Calibration method and system of current transformer and circuit breaking device

Abstract

The invention relates to the technical field of circuit breaking devices, and discloses a calibration method and system of a current transformer and a circuit breaking device.The calibration method of the current transformer comprises the steps that a transmission characteristic matrix of the current transformer is constructed, and the mapping relation between the secondary side output current and the turn number percentage of the current transformer is determined according to the transmission characteristic matrix; constructing a preset transmission characteristic curve of each current transformer; calculating the turn number percentage of the primary side input current corresponding to the unsaturated region in which the preset transmission characteristic curve is introduced into each current transformer; and calibrating the corresponding preset transmission characteristic curve according to the turn number percentage of the corresponding current transformer and the mapping relation to obtain the calibrated transmission characteristic curve of each current transformer. According to the invention, the transmission characteristic curve of the current transformer in the circuit breaking device can be dynamically calibrated, and the detection precision is effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of circuit breaker devices, and in particular to a calibration method and system for a current transformer and a circuit breaker device. Background Art

[0002] The protection time and type of the circuit breaker depend on the actual current flowing through the circuit breaker. The sampling and logical judgment of the current by the circuit breaker will determine whether to trigger the tripping action and thus disconnect the circuit. Therefore, the importance of improving the accuracy of current sampling and logical judgment is self-evident. The current transformer is a key component for the circuit breaker to implement current sampling and logical judgment. The primary input current and the secondary output current constitute the transmission characteristic curve of the current transformer. The primary input current is the unknown actual working current. After current sampling, the secondary output current is obtained. The primary input current corresponding to the secondary output current can be obtained on the preset transmission characteristic curve, and whether to perform various protections can be determined based on this.

[0003] Existing current transformers have a fixed transmission characteristic curve. However, due to individual differences between different batches of current transformers, for the same primary input current, the secondary output current sensed by the secondary side is discrete. The matching transmission characteristic curve cannot be dynamically calibrated according to individual differences, which may cause the circuit breaker to malfunction or not operate, making it impossible to achieve accurate protection and even causing safety hazards. Summary of the invention

[0004] In view of this, the embodiments of the present application provide a calibration method, system and circuit breaker device for a current transformer, which effectively solve the problem of dynamic calibration of the transmission characteristic curve that needs to be solved due to individual differences caused by different batches of current transformers.

[0005] In a first aspect, an embodiment of the present application provides a current transformer calibration method, comprising: Constructing a transmission characteristic matrix of the current transformer to determine a mapping relationship between a secondary output current of the current transformer and a percentage of turns according to the transmission characteristic matrix; Constructing a preset transmission characteristic curve for each current transformer; Calculating the percentage of turns of the primary input current corresponding to the preset transmission characteristic curve being in the non-saturated region passed through each current transformer; The corresponding preset transmission characteristic curve is calibrated according to the turns percentage of the corresponding current transformer and the mapping relationship to obtain a calibrated transmission characteristic curve of each current transformer.

[0006] In a first possible embodiment of the first aspect, constructing a transmission characteristic matrix of the current transformer includes: Sampling a target population including a plurality of current transformers to obtain a plurality of groups of current transformers having different numbers of coil turns; Passing different preset currents into the primary sides of each group of the current transformers, and collecting the secondary side output currents of each group of the current transformers; The transfer characteristic matrix is ​​constructed according to the primary input current and the secondary output current of each group of the current transformers.

[0007] In a second possible embodiment of the first aspect, when different preset currents are passed through the primary sides of each group of the current transformers, the process further includes: The temperature rise of the magnetic ring of each group of the current transformers is controlled so that different preset currents are passed through each group of the current transformers under the same magnetic ring temperature rise.

[0008] In a third possible embodiment of the first aspect, the primary coil of the current transformer is a through-core current-carrying conductor, and sampling a target population including a plurality of current transformers to obtain a plurality of groups of current transformers with different numbers of coil turns includes: Based on the set rated number of turns and sampling ratio, multiple groups of the current transformers are extracted according to the number of turns of the secondary coils of the current transformers.

