Method, medium and system for judging looseness of transformer winding

Abstract

The invention discloses a method, medium and system for judging the looseness of a transformer winding, and the method comprises the steps: applying an axial acting force to an insulating cushion block and an insulating end ring cushion block of a transformer, so as to simulate the axial acting force borne by the transformer winding in the operation process of the transformer, elastic coefficients of the insulating cushion block and the insulating end ring cushion block under different axial acting forces are collected; fitting to obtain a calculation equation of the elastic coefficients of the insulating cushion block and the insulating end ring cushion block through the elastic coefficients of the insulating cushion block and the insulating end ring cushion block under different axial acting forces; substituting the calculation equation of the elastic coefficients of the insulating cushion block and the insulating end ring cushion block into an axial mass-spring model of the transformer winding, and calculating to obtain the axial displacement of a winding wire cake under the axial acting force on the transformer winding; and comparing the calculated axial displacement of the winding wire cake with a preset axial displacement of the winding wire cake when the transformer winding is loosened, and judging whether the transformer winding is loosened or not. Whether the winding is loosened or not can be accurately judged.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to a method, medium and system for determining whether transformer windings are loose. Background Art

[0002] Transformers are expensive key components in power grids and one of the most important components for reliability and performance in distribution, transmission and generation systems. As technology develops, the size of transformers is gradually increasing. One of the most important steps in transformer design is to calculate the stress and electromagnetic forces under normal and short-circuit conditions. The large short-circuit forces generated by the interaction between the transformer winding leakage flux and the short-circuit current can cause the windings to displace. These short-circuit currents also cause a lot of heating in the transformer windings. Therefore, compared with normal conditions, the forces generated by short circuits can reach hundreds of times higher values ​​because these forces are proportional to the square of the current. When the short-circuit forces are large enough, they may cause deformation and displacement of the transformer windings. The traditional calculation formulas for the axial response of transformers are based on the axial mass-spring model. In the traditional calculation method, the elastic coefficient in the formula is constantized, which makes the calculation results inaccurate and makes it difficult to accurately determine whether the transformer windings are loose. Summary of the invention

[0003] The embodiments of the present invention provide a method, medium and system for determining whether a transformer winding is loose, so as to solve the problem that the prior art uses a constantized elastic coefficient and is difficult to accurately determine whether the transformer winding is loose.

[0004] In a first aspect, a method for determining whether a transformer winding is loose is provided, comprising:

[0005] Applying an axial force to the insulating spacer and the insulating end ring spacer of the transformer to simulate the axial force on the transformer winding during the operation of the transformer, and collecting the elastic coefficients of the insulating spacer and the insulating end ring spacer under different axial forces respectively;

[0006] Through the elastic coefficients of the insulating spacer and the insulating end ring spacer under different axial forces, respectively fitting the calculation equations of the elastic coefficients of the insulating spacer and the insulating end ring spacer;

[0007] Substituting the calculation equation of the elastic coefficient of the insulating spacer and the insulating end ring spacer into the axial mass-spring model of the transformer winding, the axial displacement of the winding coil under the axial force applied to the transformer winding is calculated;

[0008] The calculated axial displacement of the winding coil is compared with the preset axial displacement of the winding coil when the transformer winding is loose, so as to determine whether the transformer winding is loose.

[0009] In a second aspect, a computer-readable storage medium is provided, on which computer program instructions are stored; when the computer program instructions are executed by a processor, the method for determining whether a transformer winding is loose as described in the embodiment of the first aspect is implemented.

[0010] In a third aspect, a system for determining whether transformer windings are loose is provided, comprising: a computer-readable storage medium as described in the embodiment of the second aspect.

[0011] In this way, the embodiment of the present invention considers the elastic coefficients of the insulating spacer and the insulating end ring spacer, fits the elastic coefficient measured in the experiment into a function form that is more in line with the actual situation, and substitutes it into the axial mass-spring model for solution, so that the calculation steps of the axial response of the transformer winding are simple, the derived mathematical model has high integration, and the calculation efficiency is higher. At the same time, the precision and accuracy of the calculation are guaranteed, so that it can be accurately judged whether the transformer winding is loose, so as to carry out maintenance in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0013] Figure 1 is a flow chart of a method for determining a loose transformer winding according to an embodiment of the present invention;

[0014] Figure 2 is a curve diagram showing the change of the elastic coefficient of the insulating spacer with the axial force obtained by fitting in an embodiment of the present invention;

