Method and system for calculating pre-tightening force change characteristics of transformer winding

Abstract

The invention belongs to the technical field of transformers, and discloses a transformer winding pretightening force change characteristic calculation method and system, and the method comprises the steps: obtaining the mechanical characteristic measurement results of an insulation cushion block and a winding, and calculating the stress-strain curve, elastic modulus and Poisson's ratio of the insulation cushion block and the winding; the method comprises the following steps: constructing a simulation calculation model based on a relationship among an internal iron core, an insulating cushion block and a winding of the transformer, and calculating axial plastic deformation of the insulating cushion block and the winding by combining stress-strain curves of the insulating cushion block and the winding; the method comprises the following steps: constructing a multi-body mass spring model based on an equivalent relationship between an insulating cushion block in the transformer and a coil wire cake, constructing a pre-tightening force calculation model in combination with the accumulated deformation quantity of the insulating cushion block and a winding, and analyzing the attenuation characteristic of the pre-tightening force of the transformer. The method for calculating the pretightening force at the two ends of the winding in the transformer has great significance in guiding the design of the internal structure of the transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to a method and system for calculating the preload variation characteristics of transformer windings. Background Art

[0002] The reduction of transformer winding preload will lead to a decrease in the transformer's natural frequency, which is easy to approach the electromagnetic force frequency, causing resonance, leading to axial instability of the winding and causing serious mechanical failure of the transformer.

[0003] The current mainstream research focuses on analyzing the impact of different preload forces on the natural frequency of the winding, or in multi-physics field simulation software, by applying a constant pressure to both ends of the winding to approximate the effect of the preload force, thereby exploring the calculation of the cumulative deformation.

[0004] However, on the one hand, the above research cannot study the frequency changes when the preload changes. On the other hand, simply setting a constant pressure does not conform to the actual situation of the transformer preload. During operation, especially when the winding undergoes plastic deformation, the preload will be severely attenuated and will have a great impact on the axial stability of the winding.

[0005] Therefore, how to provide a calculation method and system for the change characteristics of transformer winding preload is a problem that needs to be solved urgently. Summary of the invention

[0006] The embodiment of the present invention provides a method and system for calculating the variation characteristics of transformer winding preload force, so as to solve the above-mentioned technical problems existing in the prior art.

[0007] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be a general review, nor is it intended to identify key / important components or to delineate the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0008] According to a first aspect of an embodiment of the present invention, a method for calculating a transformer winding preload variation characteristic is provided.

[0009] In one embodiment, the method for calculating the transformer winding preload variation characteristics includes:

[0010] Obtain the mechanical property measurement results of the insulating spacer and winding, and calculate the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and winding;

[0011] Based on the relationship between the transformer's internal iron core, insulating spacers and windings, a simulation model is constructed, and the axial plastic deformation of the insulating spacers and windings is calculated in combination with the stress-strain curves of the insulating spacers and windings.

[0012] Based on the equivalent relationship between the insulating spacer and the coil inside the transformer, a multi-body mass-spring model is constructed. Combined with the accumulated deformation of the insulating spacer and the winding, a preload calculation model is constructed to analyze the attenuation characteristics of the transformer preload.

[0013] In one embodiment, obtaining the mechanical property measurement results of the insulating spacer and the winding, and calculating the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and the winding include:

[0014] Real-time monitoring of the measurement process of the axial stress applied to the insulating spacer and the winding, and recording the stress-strain curves of the insulating spacer and the winding, wherein the stress-strain curves include the axial stress-strain curve and the lateral deformation-axial deformation curve;

[0015] Intercepting the axial elastic straight line segment on the axial stress-strain curve, reading the axial force change and the corresponding axial deformation change between the two end points of the axial elastic straight line segment, substituting them into the Young's modulus formula to calculate the Young's modulus as the elastic modulus of the insulating spacer and the winding;

[0016] The radial elastic straight line segment on the lateral deformation-axial deformation curve is intercepted, the radial deformation change and the corresponding axial deformation change between the two end points of the radial elastic straight line segment are read, and the Poisson's ratio formula is substituted to calculate the Poisson's ratio of the insulating spacer and the winding.

[0017] In one embodiment, the Young's modulus formula is:

[0018]

[0019] Where, E is Young's modulus; L el is the axial extensometer gauge length; F is the axial force; ΔF is the change in axial force; S0 is the original cross-sectional area of ​​the parallel length of the specimen; ΔL a is the change in axial deformation variable.

[0020] In one embodiment, the Poisson's ratio formula is:

[0021]

[0022] Where μ is Poisson's ratio; L el is the axial extensometer gauge length; ΔL a is the change of axial deformation variable; L et is the transverse extensometer gauge length; ΔL t is the change in lateral deformation.

