Transformer on-load tap-changer fault monitoring method and system

Abstract

The invention discloses a transformer on-load tap-changer fault monitoring method and system, and relates to the technical field of transformer on-load switch optimization, and the method comprises the steps: carrying out the mesh generation of an on-load tap-changer, and building an on-load tap-changer overall calculation model; on the basis of the overall calculation model of the on-load tap-changer, different boss angles of the on-load tap-changer are changed through space finite element discretization in transient dynamics simulation analysis, and key part calculation models of different boss angles are obtained; the stress distribution condition and the shaft stress condition of the key parts are obtained through the key part calculation model, so that the parts are actually replaced in time, the long-time support of the on-load tap-changer for the power grid load is effectively improved, the electric power accident rate is reduced, and the cost of the on-load tap-changer is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer on-load switch optimization, and in particular to a transformer on-load tap changer fault monitoring method and system. Background Art

[0002] On-load tap-changer (OLTC) is the core component of the converter transformer to complete the voltage regulation, which plays an important role in ensuring the stability of the high-voltage direct current transmission system. Compared with the on-load tap-changer for power transformers, the on-load tap-changer for converter transformers has a wider voltage regulation range and more frequent operation.

[0003] At present, the on-load tap-changers used in converter transformers are from Germany's MR company and Sweden's ABB company. Domestic on-load tap-changer manufacturers have no product application results. The key technologies related to on-load tap-changers for converter transformers are still in the hands of foreign manufacturers, forming a technical monopoly to a certain extent, pushing up the construction cost of DC projects.

[0004] Moreover, in the actual application of DC engineering, the on-load tap changer is not sufficient to support the grid load under high-intensity working environment, resulting in the maximum stress of some components of the on-load tap changer exceeding the yield strength and tensile limit of the material, posing a huge risk to the safe operation of the main grid of the power grid.

[0005] Some scholars have proposed that by changing the materials of the original on-load switch parts and using monitoring equipment, on the one hand, the on-load tap changer can maintain the support of the grid load under high intensity, and on the other hand, the equipment can be monitored in real time. However, this method will only increase the cost and cannot fundamentally solve the problem. Moreover, the monitoring will also have deviations in accuracy.

[0006] Therefore, how to design a load switch fault monitoring method that can save costs and support the grid load for a long time has become a problem to be solved at present. Summary of the invention

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

[0008] Therefore, the present invention provides a transformer on-load tap changer fault monitoring method to solve the problems in the background technology.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: a transformer on-load tap changer fault monitoring method, comprising: Grid the on-load tap changer and establish the overall calculation model of 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 length of 1°, and the relationship between the equivalent stress level and the yield strength and tensile limit of different boss angles is obtained, and 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 of the key components and the shaft stress condition, and the fault monitoring of the on-load tap changer is performed through the shaft stress condition.

[0010] As a preferred solution of the transformer on-load tap changer fault monitoring method of the present invention, the on-load tap changer is grid-divided, including: The components in the on-load tap-changer are divided into regular components and irregular components; The regular components in the on-load tap changer are divided by hexahedral meshes, and the irregular components are divided by tetrahedral meshes.

[0011] As a preferred solution of the transformer on-load tap changer fault monitoring method of the present invention, wherein: establishing an overall calculation model of the on-load tap changer includes: setting the load and boundary conditions of the model; According to the spring parameters of the quick mechanism, spring connections are established on the two transmission shafts of the model, and the spring preload is , stiffness is 4.43N / mm; The mechanism motion of the model's rotating shaft under no resistance torque, 5 N·m resistance torque and 10 N·m resistance torque is considered, and torque loads are set for the three torques respectively.

[0012] As a preferred solution of the transformer on-load tap changer fault monitoring method of the present invention, the boundary conditions include: According to the calculation of rotating 90° within 100ms, the angular acceleration is ; The initial time is set to the contact time between the roller and the boss, and the rotation speed of the shaft is obtained, which is expressed as: , The rotation speed of the shaft is taken as the initial rotation speed of the overall calculation model of the on-load tap changer.

