A transformer on-load tap changer fault monitoring method and system

Abstract

This invention discloses a method and system for monitoring faults in on-load tap changers of transformers, relating to the field of on-load tap changer optimization technology. The method includes: establishing an overall calculation model of the on-load tap changer by meshing the on-load tap changer; and, based on this overall calculation model, obtaining calculation models of key components with different boss angles by changing the spatial finite element discretization in transient dynamic simulation analysis; and obtaining the stress distribution and axial force conditions of the key components through these calculation models, enabling timely replacement of components. This effectively improves the long-term support of the on-load tap changer for grid loads, reduces the incidence of power accidents, and saves on-load tap changer costs.

Description

Technical Field

[0001] This invention relates to the field of transformer on-load tap changer optimization technology, and in particular to a method and system for monitoring faults in transformer on-load tap changers. Background Technology

[0002] The on-load tap-changer (OLTC) is a core component of the converter transformer for voltage regulation, playing a crucial role in ensuring the stability of the high-voltage direct current transmission system. Compared to on-load tap-changers used in power transformers, those used in converter transformers have a wider voltage regulation range and operate more frequently.

[0003] Currently, the on-load tap changers used in converter transformers are exclusively supplied by two companies: MR (Germany) and ABB (Sweden). Domestic manufacturers of on-load tap changers have no experience in their application. The key technologies related to on-load tap changers for converter transformers remain in the hands of foreign manufacturers, creating a technological monopoly and driving up the construction costs of DC projects.

[0004] Moreover, in the actual application of DC engineering, on-load tap changers are insufficient to support the grid load under high-intensity working environments, causing the maximum stress of some components of the on-load tap changer to exceed the yield strength and tensile limit of the material, which brings huge risks to the safe operation of the main grid.

[0005] Some scholars have proposed that by modifying the materials of existing on-load tap changer components and installing monitoring equipment, the on-load tap changer could maintain grid load support under high intensity and allow for real-time monitoring of the equipment. However, this approach only increases costs and does not fundamentally solve the problem; moreover, monitoring accuracy can be compromised.

[0006] Therefore, designing a method for monitoring on-load switchgear faults that can save costs and support grid loads for extended periods has become a problem that needs to be solved. Summary of the Invention

[0007] In view of the aforementioned existing problems, the present invention is proposed.

[0008] Therefore, the present invention provides a method for monitoring faults in on-load tap changers of transformers to solve the problems in the background art.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for monitoring faults in on-load tap changers of transformers, comprising:

[0010] Mesh the on-load tap changer and establish an overall calculation model of the on-load tap changer;

[0011] Based on the overall calculation model of the on-load tap changer, the angles of different bosses of the on-load tap changer are changed by spatial finite element discretization in transient dynamic simulation analysis.

[0012] The boss angle is set to 25° to 50° with a step size of 1°. The relationship between the equivalent stress level and yield strength and tensile limit of different boss angles is obtained. The calculation model of key components with different boss angles is obtained through the relationship.

[0013] The calculation model of the key components is calculated to obtain the stress distribution and shaft force of the key components. The on-load tap changer is then monitored for faults based on the shaft force.

[0014] As a preferred embodiment of the transformer on-load tap changer fault monitoring method of the present invention, the method includes: performing grid partitioning on the on-load tap changer, including:

[0015] The components in an on-load tap changer are divided into regular components and irregular components.

[0016] In the on-load tap changer, regular components are divided using a hexahedral mesh, while irregular components are divided using a tetrahedral mesh.

[0017] As a preferred embodiment of the transformer on-load tap changer fault monitoring method of the present invention, the method includes: establishing an overall calculation model of the on-load tap changer, including: setting the load and boundary conditions of the model.

[0018] Based on the spring parameters of the rapid response mechanism, spring connections are established on the two drive shafts of the model, with spring preloads of [value missing]. The stiffness is 4.43 N / mm;

[0019] Consider the motion of the model's rotating shaft under no-resistance torque, 5 N·m resistance torque, and 10 N·m resistance torque, and set torque loads for each of the three torques.

[0020] As a preferred embodiment of the transformer on-load tap changer fault monitoring method of the present invention, the boundary conditions include:

[0021] Based on a 90° rotation within 100ms, the angular acceleration is calculated as follows: ;

[0022] The initial time is set to the moment of contact between the roller and the boss, and the rotational speed of the shaft is obtained as follows:

[0023] ,

[0024] The rotational speed of the shaft is used as the initial rotational speed in the overall calculation model of the on-load tap changer.