[0015] Figure 3 It is a curve diagram showing the change of the elastic coefficient of the insulating end ring gasket with the axial force obtained by fitting according to an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Electromagnetic force is one of the factors that affect the displacement of the winding. When the transformer is working, the alternating current flows through the winding, which causes a magnetic field to be generated in the winding. This magnetic field interacts with the wires of the winding itself to generate electromagnetic force. The degree of electromagnetic force generated varies depending on the input excitation size, waveform and frequency. The electromagnetic force of the transformer winding will have a certain impact on the axial displacement of the winding. The magnitude of the axial electromagnetic force is related to factors such as the winding current, magnetic field strength, and winding length. When there is an axial electromagnetic force in the winding, it will generate a thrust or pull on the winding, which will cause the axial displacement of the winding. The axial displacement of the winding has a certain impact on the performance and reliability of the transformer. Large axial displacement may cause a short circuit or poor contact between the windings, increasing resistance and loss. In addition, axial displacement may also increase the mechanical stress of the winding, thereby affecting the mechanical strength and stability of the winding.

[0018] The transformer insulation components include insulation pads and insulation end ring pads, which will affect the axial displacement of the winding, as follows:

[0019] The insulating pads of the transformer are usually made of insulating materials, which can prevent electrical contact between the transformer and the ground or other structures and play an insulating role. The insulating pads can provide additional mechanical support, which can play a role in shock absorption and buffering, reduce the vibration and impact of the transformer during operation, protect its internal structure and equipment, and help maintain the structural integrity of the winding. By adjusting the height or thickness of the insulating pads, the level of the transformer can be adjusted to ensure that the transformer can remain level after installation.

[0020] When electromagnetic forces act on the windings, the windings may move or deform due to the axial forces if there is not enough mechanical support. Insulation blocks limit the axial displacement of the windings by providing rigid support, ensuring that the windings remain stable during operation. Under the action of electromagnetic forces, the windings are subjected to mechanical stresses. Insulation blocks can disperse these stresses and reduce local stress concentration, thereby reducing the axial displacement and deformation of the windings. By properly arranging insulation blocks, the mechanical load can be distributed more evenly to avoid excessive stress in certain areas.

[0021] The insulating end ring gaskets of the transformer are located at both ends of the winding and are used to support the transformer end rings (usually the outermost part of the winding) and fix them in place. By providing mechanical support, the axial movement of the winding is limited. The electromagnetic force will generate axial thrust on the winding during operation. Without the support of the insulating end ring gaskets, the winding may be axially displaced or even deformed, thus affecting the normal operation of the transformer. The insulating end ring gaskets can help evenly distribute the stress at the end of the winding to avoid local damage or deformation caused by excessive concentrated stress. This stress distribution helps to reduce the axial displacement of the winding and enhance its overall structural stability. It can prevent the end ring from being displaced or deformed during transportation, installation and operation, and ensure the stability of the winding structure.

[0022] Therefore, the transformer windings are affected by the mutual influence of electromagnetic forces and experience different degrees of axial displacement. The friction coefficient between the transformer windings and the insulating spacers and insulating end ring spacers will also change with the axial response of the windings. Therefore, it is necessary to consider the dynamic response curves of the transformer insulating spacers and insulating end ring spacers to quantify the influence of the insulating spacers and insulating end ring spacers on the axial displacement.

[0023] Based on this, an embodiment of the present invention discloses a method for determining whether a transformer winding is loose. Figure 1 As shown, the method of the embodiment of the present invention includes the following steps:

[0024] Step S101: applying an axial force to the insulating spacer and the insulating end ring spacer of the transformer to simulate the axial force on the transformer winding during the operation of the transformer, and collecting the elastic coefficients of the insulating spacer and the insulating end ring spacer under different axial forces.

[0025] It should be understood that the axial force includes various forces acting in the axial direction in actual situations, for example, electromagnetic force generated when short-circuiting or not short-circuiting.

[0026] The dynamic response of the insulating pad and the insulating end ring pad can be completed by a dynamic tensile tester or a dynamic pressure tester. In a specific embodiment, the dynamic pressure tester is used to complete the test. The insulating pad and the insulating end ring pad are placed together in the dynamic pressure tester box for testing. The dynamic pressure tester is controlled by the operating platform of the dynamic pressure tester to perform a series of actions to measure the elastic coefficient of the insulating pad and the insulating end ring pad. The pressure applied by the dynamic pressure tester is used as the axial force, so that the elastic coefficient under different axial forces can be obtained.