[0013] As a preferred solution of the transformer on-load tap changer fault monitoring method of the present invention, the spatial finite element discretization includes: pass , , Describing Objects At time 0, time and time The configuration coordinates of , Represents each particle In time and time displacement; Using the principle of virtual displacement, the equilibrium equation is expressed as: , in, for Momentary stress; for Always be flexible; for The external force virtual work at the moment; The nonlinear motion process of the conductor de-icing jump process includes: In the nonlinear motion process of displacement and deformation, the corresponding spatial motion description and definition are adopted, and the basic motion equation to be solved is expressed as: , in, represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the node acceleration vector; represents the node velocity vector; represents the node displacement vector; represents the load vector at time t; Time The equations represented are used as static equilibrium equations of inertial force and damping force, and are iterated using the Newmark method to determine the motion trajectory of the on-load tap changer within a given time.

[0014] As a preferred solution of the transformer on-load tap changer fault monitoring method of the present invention, the Newmark method is adopted, including: The linear assumption is expressed as: , and , Among them, Within the interval, the linear assumption is met: , The acceleration during the interval is: , time The displacement is solved as follows: , It is expressed as: , Substituting the above formula into the equation, we get , , calculate The formula is: , in, represents the node displacement, represents the node acceleration, Indicates the node speed.

[0015] As a preferred solution of the transformer on-load tap changer fault monitoring method of the present invention, the on-load tap changer fault monitoring is performed according to the shaft stress condition, including: When the value of the shaft force FX exceeds 680.3, it means that the corresponding component is at the fault position value of the external lateral force, and the component needs to be replaced in time; When the value of the shaft force FZ exceeds 3643N, it means that the corresponding component is at a fault position value where it is subjected to external forces in all directions except lateral force, and the component needs to be replaced in time.

[0016] A transformer on-load tap changer fault monitoring system, comprising: The on-load tap-changer processing module performs grid division on the on-load tap-changer and establishes the overall calculation model of the on-load tap-changer; An algorithm module for the overall calculation model of the on-load tap changer changes different boss angles of the on-load tap changer through spatial finite element discretization in transient dynamics simulation analysis based on the overall calculation model of the on-load tap changer; The on-load tap changer adjustment module sets the boss angle to 25° to 50° with a step length of 1°, obtains the relationship between the equivalent stress level and the yield strength and the 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 key component calculation model, obtains the stress distribution of the key components and the shaft force condition, and performs fault monitoring on the on-load tap changer through the shaft force condition.

[0017] A computer device comprises a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, any step of the above method is implemented.

[0018] A computer-readable storage medium stores a computer program, wherein: when the computer program is executed by a processor, any step of the above method is implemented.

[0019] Compared with the prior art, the beneficial effects of the invention are as follows: the present invention establishes an overall calculation model of the on-load tap changer by gridding the on-load tap changer; and on the basis of the overall calculation model of the on-load tap changer, changes the different boss angles of the on-load tap changer through spatial finite element discretization in transient dynamic simulation analysis; sets the boss angle to 25° to 50° with a step size of 1°, obtains the relationship between the equivalent stress level and the yield strength and the tensile limit of different boss angles, and obtains the calculation model of key components with different boss angles through the relationship; calculates the calculation model of key components, obtains the stress distribution of key components and the axial force conditions for actual and timely replacement or monitoring of components, effectively improves the long-term support of the on-load tap changer for the grid load, and saves the cost of the on-load tap changer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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 will be briefly introduced below. Obviously, the accompanying drawings described below 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 work.

