A combined mutual inductor phase-to-phase mismatch intelligent identification and verification method and system

Abstract

The application discloses a combined mutual inductor phase-to-phase mismatch intelligent identification and checking method and system, and relates to the technical field of mutual inductor simulation. Structural parameters, electrical parameters, excitation characteristic parameters and operation condition parameters of a combined mutual inductor to be detected are acquired; a three-dimensional finite element simulation model is established based on the structural parameters, the excitation characteristic parameters and phase-to-phase mutual inductor parameters are acquired; the obtained parameters are input into a circuit simulation model provided with a nonlinear excitation model, the harmonic characteristic quantities of secondary output voltages of each phase and the three-phase voltage unbalance characteristic quantities under different operation conditions are calculated, so that the phase-to-phase mismatch state is determined; actual detection data of the combined mutual inductor are acquired, the actual detection data are compared with the simulation results, the phase-to-phase mismatch identification results are obtained, and a checking result is output according to a preset checking condition. The application can take into account spatial electromagnetic characteristic analysis and multi-condition circuit calculation, and realizes comprehensive identification of the phase-to-phase mismatch state of the combined mutual inductor and checking of the secondary output performance.

Description

Technical Field

[0001] This invention relates to the field of instrument transformer simulation technology, specifically to a method and system for intelligent identification and verification of phase mismatch in combined instrument transformers. Background Technology

[0002] Combined instrument transformers typically integrate multiple voltage and current transformer units into a single device to convert high voltage and high current in power systems into standard signals that are easy to meter, protect, and monitor. Compared to multiple independent instrument transformers, combined instrument transformers have advantages such as compact structure, small footprint, and ease of installation and maintenance, and are widely used in distribution networks and substations.

[0003] For three-phase, three-element combined instrument transformers, each phase voltage transformer unit has an independent core and winding. Under operating conditions such as a floating primary neutral point, the magnetic characteristics, excitation nonlinearity, spatial arrangement, and inter-phase magnetic coupling relationships of each phase core may differ, causing inconsistencies in the secondary output characteristics of each phase voltage transformer unit. This manifests as secondary voltage waveform distortion, increased harmonic content, and three-phase voltage imbalance. These phenomena affect the metering accuracy and operational reliability of the combined instrument transformer.

[0004] Existing methods for analyzing the performance of combined instrument transformers typically employ circuit simulation or three-dimensional finite element simulation. Circuit simulation offers high computational efficiency and can analyze output characteristics under different primary voltage and secondary load conditions, but its description of the three-dimensional magnetic field distribution of the core, the spatial structure of the windings, and the magnetic coupling relationship between phases is relatively limited. Three-dimensional finite element simulation can accurately analyze the electromagnetic field distribution corresponding to the core and windings, but the computational load for multi-condition simulation is large, making it difficult to balance analytical accuracy and computational efficiency.

[0005] Furthermore, existing testing methods mostly involve setting up test platforms to measure the secondary output voltage and harmonic components of combined instrument transformers under different load conditions. This method typically requires completing multiple load tests, resulting in a long testing cycle and making it difficult to determine whether phase mismatch exists before product design or manufacturing is completed. While some methods can predict the secondary voltage harmonic content based on the excitation curve, they mainly target single harmonic indicators and fail to fully consider the core spatial structure, phase-to-phase inductance relationships, and three-phase voltage imbalance characteristics to comprehensively identify and verify the phase-to-phase mismatch status of combined instrument transformers. Summary of the Invention

[0006] The technical problem this invention aims to solve is that, for the condition monitoring requirements of combined instrument transformers in smart grids, existing detection methods struggle to simultaneously achieve both analytical accuracy in three-dimensional magnetic fields and phase-to-phase coupling characteristics, as well as computational efficiency under multiple operating conditions. Furthermore, they are difficult to intelligently identify and verify the phase-to-phase mismatch state of combined instrument transformers by combining secondary voltage harmonic characteristics and three-phase voltage imbalance characteristics. This invention provides a method and system for intelligent identification and verification of phase-to-phase mismatch in combined instrument transformers. By combining three-dimensional finite element analysis and circuit simulation analysis, it obtains the secondary voltage harmonic characteristics and three-phase voltage imbalance characteristics of the combined instrument transformer under different operating conditions, and verifies its phase-to-phase mismatch state and secondary output performance using actual detection data.

[0007] This invention is achieved through the following technical solution:

[0008] A method for intelligent identification and verification of phase mismatch in combined current transformers, comprising:

[0009] The structural parameters, electrical parameters, and operating condition parameters of the combined instrument transformer under test are obtained. The structural parameters include core structure parameters and winding arrangement parameters, and the electrical parameters include primary side voltage parameters, secondary side load parameters, and secondary output voltage parameters.