[0009] In a fourth possible embodiment of the first aspect, the step of constructing a preset transmission characteristic curve of each current transformer includes: Taking the average value of the secondary output currents of each group of the current transformers corresponding to the same primary input current to obtain the average value of the secondary output current corresponding to each primary input current; The preset transfer characteristic curve is constructed according to the average value of the primary input current and the secondary output current.

[0010] In a fifth possible embodiment of the first aspect, the rows of the transfer characteristic matrix represent the secondary output currents of the current transformers of each group when the same preset current is passed, the columns of the transfer characteristic matrix represent the secondary output currents of the same current transformer when different preset currents are passed, and the mapping relationship between the secondary output current and the percentage of turns of the current transformer is determined according to the transfer characteristic matrix, including: Based on the transfer characteristic matrix, respectively determine the linear equation groups corresponding to the same preset current passing through each group of the current transformers; Solve each of the linear equation groups to determine interpolation expressions of the secondary output current and the percentage of turns corresponding to different preset currents according to the solutions of each of the linear equation groups.

[0011] In a sixth possible embodiment of the first aspect, the calculating the percentage of turns of the primary input current corresponding to the preset transmission characteristic curve being in a non-saturated region passed through each current transformer includes: Passing the primary input current corresponding to the preset transmission characteristic curve being in the non-saturated region into each of the current transformers, to obtain the secondary output current of each of the current transformers; The number of turns of the secondary coil of each current transformer is calculated according to the current ratio formula of the current transformer, and the number of turns percentage of each current transformer is calculated according to the number of turns percentage formula.

[0012] In a seventh possible embodiment of the first aspect, calibrating the corresponding preset transmission characteristic curve according to the turns percentage corresponding to the current transformer and the mapping relationship includes: Calculating the secondary side output current of each current transformer when different preset currents are passed through the current transformer according to the percentage of turns of each current transformer and the interpolation expression; The calibrated transfer characteristic curve is constructed according to the calculated secondary output current and the corresponding primary input current.

[0013] In a second aspect, an embodiment of the present application provides a current transformer calibration system, comprising: A relationship mapping module, used to construct a transmission characteristic matrix of the current transformer, so as to determine a mapping relationship between a secondary output current of the current transformer and a percentage of turns according to the transmission characteristic matrix; A preset curve building module, used to build a preset transmission characteristic curve of each current transformer; The curve calibration module is used to calculate the percentage of turns of the primary input current of each current transformer passing through the preset transmission characteristic curve in the non-saturated area, and calibrate the corresponding preset transmission characteristic curve according to the percentage of turns of the corresponding current transformer and the mapping relationship to obtain the calibrated transmission characteristic curve of each current transformer.

[0014] In a third aspect, an embodiment of the present application provides a circuit breaker device, comprising a current transformer, wherein the circuit breaker device uses the above-mentioned current transformer calibration method to calibrate the transmission characteristic curve of the current transformer.

[0015] The embodiments of the present application have the following beneficial effects: A calibration method for a current transformer of the present embodiment includes: constructing a transmission characteristic matrix of the current transformer to determine the mapping relationship between the secondary output current and the percentage of turns of the current transformer according to the transmission characteristic matrix; constructing a preset transmission characteristic curve of each current transformer; calculating the percentage of turns of the primary input current corresponding to the preset transmission characteristic curve in the non-saturated region of each current transformer; calibrating the corresponding preset transmission characteristic curve according to the percentage of turns of the corresponding current transformer and the mapping relationship to obtain the calibrated transmission characteristic curve of each current transformer. The present application can dynamically calibrate the preset transmission characteristic curve of the current transformer according to the constructed current transformer transmission characteristic matrix, effectively improving the detection accuracy of the current transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A first flow chart of a calibration method for a current transformer according to an embodiment of the present application is shown; Figure 2 A second flow chart of the calibration method of the current transformer according to the embodiment of the present application is shown; Figure 3 A schematic diagram showing a preset transmission characteristic curve of a current transformer according to an embodiment of the present application; Figure 4 A schematic diagram showing a preset transmission characteristic curve and a calibrated transmission characteristic curve of a current transformer according to an embodiment of the present application; Figure 5 A structural schematic diagram of a current transformer calibration system according to an embodiment of the present application is shown.

