CN119738768B - A current transformer calibration method, system and circuit breaker - Google Patents
A current transformer calibration method, system and circuit breaker Download PDFInfo
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Abstract
本申请涉及断路装置技术领域，公开了一种电流互感器的校准方法、系统和断路装置，电流互感器的校准方法包括：构建电流互感器的传输特性矩阵，以根据传输特性矩阵确定电流互感器的副边输出电流和匝数百分比的映射关系；构建每个电流互感器的预置传输特性曲线；计算每个电流互感器通入预置传输特性曲线处于非饱和区对应的原边输入电流的匝数百分比；根据对应电流互感器的匝数百分比和映射关系对对应的预置传输特性曲线进行校准，得到校准后的每个电流互感器的传输特性曲线。本申请能够对断路装置中电流互感器的传输特性曲线进行动态校准，有效提升检测精度。
The present application relates to the technical field of circuit breaker devices, and discloses a calibration method, system and circuit breaker device for a current transformer. The calibration method for a current transformer 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, and obtaining 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 circuit breaker device, and effectively improve the detection accuracy.
Description
Technical Field
The application relates to the technical field of circuit breaking devices, in particular to a calibration method and system of a current transformer and a circuit breaking device.
Background
The protection time and protection type of the circuit breaking device depend on the actual current flowing in the circuit breaking device, and the sampling and logic judgment of the circuit breaking device on the current can determine whether to trigger the tripping action, so that the circuit breaking is realized, and the importance of improving the accuracy of the current sampling and logic judgment is self-evident. The current transformer is a key device for realizing current sampling and logic judgment of the circuit breaking device, and the primary side input current and the secondary side output current form a transmission characteristic curve of the current transformer. The primary side input current is unknown actual working current, the secondary side output current is obtained after current sampling, and the primary side input current corresponding to the secondary side output current can be obtained on a preset transmission characteristic curve, so that whether various protections are executed is judged.
In the prior art, the transmission characteristic curve of the current transformer is fixed, however, because of individual differences of current transformers in different batches, the same primary side input current, the secondary side output current induced by the secondary side has discreteness, and the transmission characteristic curve matched with the secondary side output current cannot be dynamically calibrated according to the individual differences, so that the problem that the circuit breaking device is in misoperation or does not act can be caused, accurate protection cannot be realized, and even potential safety hazards are caused.
Disclosure of Invention
In view of the above, the embodiments of the present application provide a calibration method, a system and a circuit breaker for a current transformer, which effectively solve the problem of dynamic calibration of a transmission characteristic curve that needs to be solved due to individual differences caused by different batches of current transformers.
In a first aspect, an embodiment of the present application provides a method for calibrating a current transformer, including:
constructing a transmission characteristic matrix of the current transformer, and determining a mapping relation between secondary side output current and turn percentage of the current transformer according to the transmission characteristic matrix;
constructing a preset transmission characteristic curve of each current transformer;
Calculating the turn percentage of the primary side input current corresponding to the unsaturated zone of each current transformer when the preset transmission characteristic curve is fed in;
And calibrating the corresponding preset transmission characteristic curves according to the turn percentage and the mapping relation of the corresponding current transformers to obtain transmission characteristic curves of the calibrated current transformers.
In a first possible embodiment of the first aspect, the constructing a transmission characteristic matrix of the current transformer includes:
sampling a target overall comprising a plurality of current transformers to obtain a plurality of groups of current transformers with different coil turns;
Different preset currents are led into the primary sides of each group of current transformers, and the secondary side output currents of each group of current transformers are collected;
And constructing the transmission characteristic matrix according to the primary side input current and the secondary side output current of each group of the current transformers.
In a second possible embodiment of the first aspect, when the primary sides of the current transformers of each group are all supplied with different preset currents, the method further includes:
And controlling the temperature rise of the magnetic rings of each group of current transformers so as to enable each group of current transformers to be fed with different preset currents under the same temperature rise of the magnetic rings.
In a third possible embodiment of the first aspect, the primary winding of the current transformer is a through current carrying conductor, and the sampling is performed on a target population including a plurality of current transformers to obtain a plurality of groups of current transformers with different winding numbers, including:
And extracting a plurality of groups of current transformers according to the number of turns of the secondary side coil of the current transformers based on the set rated number of turns and the sampling proportion.
In a fourth possible embodiment of the first aspect, the constructing a preset transmission characteristic curve of each of the current transformers includes:
Taking the average value of the secondary side output currents of the current transformers of the groups corresponding to the same primary side input current, and obtaining the average value of the secondary side output currents corresponding to each primary side input current;
and constructing the preset transmission characteristic curve according to the average value of the primary side input current and the secondary side output current.