[0010] A three-dimensional finite element simulation model of the combined instrument transformer is established based on the structural parameters. The excitation characteristic parameters and phase-to-phase mutual inductance parameters of the combined instrument transformer are obtained through the three-dimensional finite element simulation model.

[0011] The excitation characteristic parameters and the phase-to-phase mutual inductance parameters are input into the combined transformer circuit simulation model. A nonlinear excitation model is set in the circuit simulation model, and the circuit simulation model is simulated and calculated according to the operating condition parameters to obtain the corresponding secondary output characteristic parameters under different operating conditions.

[0012] The phase mismatch state of the combined transformer is determined based on the secondary output characteristic parameters, wherein the secondary output characteristic parameters include secondary voltage harmonic characteristic quantities and three-phase voltage imbalance characteristic quantities.

[0013] Obtain the actual test data of the combined current transformer, compare the actual test data with the secondary output characteristic parameters output by the circuit simulation model, and determine the phase mismatch identification result of the combined current transformer based on the comparison result.

[0014] Based on the phase mismatch identification results and preset verification conditions, the combined current transformer is verified, and the verification results are output.

[0015] Furthermore, the step of establishing a three-dimensional finite element simulation model of the combined instrument transformer based on the structural parameters, and obtaining the excitation characteristic parameters and interphase mutual inductance parameters of the combined instrument transformer through the three-dimensional finite element simulation model, includes:

[0016] A three-dimensional finite element simulation model is established based on the geometric structure parameters, material parameters, and winding arrangement parameters of each phase core in the combined instrument transformer.

[0017] Electromagnetic field simulation was performed based on the three-dimensional finite element simulation model to obtain the excitation BH curve and interphase mutual inductance parameters under different structural parameter conditions.

[0018] Based on the excitation BH curve and the interphase mutual inductance parameters, the differences in magnetic characteristics and coupling characteristics between different phases of the combined current transformer are characterized.

[0019] Furthermore, the step of inputting the excitation characteristic parameters and the interphase mutual inductance parameters into the combined transformer circuit simulation model includes:

[0020] The excitation BH curve is subjected to function fitting, discretization, or table lookup to obtain the excitation relationship characterizing the nonlinear magnetization characteristics of the iron core, and the nonlinear excitation branch in the circuit simulation model is set according to the excitation relationship.

[0021] The nonlinear excitation model is configured in the combined transformer circuit simulation model, and the interphase coupling relationship in the circuit simulation model is set according to the interphase mutual inductance parameters.

[0022] The circuit simulation model is calculated based on the operating condition parameters to obtain secondary output characteristic parameters under different operating conditions.

[0023] Furthermore, the step of performing simulation calculations on the circuit simulation model based on the operating condition parameters to obtain secondary output characteristic parameters under different operating conditions includes:

[0024] Set different primary voltage conditions and secondary load conditions;

[0025] Obtain the secondary output voltage of each phase under various operating conditions;

[0026] The corresponding harmonic characteristic and three-phase voltage imbalance characteristic are calculated based on the secondary output voltage.

[0027] Furthermore, determining the phase mismatch state of the combined current transformer based on the secondary output characteristic parameters includes:

[0028] Obtain the harmonic characteristic quantities corresponding to the secondary output voltage of each phase respectively;

[0029] Based on the amplitude differences between the secondary output voltages of each phase and the three-phase voltage imbalance characteristics, determine whether the secondary output characteristics of each phase are consistent.

[0030] When the harmonic characteristic quantity or the three-phase voltage imbalance characteristic quantity exceeds a preset threshold, it is determined that there is a phase mismatch in the combined transformer.

[0031] Furthermore, obtaining the actual test data of the combined current transformer includes:

[0032] The excitation curve, resistance, reactance, leakage current, and secondary output voltage waveform data of the combined instrument transformer are collected using the combined instrument transformer electrical parameter testing device.

[0033] The actual secondary output feature parameters are obtained based on the actual detection data.

[0034] Furthermore, the step of verifying the combined current transformer based on the phase mismatch identification results and preset verification conditions includes:

[0035] Compare the actual secondary output characteristic parameters with the simulated secondary output characteristic parameters;

[0036] Based on the comparison results, determine whether the secondary output performance of the combined current transformer meets the preset verification conditions;

[0037] The preset verification conditions include at least the limit for secondary voltage harmonic content and the limit for three-phase voltage imbalance.

[0038] This invention also provides a combined current transformer phase mismatch intelligent identification and verification system, comprising:

[0039] The parameter acquisition module is used to acquire the structural parameters, electrical parameters, excitation characteristic parameters, and operating condition parameters of the combined instrument transformer under test.