[0023] In one embodiment, the simulation calculation model is constructed based on the relationship between the internal core, insulating spacer and winding of the transformer, and the axial plastic deformation of the insulating spacer and winding is calculated in combination with the stress-strain curves of the insulating spacer and winding, including:

[0024] Construct simulation calculation models of the transformer's internal core, insulation pads and windings;

[0025] Configure the electromagnetic field material properties of the simulation model, add electromagnetic field excitation, and calculate the volume force density inside the transformer in the electromagnetic field;

[0026] The structural field material properties of the simulation calculation model are configured, the structural field excitation is added, and the volume force density is coupled to the structural field. The axial plastic deformation of the insulating spacer and the winding is calculated in combination with the stress-strain curves of the insulating spacer and the winding.

[0027] In one embodiment, the multi-body mass spring model is constructed based on the equivalent relationship between the insulating spacer and the coil coil inside the transformer, and the preload calculation model is constructed in combination with the accumulated deformation of the insulating spacer and the winding. The attenuation characteristics of the transformer preload are analyzed, including:

[0028] The coils in the transformer are equivalent to mass points, the insulating spacers are equivalent to springs, and the upper and lower iron yokes of the transformer are equivalent to absolute rigid bodies. A multi-body mass-spring model of the transformer insulating spacers and windings is constructed.

[0029] Based on the multi-body mass-spring model, an equivalent equation for the winding coil and an equivalent elastic coefficient formula for the insulating spacer are established. By calculating the equivalent equation for the winding coil, the absolute axial displacement of each coil in the winding is analyzed, the cumulative deformation of all windings and insulating spacers is evaluated, and the attenuation characteristics of the transformer preload are obtained.

[0030] In one embodiment, the winding coil equivalent equation is:

[0031]

[0032] In the formula, is the second-order derivative of the axial displacement; Z is the absolute axial displacement of each coil; F is the axial short-circuit electromagnetic force on each coil; M is the system mass matrix; g is the gravitational acceleration; K is the system stiffness matrix.

[0033] In one embodiment, the equivalent elastic coefficient formula is:

[0034]

[0035] Where K0 is the elastic equivalent coefficient; E is Young's modulus; A is the total contact area between the insulating spacer and the wire cake; h represents the height of the insulating spacer.

[0036] According to a second aspect of an embodiment of the present invention, a system for calculating a transformer winding preload force variation characteristic is provided.

[0037] In one embodiment, the calculation system of transformer winding preload variation characteristics includes:

[0038] The mechanical property measurement module is used to obtain the mechanical property measurement results of the insulating spacer and the winding, and calculate the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and the winding;

[0039] The simulation deformation calculation module is used to construct a simulation calculation model based on the relationship between the transformer's internal iron core, insulating spacers and windings, and calculate the axial plastic deformation of the insulating spacers and windings in combination with the stress-strain curves of the insulating spacers and windings;

[0040] The preload equivalent analysis module is used to construct a multi-body mass-spring model based on the equivalent relationship between the insulating spacer and the coil inside the transformer, and to construct a preload calculation model based on the accumulated deformation of the insulating spacer and the winding to analyze the attenuation characteristics of the transformer preload.

[0041] In one embodiment, the mechanical property determination module includes: a curve recording module, an elastic modulus calculation module and a Poisson's ratio calculation module, wherein:

[0042] The curve recording module is used to monitor the measurement process of the axial stress applied to the insulating spacer and the winding in real time, and record the stress-strain curve of the insulating spacer and the winding, wherein the stress-strain curve includes an axial stress-strain curve and a lateral deformation-axial deformation curve;

[0043] The elastic modulus calculation module is used to intercept the axial elastic straight line segment on the axial stress-strain curve, read the axial force change and the corresponding axial deformation change between the two end points of the axial elastic straight line segment, substitute them into the Young's modulus formula to calculate the Young's modulus as the elastic modulus of the insulating spacer and the winding;

[0044] The Poisson's ratio calculation module is used to intercept the radial elastic straight line segment on the lateral deformation-axial deformation curve, read the radial deformation change and the corresponding axial deformation change between the two end points of the radial elastic straight line segment, and substitute them into the Poisson's ratio formula to calculate the Poisson's ratio of the insulating spacer and the winding.

[0045] In one embodiment, the Young's modulus formula is:

[0046]

[0047] Where, E is Young's modulus; L elis the axial extensometer gauge length; F is the axial force; ΔF is the change in axial force; S0 is the original cross-sectional area of ​​the parallel length of the specimen; ΔL a is the change in axial deformation variable.

[0048] In one embodiment, the Poisson's ratio formula is:

[0049]

[0050] Where μ is Poisson's ratio; L el is the axial extensometer gauge length; ΔL a is the change of axial deformation variable; L et is the transverse extensometer gauge length; ΔL t is the change in lateral deformation.