[0018] Description of main component symbols: 200 - calibration system of current transformer; 210 - relationship mapping module; 220 - preset curve building module; 230 - curve calibration module. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0020] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0021] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0022] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0023] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0024] Usually, in order to dynamically calibrate the transmission characteristic curve of the current transformer and avoid the impact and damage of the circuit breaker by large current, a preset current is passed through the primary side of the current transformer during calibration, and the obtained secondary side output current is compared with the secondary side output current of the transmission characteristic curve, and the difference percentage is converted. The difference percentage is used as the calibration coefficient to calibrate the entire transmission characteristic curve. Practice has proved that this method cannot effectively improve the detection accuracy of the current transformer. The reason is that when the primary side output current is too large, the magnetic field intensity generated in the magnetic ring of the current transformer is too large, and the magnetic induction intensity may exceed its maximum value and enter the magnetic saturation region, and the current proportional conversion ability begins to be lost. Therefore, the calibration coefficient obtained in the non-magnetic saturation region cannot be used to calibrate the transmission characteristics of the magnetic saturation region.

[0025] In response to the above problems, the present application provides a calibration method for a current transformer, extracts multiple groups of current sensors, controls the temperature rise of the magnetic ring of each group of current transformers, collects the secondary output current when each group of current sensors inputs different preset currents, constructs a transmission characteristic matrix of the current transformer, determines the interpolation expression of the secondary output current and the percentage of turns, and calibrates the preset transmission characteristic curve according to the percentage of turns and the interpolation expression. The present application simultaneously considers the changes of two factors, namely the temperature rise of the magnetic ring of the current transformer and the changes of the secondary output current when different current sensors input different preset currents, and can calibrate the non-magnetic saturation region and the magnetic saturation region of the transmission characteristic curve, thereby improving the accuracy of the calibration of the transmission characteristic curve.

[0026] The calibration method of the current transformer is described below in conjunction with some specific embodiments.

[0027] Figure 1 A flow chart of a current transformer calibration method according to an embodiment of the present application is shown. Exemplarily, the current transformer calibration method includes the following steps: S110, constructing a transmission characteristic matrix of the current transformer to determine a mapping relationship between a secondary output current of the current transformer and a percentage of turns according to the transmission characteristic matrix.

[0028] In one embodiment, if Figure 2 As shown, the present application constructs the transmission characteristic matrix of the current transformer including the following steps: S111, sampling a target population including a plurality of current transformers to obtain a plurality of groups of current transformers with different numbers of coil turns.

[0029] In the embodiment of the present application, the multiple current transformers of the target population come from different batches and have differences in core characteristics, windings, etc. The differences in the core materials and manufacturing processes of the current transformers from different batches will affect their magnetic permeability, loss and other characteristics. For example, the magnetic cores from different batches may have certain fluctuations in magnetic permeability, which will cause the magnitude and waveform of the secondary output current to be different under the same primary input current. The differences in the winding process and materials of the windings from different batches will also affect the performance of the current transformer. For example, the uneven thickness of the enameled wire, the different arrangement and tightness of the windings, etc., may cause the resistance, inductance and other parameters of the windings to change, thereby affecting the transformation ratio of the current transformer.

