A calibration method, system and circuit breaker device for a current transformer

Abstract

The present application relates to the technical field of open-circuit devices, and discloses a calibration method, a system and an open-circuit device for a current transformer. The calibration method for the current transformer includes: constructing a transmission characteristic matrix of the current transformer to determine the mapping relationship between the secondary output current and the turn percentage of the current transformer according to the transmission characteristic matrix; constructing a preset transmission characteristic curve for each current transformer; calculating the turn percentage of the primary input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturated region; calibrating the corresponding preset transmission characteristic curve according to the turn percentage and the mapping relationship of the corresponding current transformer to obtain the calibrated transmission characteristic curve of each current transformer. The present application can dynamically calibrate the transmission characteristic curve of the current transformer in the open-circuit device, effectively improving the detection accuracy.

Description

Technical Field

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

[0002] The protection time and protection type of a circuit breaker device depend on the actual current flowing through the circuit breaker device. The current sampling and logical judgment of the circuit breaker device will determine whether to trigger a tripping action, thereby achieving circuit interruption. Therefore, the importance of improving the accuracy of current sampling and logical judgment is self-evident. A current transformer is a key device for a circuit breaker device to achieve current sampling and logical judgment. The primary input current and the secondary output current form the transmission characteristic curve of the current transformer. The primary input current is the unknown actual operating current. After current sampling, the secondary output current is obtained. On the preset transmission characteristic curve, the primary input current corresponding to the secondary output current can be obtained, and based on this, it is judged whether to execute various protections.

[0003] Currently, the transmission characteristic curve of a current transformer is fixed. However, due to individual differences in current transformers of different batches, for the same primary input current, there is discreteness in the secondary output current induced on the secondary side, and the matching transmission characteristic curve cannot be dynamically calibrated according to individual differences, which may lead to problems such as misoperation or non-operation of the circuit breaker device, unable to achieve precise protection, and even pose a safety hazard. Summary of the Invention

[0004] In view of this, the embodiments of this 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, the embodiments of this application provide a calibration method for a current transformer, including:

[0006] Construct a transmission characteristic matrix of the current transformer to determine the mapping relationship between the secondary output current and the turn percentage of the current transformer according to the transmission characteristic matrix;

[0007] Construct a preset transmission characteristic curve for each current transformer;

[0008] Calculate the turn percentage of the primary input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturated region;

[0009] Calibrate the corresponding preset transmission characteristic curve according to the turn percentage and the mapping relationship of the corresponding current transformer to obtain the transmission characteristic curve of each calibrated current transformer.

[0010] In the first possible embodiment of the first aspect, constructing the transmission characteristic matrix of the current transformer includes:

[0011] Sampling a target population including a plurality of current transformers to obtain multiple groups of the current transformers with different coil turns;

[0012] Apply different preset currents to the primary sides of each group of the current transformers, and collect the secondary side output currents of each group of the current transformers;

[0013] Construct the transmission characteristic matrix according to the primary side input currents and the secondary side output currents of each group of the current transformers.

[0014] In the second possible embodiment of the first aspect, when applying different preset currents to the primary sides of each group of the current transformers, it further includes:

[0015] Control the magnetic ring temperature rise of each group of the current transformers so as to apply different preset currents to each group of the current transformers at the same magnetic ring temperature rise.

[0016] In the third possible embodiment of the first aspect, the primary side coil of the current transformer is a through-hole current-carrying conductor, and sampling the target population including a plurality of current transformers to obtain multiple groups of the current transformers with different coil turns includes:

[0017] Based on the set rated turns and sampling ratio, extract multiple groups of the current transformers according to the secondary side coil turns of the current transformer.

[0018] In the fourth possible embodiment of the first aspect, constructing the preset transmission characteristic curve of each current transformer includes:

[0019] Take the average value of the secondary side output currents of each group of the current transformers corresponding to the same primary side input current to obtain the average value of the secondary side output current corresponding to each primary side input current;

[0020] Construct the preset transmission characteristic curve according to the primary side input current and the average value of the secondary side output current.

[0021] In the fifth possible embodiment of the first aspect, the rows of the transmission characteristic matrix represent the secondary side output currents when different groups of the current transformers are applied with the same preset current, and the columns of the transmission characteristic matrix represent the secondary side output currents when the same current transformer is applied with different preset currents. Determining the mapping relationship between the secondary side output current and the turn percentage of the current transformer according to the transmission characteristic matrix includes:

[0022] Based on the transmission characteristic matrix, respectively determine a system of linear equations corresponding to each group of the current transformers when the same preset current is applied;

[0023] Solve each of the systems of linear equations to determine interpolation expressions of the secondary side output current and the turn ratio percentage corresponding to different preset currents according to the solutions of each of the systems of linear equations.