[0027] Step S102: fitting the elastic coefficients of the insulating spacer and the insulating end ring spacer under different axial forces to obtain calculation equations of the elastic coefficients of the insulating spacer and the insulating end ring spacer.

[0028] Specifically, Figure 2As shown in FIG. 1 , the elastic coefficient of the insulating spacer obtained by fitting varies with the axial force. The calculation equation of the elastic coefficient of the insulating spacer is as follows:

[0029] k(F)=A1F 4 +A2F 3 +A3F 2 +A4F+A5;

[0030] Among them, k(F) is the elastic coefficient of the insulating spacer, A1~A5 are coefficients, and F is the axial force.

[0031] A1-A5 are obtained by fitting. In a specific embodiment, A1=-0.01964, A2=1.977,

[0032] A3=-78.5, A4=1644, A5=-11130.

[0033] For k(F), a fourth-order polynomial is used for curve fitting. This is because the thickness of the insulating spacer in the transformer is often thinner than that of the insulating end ring spacer. When an axial force is applied to the insulating spacer, the insulating spacer undergoes a large elastic displacement, so a fourth-order polynomial is used for curve fitting. The fourth-order polynomial is more flexible than other polynomials and can better adapt to complex data shapes and changes. It has more degrees of freedom to adjust the shape of the curve to minimize the fitting error; it can fit the details and nonlinear characteristics of the curve more accurately, so it is often more suitable in applications that require high-precision fitting. Therefore, the fourth-order polynomial is selected for curve fitting of the insulating spacer.

[0034] Specifically, Figure 3 As shown in FIG. 1 , the elastic coefficient of the insulating end ring gasket is fitted with the curve of the change of the axial force. The calculation equation of the elastic coefficient of the insulating end ring gasket is as follows:

[0035]

[0036] Among them, k b (F) is the elastic coefficient of the insulating end ring gasket, a0~a4, b1~b4, c are all coefficients, and F is the axial force.

[0037] a0~a4, b1~b4, c are obtained by fitting. In a specific embodiment, a0=166.14,

[0038] a1=541.9356, a2=455.1281, a3=90.2593, a4=-52.6750, b1=-548.9,

[0039] b2=11.9880, b3=144.3948, b4=93.6451, c=0.2292.

[0040] For k b (F), sine / cosine function is used for curve fitting. This is because the thickness of the insulating end ring gasket in the transformer is often thicker than that of the gasket. When an axial force is applied to the insulating end ring gasket, the elastic displacement of the insulating end ring gasket is small, so the sine / cosine function is used for curve fitting. The sine and cosine functions are periodic and can adapt well to certain periodically changing mechanical phenomena or signals. In addition, the sine and cosine functions are smooth in the entire definition domain and have continuity and derivative continuity. This enables them to provide smoother and continuous fitting results when fitting continuously changing force curves. The sine and cosine functions can adapt to curves of different shapes through linear combinations (i.e., weighted sums). By adjusting the amplitude, frequency, and phase, the shape of the function can be adjusted to better fit the actual data. Therefore, the sine / cosine function is selected to perform curve fitting on the insulating end ring gasket.

[0041] Step S103: Substitute the calculation equation of the elastic coefficient of the insulating spacer and the insulating end ring spacer into the axial mass-spring model of the transformer winding to calculate the axial displacement of the winding coil under the axial force acting on the transformer winding.

[0042] Specifically, the axial mass-spring model of the transformer winding is as follows:

[0043]

[0044] Among them, m n is the mass of the nth transformer winding coil, is the acceleration of the nth transformer winding coil, is the speed of the nth transformer winding coil, k(F) is the elastic coefficient of the insulating spacer, k b (F) is the elastic coefficient of the insulating end ring gasket, f is the friction coefficient, z n is the displacement of the nth transformer winding coil, F m,n is the electromagnetic force on the nth transformer winding coil, mg n is the weight of the nth transformer winding coil. Generally, for the same transformer, the mass of each winding coil is the same, and the weight of each winding coil is the same. It should be understood that the first and nth winding coils are located at both ends. The axial force and the electromagnetic force can be obtained by measurement.

[0045] The above equation can be solved analytically to obtain z n .

[0046] As the axial force F changes, k(F), k b(F) also changes accordingly, which can accurately simulate the elastic coefficient of the transformer insulation component, thereby making the calculation results of the transformer coil displacement more integrated and the calculation results more accurate.

[0047] Step S104: Compare the calculated axial displacement of the winding coil with the preset axial displacement of the winding coil when the transformer winding is loose, to determine whether the transformer winding is loose.