[0030] In one embodiment, the primary coil of the current transformer is a through-core current-carrying conductor, that is, the number of turns of the primary coil of the current transformer is 1. The calibration method of the current transformer includes: setting a rated number of turns and a sampling ratio, and extracting multiple groups of current transformers according to the number of turns of the secondary coil of the current transformer based on the set rated number of turns and sampling ratio. For example, the present application samples the current transformer according to different numbers of turns of the secondary coil, and the rated number of turns is , the sampling ratio is ±1% , ±2% , ±3% , the number of turns of the secondary coil can be extracted as 、(1±1%) 、(1±2%) 、(1±3%) The 7 groups of current transformers can expand or reduce the sampling ratio as needed.

[0031] S112, passing different preset currents through the primary sides of each group of current transformers, and collecting the output currents of the secondary sides of each group of current transformers.

[0032] In one embodiment, the primary input current of each group of current transformers is equal to the preset current passed through, and the calibration method of the current transformer also includes: controlling the magnetic ring temperature rise of each group of current transformers to pass different preset currents through each group of current transformers under the same magnetic ring temperature rise, and the magnetic ring temperature rise is the change of the magnetic ring temperature per unit time.

[0033] It can be understood that the present application equates the current transformer used in the circuit breaker device to a black box magnetic system affected by electrical parameters and magnetic parameters to reflect the transmission characteristics from the primary input current to the secondary output current. By measuring the response of the black box magnetic system to the change of electrical parameters or magnetic parameters, the current transformer transmission characteristic matrix is ​​constructed, and the non-saturation zone calibration method and the saturation zone calibration method are extracted from the transmission characteristic matrix. The present application selects the change in the number of coil turns to reflect the change in electrical parameters, and the change in the magnetic permeability of the magnetic ring to reflect the change in magnetic parameters. The number of coil turns of the current transformer is a function of the length of the wire package, the width of the wire package and the diameter of the wire. The resistance and inductance of the coil are functions of the number of coil turns, the resistivity of the wire package, the length of the wire package, the width of the wire package and the diameter of the wire. It can be seen that the number of coil turns is a comprehensive reflection of the electrical parameters of the coil, so the change in the number of coil turns is selected to reflect the change in electrical parameters. The magnetic permeability of the magnetic ring is sensitive to temperature rise, there is a certain mapping relationship, and there is almost no individual difference in the size of the magnetic ring structure, so the change in the magnetic permeability of the magnetic ring is selected to reflect the change in magnetic parameters.

[0034] In one embodiment, the present application controls the temperature rise of the magnetic ring of each group of current transformers to be consistent, thereby achieving consistent changes in the magnetic permeability of the magnetic ring of each group of current transformers. The present application installs a temperature sensor near the magnetic ring of each group of current transformers to monitor the temperature change of the magnetic ring in real time. When the temperature change of the magnetic ring is too large, the temperature rise of the magnetic ring is adjusted through a feedback mechanism. For example, a heat sink or a fan can be used to help the magnetic ring dissipate heat, reduce its temperature, and change the temperature rise of the magnetic ring.

[0035] In another embodiment, the present application passes preset currents of 1In, 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In and 21In into the sampled primary side of the current transformer, obtains the corresponding secondary side output current through AD sampling, and controls the temperature rise of the magnetic ring before each AD sampling to be consistent with the temperature rise of the magnetic ring corresponding to 1In.

[0036] S113, constructing a transfer characteristic matrix according to the primary input current and the secondary output current of each group of current transformers.

[0037] In one embodiment, the rows of the transfer characteristic matrix represent the secondary output currents of each group of current transformers when the same preset current is passed through them, and the columns of the transfer characteristic matrix represent the secondary output currents of the same current transformer when different preset currents are passed through them.