[0051] In one embodiment, the simulation deformation calculation module includes: a model building module, an electromagnetic field module and a structural field module, wherein:

[0052] The model building module is used to build a simulation calculation model of the transformer's internal iron core, insulating spacers and windings;

[0053] The electromagnetic field module is used to configure the electromagnetic field material properties of the simulation calculation model, add electromagnetic field excitation, and calculate the volume force density borne by the transformer in the electromagnetic field;

[0054] The structural field module is used to configure the structural field material properties of the simulation calculation model, add structural field excitation, and couple the volume force density to the structural field, and calculate the axial plastic deformation of the insulating spacer and the winding in combination with the stress-strain curves of the insulating spacer and the winding.

[0055] In one embodiment, the preload equivalent analysis module includes: an equivalent model module and an equivalent calculation analysis module, wherein:

[0056] The equivalent model module is used to equate the coils in the transformer to mass points, the insulating spacers to springs, and the upper and lower iron yokes of the transformer to absolute rigid bodies, so as to construct a multi-body mass-spring model of the insulating spacers and windings of the transformer;

[0057] The equivalent calculation and analysis module is used to establish an equivalent equation for the winding coil and an equivalent elastic coefficient formula for the insulating spacer based on the multi-body mass-spring model, calculate the equivalent equation for the winding coil, analyze the axial absolute displacement of each coil in the winding, evaluate the cumulative deformation of all windings and insulating spacers, and obtain the attenuation characteristics of the transformer preload.

[0058] In one embodiment, the winding coil equivalent equation is:

[0059]

[0060] In the formula, is the second-order derivative of the axial displacement; Z is the absolute axial displacement of each coil; F is the axial short-circuit electromagnetic force on each coil; M is the system mass matrix; g is the gravitational acceleration; K is the system stiffness matrix.

[0061] In one embodiment, the equivalent elastic coefficient formula is:

[0062]

[0063] Where K0 is the elastic equivalent coefficient; E is Young's modulus; A is the total contact area between the insulating spacer and the wire cake; h represents the height of the insulating spacer.

[0064] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0065] In some embodiments, the computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0066] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0067] In one embodiment, the computer-readable storage medium stores a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0068] The technical solution provided by the embodiment of the present invention may include the following beneficial effects: through the proposed method for calculating the preload force at both ends of the internal winding of the transformer, the accuracy of the internal mechanical structure analysis of the transformer is further improved, which is of great significance for guiding the internal structure design of the transformer.

[0069] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0071] Figure 1 is a flow chart showing a method for calculating a transformer winding preload variation characteristic according to an exemplary embodiment;

[0072] Figure 2 is a structural schematic diagram of a system for calculating a transformer winding preload variation characteristic according to an exemplary embodiment;

[0073] Figure 3 is a graph showing a graphical method for calculating Young's modulus according to an exemplary embodiment;

[0074] Figure 4 is a graph showing a graphical method for calculating Poisson's ratio according to an exemplary embodiment;

[0075] Figure 5 is a flowchart of transformer electromagnetic-structural field sequential coupling calculation according to an exemplary embodiment;

[0076] Figure 6 is a schematic diagram of a transformer multi-body mass-spring model structure according to an exemplary embodiment;

[0077] Figure 7 The figure is a schematic diagram showing the structure of a computer device according to an exemplary embodiment. DETAILED DESCRIPTION

[0078] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0079] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0080] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0081] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0082] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0083] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0084] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0085] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0086] Figure 1An embodiment of a method for calculating the variation characteristics of transformer winding preload force according to the present invention is shown.

[0087] In this optional embodiment, the method for calculating the transformer winding preload variation characteristics includes:

[0088] Step S101, obtaining the mechanical property measurement results of the insulating spacer and the winding, and calculating the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and the winding;

[0089] Step S103: construct a simulation calculation model based on the relationship between the transformer internal iron core, insulating spacer and winding, and calculate the axial plastic deformation of the insulating spacer and winding in combination with the stress-strain curves of the insulating spacer and winding;

[0090] Step S105: Based on the equivalent relationship between the insulating spacer and the coil inside the transformer, a multi-body mass-spring model is constructed, and a preload calculation model is constructed in combination with the accumulated deformation of the insulating spacer and the winding to analyze the attenuation characteristics of the transformer preload.

[0091] In this optional embodiment, when obtaining the measurement results of the mechanical properties of the insulating spacer and the winding, and calculating the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and the winding, the measurement process of the axial stress applied to the insulating spacer and the winding can be monitored in real time, and the stress-strain curve of the insulating spacer and the winding can be recorded, wherein the stress-strain curve includes an axial stress-strain curve and a transverse deformation-axial deformation curve; the axial elastic straight line segment on the axial stress-strain curve is intercepted, the axial force change and the corresponding axial deformation change between the two end points of the axial elastic straight line segment are read, and the Young's modulus is substituted into the Young's modulus formula to calculate the Young's modulus as the elastic modulus of the insulating spacer and the winding; the radial elastic straight line segment on the transverse deformation-axial deformation curve is intercepted, the radial deformation change and the corresponding axial deformation change between the two end points of the radial elastic straight line segment are read, and the Poisson's ratio formula is substituted to calculate the Poisson's ratio of the insulating spacer and the winding.