[0048] Specifically, if the calculated axial displacement of the winding coil is greater than the preset axial displacement of the winding coil when the transformer winding is loose, it is determined that the transformer winding is loose; otherwise, it is determined that the transformer winding is not loose.

[0049] It should be understood that the above comparison is a comparison between the axial displacement of a winding coil and the preset axial displacement of the winding coil when the transformer winding is loose. Therefore, for the transformer, as long as the axial displacement of one winding coil is greater than the preset axial displacement of the winding coil when the transformer winding is loose, the transformer winding is considered to be loose.

[0050] Among them, the displacement of the winding coil when the transformer winding is loose can be preset based on experience.

[0051] In addition, an embodiment of the present invention further provides a computer-readable storage medium, on which computer program instructions are stored; when the computer program instructions are executed by a processor, the method for determining whether a transformer winding is loose as described in the above embodiment is implemented.

[0052] In addition, an embodiment of the present invention further provides a transformer winding looseness determination system, comprising: a computer-readable storage medium as described in the above embodiment.

[0053] In summary, in the embodiment of the present invention, by considering the elastic coefficients of the insulating spacer and the insulating end ring spacer, the elastic coefficient measured in the experiment is fitted into a function form that is more in line with the actual situation, and is substituted into the axial mass-spring model for analytical calculation and solution, so that the calculation steps of the axial response of the transformer winding are simple, the derived mathematical model has high integration, and the calculation efficiency is higher. At the same time, the precision and accuracy of the calculation are guaranteed, so that it is possible to accurately judge whether the transformer winding is loose so as to carry out maintenance in time.

[0054] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for determining whether transformer windings are loose, characterized in that: include: Applying an axial force to the insulating spacer and the insulating end ring spacer of the transformer to simulate the axial force on the transformer winding during the operation of the transformer, and collecting the elastic coefficients of the insulating spacer and the insulating end ring spacer under different axial forces respectively; Through the elastic coefficients of the insulating spacer and the insulating end ring spacer under different axial forces, respectively fitting the calculation equations of the elastic coefficients of the insulating spacer and the insulating end ring spacer; Substituting the calculation equation of the elastic coefficient of the insulating spacer and the insulating end ring spacer into the axial mass-spring model of the transformer winding, the axial displacement of the winding coil under the axial force applied to the transformer winding is calculated; The calculated axial displacement of the winding coil is compared with the preset axial displacement of the winding coil when the transformer winding is loose, so as to determine whether the transformer winding is loose.

2. The method for determining whether transformer windings are loose according to claim 1, characterized in that: The calculation equation of the elastic coefficient of the insulating spacer includes: <h2 style=";text-align:left;direction:ltr">k(F)=A1F<h2 style=";text-align:left;direction:ltr"> 4 <h2 style=";text-align:left;direction:ltr"> +A2F<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> +A3F<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +A4F+A5; Among them, k(F) is the elastic coefficient of the insulating spacer, A1~A5 are coefficients, and F is the axial force.

3. The method for determining whether transformer windings are loose according to claim 1, characterized in that: The calculation equation of the elastic coefficient of the insulating end ring spacer includes: Among them, k b (F) is the elastic coefficient of the insulating end ring gasket, a0~a4, b1~b4, c are all coefficients, and F is the axial force.

4. The method for determining whether transformer windings are loose according to claim 1, characterized in that: The axial mass-spring model of the transformer winding includes: Among them, m n is the mass of the nth transformer winding coil, is the acceleration of the nth transformer winding coil, is the speed of the nth transformer winding coil, k(F) is the elastic coefficient of the insulating spacer, k b (F) is the elastic coefficient of the insulating end ring pad, f is the friction coefficient, z n is the displacement of the winding coil of the nth transformer, F m,n is the electromagnetic force on the nth transformer winding coil, mg n is the gravity of the nth transformer winding coil.

5. The method for determining whether transformer windings are loose according to claim 1, characterized in that: The step of determining whether the transformer winding is loose comprises: If the calculated axial displacement of the winding coil is greater than the preset axial displacement of the winding coil when the transformer winding is loose, it is determined that the transformer winding is loose; otherwise, it is determined that the transformer winding is not loose.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions; when the computer program instructions are executed by the processor, the method for determining whether transformer windings are loose according to any one of claims 1 to 5 is implemented.

7. A transformer winding loosening judgment system, characterized in that: include: The computer readable storage medium of claim 6.

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