[0038] In one embodiment, when 1In is 125A, The current transformer transmission characteristic matrix is ​​constructed by measuring the primary input current and secondary output current data. For example, when the preset currents of 1In, 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In and 21In are respectively passed through the primary sides of 7 groups of current transformers, the transmission characteristic matrix is ​​a matrix with 11 rows and 7 columns. The elements in the first row and the first column of the transmission characteristic matrix represent the number of turns of the secondary coil (1-3%). The secondary output current when the preset current 1In is passed. The elements in the first row and second column represent the number of turns of the secondary coil (1-2%). The secondary output current when the preset current 1In is passed. The element in the second row and first column indicates the number of turns of the secondary coil (1-3%) The secondary output current when the preset current 3In is passed through, and so on, the transfer characteristic matrix is ​​as follows:

[0039] In one embodiment, the calibration method of the current transformer determines the linear equation groups corresponding to the same preset current passing through each group of current transformers based on the transfer characteristic matrix; solves each linear equation group to determine the interpolation expressions of the secondary side output current and the percentage of turns corresponding to different preset currents according to the solutions of each linear equation group.

[0040] In one embodiment, the interpolation expression is assumed to be , the linear equation group corresponding to each primary input current can be extracted from the transfer characteristic matrix. The linear equation group corresponding to the primary input current 1In is:

[0041] This application determines the determinant corresponding to the coefficient matrix based on the linear equation, and solves the coefficient matrix determinant to obtain: ; When the coefficient matrix determinant is not zero, the system of equations has a unique solution, and the solution to the system of equations is obtained: , , , , , , The interpolation expression of the secondary output current and the percentage of turns when the primary side is fed with a preset current of 1In is obtained as follows:

[0042] .

[0043] Similarly, the interpolation expressions of the corresponding secondary output current and turns percentage under 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In and 21In can be obtained through the transfer characteristic matrix.

[0044] S120: construct a preset transmission characteristic curve for each current transformer.

[0045] In one embodiment, Figure 3 A schematic diagram of a preset transmission characteristic curve is shown. The calibration method of the current transformer takes the average value of the secondary output current of each group of current transformers corresponding to the same primary input current to obtain the average value of the secondary output current corresponding to each primary input current; and constructs the preset transmission characteristic curve according to the average value of the primary input current and the secondary output current.

[0046] S130, calculating the percentage of turns of the primary input current corresponding to the preset transmission characteristic curve in the non-saturated region passing through each current transformer.

[0047] In one embodiment, the present application passes a preset transmission characteristic curve into each current transformer, which corresponds to the primary input current in the unsaturated region, to obtain the secondary output current of each current transformer; the secondary coil turns of each current transformer are calculated according to the current ratio formula of the current transformer, and the percentage of turns of each current transformer is calculated according to the percentage of turns formula. It can be understood that if the primary input current of the current transformer is too large, the proportional conversion capability of the current is missing, resulting in inaccurate calculation of the percentage of turns of the current transformer. Therefore, the present application passes a preset transmission characteristic curve into the unsaturated region, which corresponds to the primary input current, to accurately calculate the percentage of turns of each current transformer. Among them, the current ratio formula is: , is the primary input current of the current transformer, is the secondary output current of the current transformer, is the number of turns of the primary coil of the current transformer, 1, is the number of turns of the secondary coil of the current transformer. The formula for the percentage of turns is , is the rated number of turns.

[0048] S140, calibrating the corresponding preset transmission characteristic curve according to the turns percentage of the corresponding current transformer and the mapping relationship to obtain a calibrated transmission characteristic curve of each current transformer.

[0049] In one embodiment, the present application calculates the secondary output current of each current transformer when different preset currents are passed through it according to the percentage of the number of turns of each current transformer and the interpolation expression, and uses the calculated secondary output current and primary input current as points in the transmission characteristic curve to adjust the preset transmission characteristic curve, and constructs a calibrated transmission characteristic curve according to the calculated secondary output current and the corresponding primary input current. In one embodiment, when a preset current 1In is passed through the primary side of a current transformer, 1In is 125A, and the corresponding secondary output current obtained by AD sampling is 48.65mA. The secondary coil turns can be calculated by substituting it into the current ratio formula, and then the turns percentage is calculated to be 2.76%. The turns percentage is substituted into the interpolation expression of the corresponding secondary output current and the turns percentage under different preset currents, and the secondary output current after dynamic calibration is calculated. Based on the calculated secondary output current and the corresponding primary input current, the transfer characteristic curve after dynamic calibration is obtained, and the preset transfer characteristic curve is calibrated. The transfer characteristic curve after dynamic calibration is as follows: Figure 4 shown.