[0024] In a sixth possible embodiment of the first aspect, calculating the turn ratio percentage of the primary side input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturated region includes:

[0025] Apply the primary side input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturated region to obtain the secondary side output current of each current transformer;

[0026] Calculate the secondary side coil turns of each current transformer according to the current ratio formula of the current transformer, and calculate the turn ratio percentage of each current transformer according to the turn ratio percentage formula.

[0027] In a seventh possible embodiment of the first aspect, calibrating the corresponding preset transmission characteristic curve according to the turn ratio percentage of the corresponding current transformer and the mapping relationship includes:

[0028] Calculate the secondary side output current of each current transformer when different preset currents are applied according to the turn ratio percentage of each current transformer and the interpolation expression;

[0029] Construct the calibrated transmission characteristic curve according to the calculated secondary side output current and the corresponding primary side input current.

[0030] In a second aspect, an embodiment of the present application provides a calibration system for a current transformer, including:

[0031] A relationship mapping module, configured to construct a transmission characteristic matrix of the current transformer to determine a mapping relationship between the secondary side output current and the turn ratio percentage of the current transformer according to the transmission characteristic matrix;

[0032] A preset curve construction module, configured to construct a preset transmission characteristic curve of each current transformer;

[0033] A curve calibration module, configured to calculate the turn ratio percentage of the primary side input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturated region, and calibrate the corresponding preset transmission characteristic curve according to the turn ratio percentage of the corresponding current transformer and the mapping relationship to obtain the calibrated transmission characteristic curve of each current transformer.

[0034] In a third aspect, an embodiment of the present application provides a circuit breaker device, including a current transformer, and the circuit breaker device calibrates the transmission characteristic curve of the current transformer by using the above-mentioned calibration method of the current transformer.

[0035] The embodiments of the present application have the following beneficial effects:

[0036] A calibration method for a current transformer according to an embodiment of the present application includes: constructing a transmission characteristic matrix of the current transformer to determine the mapping relationship between the secondary output current and the turn percentage of the current transformer according to the transmission characteristic matrix; constructing a preset transmission characteristic curve for each current transformer; calculating the turn percentage of the primary input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturation region; and calibrating the corresponding preset transmission characteristic curve according to the turn percentage and the mapping relationship of the corresponding current transformer 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 transmission characteristic matrix of the current transformer, effectively improving the detection accuracy of the current transformer. Description of the Drawings

[0037] 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 some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 The first flowchart shows the calibration method of the current transformer according to the embodiment of the present application;

[0039] Figure 2 The second flowchart shows the calibration method of the current transformer according to the embodiment of the present application;

[0040] Figure 3 A schematic diagram shows a preset transmission characteristic curve of the current transformer according to the embodiment of the present application;

[0041] Figure 4 A schematic diagram shows a preset transmission characteristic curve and a calibrated transmission characteristic curve of the current transformer according to the embodiment of the present application;

[0042] Figure 5 A schematic diagram shows a structure of the calibration system of the current transformer according to the embodiment of the present application.

[0043] Main Element Symbol Description:

[0044] 200 - Current Transformer Calibration System; 210 - Relationship Mapping Module; 220 - Preset Curve Construction Module; 230 - Curve Calibration Module. Detailed Embodiment

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0046] Generally, the components of the embodiments of the present application described and illustrated herein can be arranged and designed in various different 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 claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0047] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are only intended to represent specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be construed as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0048] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the various embodiments of the present application belong. The terms (such as those defined in a general-use dictionary) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present application.

[0049] The following will describe some embodiments of the present application in detail with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0050] Generally, in order to dynamically calibrate the transfer characteristic curve of a current transformer and avoid the impact damage of large current on the disconnection device, a preset current is passed through the primary side of the current transformer during calibration. The secondary output current obtained is compared with the secondary output current of the transfer characteristic curve, and the difference percentage is calculated and used as the calibration coefficient to calibrate the entire transfer 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 output current is too large, the magnetic field intensity generated in the magnetic core of the current transformer is too large, and the magnetic induction intensity may exceed its maximum value and enter the magnetic saturation region, resulting in the loss of the current proportional transformation ability. Therefore, the calibration coefficient obtained in the non-magnetic saturation region cannot be used to calibrate the transfer characteristic in the magnetic saturation region.