[0092] In this optional embodiment, the Young's modulus formula is:

[0093]

[0094] Where, E is Young's modulus; L el is the axial extensometer gauge length; F is the axial force; ΔF is the change in axial force; S0 is the original cross-sectional area of ​​the parallel length of the specimen; ΔL a is the change in axial deformation variable.

[0095] In this optional embodiment, the Poisson's ratio formula is:

[0096]

[0097] Where μ is Poisson's ratio; L el is the axial extensometer gauge length; ΔL a is the change of axial deformation variable; L et is the transverse extensometer gauge length; ΔL t is the change in lateral deformation.

[0098] In this optional embodiment, when constructing a simulation calculation model based on the relationship between the internal iron core, insulating spacers and windings of the transformer, and calculating the axial plastic deformation of the insulating spacers and windings in combination with the stress-strain curves of the insulating spacers and windings, a simulation calculation model of the internal iron core, insulating spacers and windings of the transformer can be constructed; the electromagnetic field material properties of the simulation calculation model are configured, electromagnetic field excitation is added, and the volume force density borne by the transformer in the electromagnetic field is calculated; the structural field material properties of the simulation calculation model are configured, structural field excitation is added, and the volume force density is coupled to the structural field, and the axial plastic deformation of the insulating spacers and windings is calculated in combination with the stress-strain curves of the insulating spacers and windings.

[0099] In this optional embodiment, based on the equivalent relationship between the insulating spacer and the coil winding inside the transformer, a multi-body mass-spring model is constructed, and in combination with the accumulated deformation of the insulating spacer and the winding, a preload calculation model is constructed. When analyzing the attenuation characteristics of the transformer preload, the winding winding in the transformer can be equivalent to a mass point, the insulating spacer can be equivalent to a spring, and the upper and lower iron yokes of the transformer can be equivalent to an absolute rigid body to construct a multi-body mass-spring model of the transformer insulating spacer and winding; based on the multi-body mass-spring model, an equivalent equation for the winding winding and an equivalent elastic coefficient formula for the insulating spacer are established, and by calculating the equivalent equation for the winding winding, the axial absolute displacement of each winding in the winding is analyzed, and the accumulated deformation of all windings and insulating spacers is evaluated to obtain the attenuation characteristics of the transformer preload.

[0100] In this optional embodiment, the winding coil equivalent equation is:

[0101]

[0102] In the formula, is the second-order derivative of the axial displacement; Z is the absolute axial displacement of each coil; F is the axial short-circuit electromagnetic force on each coil; M is the system mass matrix; g is the gravitational acceleration; K is the system stiffness matrix.

[0103] In this optional embodiment, the equivalent elastic coefficient formula is:

[0104]

[0105] Where K0 is the elastic equivalent coefficient; E is Young's modulus; A is the total contact area between the insulating spacer and the wire cake; h represents the height of the insulating spacer.

[0106] Figure 2 An embodiment of a calculation system for transformer winding preload variation characteristics of the present invention is shown.

[0107] In this optional embodiment, the calculation system of the transformer winding preload force variation characteristic includes:

[0108] The mechanical property measurement module 201 is used to obtain the mechanical property measurement results of the insulating spacer and the winding, and calculate the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and the winding;

[0109] The simulation deformation calculation module 203 is used to construct a simulation calculation model based on the relationship between the transformer internal core, the insulating spacer and the winding, and calculate the axial plastic deformation of the insulating spacer and the winding in combination with the stress-strain curves of the insulating spacer and the winding;

[0110] The preload equivalent analysis module 205 is used to construct a multi-body mass spring model based on the equivalent relationship between the insulating spacer and the coil coil inside the transformer, and to construct a preload calculation model in combination with the accumulated deformation of the insulating spacer and the winding to analyze the attenuation characteristics of the transformer preload.

[0111] In this optional embodiment, the mechanical property measurement module 201 includes: a curve recording module (not shown in the figure), an elastic modulus calculation module (not shown in the figure) and a Poisson's ratio calculation module (not shown in the figure), wherein the curve recording module is used to monitor the measurement process of the axial stress applied to the insulating spacer and the winding in real time, and record the stress-strain curve of the insulating spacer and the winding, wherein the stress-strain curve includes an axial stress-strain curve and a lateral deformation-axial deformation curve; the elastic modulus calculation module is used to intercept the axial elastic straight line segment on the axial stress-strain curve, read the axial force change and the corresponding axial deformation change between the two end points of the axial elastic straight line segment, substitute them into the Young's modulus formula to calculate the Young's modulus as the elastic modulus of the insulating spacer and the winding; the Poisson's ratio calculation module is used to intercept the radial elastic straight line segment on the lateral deformation-axial deformation curve, read the radial deformation change and the corresponding axial deformation change between the two end points of the radial elastic straight line segment, and substitute them into the Poisson's ratio formula to calculate the Poisson's ratio of the insulating spacer and the winding.