[0050] The present application also provides a current transformer calibration system 200, such as Figure 5 As shown, exemplarily, the current transformer calibration system 200 includes: The relationship mapping module 210 is used to construct a transmission characteristic matrix of the current transformer, so as to determine a mapping relationship between the secondary output current of the current transformer and the percentage of turns according to the transmission characteristic matrix.

[0051] The preset curve building module 220 is used to build a preset transmission characteristic curve for each current transformer.

[0052] The curve calibration module 230 is used to calculate the percentage of turns of the primary input current corresponding to each current transformer passing through the preset transmission characteristic curve in the non-saturated region, and calibrate the corresponding preset transmission characteristic curve according to the percentage of turns of the corresponding current transformer and the mapping relationship to obtain the calibrated transmission characteristic curve of each current transformer.

[0053] The present application also provides a circuit breaker, which may be a vacuum circuit breaker, a universal circuit breaker, a molded case circuit breaker, a leakage circuit breaker, etc. Exemplarily, the circuit breaker includes a current transformer, and the circuit breaker uses the current transformer calibration method of the above embodiment to calibrate the transmission characteristic curve of the current transformer.

[0054] In one embodiment, after the transmission characteristic curve of the current transformer in the circuit breaker is calibrated, when a certain unknown working current passes through the circuit breaker, the corresponding secondary output current is obtained through AD sampling. Combined with the transmission characteristic curve after dynamic calibration, the unknown working current can be reversely determined through the mapping relationship, thereby confirming the need to perform the protection function. When the unknown working current exceeds the set overcurrent protection action value, the circuit breaker is used to cut off the circuit to protect the safety of equipment and personnel. The circuit breaker is also used to measure the primary input current and the secondary output current using a current transformer. When the difference between the two exceeds the set differential protection action value, the differential protection device is activated. The circuit breaker also has other protection functions, such as undervoltage protection, overvoltage protection, leakage protection, etc.

[0055] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can also be implemented in other ways. The apparatus embodiments described above are merely schematic, for example, the flowcharts and structure diagrams in the accompanying drawings show the possible architecture, functions and operations of the apparatus, method and computer program product according to multiple embodiments of the present application. In this regard, each group of boxes in the flowchart or block diagram can represent a module, a program segment or a part of a code, and a module, a program segment or a part of a code contains one or more executable instructions for implementing a specified logical function. It should also be noted that in an alternative implementation, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each group of boxes in the structure diagram and / or the flowchart, and the combination of boxes in the structure diagram and / or the flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0056] In addition, the functional modules or units in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0057] If the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a smart phone, a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods of each embodiment of the present application.

[0058] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A current transformer calibration method, characterized in that: include: Constructing a transmission characteristic matrix of the current transformer to determine a mapping relationship between a secondary output current of the current transformer and a percentage of turns according to the transmission characteristic matrix; Constructing a preset transmission characteristic curve for each current transformer; Calculating the percentage of turns of the primary input current corresponding to the preset transmission characteristic curve being in the non-saturated region passed through each current transformer; The corresponding preset transmission characteristic curve is calibrated according to the turns percentage of the corresponding current transformer and the mapping relationship to obtain a calibrated transmission characteristic curve of each current transformer.