[0051] To address the above problems, the present application provides a calibration method for a current transformer. Multiple groups of current sensors are selected, the temperature rise of the magnetic core of each group of current transformers is controlled, the secondary output current is collected when different preset currents are input to each group of current sensors, and a transfer characteristic matrix of the current transformer is constructed to determine the interpolation expression between the secondary output current and the turn percentage. The preset transfer characteristic curve is calibrated according to the turn percentage and the interpolation expression. The present application takes into account the changes of two factors at the same time, namely the temperature rise of the magnetic core of the current transformer and the change of the secondary output current when different preset currents are input to different current sensors, and can calibrate both the non-magnetic saturation region and the magnetic saturation region of the transfer characteristic curve, improving the calibration accuracy of the transfer characteristic curve.

[0052] The following will illustrate the calibration method of the current transformer with some specific embodiments.

[0053] Figure 1 A flowchart showing the calibration method of the current transformer according to an embodiment of the present application is presented. Exemplarily, the calibration method of the current transformer includes the following steps:

[0054] S110, construct a transfer characteristic matrix of the current transformer to determine the mapping relationship between the secondary output current and the turn percentage of the current transformer according to the transfer characteristic matrix.

[0055] In one embodiment, as Figure 2 shown, the steps for constructing the transfer characteristic matrix of the current transformer in the present application include:

[0056] S111, sample the target population including multiple current transformers to obtain multiple groups of current transformers with different coil turns.

[0057] In the embodiments of the present application, multiple current transformers of the target population come from different batches and have differences in magnetic core characteristics, windings, etc. Differences in different batches of magnetic core materials and manufacturing processes of current transformers will affect their characteristics such as magnetic permeability and loss. For example, different batches of magnetic cores may have certain fluctuations in magnetic permeability, which will cause differences in the magnitude and waveform of the secondary output current under the same primary input current. Differences in different batches of winding processes and materials of the windings will also affect the performance of the current transformer. For example, uneven thickness of enameled wires, different arrangements and tightness of winding, etc. may all cause changes in parameters such as the resistance and inductance of the winding, thereby affecting the transformation ratio of the current transformer.

[0058] In one embodiment, the primary coil of the current transformer is a through-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 the rated number of turns and the sampling ratio, and based on the set rated number of turns and sampling ratio, extracting multiple groups of current transformers according to the number of turns of the secondary coil of the current transformer. For example, in the present application, the current transformers are sampled according to different numbers of turns of the secondary coil, the rated number of turns is , and the sampling ratio is ±1% , ±2% , ±3% . Seven groups of current transformers with the number of turns of the secondary coil being , (1 ± 1%) , (1 ± 2%) , (1 ± 3%) can be extracted, and the sampling ratio can be enlarged or reduced as needed.

[0059] S112, passing different preset currents through the primary sides of each group of current transformers, and collecting the secondary output currents of each group of current transformers.

[0060] In one embodiment, the primary input current of each group of current transformers is equal to the applied preset current. The calibration method of the current transformer further includes: controlling the temperature rise of the magnetic ring of each group of current transformers, so as to pass different preset currents through each group of current transformers at the same temperature rise of the magnetic ring. The temperature rise of the magnetic ring is the change in the temperature of the magnetic ring per unit time.

[0061] It can be understood that in this application, the current transformer for the disconnection device is equivalently regarded as 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 actually measuring the response of the black-box magnetic system to changes in electrical parameters or magnetic parameters, a transmission characteristic matrix of the current transformer is constructed, and a calibration method for the non-saturated region and a calibration method for the saturated region are extracted from the transmission characteristic matrix. In this application, the change in the number of turns of the coil is selected to reflect the change in electrical parameters, and the change in the magnetic permeability of the magnetic core is selected to reflect the change in magnetic parameters. The number of turns of the coil of the current transformer is a function of the length of the wire coil, the width of the wire coil, and the wire diameter. The resistance and inductance of the coil are functions of the number of turns of the coil, the resistivity of the wire, the length of the wire coil, the width of the wire coil, and the wire diameter. It can be seen that the number of turns of the coil is a comprehensive reflection of the electrical parameters of the coil. Therefore, the change in the number of turns of the coil is selected to reflect the change in electrical parameters. The magnetic permeability of the magnetic core is sensitive to temperature rise and there is a certain mapping relationship, and there are almost no individual differences in the structural dimensions of the magnetic core. Therefore, the change in the magnetic permeability of the magnetic core is selected to reflect the change in magnetic parameters.