[0040] The finite element analysis module, connected to the parameter acquisition module, is used to establish a three-dimensional finite element simulation model of the combined instrument transformer based on the structural parameters, and to obtain the excitation characteristic parameters and phase-to-phase mutual inductance parameters of the combined instrument transformer.

[0041] The joint modeling module, connected to the finite element analysis module, is used to input the excitation characteristic parameters and the interphase mutual inductance parameters into the combined transformer circuit simulation model, and to perform secondary output characteristic analysis based on the nonlinear excitation model.

[0042] The feature analysis module, connected to the joint modeling module, is used to determine the phase mismatch state of the combined transformer based on the secondary output feature parameters output by the circuit simulation model. The secondary output feature parameters include secondary voltage harmonic features and three-phase voltage imbalance features.

[0043] The verification module, connected to the parameter acquisition module and the feature analysis module, is used to compare the secondary output feature parameters obtained from actual detection with the simulation analysis results, and output the verification result of the combined current transformer.

[0044] The actual testing module is used to obtain the actual testing data of the combined current transformer through the combined current transformer electrical parameter testing device, and to obtain the actual secondary output characteristic parameters based on the actual testing data.

[0045] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the intelligent identification and verification method for phase mismatch of combined current transformers as described above.

[0046] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the intelligent identification and verification method for phase mismatch of combined current transformers as described above.

[0047] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0048] This invention establishes a three-dimensional finite element simulation model based on the core structure parameters, material parameters, and winding arrangement parameters of a combined current transformer, and obtains excitation characteristic parameters and interphase mutual inductance parameters. It can consider the magnetic characteristics of each phase core and the interphase magnetic coupling relationship during the secondary output analysis, reducing the impact of insufficient description of spatial electromagnetic characteristics when simply using an equivalent circuit model.

[0049] This invention introduces the excitation characteristic parameters and interphase mutual inductance parameters obtained from three-dimensional finite element simulation into the simulation model of the combined transformer circuit, and sets up a nonlinear excitation model. This combines the electromagnetic field analysis capability of the finite element model with the rapid calculation capability of the circuit model under multiple operating conditions, thereby improving the analysis efficiency under different primary voltage and secondary load conditions while ensuring the analysis accuracy.

[0050] This invention simultaneously acquires the harmonic characteristics of the secondary voltage of each phase and the three-phase voltage imbalance characteristics, no longer evaluating the output performance of the combined instrument transformer solely based on a single harmonic index. It can determine the phase mismatch state of the combined instrument transformer from two aspects: secondary voltage distortion and three-phase output consistency.

[0051] This invention compares the secondary output characteristic parameters output by the circuit simulation model with the actual test data, and can use the measured secondary voltage waveform, harmonic components and three-phase voltage imbalance to verify the phase mismatch identification results, thereby improving the reliability of the verification results.

[0052] This invention enables the pre-analysis of the impact of different structural parameters, excitation characteristic parameters, and operating conditions on the secondary output performance during the design, manufacturing, or testing stages of combined instrument transformers. This reduces the workload required for performance judgment based solely on physical tests with multiple loads, and provides a basis for the design, selection, factory verification, and operational testing of combined instrument transformers.

[0053] This invention achieves a transformation from traditional manual testing to intelligent testing based on model analysis and data feature extraction by comprehensively analyzing the structural parameters, electromagnetic characteristic parameters, and operating condition parameters of combined instrument transformers. It can provide technical support for instrument transformer status monitoring, fault early warning, and operation and maintenance in smart grids and smart substations. Attached Figure Description

[0054] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0055] Figure 1 This is a schematic diagram of the overall process for intelligent identification and verification of phase mismatch in combined current transformers. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0057] Example 1

[0058] This embodiment applies to three-phase, three-element combined instrument transformers, especially to Yyn0 connection structures with the primary neutral point suspended. This type of combined instrument transformer is formed by integrating three independent voltage inductance units. During operation, due to differences in the magnetic characteristics of the cores, the degree of excitation nonlinearity, spatial arrangement, and magnetic circuit distribution of each phase, the secondary output voltages of each phase may exhibit inconsistencies in amplitude, phase, and frequency components, resulting in increased secondary voltage harmonic content and three-phase voltage imbalance.

[0059] This embodiment can be applied to substations, distribution stations and other scenarios in smart grids. By collecting electromagnetic parameters and secondary output signals during the operation of combined instrument transformers, it can realize intelligent perception and performance verification of the instrument transformer's operating status.

[0060] A method for intelligent identification and verification of phase-to-phase mismatch in combined current transformers, such as... Figure 1 As shown, it includes:

[0061] The structural parameters, electrical parameters, and operating condition parameters of the combined instrument transformer under test are obtained. The structural parameters include core structure parameters and winding arrangement parameters, and the electrical parameters include primary side voltage parameters, secondary side load parameters, and secondary output voltage parameters.

