A method and system for measuring strain of transformer windings under multiple short circuit impulses

Abstract

The application discloses a kind of measurement methods and systems of transformer winding strain under multiple short-circuit impacts, comprising: data measurement stage: a plurality of fiber grating sensors are arranged on transformer winding, multiple short-circuit impacts are implemented to transformer winding, and the center wavelength variation and temperature variation value of each fiber grating sensor are obtained;Data processing stage: based on the center wavelength variation and temperature variation value, according to the light-force theory conversion equation, the strain of transformer winding is generated;Result verification stage: a magnetic-circuit-force equivalent model for simulating transformer winding is constructed, the theoretical electromagnetic force and theoretical strain are obtained, the error between the strain of transformer winding and theoretical strain is calculated, and the measurement accuracy of the strain of transformer winding is verified;The application converts the measurement data of fiber grating sensor into strain size, monitors the deformation of winding, prevents the loosening and damage of winding under sudden short-circuit of transformer winding, and guarantees the safe and stable operation of transformer.

Description

Technical Field

[0001] This invention relates to the field of irregular flight management in air transport, and more particularly to a method and system for measuring the strain of transformer windings under multiple short-circuit impacts. Background Technology

[0002] Short-circuit faults are the main cause of transformer winding deformation and account for a high proportion of all fault accidents. Therefore, short-circuit withstand capability is one of the important indicators of a transformer. When short-circuit current and leakage magnetic field work together, a huge short-circuit electromagnetic force is generated. When the winding is subjected to this electromagnetic force, it may deform, bulge, or experience other problems, leading to winding loosening, decreased insulation performance, and a reduction in the overall short-circuit withstand capability of the transformer.

[0003] Current measurement methods can determine whether winding deformation occurs under short-circuit conditions, but they also have some drawbacks. For example, the transverse and longitudinal leakage reactance of the short-circuit impedance method are easily affected by environmental factors, impacting measurement accuracy. The connection method of the low-voltage pulse method measurement circuit and cables can affect the distribution of stray coupling capacitance in the test circuit, thus affecting experimental accuracy. Therefore, a reasonable and universally applicable method for measuring transformer winding deformation is urgently needed, possessing significant theoretical and engineering value. Summary of the Invention

[0004] To address the existing technical problems, the present invention aims to provide a method for measuring the strain of transformer windings under multiple short-circuit impacts, thereby solving the problem of strain measurement of transformer windings under short-circuit impacts.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a method for measuring the strain of a transformer winding under multiple short-circuit impacts, comprising the following steps:

[0006] Data measurement stage: Several fiber Bragg grating sensors are arranged on the transformer windings, and multiple short-circuit impacts are applied to the transformer windings to obtain the center wavelength change and temperature change value of each fiber Bragg grating sensor.

[0007] Data processing stage: Based on the change in center wavelength and temperature, the transformer winding strain is generated according to the optical-mechanical conversion equation;

[0008] Results Verification Phase: Construct an equivalent magnetic-circuit-force model for simulating transformer windings, obtain theoretical electromagnetic force and theoretical strain, and verify the accuracy of transformer winding strain measurement by calculating the error between transformer winding strain and theoretical strain.

[0009] Preferably, during the data measurement stage, the fiber Bragg grating sensor is wound at 1 / 4 and / or 1 / 2 of the transformer winding, wherein each fiber of the fiber Bragg grating sensor is paired with 4 sets of grating sensors, arranged at the same height of the winding and spaced 90° apart.

[0010] Preferably, during the data processing stage, the expression for the optical-mechanical theory conversion equation is:

[0011]

[0012] Where, ε 实测 For the measured radial strain of the winding, Δλ B λ represents the change in center wavelength before and after the test. B This represents the center wavelength parameter of the sensor, with a value of 1550nm; P e This represents the effective photoelastic coefficient, which is 0.216 depending on the optical material used in the experiment. ζ represents the average strain transmissibility. ζ represents the thermo-optic coefficient, which depends only on the fiber grating material itself and is independent of environmental changes; its value is 6.7 * 10⁻⁶. -6 / ℃; α represents the coefficient of thermal expansion, which is independent of environmental changes and takes a value of 0.5*10. -6 / ℃.