[0025] As a preferred embodiment of the transformer on-load tap changer fault monitoring method of the present invention, the method includes: spatial finite element discretization, comprising:

[0026] pass , , Describe objects Each point within the time frame is at time 0, time... and time Configuration coordinates;

[0027] , Representing each particle In time and time The displacement;

[0028] Using the principle of virtual displacement, the equilibrium equation is expressed as follows:

[0029] ,

[0030] in, for Constant stress; for Be prepared to react at any time; for External forces working in vain at all times;

[0031] The nonlinear motion process of the conductor detaching from ice and jumping includes:

[0032] In the nonlinear motion process of displacement and deformation, the corresponding spatial motion description and definition are adopted, and the basic motion equations for solving are expressed as follows:

[0033] ,

[0034] in, Represents the mass matrix; Represents the damping matrix; Represents the stiffness matrix; Represents the nodal acceleration vector; Represents the node velocity vector; Represents the nodal displacement vector; This represents the load vector at time t;

[0035] Time The equations represented are static equilibrium equations for inertial forces and damping forces. The Newmark method is used for iteration to determine the on-load tap changer trajectory within a given time.

[0036] As a preferred embodiment of the transformer on-load tap changer fault monitoring method of the present invention, the method employs the Newmark method, including:

[0037] The linear hypothesis is expressed as:

[0038] ,

[0039] and

[0040] ,

[0041] Among them, Within the interval, the linearity assumption is satisfied:

[0042] ,

[0043] The acceleration within the interval is:

[0044] ,

[0045] time The displacement is calculated as follows:

[0046] ,

[0047] Represented as:

[0048] ,

[0049] Substituting the above formula, we get... , , calculate The formula:

[0050] ,

[0051] in, Indicates nodal displacement. Represents nodal acceleration. Indicates the node speed.

[0052] As a preferred embodiment of the transformer on-load tap changer fault monitoring method of the present invention, the fault monitoring of the on-load tap changer by means of shaft stress includes:

[0053] When the value of the shaft force FX exceeds 680.3, it indicates that the corresponding component is at the fault position of being subjected to external lateral force and needs to be replaced in time.

[0054] When the value of the shaft force FZ exceeds 3643N, it indicates that the corresponding component is under stress in all directions except for the lateral force, and the component needs to be replaced in time.

[0055] A transformer on-load tap changer fault monitoring system includes:

[0056] The on-load tap changer processing module performs mesh generation on the on-load tap changer and establishes an overall calculation model of the on-load tap changer.

[0057] The algorithm module for the overall calculation model of the on-load tap changer, based on the overall calculation model of the on-load tap changer, changes the angles of different bosses of the on-load tap changer through spatial finite element discretization in transient dynamic simulation analysis.

[0058] The on-load tap changer adjustment module sets the boss angle to 25° to 50° with a step size of 1°, obtains the relationship between the equivalent stress level and yield strength and tensile limit of different boss angles, and obtains the calculation model of key components with different boss angles through the relationship.

[0059] The key component analysis module calculates the calculation model of the key components to obtain the stress distribution and shaft force of the key components, and uses the shaft force to monitor the fault of the on-load tap changer.

[0060] A computer device includes a memory and a processor, the memory storing a computer program, wherein the processor executes the computer program to implement any step of the method described above.

[0061] A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements any step of the above-described method.

[0062] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention establishes an overall calculation model of the on-load tap changer by meshing the on-load tap changer; based on the overall calculation model of the on-load tap changer, different boss angles of the on-load tap changer are changed through spatial finite element discretization in transient dynamic simulation analysis; the boss angle is set to 25° to 50° with a step size of 1°, and the relationship between the equivalent stress level and yield strength and tensile limit of different boss angles is obtained. Through the relationship, the calculation model of key components with different boss angles is obtained; the calculation model of key components is calculated to obtain the stress distribution and axial force of key components for timely replacement or monitoring of components, which effectively improves the long-term support of the on-load tap changer for the power grid load and saves the cost of the on-load tap changer. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a flowchart illustrating the overall process of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention.

[0065] Figure 2 This is a mesh partitioning diagram of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention;

[0066] Figure 3 This is a spring parameter curve diagram of the transformer on-load tap changer fault monitoring method according to an embodiment of the present invention;

[0067] Figure 4 This is a curve showing the change of the rotation angle of the rotating shaft over time under different resistance torques in the transformer on-load tap changer fault monitoring method according to an embodiment of the present invention.

[0068] Figure 5 This is a schematic diagram illustrating the application of boundary conditions in the overall calculation model of the on-load tap changer fault monitoring method for transformers according to an embodiment of the present invention.