[0062] A three-dimensional finite element simulation model of the combined instrument transformer is established based on the structural parameters. The excitation characteristic parameters and phase-to-phase mutual inductance parameters of the combined instrument transformer are obtained through the three-dimensional finite element simulation model.

[0063] The excitation characteristic parameters and the phase-to-phase mutual inductance parameters are input into the combined transformer circuit simulation model. A nonlinear excitation model is set in the circuit simulation model, and the circuit simulation model is simulated and calculated according to the operating condition parameters to obtain the corresponding secondary output characteristic parameters under different operating conditions.

[0064] The phase mismatch state of the combined transformer is determined based on the secondary output characteristic parameters, wherein the secondary output characteristic parameters include secondary voltage harmonic characteristic quantities and three-phase voltage imbalance characteristic quantities.

[0065] Obtain the actual test data of the combined current transformer, compare the actual test data with the secondary output characteristic parameters output by the circuit simulation model, and determine the phase mismatch identification result of the combined current transformer based on the comparison result.

[0066] Based on the phase mismatch identification results and preset verification conditions, the combined instrument transformer is verified, and the verification results are output. The verification results include at least the phase mismatch status, whether the secondary voltage harmonic content meets the limit, and whether the three-phase voltage imbalance meets the limit.

[0067] This embodiment analyzes the magnetic field characteristics corresponding to the spatial structure of the iron core and winding through a three-dimensional finite element simulation model, analyzes the secondary output characteristics under different primary voltage and secondary load conditions through a circuit simulation model, and verifies and validates the phase mismatch state obtained from the simulation by combining actual detection data.

[0068] In this embodiment, the step of establishing a three-dimensional finite element simulation model of the combined instrument transformer based on the structural parameters, and obtaining the excitation characteristic parameters and interphase mutual inductance parameters of the combined instrument transformer through the three-dimensional finite element simulation model, includes:

[0069] A three-dimensional finite element simulation model is established based on the geometric structure parameters, material parameters, and winding arrangement parameters of each phase core in the combined instrument transformer.

[0070] Electromagnetic field simulation was performed based on the three-dimensional finite element simulation model to obtain the excitation BH curve and interphase mutual inductance parameters under different structural parameter conditions.

[0071] Based on the excitation BH curve and the interphase mutual inductance parameters, the differences in magnetic characteristics and coupling characteristics between different phases of the combined current transformer are characterized.

[0072] In a specific embodiment, the structural parameters include: the geometric dimensions of each phase core, the core cross-sectional dimensions, the core material, the spacing between each phase core, the number of turns of the primary and secondary windings, the winding radius, the arrangement position of the windings on the core, and the spatial relationship between the three phase cores. These structural parameters are obtained based on the product design data, physical dimensions, or manufacturing parameters of the combined instrument transformer to be tested.

[0073] The electrical parameters include: primary winding resistance and reactance, secondary winding resistance and reactance, excitation branch parameters, leakage current, primary side voltage, secondary side load, and secondary output voltage of each phase.

[0074] Excitation characteristic parameters are used to characterize the nonlinear characteristics of the core flux as a function of the excitation current, including measured excitation curves or characteristic parameters obtained by fitting excitation curves.

[0075] In one specific implementation, the excitation curve is fitted using a hyperbolic tangent function, and the nonlinear relationship between the excitation current and the magnetic flux is expressed as:

[0076]

[0077] in, For excitation current, Magnetic flux, where A, B, and C are characteristic coefficients of the excitation curve.

[0078] The three-dimensional finite element simulation model includes at least: a three-phase iron core, a primary winding, a secondary winding, an air region between each phase of the iron core, and the material properties corresponding to the iron core and the winding.

[0079] The BH curve of the core material is set according to its magnetization characteristics to characterize the nonlinear magnetization characteristics of the core under different excitation states. Three-phase electrical excitation is applied to the three-phase primary windings according to the primary voltage condition or primary winding excitation condition. An electromagnetic field solution region is set around the combined instrument transformer, and the core, windings, and their adjacent regions are meshed to obtain the electromagnetic field distribution of each phase core and interphase regions. The excitation BH curves and interphase mutual inductance parameters under different structural parameter conditions are obtained from a three-dimensional finite element simulation model. By comparing the corresponding excitation BH curves and interphase mutual inductance parameters, the differences in the magnetic characteristics of each phase and the interphase coupling relationship are characterized.

[0080] With other parameters remaining constant, the effects of core material, core spacing, and winding radius on secondary voltage distortion can be analyzed by changing these parameters individually. Simulation results show that the excitation characteristics corresponding to the core material have a significant impact on the secondary voltage distortion of the three-phase combined instrument transformer, while the effects of structural parameters such as core spacing and winding radius are relatively weak within the scope of the study.