[0062] In one embodiment, this application makes the temperature rise of the magnetic core of each group of current transformers consistent, so as to achieve consistent changes in the magnetic permeability of the magnetic core of each group of current transformers. This application installs temperature sensors near the magnetic cores of each group of current transformers to monitor the temperature changes of the magnetic cores in real time. When the temperature change of the magnetic core is too large, the temperature rise of the magnetic core is adjusted through a feedback mechanism. For example, heat sinks or fans can be used to help the magnetic core dissipate heat, reduce its temperature, and change the temperature rise of the magnetic core.

[0063] In another embodiment, this application passes preset currents of 1In, 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In, and 21In into the primary sides of the sampled current transformers respectively, obtains the corresponding secondary output currents through AD sampling, and controls the temperature rise of the magnetic core before each AD sampling to be consistent with the temperature rise of the magnetic core corresponding to 1In.

[0064] S113. Construct a transmission characteristic matrix according to the primary input current and the secondary output current of each group of current transformers.

[0065] In one embodiment, the rows of the transmission characteristic matrix represent the secondary output currents of each group of current transformers passing the same preset current, and the columns of the transmission characteristic matrix represent the secondary output currents of the same current transformer passing different preset currents.

[0066] In one embodiment, when 1In is 125A, is 2500. The transmission characteristic matrix of the current transformer is constructed based on the measured primary input current and secondary output current data. For example, when the primary windings of 7 current transformers are respectively fed with preset currents of 1In, 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In, and 21In, the transmission characteristic matrix is an 11-row and 7-column matrix. The element in the first row and first column of the transmission characteristic matrix represents the secondary winding turns as (1 - 3%) the secondary output current when the preset current 1In is fed, and the element in the first row and second column represents the secondary winding turns as (1 - 2%) the secondary output current when the preset current 1In is fed, and the element in the second row and first column represents the secondary winding turns as (1 - 3%) the secondary output current when the preset current 3In is fed, and so on. The transmission characteristic matrix is as follows:

[0067]

[0068] In one embodiment, the calibration method of the current transformer respectively determines the linear equations corresponding to each group of current transformers when the same preset current is fed based on the transmission characteristic matrix; solves each linear equation to determine the interpolation expressions of the secondary output current and turns percentage corresponding to different preset currents according to the solutions of each linear equation.

[0069] In one implementation manner, let the interpolation expression be , and the linear equation corresponding to each primary input current can be extracted from the transmission characteristic matrix. The linear equation corresponding to the primary input current 1In is:

[0070] This application determines the determinant corresponding to the coefficient matrix according to this linear equation, and solves the determinant of the coefficient matrix to obtain: ; when the determinant of the coefficient matrix is not zero, the system of equations has a unique solution, and the solution of the system of equations is obtained as: , , , , , , . The interpolation expressions of the secondary output current and turns percentage when the primary is fed with the preset current 1In are obtained as:

[0071]

[0072] .

[0073] Similarly, through the transmission characteristic matrix, interpolation expressions of the corresponding secondary side output current and turn percentage can be obtained under 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In, and 21In.

[0074] S120. Construct a preset transmission characteristic curve for each current transformer.

[0075] In one embodiment, Figure 3 A schematic diagram of the preset transmission characteristic curve is shown. The calibration method of this current transformer takes the average value of the secondary side output currents of each group of current transformers corresponding to the same primary side input current to obtain the average value of the secondary side output current corresponding to each primary side input current; and constructs a preset transmission characteristic curve based on the primary side input current and the average value of the secondary side output current.

[0076] S130. Calculate the turn percentage of the primary side input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturation region.

[0077] In one embodiment of the present application, each current transformer is passed through the primary side input current corresponding to the non-saturation region of the preset transmission characteristic curve to obtain the secondary side output current of each current transformer; calculate the secondary side coil turns of each current transformer according to the current ratio formula of the current transformer, and calculate the turn percentage of each current transformer according to the turn percentage formula. It can be understood that if the primary side input current of the current transformer is too large, the current ratio transformation ability is missing, resulting in inaccurate calculation of the turn percentage of the current transformer. Therefore, in the present application, each current transformer is passed through the primary side input current corresponding to the non-saturation region of the preset transmission characteristic curve, and the turn percentage of each current transformer can be accurately calculated. Among them, the current ratio formula is: , is the primary side input current of the current transformer, is the secondary side output current of the current transformer, is the primary side coil turns of the current transformer, 1, is the secondary side coil turns of the current transformer. The turn percentage formula is , is the rated number of turns.