[0021] Figure 1 This is an overall flow chart of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention; Figure 2 A grid division diagram of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention; Figure 3 A spring parameter curve diagram of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention; Figure 4 A curve showing a change in the rotation angle of a rotating shaft over time under different resistance torques of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention; Figure 5 A schematic diagram of applying boundary conditions in a tap changer overall calculation model of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention; Figure 6 A yield strength curve diagram of a transformer on-load tap changer fault monitoring method according to an embodiment of the present invention; Figure 7 This is an equivalent stress cloud diagram of component 9 of the transformer on-load tap changer fault monitoring method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0023] Example 1, reference Figures 1 to 5 , which is the first embodiment of the present invention, provides a transformer on-load tap changer fault monitoring method, comprising: S1. Grid the on-load tap changer and establish an overall calculation model of the on-load tap changer; Further, the components in the on-load tap changer are divided into regular components and irregular components; Among them, the regular components in the on-load tap changer are divided by hexahedral meshes, and the irregular components are divided by tetrahedral meshes; It should be noted that the quality of meshing is directly related to the accuracy and speed of model solution; Specifically, the present invention mainly uses tetrahedral units, and divides a total of 180,000 units. The divided grid is as follows Figure 2 As shown; Furthermore, the boundary conditions of the model are set for the overall calculation model of the on-load tap changer, such as Figure 5 As shown; It should be noted that fixed boundary conditions are applied at A (the connection between the epoxy phenolic laminated glass cloth board and the epoxy glass fiber extrusion rod); at B, the translational freedom is constrained at the shaft end, and the rotational freedom around the axis is released; fixed boundary conditions are applied at C and D; at E, the translational freedom is constrained at the shaft bottom, and the rotational freedom around the axis is released, and at the same time, a rotational displacement (angle) is applied according to uniform acceleration motion; Furthermore, according to the calculation of rotating 90° within 100ms, the angular acceleration is , and the initial calculation time is set to start from the contact time between the roller and the boss, and the rotation speed of the shaft is , and use this speed as the initial speed of the overall calculation model of the on-load tap changer; Furthermore, according to the spring parameters contained in the quick mechanism in the model, spring connections are established on the two transmission shafts of the model, with a spring preload of 420 N and a stiffness of 4.43 N / mm, as shown in Figure 3 As shown; Furthermore, the mechanism motion of the model rotating shaft under no resistance torque, 5N·m resistance torque and 10N·m resistance torque is considered, and torque loads are set for the above three torques respectively; It should be noted that under the action of the spring compression force, the driven rack will move linearly, thereby driving the half gear to rotate, and then causing the rotating shaft to rotate. Under no resistance torque, the half gear reaches the limit position at about 27ms; under 5N·m resistance torque, the half gear reaches the limit position at about 29.5ms; under 10N·m resistance torque, the half gear reaches the limit position at about 19ms; It should be noted that when the resistance torque is 0, 5 and 10 N·m, the curves of the rotation angle of the rotating shaft with time are as follows: Figure 4 As shown, the time to reach the limit position is 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; S2. Based on the overall calculation model of the on-load tap changer, the different boss angles of the on-load tap changer are changed through spatial finite element discretization in transient dynamic simulation analysis; It should be noted that transient dynamics simulation analysis is an analytical method used to determine the dynamic response of a structure under any time-varying load; Furthermore, transient dynamics simulation analysis includes: For spatial finite element discretization, we use , , ( ) describes each point in the object at time 0, time and time The configuration coordinates of , ( ) represents the time at which each particle and time The displacement of , through the equilibrium equation, using the principle of virtual displacement: (1) in, for Momentary stress; for Always be flexible; for The external force virtual work at the moment; Since the conductor de-icing jumping process is a nonlinear motion process with large displacement and small deformation, it is necessary to adopt corresponding spatial motion description and definition, such as TL or UL coordinates and corresponding metrics. The basic motion equation solved by transient dynamics analysis is: (2) in, represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the node acceleration vector; represents the node velocity vector; represents the node displacement vector; represents the load vector at time t; At any given time t, the above equations can be regarded as a series of static equilibrium equations taking into account inertial force and damping force; for time integration, the Newmark method is used to express it as: (3) and (4) Furthermore, in Within the interval, the linear assumption is met: (5) Furthermore, The acceleration during the interval is: (6) Furthermore, the time point The displacement solution at , can be solved by: (7) Furthermore, It is expressed as: (8) Furthermore, substituting the above formula into , , calculate The formula is: (9) Repeat the above calculation process to obtain the motion trajectory of the on-load tap changer within a given time. in, represents the node displacement, represents the node acceleration, represents the node speed; S3, setting the boss angle to 25° to 50° with a step length of 1°, obtaining the relationship between the equivalent stress level and the yield strength and tensile limit of different boss angles, and obtaining the calculation model of key components with different boss angles through the relationship; Furthermore, the relationship between the equivalent stress level and yield strength for different boss angles is obtained by von Mises equivalent stress and von Mises criterion; Furthermore, the von Mises equivalent stress is expressed as: , in, , and is the principal stress; Furthermore, the von Mises criterion is expressed as: , in, is the yield strength, is a constant; 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 the yield strength and tensile limit of different boss angles was obtained; S4. Calculate the calculation model of key components to obtain the stress distribution of key components and the shaft stress condition, and perform fault monitoring on the on-load tap changer based on the shaft stress condition; Furthermore, when the value of the axial force FX exceeds 680.3, it shows that the corresponding component is at the fault position value of external lateral force, and the component needs to be replaced in time; when the value of the axial force FZ exceeds 3643N, it shows that the corresponding component is at the fault position value of external multi-faceted force, and the component needs to be replaced in time.