[0081] The average three-phase load is:

[0082]

[0083] in, , and The loads are three-phase secondary loads, namely A, B, and C.

[0084] The asymmetry of a three-phase load is expressed as:

[0085]

[0086] in, Three-phase load asymmetry is used to characterize the degree of imbalance in input operating conditions, while three-phase voltage imbalance is used to characterize the degree of mismatch in the secondary output characteristics of a combined instrument transformer.

[0087] In this embodiment, inputting the excitation characteristic parameters and the interphase mutual inductance parameters into the combined transformer circuit simulation model includes:

[0088] The excitation BH curve is subjected to function fitting, discretization, or table lookup to obtain the excitation relationship characterizing the nonlinear magnetization characteristics of the iron core, and the nonlinear excitation branch in the circuit simulation model is set according to the excitation relationship.

[0089] The nonlinear excitation model is configured in the combined transformer circuit simulation model, and the interphase coupling relationship in the circuit simulation model is set according to the interphase mutual inductance parameters.

[0090] The circuit simulation model is calculated based on the operating condition parameters to obtain secondary output characteristic parameters under different operating conditions.

[0091] Operating parameters include: primary voltage amplitude, primary voltage frequency, secondary load capacity, secondary load size of each phase, and whether the secondary load of each phase is symmetrical.

[0092] The excitation BH curve is fitted by function or represented piecewise to obtain a nonlinear excitation relationship that can characterize the magnetization characteristics of the linear region, transition region and saturation region of the iron core, and this nonlinear excitation relationship is configured in the excitation branch of the circuit simulation model.

[0093] To further determine the relationship between operating parameters and secondary output characteristic parameters, while keeping the core structure parameters, winding parameters, excitation characteristic parameters, and other electrical parameters of the combined instrument transformer constant, the secondary load and primary voltage were varied, and spectral analysis and three-phase unbalance calculations were performed on the secondary output voltage under each operating condition. Quantitative relationships between the secondary load, primary voltage, and secondary output characteristic parameters were obtained by fitting the obtained simulation data to a function.

[0094] When the secondary load S is taken as the independent variable and the third harmonic content of the secondary voltage is taken as the independent variable... When one variable is the dependent variable, the two satisfy the following fitting relationship:

[0095]

[0096] The coefficient of determination of the fitting relationship The value of 0.9711 indicates that within the load range set in this embodiment, the overall third harmonic content of the secondary voltage decreases as the secondary load increases.

[0097] When the secondary load S is taken as the independent variable and the three-phase voltage imbalance is taken as the independent variable... When one variable is the dependent variable, the two satisfy the following fitting relationship:

[0098]

[0099] The coefficient of determination of the fitting relationship The value of 0.992 indicates that within the load range set in this embodiment, the overall three-phase voltage imbalance increases with the increase of the secondary load.

[0100] When the primary side voltage percentage As the independent variable, the third harmonic content of the second voltage is used. When one variable is the dependent variable, the two satisfy the following fitting relationship:

[0101]

[0102] The coefficient of determination of the fitting relationship The value of 0.9987 indicates that as the primary voltage increases, the third harmonic content of the secondary voltage tends to increase, while the three-phase voltage imbalance does not change significantly with the change of the primary voltage.

[0103] The circuit simulation model includes at least a three-phase power supply, phase voltage inductance units, load units, secondary voltage measurement units, harmonic analysis units, and three-phase unbalance calculation units.

[0104] In this embodiment, the step of performing simulation calculations on the circuit simulation model based on the operating condition parameters to obtain secondary output characteristic parameters under different operating conditions includes:

[0105] Set different primary voltage conditions and secondary load conditions;

[0106] Obtain the secondary output voltage of each phase under various operating conditions;

[0107] The corresponding harmonic characteristic quantity and three-phase voltage imbalance characteristic quantity are calculated based on the secondary output voltage. The three-phase voltage imbalance is expressed as a percentage of the difference between the maximum and minimum amplitudes of the three-phase secondary voltages relative to the average value of the three-phase voltages.

[0108] While keeping the structural parameters and excitation characteristic parameters of the combined instrument transformer constant, multiple simulation conditions are generated by changing the primary side voltage and secondary side load. For each simulation condition, the time-domain waveforms of the secondary output voltages of each phase are acquired, and spectral analysis is performed on these waveforms. Based on the spectral analysis results, the fundamental component, third harmonic component, and total harmonic content are obtained. The three-phase voltage imbalance is calculated based on the effective value or amplitude of the secondary output voltages of each phase.