[0013] Preferably, in the result verification stage, based on the transformer winding, by setting the materials and parameters of each part, setting the circuit module according to the short-circuit impact test wiring diagram, and refining the mesh of the model, a magnetic-circuit-force equivalent model is constructed.

[0014] Preferably, in the result verification stage, based on the magnetic-circuit-force equivalent model, the radial electromagnetic force at different times and locations is obtained sequentially by acquiring the leakage flux distribution law of the transformer;

[0015] Based on Hooke's law, radial strain is obtained from radial electromagnetic force, where radial strain is used to represent theoretical strain.

[0016] Preferably, in the process of obtaining radial strain, radial strain is generated based on Hooke's law and the elastic modulus of the copper wire according to the radial electromagnetic force.

[0017] Preferably, in the process of obtaining radial strain, the relationship between strain and stress is:

[0018]

[0019] Where, ε 理论 σ represents the theoretical radial strain; σ represents the radial stress of the conductor (whether it is radial electromagnetic force); E represents the elastic modulus of the copper conductor.

[0020] This invention discloses a system for measuring the strain of a transformer winding under multiple short-circuit impacts, comprising:

[0021] The data acquisition module is used to acquire the center wavelength change and temperature change value of each fiber optic grating sensor by arranging several fiber optic grating sensors on the transformer winding and subjecting the transformer winding to multiple short-circuit impacts.

[0022] The data processing module is used to generate transformer winding strain based on the center wavelength change and temperature change, according to the optical-mechanical theory conversion equation.

[0023] The result verification module is used to obtain the theoretical electromagnetic force and theoretical strain by constructing a magnetic-circuit-force equivalent model for simulating transformer windings. By calculating the error between the transformer winding strain and the theoretical strain, the accuracy of the transformer winding strain measurement is verified.

[0024] The present invention discloses the following technical effects:

[0025] This invention enables strain observation of transformer windings, converts the measurement data from fiber optic grating sensors into strain magnitudes, monitors the deformation of the windings, prevents loosening or damage of the transformer windings under sudden short circuits, and ensures the safe and stable operation of the transformer. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is an installation diagram of the fiber Bragg grating sensor described in this invention;

[0028] Figure 2 This is a simulation model diagram of the transformer magnetic-circuit-force described in this invention;

[0029] Figure 3 This is a flowchart illustrating the method described in this invention;

[0030] Figure 4 This is a schematic diagram of the fiber Bragg grating sensor described in this invention.

[0031] Figure 5 This is a schematic diagram of the sensor arrangement described in this invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] like Figure 1-5 As shown, this invention provides a method for measuring the strain of a transformer winding under multiple short-circuit impacts, comprising the following steps:

[0034] Data measurement stage: Several fiber Bragg grating sensors are arranged on the transformer windings, and multiple short-circuit impacts are applied to the transformer windings to obtain the center wavelength change and temperature change value of each fiber Bragg grating sensor.

[0035] Data processing stage: Based on the change in center wavelength and temperature, the transformer winding strain is generated according to the optical-mechanical conversion equation;

[0036] Results Verification Phase: Construct an equivalent magnetic-circuit-force model for simulating transformer windings, obtain theoretical electromagnetic force and theoretical strain, and verify the accuracy of transformer winding strain measurement by calculating the error between transformer winding strain and theoretical strain.

[0037] More preferably, during the data measurement stage, the fiber Bragg grating sensor is wound at 1 / 4 and / or 1 / 2 of the transformer winding, wherein each fiber of the fiber Bragg grating sensor is paired with 4 sets of grating sensors, arranged at the same height of the winding and spaced 90° apart.