[0112] In this optional embodiment, the Young's modulus formula is:

[0113]

[0114] Where, E is Young's modulus; L elis the axial extensometer gauge length; F is the axial force; ΔF is the change in axial force; S0 is the original cross-sectional area of ​​the parallel length of the specimen; ΔL a is the change in axial deformation variable.

[0115] In this optional embodiment, the Poisson's ratio formula is:

[0116]

[0117] Where μ is Poisson's ratio; L el is the axial extensometer gauge length; ΔL a is the change of axial deformation variable; L et is the transverse extensometer gauge length; ΔL t is the change in lateral deformation.

[0118] In this optional embodiment, the simulation deformation calculation module 203 includes: a model construction module (not shown in the figure), an electromagnetic field module (not shown in the figure) and a structural field module (not shown in the figure), wherein the model construction module is used to construct a simulation calculation model of the internal iron core, insulating spacers and windings of the transformer; the electromagnetic field module is used to configure the electromagnetic field material properties of the simulation calculation model, add electromagnetic field excitation, and calculate the volume force density borne by the transformer inside the electromagnetic field; the structural field module is used to configure the structural field material properties of the simulation calculation model, add structural field excitation, and couple the volume force density to the structural field, and calculate the axial plastic deformation of the insulating spacers and windings in combination with the stress-strain curves of the insulating spacers and windings.

[0119] In this optional embodiment, the preload equivalent analysis module 205 includes: an equivalent model module (not shown in the figure) and an equivalent calculation analysis module (not shown in the figure), wherein the equivalent model module is used to equate the coils in the transformer to particles, the insulating pads to springs, and the upper and lower iron yokes of the transformer to absolute rigid bodies, so as to construct a multi-body mass spring model of the insulating pads and windings of the transformer; the equivalent calculation analysis module is used to establish an equivalent equation for the winding coils and an equivalent elastic coefficient formula for the insulating pads based on the multi-body mass spring model, calculate the equivalent equation for the winding coils, analyze the axial absolute displacement of each coil in the winding, evaluate the cumulative deformation of all windings and insulating pads, and obtain the attenuation characteristics of the transformer preload.

[0120] In this optional embodiment, the winding coil equivalent equation is:

[0121]

[0122] In the formula, is the second-order derivative of the axial displacement; Z is the absolute axial displacement of each coil; F is the axial short-circuit electromagnetic force on each coil; M is the system mass matrix; g is the gravitational acceleration; K is the system stiffness matrix.

[0123] In this optional embodiment, the equivalent elastic coefficient formula is:

[0124]

[0125] Where K0 is the elastic equivalent coefficient; E is Young's modulus; A is the total contact area between the insulating spacer and the wire cake; h represents the height of the insulating spacer.

[0126] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0127] The present invention proposes a method for calculating the variation characteristics of transformer winding preload force for a transformer. The main steps of the method are divided into three steps, which can be summarized as follows:

[0128] 1. Determination of mechanical properties of insulating spacers and windings: The test platform supports applying compressive stress and tensile stress to insulating spacers and windings respectively, and obtaining stress-strain curves, elastic modulus and Poisson's ratio.

[0129] 2. Calculation considering the deformation of insulating spacers and windings: Based on the stress-strain curves of insulating spacers and windings, the finite element simulation calculation method is used to obtain the axial cumulative deformation of the transformer windings and insulating spacers under different operating conditions.

[0130] 3. Construction of preload calculation model: Based on the mass-spring model and the cumulative deformation of the insulating spacer and winding, the attenuation characteristics of the transformer preload are obtained.

[0131] Specifically, the detailed execution content of each step includes the following aspects.

[0132] 1. Determination of mechanical properties of insulating spacers and windings

[0133] Referring to GB / T 38989-2020 Test method for uniaxial compression elastic modulus of inorganic binder stabilized materials (middle section method) and GB / T 22315-2008 Test method for elastic modulus and Poisson's ratio of metallic materials, a test platform was built to test the stress-strain, elastic modulus and Poisson's ratio of insulating spacers and windings.

[0134] Test method: Before the test, the insulating spacers are dried and vacuum-oiled in the same way as in actual production to ensure the consistency of the mechanical properties of the materials. During the test, the motor is controlled to apply a steadily increasing axial stress to the test material, and the axial stress-strain curve and the transverse deformation-axial deformation curve of the material are recorded. The elastic modulus and Poisson's ratio of the material are calculated based on the graphical method.