[0109] In this embodiment, determining the phase mismatch state of the combined current transformer based on the secondary output characteristic parameters includes:

[0110] Obtain the harmonic characteristic quantities corresponding to the secondary output voltage of each phase respectively;

[0111] Based on the amplitude differences between the secondary output voltages of each phase and the three-phase voltage imbalance characteristics, determine whether the secondary output characteristics of each phase are consistent.

[0112] When the harmonic characteristic quantity or the three-phase voltage imbalance characteristic quantity exceeds a preset threshold, it is determined that there is a phase mismatch in the combined transformer.

[0113] The preset threshold is determined based on the application scenario, testing requirements, and relevant standards of the combined instrument transformer. For example, in one embodiment, the limit for secondary voltage harmonic content can be set to 2%, and the limit for three-phase voltage imbalance can be set to 3%. When the corresponding characteristic parameters exceed the preset threshold, it is determined that the combined instrument transformer has phase mismatch.

[0114] In the three-phase, three-element combined instrument transformer studied in this embodiment, changes in the secondary load simultaneously affect both the secondary voltage harmonics and the degree of three-phase imbalance. As the secondary load increases, the overall harmonic content of the secondary voltage in each phase decreases, while the degree of three-phase voltage imbalance increases.

[0115] The secondary voltage harmonic content has a logarithmic relationship with the secondary load and a nonlinear relationship with the excitation curve parameters; the three-phase unbalance has a power function relationship with the secondary load.

[0116] In this embodiment, obtaining the actual detection data of the combined current transformer includes:

[0117] The excitation curve, resistance, reactance, leakage current, and secondary output voltage waveform data of the combined instrument transformer are collected using the combined instrument transformer electrical parameter testing device.

[0118] The actual secondary output feature parameters are obtained based on the actual detection data.

[0119] The combined instrument transformer under test is connected to a three-phase test power supply and an adjustable secondary load. Under different load conditions, the secondary output voltage waveforms and harmonic components of each phase are collected. The electrical parameter testing device includes a signal extraction circuit, a low-pass filter circuit, a level boosting circuit, a buffer follower circuit, a data acquisition circuit, a data processing circuit, and a communication circuit. The collected secondary output voltage waveforms are digitally processed to obtain the effective values ​​of the secondary voltages of each phase, harmonic components, and three-phase voltage imbalance, which are used as the actual secondary output characteristic parameters.

[0120] In a specific experiment, the test platform measured the third harmonic content of phases A, B, and C to be 5.06%, 4.77%, and 5.34%, respectively, corresponding to field data of 5.16%, 5.07%, and 5.54%, with differences of 0.1%, 0.3%, and 0.2%. The differences between the experimental results and the field data for the three-phase secondary output voltage were 0.1V, 0.2V, and 0.3V, respectively. These results demonstrate that the test platform can reproduce the secondary voltage distortion and imbalance phenomena observed in the field.

[0121] Under different load conditions, the error between the harmonic content obtained from circuit simulation and the experimental data does not exceed 5%.

[0122] In this embodiment, the step of verifying the combined current transformer based on the phase mismatch identification result and preset verification conditions includes:

[0123] The actual secondary output characteristic parameters are compared with the secondary output characteristic parameters obtained from the simulation.

[0124] Based on the comparison results, determine whether the secondary output performance of the combined current transformer meets the preset verification conditions;

[0125] The preset verification conditions include at least the limit for secondary voltage harmonic content and the limit for three-phase voltage imbalance.

[0126] In this embodiment, the secondary voltage harmonic content and three-phase voltage imbalance are used as criteria to determine the abnormal state of the secondary output of the combined instrument transformer. Specifically, the threshold for secondary voltage harmonic content is set to 2%, and the threshold for three-phase voltage imbalance is set to 3%. It should be noted that these thresholds are only used to illustrate the determination process of this embodiment; in actual applications, they can be adjusted according to the detection object, operating environment, and relevant standards.

[0127] Based on the harmonic content, amplitude difference, and three-phase voltage imbalance of each phase secondary output voltage, it is determined whether there is inconsistency in the secondary output characteristics of each phase; when the secondary output characteristics are inconsistent and the corresponding characteristic quantities do not meet the preset requirements, it is determined that the combined current transformer is in a phase mismatch state.

[0128] In this embodiment, the phase mismatch state is used to indicate that the secondary output characteristics of the three-phase voltage inductance unit are inconsistent, and the specific causes of the phase mismatch are not classified.