[0038] More preferably, in the data processing stage, the expression for the optical-mechanical theory conversion equation is:

[0039]

[0040] Where, ε 实测 For the measured radial strain of the winding, Δλ B λ represents the change in center wavelength before and after the test. B This represents the center wavelength parameter of the sensor, with a value of 1550nm; P e This represents the effective photoelastic coefficient, which is 0.216 based on the optical material used in the experiment. ζ represents the average strain transmissibility. ζ represents the thermo-optic coefficient, which depends only on the fiber grating material itself and is independent of environmental changes; its value is 6.7 * 10⁻⁶. -6 / ℃; α represents the coefficient of thermal expansion, which is independent of environmental changes and takes a value of 0.5*10. -6 / ℃.

[0041] More preferably, in the result verification stage, based on the transformer winding, by setting the materials and parameters of each part, setting the circuit module according to the short-circuit impact test wiring diagram, and refining the mesh of the model, a magnetic-circuit-force equivalent model is constructed.

[0042] More preferably, in the result verification stage, based on the magnetic-circuit-force equivalent model, the radial electromagnetic force at different times and locations is obtained sequentially by acquiring the leakage flux distribution law of the transformer;

[0043] Based on Hooke's law, radial strain is obtained from radial electromagnetic force, where radial strain is used to represent theoretical strain.

[0044] More preferably, in the process of obtaining radial strain, based on Hooke's law and the radial electromagnetic force, radial strain is generated by obtaining the elastic modulus of the copper wire.

[0045] More preferably, in the process of obtaining radial strain, the relationship between strain and stress is:

[0046]

[0047] Where, ε 理论 σ represents the theoretical radial strain; σ represents the radial stress of the conductor (whether it is radial electromagnetic force); E represents the elastic modulus of the copper conductor.

[0048] This invention discloses a system for measuring the strain of a transformer winding under multiple short-circuit impacts, comprising:

[0049] The data acquisition module is used to acquire the center wavelength change and temperature change value of each fiber optic grating sensor by arranging several fiber optic grating sensors on the transformer winding and subjecting the transformer winding to multiple short-circuit impacts.

[0050] The data processing module is used to generate transformer winding strain based on the change in center wavelength and temperature change, according to the optical-mechanical conversion equation.

[0051] The result verification module is used to obtain the theoretical electromagnetic force and theoretical strain by constructing a magnetic-circuit-force equivalent model for simulating transformer windings. By calculating the error between the transformer winding strain and the theoretical strain, the accuracy of the transformer winding strain measurement is verified.

[0052] This invention provides a method for measuring the strain of a transformer winding under multiple short-circuit impacts, comprising the following steps:

[0053] Step 1: Install fiber optic grating sensors on the transformer windings, respectively wound at 1 / 4 and 1 / 2 of the distance from the top of the winding. Each fiber is paired with 4 sets of grating sensors, arranged at the same height of the winding, 90° apart.

[0054] Step 2: Record the center wavelength value acquired by the fiber Bragg grating sensor in real time;

[0055] Step 3: Calculate the change in center wavelength and temperature of each grating, and calculate the measured strain according to the optical-mechanical conversion equation;

[0056] Step 4: Establish a full-scale transformer magnetic-circuit-force simulation model using Comsol software and mesh it.

[0057] Step 5: Set up simulation conditions according to the actual working conditions of the short-circuit test, obtain the theoretical electromagnetic force and theoretical strain through simulation, calculate the error between the measured strain and the theoretical strain, and verify the accuracy of the measurement method.

[0058] Step 1: During the transformer winding process, FBG (fiber optic strain gauge) and fiber optic temperature sensor need to be installed in advance. Considering that the axial deformation of the winding coil often follows an M-shape and the deformation position is random, optical fibers are installed at 1 / 4 and 1 / 2 of the distance from the top of the winding, respectively. The four grates of each optical fiber are evenly distributed around the winding at 90° intervals. Figure 1 As shown.