[0024] Furthermore, this embodiment also provides a transformer on-load tap changer fault monitoring system, including: The on-load tap-changer processing module performs grid division on the on-load tap-changer and establishes the overall calculation model of the on-load tap-changer; An algorithm module for the overall calculation model of the on-load tap changer changes different boss angles of the on-load tap changer through spatial finite element discretization in transient dynamics simulation analysis based on the overall calculation model of the on-load tap changer; The on-load tap changer adjustment module sets the boss angle to 25° to 50° with a step length of 1°, obtains the relationship between the equivalent stress level and the yield strength and the 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 key component calculation model to obtain the stress distribution and shaft force conditions of the key components, and performs fault monitoring on the on-load tap changer through the stress distribution and shaft force conditions.

[0025] This embodiment further provides a computer device, which is applicable to the transformer on-load tap changer fault monitoring method, and includes: A memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the transformer on-load tap changer fault monitoring method proposed in the above embodiment.

[0026] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through Wi-Fi, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0027] This embodiment further provides a storage medium on which a computer program is stored. When the program is executed by a processor, the transformer on-load tap changer fault monitoring method proposed in the above embodiment is implemented.

[0028] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0029] Example 2, reference Figure 6 and Figure 7 , which is a second embodiment of the present invention, provides a transformer on-load tap changer fault monitoring method, comprising: 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; Table 1 Material parameters of key components , The maximum stress values ​​of key components of on-load tap-changer are shown in Table 2 below; Table 2 Maximum stress values ​​of key parts of on-load tap-changer at different boss angles , The geometric model of key components was created using computer-aided design (CAD) software based on the relationship between the equivalent stress level and the yield strength and tensile limit at different boss angles. It can be seen that at some boss angles (bold parts), the maximum stress of component 9 (cam) exceeds the yield strength of the material (e.g. Figure 6As shown), but it does not exceed the tensile limit of the material, and the other components do not exceed the yield strength or tensile limit of the material; wherein, friction contact is adopted between component 10 and component 11, and at different boss angles during the movement process, the maximum value of FX of component 11 in the X and Z directions fluctuates between 575.9-680.3N, and the maximum value of FZ fluctuates between 3215.6-3643N; Through the analysis of shaft stress, it is possible to timely monitor and replace components in actual work, thereby reducing the power failure rate, improving long-term load support, and bringing stability to the safe operation of the main grid of the power grid.