[0069] Figure 6 This is a yield strength curve of the transformer on-load tap changer fault monitoring method according to an embodiment of the present invention;

[0070] Figure 7 This is an equivalent stress cloud diagram of component 9 in the transformer on-load tap changer fault monitoring method according to an embodiment of the present invention. Detailed Implementation

[0071] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0072] Example 1, referring to Figures 1 to 5 This is the first embodiment of the present invention, which provides a method for monitoring faults in an on-load tap changer of a transformer, including:

[0073] S1. Mesh the on-load tap changer and establish an overall calculation model of the on-load tap changer.

[0074] Furthermore, the components in the on-load tap changer are divided into regular components and irregular components;

[0075] In the on-load tap changer, regular components are divided using a hexahedral mesh, while irregular components are divided using a tetrahedral mesh.

[0076] It should be noted that the quality of mesh generation directly affects the accuracy and speed of model solving;

[0077] Specifically, this invention mainly uses tetrahedral elements, dividing the space into 180,000 elements, with the mesh structure as follows: Figure 2 As shown;

[0078] Furthermore, boundary conditions are set for the overall calculation model of the on-load tap changer, such as... Figure 5 As shown;

[0079] It should be noted that fixed boundary conditions are applied at point A (the connection between the epoxy phenolic laminated glass cloth board and the epoxy glass fiber extrusion rod); at point B, the translational degree of freedom is constrained at the shaft end, and the rotational degree of freedom around the shaft is released; fixed boundary conditions are applied at points C and D; at point E, the translational degree of freedom is constrained at the bottom of the shaft, and the rotational degree of freedom around the shaft is released, while a rotational displacement (angle) is applied according to uniform acceleration motion.

[0080] Furthermore, based on a 90° rotation within 100ms, the angular acceleration is calculated as follows: The initial calculation time is set to start from the moment of contact between the roller and the boss, and the rotational speed of the shaft is obtained as follows: This speed is used as the initial rotational speed of the overall calculation model of the on-load tap changer;

[0081] Furthermore, based on the spring parameters included in the rapid mechanism of the model, spring connections are established on the two drive shafts of the model, with a spring preload of 420N and a stiffness of 4.43N / mm. Figure 3 As shown;

[0082] Furthermore, we consider the mechanism motion of the model's rotating shaft under no-resistance torque, 5 N·m resistance torque, and 10 N·m resistance torque, and set torque loads for the above three torques respectively.

[0083] It should be noted that under the action of spring compression force, the rack will move linearly, thereby driving the half gear to rotate, which in turn causes the rotating shaft to rotate. Under no resistance torque, the half gear reaches the limit position in about 27ms; under a resistance torque of 5 N·m, the half gear reaches the limit position in about 29.5ms; under a resistance torque of 10 N·m, the half gear reaches the limit position in about 19ms.

[0084] It should be noted that the curves showing the change of the rotational shaft angle over time for resistance torques of 0, 5, and 10 N·m are as follows: Figure 4 As shown, the times to reach the limit position are 27ms, 29.5ms, and 33ms respectively. That is, the greater the resistance torque, the slower the rotation and the longer the time to reach the limit position.

[0085] S2. Based on the overall calculation model of the on-load tap changer, the angles of different bosses of the on-load tap changer are changed by spatial finite element discretization in transient dynamic simulation analysis.

[0086] It should be noted that transient dynamic simulation analysis is an analytical method used to determine the dynamic response of a structure under any time-varying load.

[0087] Further transient dynamic simulation analysis includes:

[0088] For spatial finite element discretization, using , , ( Describe the points within the object at time 0, time... and time configuration coordinates, , ( () indicates the time interval of each particle. and time The displacement, obtained from the equilibrium equations and using the principle of virtual displacement, is:

[0089] (1)

[0090] in, for Constant stress; for Be prepared to react at any time; for External forces working in vain at all times;

[0091] Since the conductor de-icing and jumping process is a nonlinear motion process with large displacement and small deformation, it is necessary to adopt corresponding spatial motion descriptions and definitions, such as TL or UL coordinates and corresponding metrics. The basic motion equations for transient dynamic analysis can be obtained as follows:

[0092] (2)

[0093] in, Represents the mass matrix; Represents the damping matrix; Represents the stiffness matrix; Represents the nodal acceleration vector; Represents the node velocity vector; Represents the nodal displacement vector; This represents the load vector at time t;

[0094] At any given time t, the above equations can be viewed as a series of static equilibrium equations considering inertial forces and damping forces; the time integral, expressed using the Newmark method, is as follows:

[0095] (3)

[0096] and

[0097] (4)

[0098] Furthermore, in Within the interval, the linearity assumption is satisfied:

[0099] (5)

[0100] Furthermore, The acceleration within the interval is:

[0101] (6)

[0102] Furthermore, the timing Displacement solution at point This can be solved by:

[0103] (7)

[0104] Furthermore, Represented as:

[0105] (8)

[0106] Furthermore, substituting the above formula, we obtain from , , calculate The formula:

[0107]

[0108] (9)

[0109] Repeat the above calculation process iteratively to obtain the on-load tap changer trajectory within a given time period;

[0110] in, Indicates nodal displacement. Represents nodal acceleration. Indicates node velocity;

[0111] S3. Set the boss angle to 25° to 50° with a step size of 1°, obtain the relationship between the equivalent stress level and yield strength and tensile limit for different boss angles, and obtain the calculation model of key components with different boss angles through the relationship.

[0112] Furthermore, the relationship between the equivalent stress level and yield strength for different boss angles is obtained by von Mises equivalent stress and the von Mises criterion;

[0113] Furthermore, the von Mises equivalent stress is expressed as:

[0114] ,

[0115] in, , and Principal stress;

[0116] Furthermore, the von Mises criterion is expressed as:

[0117] ,

[0118] in, For yield strength, It is a constant;

[0119] Furthermore, the boss angle was set to 25° to 50° with a step size of 1°, for a total of 26 working conditions, and the relationship between the equivalent stress level and yield strength and tensile limit for different boss angles was obtained.

[0120] S4. Calculate the calculation model of key components to obtain the stress distribution and shaft force of key components, and use the shaft force to monitor the fault of the on-load tap changer.

[0121] Furthermore, when the shaft force FX value exceeds 680.3, it indicates that the corresponding component is under external lateral force and needs to be replaced in time; when the shaft force FZ value exceeds 3643N, it indicates that the corresponding component is under external multi-directional force and needs to be replaced in time.

[0122] Furthermore, this embodiment also provides a transformer on-load tap changer fault monitoring system, including:

[0123] The on-load tap changer processing module performs mesh generation on the on-load tap changer and establishes an overall calculation model of the on-load tap changer.

[0124] The algorithm module for the overall calculation model of the on-load tap changer, based on the overall calculation model of the on-load tap changer, changes the angles of different bosses of the on-load tap changer through spatial finite element discretization in transient dynamic simulation analysis.

[0125] The on-load tap changer adjustment module sets the boss angle to 25° to 50° with a step size of 1°, obtains the relationship between the equivalent stress level and yield strength and tensile limit of different boss angles, and obtains the calculation model of key components with different boss angles through the relationship.

[0126] The key component analysis module calculates the calculation model of the key components to obtain the stress distribution and shaft force of the key components, and uses the stress distribution and shaft force to monitor the fault of the on-load tap changer.

[0127] This embodiment also provides a computer device applicable to the method for monitoring faults in on-load tap changers of transformers, including:

[0128] The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement the transformer on-load tap changer fault monitoring method proposed in the above embodiments.

[0129] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad mounted on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0130] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the transformer on-load tap changer fault monitoring method as proposed in the above embodiments.

[0131] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0132] Example 2, refer to Figure 6 and Figure 7 This is the second embodiment of the present invention, which provides a method for monitoring faults in an on-load tap changer of a transformer, including:

[0133] By changing the different boss angles of the on-load tap changer, when the movement reaches 0.009499s, the material parameters of the key components of the on-load tap changer are shown in Table 1.

[0134] Table 1 Material parameters of key components

[0135] ,

[0136] The maximum stress values ​​of key components of on-load tap changers are shown in Table 2 below.

[0137] Table 2 Maximum stress values ​​of key components of on-load tap changers under different boss angles

[0138] ,

[0139] By analyzing the relationship between the equivalent stress level and yield strength and tensile limit of different boss angles, geometric models of key components were created using computer-aided design (CAD) software. It can be seen that at certain boss angles (thickened portion), the maximum stress of component 9 (cam) exceeds the material's yield strength (e.g., ...). Figure 6 As shown), but it does not exceed the tensile strength limit of the material, and the other parts do not exceed the yield strength or tensile strength limit of the material; among them, the parts 10 and 11 are in frictional contact, and under different boss angles during the movement, the maximum value of FX of part 11 in the X and Z directions fluctuates between 575.9-680.3N, and the maximum value of FZ fluctuates between 3215.6-3643N;

[0140] By analyzing the axial forces, components in actual operation can be monitored and replaced in a timely manner, thereby reducing the power failure rate, improving long-term load support, and bringing stability to the safe operation of the main power grid.