[0129] This embodiment combines the analytical capabilities of a three-dimensional finite element model for the three-dimensional magnetic field and interphase coupling relationships of the iron core with the ability of a circuit simulation model to rapidly calculate various primary voltage and secondary load conditions. This allows for the simultaneous acquisition of secondary voltage harmonic characteristics and three-phase voltage imbalance characteristics, and, combined with actual test data, verification of interphase mismatch and performance validation. Compared to step-by-step testing through physical experiments, this method enables pre-analysis of the secondary output characteristics of combined instrument transformers during the design or testing phase.

[0130] This embodiment utilizes the fusion analysis of finite element simulation, circuit simulation, and actual test data to achieve intelligent sensing of the operating status of combined instrument transformers and identification of phase mismatch. Compared with the method of relying on a single manual test for judgment, it can provide auxiliary basis for the status evaluation and intelligent operation and maintenance of metering equipment in smart grids.

[0131] Example 2

[0132] A combined current transformer phase-to-phase mismatch intelligent identification and verification system is provided to implement the combined current transformer phase-to-phase mismatch intelligent identification and verification method of Embodiment 1, comprising:

[0133] The parameter acquisition module is used to acquire the structural parameters, electrical parameters, excitation characteristic parameters, and operating condition parameters of the combined instrument transformer under test.

[0134] The finite element analysis module, connected to the parameter acquisition module, is used to establish a three-dimensional finite element simulation model of the combined instrument transformer based on the structural parameters, and to obtain the excitation characteristic parameters and phase-to-phase mutual inductance parameters of the combined instrument transformer.

[0135] The joint modeling module, connected to the finite element analysis module, is used to input the excitation characteristic parameters and the interphase mutual inductance parameters into the combined transformer circuit simulation model, and to perform secondary output characteristic analysis based on the nonlinear excitation model.

[0136] The feature analysis module, connected to the joint modeling module, is used to determine the phase mismatch state of the combined transformer based on the secondary output feature parameters output by the circuit simulation model. The secondary output feature parameters include secondary voltage harmonic features and three-phase voltage imbalance features.

[0137] The verification module, connected to the parameter acquisition module and the feature analysis module, is used to compare the secondary output feature parameters obtained from actual detection with the simulation analysis results, and output the verification result of the combined current transformer.

[0138] The actual testing module is used to obtain the actual testing data of the combined current transformer through the combined current transformer electrical parameter testing device, and to obtain the actual secondary output characteristic parameters based on the actual testing data.

[0139] Example 3

[0140] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the intelligent identification and verification method for phase mismatch of combined current transformers as described in Embodiment 1.

[0141] Example 4

[0142] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the intelligent identification and verification method for phase mismatch of combined current transformers as described in Embodiment 1.

[0143] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0144] 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, as well as 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. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0145] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0146] 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.

[0147] Those skilled in the art will understand that all or part of the steps in the above method can be implemented by a program instructing related hardware. The program or the program described therein can be stored in a computer-readable storage medium. When the program is executed to implement the steps of the above-described intelligent identification and verification method for phase mismatch of combined current transformers, the storage medium can be ROM / RAM, magnetic disk, optical disk, etc.

[0148] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for intelligent identification and verification of phase mismatch in a combined current transformer, characterized in that, include: Obtain the structural parameters, electrical parameters, and operating condition parameters of the combined instrument transformer under test; A three-dimensional finite element simulation model of the combined instrument transformer is established based on the structural parameters. The excitation characteristic parameters and phase-to-phase mutual inductance parameters of the combined instrument transformer are obtained through the three-dimensional finite element simulation model. The excitation characteristic parameters and the phase-to-phase mutual inductance parameters are input into the combined transformer circuit simulation model. A nonlinear excitation model is set in the circuit simulation model, and the circuit simulation model is simulated and calculated according to the operating condition parameters to obtain the corresponding secondary output characteristic parameters under different operating conditions. The phase mismatch state of the combined transformer is determined based on the secondary output characteristic parameters, wherein the secondary output characteristic parameters include secondary voltage harmonic characteristic quantities and three-phase voltage imbalance characteristic quantities. Obtain the actual test data of the combined current transformer, compare the actual test data with the secondary output characteristic parameters output by the circuit simulation model, and determine the phase mismatch identification result of the combined current transformer based on the comparison result. Based on the phase mismatch identification results and preset verification conditions, the combined current transformer is verified, and the verification results are output.

2. The intelligent identification and verification method for phase-to-phase mismatch of combined instrument transformers according to claim 1, characterized in that, The structural parameters include core structural parameters and winding arrangement parameters, and the electrical parameters include primary side voltage parameters, secondary side load parameters, and secondary output voltage parameters. The establishment of a three-dimensional finite element simulation model of the combined instrument transformer based on the structural parameters, and the acquisition of the excitation characteristic parameters and interphase mutual inductance parameters of the combined instrument transformer through the three-dimensional finite element simulation model, includes: A three-dimensional finite element simulation model is established based on the geometric structure parameters, material parameters, and winding arrangement parameters of each phase core in the combined instrument transformer. Electromagnetic field simulation was performed based on the three-dimensional finite element simulation model to obtain the excitation BH curve and interphase mutual inductance parameters under different structural parameter conditions. Based on the excitation BH curve and the phase mutual inductance parameters, the differences in magnetic characteristics and coupling characteristics between different phases of the combined transformer are characterized.