[0059] Step 2: Record the values ​​measured by the fiber optic strain sensor and the temperature sensor.

[0060] Step 3: Measure the center wavelength change using an FBG (fiber Bragg grating), calculate the center wavelength change and temperature change for each grating, and calculate the measured strain using the optical-mechanical conversion equation, as shown in the following equation:

[0061]

[0062] When the winding state changes, the alterations in the grating's photoelastic properties and pitch size will cause a change in the wavelength of the grating's center reflection. Similarly, changes in temperature will lead to changes in the fiber's thermo-optical properties and thermal expansion characteristics, resulting in a final wavelength that is the superposition of these two factors. Simultaneously, the data measured by the fiber optic grating temperature sensor is used for temperature compensation through an equation. Substituting the measured data into the above equation yields the actual strain magnitude.

[0063] Step 4: Using COMSOL simulation software, establish a magnetic-circuit-force equivalent model of the transformer based on its actual structural parameters. Set the materials and parameters for each part, and configure its circuit modules according to the short-circuit impulse test wiring diagram. Refine the mesh of the model to ensure calculation accuracy. Figure 2 As shown.

[0064] Step 5: Establish an equivalent model of the transformer using COMSOL software based on the actual parameters of the transformer. Based on the established model and the basic theory of electromagnetic fields, conduct a theoretical analysis of the leakage magnetic field to obtain the distribution law of the transformer leakage flux. Calculate the magnitude of the radial electromagnetic force of the winding.

[0065] In a magnetic field, the following governing equations and boundary conditions exist based on the vector magnetic potential A:

[0066]

[0067] Control domain perimeter:

[0068] n×A=0

[0069] The vector magnetic potential A can be obtained by using the vector Poisson equation.

[0070]

[0071] The relationship between the axial leakage flux density and the vector magnetic potential of the winding is as follows:

[0072]

[0073] The radial electromagnetic force on the transformer winding is calculated using the Lorentz force formula. Within each finite element element, the radial electromagnetic force is:

[0074] F ρ =JB z S ε 2πL ε

[0075] Therefore, the radial electromagnetic force of the transformer winding is:

[0076] F = ∑F ρ

[0077] Among them, B z T is the axial component of the leakage flux density; J is the current density (A / m). 2 ); J s The table shows the source current density (A / m). 2 μ is the magnetic permeability (H / m); γ is the electrical conductivity (S / m); denoted as scalar potential (V); r is the position vector; S ε L represents the area of ​​a single finite element; εThe distance between the centroid of the finite element and the centerline of the iron core. Vector differential operator.

[0078] Based on the current magnitude and leakage flux at different times, the radial electromagnetic force at different times and locations is calculated sequentially.

[0079] Step 6: In this experiment, the theoretical radial stress of the conductor is obtained through the radial stress equation, and the theoretical radial strain at the corresponding conductor position is calculated through the strain equation.

[0080] The relationship between radial stress and radial electromagnetic force is shown in the following equation:

[0081]

[0082] Where σ is the radial stress of the conductor; F is the radial electromagnetic force at the sensor measuring point; and S is the cross-sectional area of ​​the conductor, S = 1.272 * 10⁻⁶. -5 m 2 W represents the number of turns in the low-voltage winding, W = 107. The theoretical radial stress at the sensor measuring point can be calculated using the values ​​at the sensor measuring point and the above equation.

[0083] Within a certain elastic limit, stress and strain obey Hooke's law, and the relationship between radial stress and theoretical radial strain is shown in the following equation:

[0084]

[0085] Where, ε 理论 σ is the theoretical radial strain; σ is the radial stress of the conductor; E is the elastic modulus of the copper conductor, with a value of 115000 MPa.

[0086] A comparative analysis of theoretical and actual strain revealed an error within 5%, verifying the accuracy of the experimental results. This allows for the assessment of the transformer winding condition. The results demonstrate the precision of the FBG sensor measurement, indicating that this method can be used to measure transformer winding deformation, which has significant practical engineering value.