2. The current transformer calibration method according to claim 1, characterized in that: The step of constructing the transmission characteristic matrix of the current transformer comprises: Sampling a target population including a plurality of current transformers to obtain a plurality of groups of current transformers having different numbers of coil turns; Passing different preset currents into the primary sides of each group of the current transformers, and collecting the secondary side output currents of each group of the current transformers; The transfer characteristic matrix is ​​constructed according to the primary input current and the secondary output current of each group of the current transformers.

3. The current transformer calibration method according to claim 2, characterized in that: When different preset currents are passed through the primary sides of each group of current transformers, the method further includes: The temperature rise of the magnetic ring of each group of the current transformers is controlled so that different preset currents are passed through each group of the current transformers under the same magnetic ring temperature rise.

4. The current transformer calibration method according to claim 2, characterized in that: The primary coil of the current transformer is a through-core current-carrying conductor, and the target population including multiple current transformers is sampled to obtain multiple groups of current transformers with different numbers of coil turns, including: Based on the set rated number of turns and sampling ratio, multiple groups of the current transformers are extracted according to the number of turns of the secondary coils of the current transformers.

5. The current transformer calibration method according to claim 1, characterized in that: The step of constructing a preset transmission characteristic curve of each current transformer comprises: Taking the average value of the secondary output currents of each group of the current transformers corresponding to the same primary input current to obtain the average value of the secondary output current corresponding to each primary input current; The preset transfer characteristic curve is constructed according to the average value of the primary input current and the secondary output current.

6. The current transformer calibration method according to claim 1, characterized in that: The rows of the transfer characteristic matrix represent the secondary output currents of the current transformers of each group when the same preset current is passed through, and the columns of the transfer characteristic matrix represent the secondary output currents of the same current transformer when different preset currents are passed through. The mapping relationship between the secondary output current and the percentage of turns of the current transformer is determined according to the transfer characteristic matrix, including: Based on the transmission characteristic matrix, respectively determine the linear equation groups corresponding to the same preset current passing through each group of the current transformers; Solve each of the linear equation groups to determine interpolation expressions of the secondary output current and the percentage of turns corresponding to different preset currents according to the solutions of each of the linear equation groups.

7. The current transformer calibration method according to claim 6, characterized in that: The calculating the percentage of turns of the primary input current corresponding to the preset transmission characteristic curve being in the non-saturated region passed through each current transformer comprises: Passing the primary input current corresponding to the preset transmission characteristic curve being in the non-saturated region into each of the current transformers, to obtain the secondary output current of each of the current transformers; The number of turns of the secondary coil of each current transformer is calculated according to the current ratio formula of the current transformer, and the number of turns percentage of each current transformer is calculated according to the number of turns percentage formula.

8. The current transformer calibration method according to claim 7, characterized in that: The calibrating the corresponding preset transmission characteristic curve according to the turns percentage of the corresponding current transformer and the mapping relationship includes: Calculating the secondary side output current of each current transformer when different preset currents are passed through the current transformer according to the percentage of turns of each current transformer and the interpolation expression; The calibrated transfer characteristic curve is constructed according to the calculated secondary output current and the corresponding primary input current.

9. A current transformer calibration system, characterized in that: include: A relationship mapping module, used to construct a transmission characteristic matrix of the current transformer, so as to determine a mapping relationship between a secondary output current of the current transformer and a percentage of turns according to the transmission characteristic matrix; A preset curve building module, used to build a preset transmission characteristic curve of each current transformer; The curve calibration module is used to calculate the percentage of turns of the primary input current of each current transformer passing through the preset transmission characteristic curve in the non-saturated area, and calibrate the corresponding preset transmission characteristic curve according to the percentage of turns of the corresponding current transformer and the mapping relationship to obtain the calibrated transmission characteristic curve of each current transformer.

10. A circuit breaker device, characterized in that: Comprising a current transformer, the circuit breaker device calibrates the transmission characteristic curve of the current transformer using the calibration method of the current transformer according to any one of claims 1 to 8.

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