3. The intelligent identification and verification method for phase-to-phase mismatch of combined current transformers according to claim 2, characterized in that, The step of inputting the excitation characteristic parameters and the interphase mutual inductance parameters into the combined transformer circuit simulation model includes: The excitation BH curve is subjected to function fitting, discretization, or table lookup to obtain the excitation relationship characterizing the nonlinear magnetization characteristics of the iron core, and the nonlinear excitation branch in the circuit simulation model is set according to the excitation relationship. The nonlinear excitation model is configured in the combined transformer circuit simulation model, and the interphase coupling relationship in the circuit simulation model is set according to the interphase mutual inductance parameters. The circuit simulation model is calculated based on the operating condition parameters to obtain secondary output characteristic parameters under different operating conditions.

4. The intelligent identification and verification method for phase-to-phase mismatch of combined current transformers according to claim 2, characterized in that, The step of performing simulation calculations on the circuit simulation model based on the operating condition parameters to obtain secondary output characteristic parameters under different operating conditions includes: Set different primary voltage conditions and secondary load conditions; Obtain the secondary output voltage of each phase under various operating conditions; The corresponding harmonic characteristic and three-phase voltage imbalance characteristic are calculated based on the secondary output voltage.

5. The intelligent identification and verification method for phase-to-phase mismatch of combined instrument transformers according to claim 1, characterized in that, Determining the phase mismatch state of the combined current transformer based on the secondary output characteristic parameters includes: Obtain the harmonic characteristic quantities corresponding to the secondary output voltage of each phase respectively; Based on the amplitude differences between the secondary output voltages of each phase and the three-phase voltage imbalance characteristics, determine whether the secondary output characteristics of each phase are consistent. When the harmonic characteristic quantity or the three-phase voltage imbalance characteristic quantity exceeds a preset threshold, it is determined that there is a phase mismatch in the combined transformer.

6. The intelligent identification and verification method for phase-to-phase mismatch of combined current transformers according to claim 1, characterized in that, The acquisition of the actual test data of the combined current transformer includes: The excitation curve, resistance, reactance, leakage current, and secondary output voltage waveform data of the combined instrument transformer are collected using the combined instrument transformer electrical parameter testing device. The actual secondary output feature parameters are obtained based on the actual detection data.

7. The intelligent identification and verification method for phase-to-phase mismatch of combined current transformers according to claim 6, characterized in that, The step of verifying the combined current transformer based on the phase mismatch identification results and preset verification conditions includes: The actual secondary output characteristic parameters are compared with the secondary output characteristic parameters obtained from the simulation. Based on the comparison results, determine whether the secondary output performance of the combined current transformer meets the preset verification conditions; The preset verification conditions include at least the limit for secondary voltage harmonic content and the limit for three-phase voltage imbalance.

8. A combined current transformer phase-to-phase mismatch intelligent identification and verification system, characterized in that, include: The parameter acquisition module is used to acquire the structural parameters, electrical parameters, excitation characteristic parameters, and operating condition parameters of the combined instrument transformer under test. The finite element analysis module, connected to the parameter acquisition module, is used to establish a three-dimensional finite element simulation model of the combined instrument transformer based on the structural parameters, and to obtain the excitation characteristic parameters and phase-to-phase mutual inductance parameters of the combined instrument transformer. The joint modeling module, connected to the finite element analysis module, is used to input the excitation characteristic parameters and the interphase mutual inductance parameters into the combined transformer circuit simulation model, and to perform secondary output characteristic analysis based on the nonlinear excitation model. The feature analysis module, connected to the joint modeling module, is used to determine the phase mismatch state of the combined transformer based on the secondary output feature parameters output by the circuit simulation model. The secondary output feature parameters include secondary voltage harmonic features and three-phase voltage imbalance features. The verification module, connected to the parameter acquisition module and the feature analysis module, is used to compare the secondary output feature parameters obtained from actual detection with the simulation analysis results, and output the verification result of the combined current transformer. The actual testing module is used to obtain the actual testing data of the combined current transformer through the combined current transformer electrical parameter testing device, and to obtain the actual secondary output characteristic parameters based on the actual testing data.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the intelligent identification and verification method for phase mismatch of combined current transformers as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the intelligent identification and verification method for phase mismatch of combined current transformers as described in any one of claims 1 to 7.

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