[0135] Young's modulus calculation method: According to the axial force-axial deformation curve recorded in the test, such as Figure 3 As shown, an elastic straight line segment is determined on the curve, and the change in axial force and the corresponding change in axial deformation between two points A and B that are as far apart as possible are read on the straight line segment, and the Young's modulus is calculated according to the following formula.

[0136]

[0137] Where, E is Young's modulus; L el is the axial extensometer gauge length; F is the axial force; ΔF is the change in axial force; S0 is the original cross-sectional area of ​​the parallel length of the specimen; ΔL a is the change in axial deformation variable.

[0138] Poisson's ratio calculation method: According to the radial deformation-axial deformation curve recorded in the test, such as Figure 4 As shown, determine the elastic straight line segment on the curve, read the radial deformation change and the corresponding axial deformation change between two points C and D that are as far apart as possible on the straight line segment. Calculate the Poisson's ratio according to the following formula.

[0139]

[0140] 2. Calculation considering plastic deformation of insulating spacers and windings

[0141] Using multi-physics field analysis and calculation software, a simulation calculation model of the transformer's internal core, winding, and insulation pad is constructed. Figure 5 As shown, based on the electromagnetic-structural field sequential coupling, the volume force density inside the transformer in the electromagnetic field is first calculated, and then it is directly coupled to the structural field. Combined with the mechanical characteristic curves of the winding and the insulating spacer measured in the first part, the axial deformation of the winding and the insulating spacer is calculated.

[0142] 3. Calculation of preload attenuation model

[0143] In the calculation process of transformer winding preload, the transformer coil can be regarded as a mass point with concentrated mass, the pad is equivalent to a spring, and its mass is ignored. The upper and lower iron yokes of the transformer are regarded as absolute rigid bodies, and no displacement occurs during operation. A multi-body mass-spring system of transformer windings and insulating pads is constructed, such as Figure 6 shown.

[0144] Each coil of the winding satisfies the equation:

[0145]

[0146] Where Z is the absolute axial displacement of each coil, Z = [z1 z2 … zn ] T ; F is the axial short-circuit electromagnetic force on each coil, F=[F1 F2 … F n ] T ; M is the system mass matrix; g is the gravitational acceleration; K is the system stiffness matrix, K = trid[k ij ],k ii =k i-1 +k i ,k i,i+1 =k i+1,i =-k i (i=1,2,…,n).

[0147] For the insulating spacer, its equivalent elastic coefficient can be expressed as:

[0148]

[0149] Where K0 is the elastic equivalent coefficient; E is Young's modulus; A is the total contact area between the insulating spacer and the wire cake; h represents the height of the insulating spacer.

[0150] In the factory state, the preload force generated at both ends of the transformer winding and the insulating spacer is F N At this time, the deformation variables of each wire cake are X c =[X c1 ,X c2, …,X cn ], the initial deformation of each pad is X b =[X b0 ,X b1, …,X bn ]. At this time, in the multi-body mass-spring model, the stress of each spring can be expressed as:

[0151]

[0152] Where i is the index of the spring in the mass-spring system; E bi is the Young's modulus of the i-th spring; X bi is the deformation of the i-th spring; m j is the mass of the jth particle; g is the gravitational acceleration; F N is the preload force at both ends of the transformer winding, which is a known value in the factory state.

[0153] Therefore, the initial deformation magnitude of each insulating spacer under the initial compression state can be calculated based on the above formula.

[0154] When the transformer is subjected to short-circuit impact and the winding undergoes plastic deformation, and multiple short-circuit impacts produce cumulative deformation, the electromagnetic force on the winding when the short-circuit current exists can be calculated based on the multi-physics field simulation software, and the axial deformation ΔX of the winding when the axial component of the electromagnetic force acts on the winding can be calculated based on the Young's modulus of the winding. c =[ΔX c1 ,ΔX c2, …,ΔX cn ]. In addition, the axial displacement ΔZ of each winding can be calculated based on the multi-physics field simulation software c =[ΔZ c1 ,ΔZ c2, …,ΔZ cn ].

[0155] The insulating spacer itself does not bear the effect of electromagnetic force. Its high elasticity can ensure that the winding-insulating spacer system can always be in close contact with the transformer clamp within a certain deformation range, ensuring that there is no gap on the contact surface of the winding, insulating spacer and clamp.

[0156] If the winding compression is taken as the positive direction of deformation, the winding center reduces the positive direction of axial displacement. At this time, the stress of each spring can be expressed as:

[0157]

[0158] Where i is the index of the spring in the mass-spring system; E bi is the Young's modulus of the i-th spring; X bi is the deformation of the i-th spring; m j is the mass of the jth particle; g is the gravitational acceleration; F′ N is the new preload at both ends of the transformer winding after deformation; ΔZ ci is the axial displacement of the i-th winding; ΔX ch is the deformation of the first pancake winding.

