141] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by the processor, implements any of the steps of the transformer short-circuit withstand capability detection method described in this invention.

[0142] Example 5

[0143] This invention also provides a computer program product, including a computer program, characterized in that when the computer program is executed by a processor, it implements any of the steps of the transformer short-circuit withstand capability detection method described in this invention.

[0144] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. That is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected to achieve the purpose of this embodiment according to actual needs.

[0145] Those skilled in the art will understand that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, or suitable combinations thereof. Some or all physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or temporary media). As is known to those skilled in the art, the term computer storage media includes media used for storing information (such as computer-readable instructions, data structures, programs, etc.). The volatile and non-volatile, removable and non-removable media implemented in any method or technology (program modules or other data), computer storage media including but not limited to RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. In addition, as is known to those skilled in the art, communication media generally contain computer-readable instructions, data structures, program modules or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0146] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0147] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0148] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0149] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0150] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method of detecting short circuit resistance of a transformer, characterized by, The method comprises the following steps: obtaining transformer design parameters and the operating condition of the power system where the transformer is located; obtaining the maximum short-circuit current value of the transformer winding according to the transformer design parameters and the operating condition of the power system where the transformer is located; inputting the maximum short-circuit current value of the transformer winding into a first pre-design calculation model to obtain the first stress value of each wire cake of the transformer winding; wherein the first pre-design calculation model is determined by the transformer design parameters; obtaining the second stress value of each wire cake of the transformer winding by a second preset method according to the transformer design parameters; obtaining the second current value of the transformer winding by a third preset method according to the first stress value of each wire cake of the transformer winding and the second stress value of each wire cake of the transformer winding; obtaining the safety margin of the transformer according to the second current value of the transformer winding and the maximum short-circuit current value of the transformer winding; determining the short-circuit resistance of the transformer according to the safety margin of the transformer.

2. The method of claim 1, wherein, The transformer design parameters include the rated current of the transformer winding and the short-circuit impedance reference value of the transformer; and the operating condition of the power system where the transformer is located includes the short-circuit impedance reference value of the power grid system; The maximum short-circuit current value of the transformer winding is obtained by the following way: where I m is the maximum short circuit current value of the transformer winding, I N is the rated current of the transformer winding, Z T is the short circuit impedance of the transformer, Z S is the short circuit impedance of the power grid system.

3. The method for testing the short-circuit withstand capability of a transformer as described in claim 1, characterized in that, The transformer design parameters include core structure parameters, winding structure parameters based on ineffective radial support, compression structure parameters, and oil tank parameters; and the first pre-design calculation model is a finite element electromagnetic model; The finite element electromagnetic model is established according to the core structure parameters, winding structure parameters based on ineffective radial support, compression structure parameters, and oil tank parameters; The first stress value of each wire cake of the transformer winding is obtained by inputting the maximum short-circuit current value of the transformer winding into the finite element electromagnetic model.

4. The method of claim 1, wherein the step of detecting the short circuit resistance of the transformer is performed by a method comprising: The transformer design parameters include the yield strength and thickness of the transformer wire; The second stress value of each wire cake of the transformer winding is determined by the following manner: σ l = (Aσ 0.2 +B) ln b eq +C σ l is the second stress value for each coil of the transformer winding, σ 0.2 is the yield strength of the conductor, b eq is the thickness of the conductor, A, B and C are preset coefficients.

5. The method of claim 4, wherein the step of detecting the short circuit resistance of the transformer is performed by the steps of: applying a predetermined voltage to the transformer; measuring a current flowing through the transformer; and determining the short circuit resistance of the transformer based on the measured current. The numerical range of the preset coefficient A includes 0.13-0.15; the numerical range of the preset coefficient B includes 6-8; and the numerical range of the preset coefficient C includes 12-15.

6. The method of claim 1, wherein the step of detecting the short circuit resistance of the transformer is performed by a method comprising: applying a short circuit current to the transformer; and measuring a voltage across the transformer. The second current value of the transformer winding is obtained by a third preset method according to the first stress value of each wire cake of the transformer winding and the second stress value of each wire cake of the transformer winding, specifically as follows: The estimated range of the second current value is obtained according to the first stress value of each wire cake of the transformer winding and the second stress value of each wire cake of the transformer winding; The second current value is obtained according to the estimated range of the second current value and the second stress value of each wire cake of the transformer winding.

7. The method of claim 1, wherein the step of detecting the short circuit resistance of the transformer is performed by a method comprising: applying a short circuit current to the transformer; and measuring a voltage across the transformer. The safety margin of the transformer is obtained according to the second current value of the transformer winding and the maximum crossing short-circuit current value of the transformer winding, and specifically is: where K is a safety margin, I2 is a second current value, I m is a maximum crossing short-circuit current value of the winding.

8. The method of claim 1, wherein the step of detecting the short circuit resistance of the transformer is performed by a method comprising: applying a short circuit current to the transformer; and measuring a voltage across the transformer. The short-circuit resistance of the transformer is determined according to the safety margin of the transformer, specifically as follows: When the safety margin of the transformer is greater than a first threshold value, the short-circuit resistance of the transformer is qualified; When the safety margin of the transformer is less than the first threshold value, the short-circuit resistance of the transformer is unqualified.

9. A system for detecting short circuit resistance of a transformer, characterized by The method comprises the following steps: obtaining module, first calculation module, second calculation module, third calculation module, fourth calculation module, fifth calculation module, and judgment module; The obtaining module is used to obtain transformer design parameters and the operating condition of the power system where the transformer is located; The first calculation module is configured to obtain the maximum short-circuit current value of the transformer winding according to the transformer design parameters and the operation state of the power system where the transformer is located; The second calculation module is configured to input the maximum short-circuit current value of the transformer winding into a first pre-design calculation model to obtain first stress values of each line cake of the transformer winding, wherein the first pre-design calculation model is determined by the transformer design parameters; The third calculation module is configured to obtain second stress values of each line cake of the transformer winding according to the transformer design parameters and a second preset method; The fourth calculation module is configured to obtain a second current value of the transformer winding according to the first stress values of each line cake of the transformer winding and the second stress values of each line cake of the transformer winding and a third preset method; The fifth calculation module is configured to obtain a safety margin of the transformer according to the second current value of the transformer winding and the maximum short-circuit current value of the transformer winding; The judging module is configured to determine the short-circuit resistance of the transformer according to the safety margin of the transformer.

10. A terminal device, comprising: The computer program is executed by the processor to implement the steps of the transformer short-circuit resistance detection method according to any one of claims 1 to 8.

11. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the transformer short-circuit resistance detection method according to any one of claims 1 to 8.

12. A computer program product comprising a computer program, characterised in that The computer program is executed by the processor to implement the steps of the transformer short-circuit resistance detection method according to any one of claims 1 to 8.

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