[0141] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for monitoring faults in an on-load tap changer of a transformer, characterized in that, include: Mesh the on-load tap changer and establish an overall calculation model of the on-load tap changer; Based on the overall calculation model of the on-load tap changer, the angles of different bosses of the on-load tap changer are changed by spatial finite element discretization in transient dynamic simulation analysis. The boss angle is set to 25° to 50° with a step size of 1°. The relationship between the equivalent stress level and yield strength and tensile limit of different boss angles is obtained. The calculation model of key components with different boss angles is obtained through the relationship. The calculation model of the key components is calculated to obtain the stress distribution and shaft force of the key components. The on-load tap changer is then monitored for faults based on the shaft force. Establish an overall calculation model for the on-load tap changer, including setting the loads and boundary conditions of the model; Based on the spring parameters of the rapid response mechanism, spring connections are established on the two drive shafts of the model, with spring preloads of [value missing]. The stiffness is 4.43 N / mm; Consider the motion of the model's rotating shaft under no-resistance torque, 5 N·m resistance torque, and 10 N·m resistance torque, and set torque loads for the three torques respectively; Boundary conditions include: Based on a 90° rotation within 100ms, the angular acceleration is calculated as follows: ; The initial time is set to the moment of contact between the roller and the boss, and the rotational speed of the shaft is obtained as follows: The rotational speed of the shaft is used as the initial rotational speed of the overall calculation model of the on-load tap changer; Spatial finite element discretization includes: pass , , Describe objects Each point within the time frame is at time 0, time... and time Configuration coordinates; , Representing each particle In time and time The displacement; Using the principle of virtual displacement, the equilibrium equation is expressed as follows: in, for Constant stress; for Be prepared to react at any time; for External forces working in vain at all times; The nonlinear motion process of the conductor detaching from ice and jumping includes: In the nonlinear motion process of displacement and deformation, the corresponding spatial motion description and definition are adopted, and the basic motion equations for solving are expressed as follows: in, Represents the mass matrix; Represents the damping matrix; Represents the stiffness matrix; Represents the nodal acceleration vector; Represents the node velocity vector; Represents the nodal displacement vector; This represents the load vector at time t; Time The equations represented are static equilibrium equations for inertial forces and damping forces. The Newmark method is used for iteration to determine the on-load tap changer motion trajectory within a given time. The Newmark method is used, including: The linear hypothesis is expressed as: and Among them, Within the interval, the linearity assumption is satisfied: The acceleration within the interval is: time The displacement is calculated as follows: Represented as: Substituting the above formula, we get... , , calculate The formula: in, Indicates nodal displacement. Represents nodal acceleration. Indicates the node speed.

2. The method for monitoring on-load tap changer faults in a transformer as described in claim 1, characterized in that, Mesh partitioning of on-load tap changers includes: The components in an on-load tap changer are divided into regular components and irregular components. In the on-load tap changer, regular components are divided using a hexahedral mesh, while irregular components are divided using a tetrahedral mesh.

3. The transformer on-load tap changer fault monitoring method as described in claim 2, characterized in that, Fault monitoring of on-load tap changers based on shaft stress conditions includes: When the value of the shaft force FX exceeds 680.3, it indicates that the corresponding component is at the fault position of being subjected to external lateral force and needs to be replaced in time. When the value of the shaft force FZ exceeds 3643N, it indicates that the corresponding component is under stress in all directions except for the lateral force, and the component needs to be replaced in time.

4. A transformer on-load tap changer fault monitoring system, based on the transformer on-load tap changer fault monitoring method according to any one of claims 1 to 3, characterized in that, include: The on-load tap changer processing module performs mesh generation on the on-load tap changer and establishes an overall calculation model of the on-load tap changer. The algorithm module for the overall calculation model of the on-load tap changer, based on the overall calculation model of the on-load tap changer, changes the angles of different bosses of the on-load tap changer through spatial finite element discretization in transient dynamic simulation analysis. The on-load tap changer adjustment module sets the boss angle to 25° to 50° with a step size of 1°, obtains the relationship between the equivalent stress level and yield strength and tensile limit of different boss angles, and obtains the calculation model of key components with different boss angles through the relationship. The key component analysis module calculates the calculation model of the key components to obtain the stress distribution and shaft force of the key components, and uses the shaft force to monitor the fault of the on-load tap changer.

5. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 3.

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