[0159] Based on the above formula and the calculation results of multiple physical fields, the change of preload force based on deformation can be calculated.

[0160] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 7As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, 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, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in the above method embodiment are implemented.

[0161] Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0162] In addition, the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiment when executing the computer program.

[0163] In addition, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0164] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0165] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for calculating the variation characteristics of transformer winding preload, characterized in that: include: Obtain the mechanical property measurement results of the insulating spacer and winding, and calculate the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and winding; Based on the relationship between the transformer's internal iron core, insulating spacers and windings, a simulation model is constructed, and the axial plastic deformation of the insulating spacers and windings is calculated in combination with the stress-strain curves of the insulating spacers and windings. Based on the equivalent relationship between the insulating spacer and the coil inside the transformer, a multi-body mass-spring model is constructed. Combined with the accumulated deformation of the insulating spacer and the winding, a preload calculation model is constructed to analyze the attenuation characteristics of the transformer preload.

2. The method for calculating the transformer winding preload variation characteristics according to claim 1, characterized in that: The obtaining of the mechanical property measurement results of the insulating spacer and the winding, and the calculation of the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and the winding include: Real-time monitoring of the measurement process of the axial stress applied to the insulating spacer and the winding, and recording the stress-strain curves of the insulating spacer and the winding, wherein the stress-strain curves include the axial stress-strain curve and the lateral deformation-axial deformation curve; Intercepting the axial elastic straight line segment on the axial stress-strain curve, reading the axial force change and the corresponding axial deformation change between the two end points of the axial elastic straight line segment, substituting them into the Young's modulus formula to calculate the Young's modulus as the elastic modulus of the insulating spacer and the winding; The radial elastic straight line segment on the lateral deformation-axial deformation curve is intercepted, the radial deformation change and the corresponding axial deformation change between the two end points of the radial elastic straight line segment are read, and the Poisson's ratio formula is substituted to calculate the Poisson's ratio of the insulating spacer and the winding.

3. The method for calculating the transformer winding preload variation characteristics according to claim 2, characterized in that: The Young's modulus formula is: Where, E is Young's modulus; L el is the axial extensometer gauge length; F is the axial force; ΔF is the change in axial force; S0 is the original cross-sectional area of ​​the parallel length of the specimen; ΔL a is the change in axial deformation variable.

4. The method for calculating the transformer winding preload variation characteristics according to claim 2, characterized in that: The Poisson's ratio formula is: Where μ is Poisson's ratio; L el is the axial extensometer gauge length; ΔL a is the change of axial deformation variable; L et is the transverse extensometer gauge length; ΔL t is the change in lateral deformation.

5. The method for calculating the transformer winding preload variation characteristics according to claim 1, characterized in that: The simulation calculation model is constructed based on the relationship between the transformer internal core, the insulating spacer and the winding, and the axial plastic deformation of the insulating spacer and the winding is calculated in combination with the stress-strain curves of the insulating spacer and the winding, including: Construct simulation calculation models of the transformer's internal core, insulation pads and windings; Configure the electromagnetic field material properties of the simulation model, add electromagnetic field excitation, and calculate the volume force density inside the transformer in the electromagnetic field; The structural field material properties of the simulation calculation model are configured, the structural field excitation is added, and the volume force density is coupled to the structural field. The axial plastic deformation of the insulating spacer and the winding is calculated in combination with the stress-strain curves of the insulating spacer and the winding.

6. The method for calculating the transformer winding preload variation characteristics according to claim 2, characterized in that: Based on the equivalent relationship between the insulating spacer and the coil inside the transformer, a multi-body mass spring model is constructed, and the cumulative deformation of the insulating spacer and the winding is combined to construct a preload calculation model to analyze the attenuation characteristics of the transformer preload, including: The coils in the transformer are equivalent to mass points, the insulating spacers are equivalent to springs, and the upper and lower iron yokes of the transformer are equivalent to absolute rigid bodies. A multi-body mass-spring model of the transformer insulating spacers and windings is constructed. Based on the multi-body mass-spring model, an equivalent equation for the winding coil and an equivalent elastic coefficient formula for the insulating spacer are established. By calculating the equivalent equation for the winding coil, the absolute axial displacement of each coil in the winding is analyzed, the cumulative deformation of all windings and insulating spacers is evaluated, and the attenuation characteristics of the transformer preload are obtained.

7. The method for calculating the transformer winding preload variation characteristics according to claim 6, characterized in that: The winding coil equivalent equation is: In the formula, is the second-order derivative of the axial displacement; Z is the absolute axial displacement of each coil; F is the axial short-circuit electromagnetic force on each coil; M is the system mass matrix; g is the gravitational acceleration; K is the system stiffness matrix.

8. The method for calculating the transformer winding preload variation characteristics according to claim 6, characterized in that: The equivalent elastic coefficient formula is: Where K0 is the elastic equivalent coefficient; E is Young's modulus; A is the total contact area between the insulating spacer and the wire cake; h represents the height of the insulating spacer.