[0087] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1A device that provides the functions specified in one or more boxes.

[0088] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0089] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0090] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

Claims

1. A method for measuring the strain of a transformer winding under multiple short-circuit impacts, characterized in that, Includes the following steps: Data measurement stage: Several fiber Bragg grating sensors are arranged on the transformer winding, and multiple short-circuit impacts are applied to the transformer winding to obtain the center wavelength change and temperature change value of each fiber Bragg grating sensor. Data processing stage: Based on the change in center wavelength and the change in temperature, the transformer winding strain is generated according to the optical-mechanical conversion equation; Results Verification Stage: Construct an equivalent magnetic-circuit-force model for simulating the transformer winding to obtain theoretical electromagnetic force and theoretical strain. Verify the accuracy of the transformer winding strain measurement by calculating the error between the transformer winding strain and the theoretical strain.

2. The method for measuring transformer winding strain under multiple short-circuit impacts according to claim 1, characterized in that: During the data measurement phase, the fiber Bragg grating sensor is wound at 1 / 4 and / or 1 / 2 of the transformer winding. Each fiber of the fiber Bragg grating sensor is paired with 4 sets of grating sensors, which are arranged at the same height of the winding and spaced 90° apart.

3. The method for measuring transformer winding strain under multiple short-circuit impacts according to claim 2, characterized in that: In the data processing stage, the expression for the optical-mechanical theory conversion equation is: in, ε 实测 For the measured radial strain of the winding, Δ λ B This indicates the change in center wavelength before and after the test; λ B Indicates the center wavelength parameter of the sensor. P e Indicates the effective elastic coefficient. Indicates the average strain transmissibility. Indicates the thermo-optic coefficient. α The coefficient of thermal expansion, Δ T It represents the amount of temperature change.

4. The method for measuring transformer winding strain under multiple short-circuit impacts according to claim 3, characterized in that: In the result verification stage, based on the transformer winding, by setting the materials and parameters of each part, setting the circuit module according to the short-circuit impact test wiring diagram, and refining the mesh of the model, the magnetic-circuit-force equivalent model is constructed.

5. The method for measuring transformer winding strain under multiple short-circuit impacts according to claim 4, characterized in that: During the result verification stage, based on the magnetic-circuit-force equivalent model, the radial electromagnetic force at different times and locations is obtained sequentially by acquiring the distribution law of transformer leakage flux. Based on Hooke's law, radial strain is obtained according to the radial electromagnetic force, wherein the radial strain is used to represent the theoretical strain.

6. The method for measuring transformer winding strain under multiple short-circuit impacts according to claim 5, characterized in that: In the process of obtaining radial strain, based on Hooke's law and the radial electromagnetic force, the radial strain is generated by obtaining the elastic modulus of the copper wire.

7. The method for measuring transformer winding strain under multiple short-circuit impacts according to claim 6, characterized in that: In obtaining radial strain, the relationship between strain and stress is as follows: in, ε 理论 Indicates theoretical radial strain; σ Indicates radial stress in the conductor; E This represents the elastic modulus of a copper conductor.

8. A system for measuring the strain of a transformer winding under multiple short-circuit impacts, characterized in that, include: The data acquisition module is used to acquire the center wavelength change and temperature change value of each fiber optic grating sensor by arranging several fiber optic grating sensors on the transformer winding and subjecting the transformer winding to multiple short-circuit impacts. The data processing module is used to generate transformer winding strain based on the change in center wavelength and the change in temperature, according to the optical-mechanical theory conversion equation. The result verification module is used to obtain the theoretical electromagnetic force and theoretical strain by constructing a magnetic-circuit-force equivalent model for simulating the transformer winding, and to verify the measurement accuracy of the transformer winding strain by calculating the error between the transformer winding strain and the theoretical strain.

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