[0078] S140. Calibrate the corresponding preset transmission characteristic curve according to the turn percentage of the corresponding current transformer and the mapping relationship to obtain the calibrated transmission characteristic curve of each current transformer.

[0079] In one embodiment, the present application calculates the secondary output current of each current transformer when different preset currents are applied according to the turn percentage of each current transformer and the interpolation expression, and uses the calculated secondary output current and the 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.

[0080] In one implementation manner, when a preset current 1In (1In = 125A) is applied to the primary side of a current transformer, the corresponding secondary output current obtained by AD sampling is 48.65mA. Substituting it into the current ratio formula, the number of turns of the secondary coil can be calculated, and then substituting it into the turn percentage formula, the turn percentage is calculated to be 2.76%. Substituting the turn percentage into the interpolation expression of the corresponding secondary output current and turn percentage under different preset currents, the dynamically calibrated secondary output current is calculated. Based on the calculated secondary output current and the corresponding primary input current, a dynamically calibrated transmission characteristic curve is obtained to realize the calibration of the preset transmission characteristic curve. The dynamically calibrated transmission characteristic curve is as Figure 4 shown.

[0081] The present application also provides a calibration system 200 for a current transformer, as Figure 5 shown. Exemplarily, the calibration system 200 for the current transformer includes:

[0082] A relationship mapping module 210, configured to construct a transmission characteristic matrix of the current transformer to determine the mapping relationship between the secondary output current and the turn percentage of the current transformer according to the transmission characteristic matrix.

[0083] A preset curve construction module 220, configured to construct a preset transmission characteristic curve for each current transformer.

[0084] A curve calibration module 230, configured to calculate the turn percentage of the primary input current corresponding to each current transformer when the preset transmission characteristic curve is in the non-saturation region, and calibrate the corresponding preset transmission characteristic curve according to the turn percentage of the corresponding current transformer and the mapping relationship to obtain the transmission characteristic curve of each calibrated current transformer.

[0085] The present application also provides a circuit breaker. The circuit breaker can be a vacuum circuit breaker, an air 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.

[0086] In one embodiment, after the calibration of the transmission characteristic curve of the current transformer in the circuit breaker device, when the circuit breaker device passes through a certain unknown operating current, the corresponding secondary output current is obtained through AD sampling. Combining with the dynamically calibrated transmission characteristic curve, the unknown operating current can be reversely determined through the mapping relationship, so as to confirm that the protection function needs to be executed. When the unknown operating current exceeds the set overcurrent protection action value, the circuit breaker device is used to cut off the circuit to protect the safety of equipment and personnel. The circuit breaker device is also used to measure the primary input current and the secondary output current by using the current transformer. When the difference between the two exceeds the set differential protection action value, the differential protection device acts. The circuit breaker device also has other protection functions, such as undervoltage protection, overvoltage protection, leakage protection, etc.

[0087] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are only illustrative. For example, the flowcharts and structure diagrams in the drawings show the possible architectures, functions, and operations of the devices, methods, and computer program products 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 the code. A module, a program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in the alternative implementation, the functions marked in the boxes may occur in a different order from that marked in the drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each group of boxes in the structure diagram and / or flowchart, as well as the combination of boxes in the structure diagram and / or flowchart, can be implemented by a dedicated hardware-based system for performing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0088] In addition, each functional module or unit in each embodiment of the present application can be integrated together to form an independent part, or each module can exist alone, or two or more modules can be integrated to form an independent part.

[0089] If the function is implemented in the form of a software functional 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, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing 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 in each embodiment of the present application.

[0090] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within 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; Calibrate 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; 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; Constructing the transfer characteristic matrix according to the primary input current and the secondary output current of each group of the current transformers; 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 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; The formula for turns percentage is: , is the rated number of turns, is the number of turns of the secondary coil.

2. The current transformer calibration method according to claim 1, 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.

3. The current transformer calibration method according to claim 1, 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.

4. 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.

5. The current transformer calibration method according to claim 1, characterized in that: The determining, according to the transmission characteristic matrix, a mapping relationship between the secondary output current of the current transformer and the percentage of turns includes: 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.

6. The current transformer calibration method according to claim 5, 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.

7. The current transformer calibration method according to claim 6, 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.

8. 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; 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; Constructing the transfer characteristic matrix according to the primary input current and the secondary output current of each group of the current transformers; 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 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; The formula for turns percentage is: , is the rated number of turns, is the number of turns of the secondary coil; 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.

9. 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 7.

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