9. A calculation system for transformer winding preload variation characteristics, characterized in that: include: The mechanical property measurement module is used to obtain the mechanical property measurement results of the insulating spacer and the winding, and calculate the stress-strain curve, elastic modulus and Poisson's ratio of the insulating spacer and the winding; The simulation deformation calculation module is used to construct a simulation calculation model based on the relationship between the transformer's internal iron core, insulating spacers and windings, and calculate the axial plastic deformation of the insulating spacers and windings in combination with the stress-strain curves of the insulating spacers and windings; The preload equivalent analysis module is used to construct a multi-body mass-spring model based on the equivalent relationship between the insulating spacer and the coil inside the transformer, and to construct a preload calculation model based on the accumulated deformation of the insulating spacer and the winding to analyze the attenuation characteristics of the transformer preload.

10. The calculation system for transformer winding preload variation characteristics according to claim 9, characterized in that: The mechanical property determination module includes: a curve recording module, an elastic modulus calculation module and a Poisson's ratio calculation module, wherein: The curve recording module is used to monitor the measurement process of the axial stress applied to the insulating spacer and the winding in real time, and record the stress-strain curve of the insulating spacer and the winding, wherein the stress-strain curve includes an axial stress-strain curve and a lateral deformation-axial deformation curve; The elastic modulus calculation module is used to intercept the axial elastic straight line segment on the axial stress-strain curve, read the axial force change and the corresponding axial deformation change between the two end points of the axial elastic straight line segment, substitute them into the Young's modulus formula to calculate the Young's modulus as the elastic modulus of the insulating spacer and the winding; The Poisson's ratio calculation module is used to intercept the radial elastic straight line segment on the lateral deformation-axial deformation curve, read the radial deformation change and the corresponding axial deformation change between the two end points of the radial elastic straight line segment, and substitute them into the Poisson's ratio formula to calculate the Poisson's ratio of the insulating spacer and the winding.

11. The calculation system for transformer winding preload variation characteristics according to claim 10, characterized in that: The Young's modulus formula is: Where, E is Young's modulus; L el is the axial extensometer gauge length; F is the axial force; ΔF is the change in axial force; S0 is the original cross-sectional area of ​​the parallel length of the specimen; ΔL a is the change in axial deformation variable.

12. The calculation system for transformer winding preload variation characteristics according to claim 10, characterized in that: The Poisson's ratio formula is: Where μ is Poisson's ratio; L el is the axial extensometer gauge length; ΔL a is the change of axial deformation variable; L et is the transverse extensometer gauge length; ΔL t is the change in lateral deformation.

13. The calculation system of transformer winding preload variation characteristics according to claim 9, characterized in that: The simulation deformation calculation module includes: a model building module, an electromagnetic field module and a structural field module, wherein: The model building module is used to build a simulation calculation model of the transformer's internal iron core, insulating spacers and windings; The electromagnetic field module is used to configure the electromagnetic field material properties of the simulation calculation model, add electromagnetic field excitation, and calculate the volume force density borne by the transformer in the electromagnetic field; The structural field module is used to configure the structural field material properties of the simulation calculation model, add structural field excitation, and couple the volume force density to the structural field, and calculate the axial plastic deformation of the insulating spacer and the winding in combination with the stress-strain curves of the insulating spacer and the winding.

14. The calculation system for transformer winding preload variation characteristics according to claim 9, characterized in that: The preload equivalent analysis module includes: an equivalent model module and an equivalent calculation analysis module, wherein: The equivalent model module is used to equate the coils in the transformer to mass points, the insulating spacers to springs, and the upper and lower iron yokes of the transformer to absolute rigid bodies, so as to construct a multi-body mass-spring model of the insulating spacers and windings of the transformer; The equivalent calculation and analysis module is used to establish an equivalent equation for the winding coil and an equivalent elastic coefficient formula for the insulating spacer based on the multi-body mass-spring model, calculate the equivalent equation for the winding coil, analyze the axial absolute displacement of each coil in the winding, evaluate the cumulative deformation of all windings and insulating spacers, and obtain the attenuation characteristics of the transformer preload.

15. The calculation system for transformer winding preload variation characteristics according to claim 14, characterized in that: The winding coil equivalent equation is: In the formula, is the second-order derivative of the axial displacement; Z is the absolute axial displacement of each coil; F is the axial short-circuit electromagnetic force on each coil; M is the system mass matrix; g is the gravitational acceleration; K is the system stiffness matrix.

16. The calculation system for transformer winding preload variation characteristics according to claim 14, characterized in that: The equivalent elastic coefficient formula is: Where K0 is the elastic equivalent coefficient; E is Young's modulus; A is the total contact area between the insulating spacer and the wire cake; h represents the height of the insulating spacer.

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