[0030] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A transformer on-load tap changer fault monitoring method, characterized in that: include: Grid the on-load tap changer and establish the overall calculation model of 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 length of 1°, and the relationship between the equivalent stress level and the yield strength and tensile limit of different boss angles is obtained, and 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 of the key components and the shaft stress condition, and the fault monitoring of the on-load tap changer is performed through the shaft stress condition.

2. The transformer on-load tap changer fault monitoring method according to claim 1, characterized in that: Meshing of on-load tap-changers, including: The components in the on-load tap-changer are divided into regular components and irregular components; The regular components in the on-load tap changer are divided by hexahedral meshes, and the irregular components are divided by tetrahedral meshes.

3. The transformer on-load tap changer fault monitoring method according to claim 2, characterized in that: Establishing the overall calculation model of the on-load tap changer, including: setting the load and boundary conditions of the model; According to the spring parameters of the quick mechanism, spring connections are established on the two transmission shafts of the model, and the spring preload is , stiffness is 4.43N / mm; The mechanism motion of the model's rotating shaft under no resistance torque, 5 N·m resistance torque and 10 N·m resistance torque is considered, and torque loads are set for the three torques respectively.

4. The transformer on-load tap changer fault monitoring method according to claim 3, characterized in that: Boundary conditions, including: According to the calculation of rotating 90° within 100ms, the angular acceleration is ; The initial time is set to the contact time between the roller and the boss, and the rotation speed of the shaft is obtained, which is expressed as: ， The rotation speed of the shaft is taken as the initial rotation speed of the overall calculation model of the on-load tap changer.

5. The transformer on-load tap changer fault monitoring method according to any one of claims 2 to 4, characterized in that: Spatial finite element discretization, including: pass , , Describing Objects At time 0, time and time The configuration coordinates of , Represents each particle In time and time displacement; Using the principle of virtual displacement, the equilibrium equation is expressed as: ， in, for Momentary stress; for Always be flexible; for The external force virtual work at the moment; The nonlinear motion process of the conductor de-icing jump process includes: In the nonlinear motion process of displacement and deformation, the corresponding spatial motion description and definition are adopted, and the basic motion equation to be solved is expressed as: ， in, represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the node acceleration vector; represents the node velocity vector; represents the node displacement vector; represents the load vector at time t; Time The equations represented are used as static equilibrium equations of inertial force and damping force, and are iterated using the Newmark method to determine the motion trajectory of the on-load tap changer within a given time.

6. The transformer on-load tap changer fault monitoring method according to claim 5, characterized in that: Adopt the Newmark method, including: The linear assumption is expressed as: ， and ， Among them, Within the interval, the linear assumption is met: ， The acceleration during the interval is: ， time The displacement is solved as follows: ， It is expressed as: ， Substituting the above formula into the equation, we get , , calculate The formula is: ， in, represents the node displacement, represents the node acceleration, Indicates the node speed.

7. The transformer on-load tap changer fault monitoring method according to claim 6, characterized in that: Fault monitoring of on-load tap-changer based on shaft stress, including: When the value of the shaft force FX exceeds 680.3, it means that the corresponding component is at the fault position value of the external lateral force, and the component needs to be replaced in time; When the value of the shaft force FZ exceeds 3643N, it means that the corresponding component is at a fault position value where it is subjected to external forces in all directions except lateral force, and the component needs to be replaced in time.

8. 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 7, characterized in that: include: The on-load tap-changer processing module performs grid division on the on-load tap-changer and establishes the overall calculation model of the on-load tap-changer; An algorithm module for the overall calculation model of the on-load tap changer changes different boss angles of the on-load tap changer through spatial finite element discretization in transient dynamics simulation analysis based on the overall calculation model of the on-load tap changer; The on-load tap changer adjustment module sets the boss angle to 25° to 50° with a step length of 1°, obtains the relationship between the equivalent stress level and the yield strength and the 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 key component calculation model, obtains the stress distribution of the key components and the shaft force condition, and performs fault monitoring on the on-load tap changer through the shaft force condition.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of any one of the methods of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of any method described in claims 1 to 7 are implemented.

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