In a fifth possible embodiment of the first aspect, the rows of the transmission characteristic matrix represent secondary side output currents when the current transformers of each group are supplied with the same preset current, the columns of the transmission characteristic matrix represent secondary side output currents when the current transformers of the same group are supplied with different preset currents, and the determining, according to the transmission characteristic matrix, a mapping relationship between the secondary side output currents and the percentage of turns of the current transformers includes:
Based on the transmission characteristic matrix, respectively determining a linear equation set corresponding to the current transformer of each group fed with the same preset current;
And solving each linear equation set to determine interpolation expressions of the secondary side output current and the turn percentage corresponding to different preset currents according to the solution of each linear equation set.
In a sixth possible embodiment of the first aspect, the calculating a percentage of turns of the primary input current of each of the current transformers corresponding to the unsaturated zone by passing the preset transmission characteristic curve includes:
inputting current to the primary side of each current transformer corresponding to the unsaturated zone of the preset transmission characteristic curve, and obtaining secondary side output current of each current transformer;
and calculating the number of turns of the secondary side coil of each current transformer according to a current ratio formula of the current transformers, and calculating the percentage of turns of each current transformer according to a percentage of turns formula.
In a seventh possible embodiment of the first aspect, the calibrating the corresponding preset transmission characteristic curve according to the turn percentage and the mapping relation of the corresponding current transformer includes:
calculating secondary side output currents of different preset currents fed by each current transformer according to the turn percentage of each current transformer and the interpolation expression;
and constructing the calibrated transmission characteristic curve according to the calculated secondary side output current and the corresponding primary side input current.
In a second aspect, an embodiment of the present application provides a calibration system for a current transformer, including:
The relation mapping module is used for constructing a transmission characteristic matrix of the current transformer so as to determine the mapping relation between the secondary side output current of the current transformer and the percentage of turns according to the transmission characteristic matrix;
the preset curve construction module is used for constructing a preset transmission characteristic curve of each current transformer;
And the curve calibration module is used for calculating the turn percentage of the primary side input current corresponding to the unsaturated zone of each current transformer when the preset transmission characteristic curve is fed, and calibrating the corresponding preset transmission characteristic curve according to the turn percentage and the mapping relation of the corresponding current transformer to obtain the transmission characteristic curve of each calibrated current transformer.
In a third aspect, an embodiment of the present application provides a circuit breaker, including a current transformer, where the circuit breaker uses the calibration method of the current transformer to calibrate a transmission characteristic curve of the current transformer.
The embodiment of the application has the following beneficial effects:
The calibration method of the current transformers comprises the steps of constructing a transmission characteristic matrix of the current transformers to determine a mapping relation between secondary side output current and turn percentage of the current transformers according to the transmission characteristic matrix, constructing preset transmission characteristic curves of the current transformers, calculating turn percentage of primary side input current corresponding to a non-saturated region of each current transformer when the preset transmission characteristic curves are fed in, and calibrating the corresponding preset transmission characteristic curves according to the turn percentage and the mapping relation of the corresponding current transformers to obtain the transmission characteristic curves of the calibrated current transformers. The application can dynamically calibrate the preset transmission characteristic curve of the current transformer according to the constructed transmission characteristic matrix of the current transformer, and effectively improves the detection precision of the current transformer.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a first flow chart of a calibration method of a current transformer according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a second flow chart of a calibration method of a current transformer according to an embodiment of the present application;
FIG. 3 is a schematic diagram showing a preset transmission characteristic of a current transformer according to an embodiment of the present application;
FIG. 4 is 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;
Fig. 5 shows a schematic structural diagram of a calibration system for a current transformer according to an embodiment of the present application.
Description of main reference numerals:
the system comprises a calibration system of a 200-current transformer, a 210-relation mapping module, a 220-preset curve construction module and a 230-curve calibration module.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments.
The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present application.
The terms "comprises," "comprising," "including," or any other variation thereof, are intended to cover a specific feature, number, step, operation, element, component, or combination of the foregoing, which may be used in various embodiments of the present application, and are not intended to first exclude the presence of or increase the likelihood of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the application belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having a meaning that is the same as the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in connection with the various embodiments of the application.
Some embodiments of the present application are described in detail below with reference to the accompanying drawings. The embodiments described below and features of the embodiments may be combined with each other without conflict.
In general, in order to dynamically calibrate a transmission characteristic curve of a current transformer, and avoid impact damage of a large current to a circuit breaker, a primary side of the current transformer is fed with a preset current during calibration, an obtained secondary side output current is compared with a secondary side output current of the transmission characteristic curve, a difference percentage is obtained through conversion, the difference percentage is used as a calibration coefficient, and the whole transmission characteristic curve is calibrated. Practice proves that the method cannot effectively improve the detection precision of the current transformer, because when the primary side output current is overlarge, the magnetic field intensity generated in the magnetic ring of the current transformer is overlarge, the magnetic induction intensity possibly exceeds the maximum value of the magnetic field intensity and enters a magnetic saturation region, and the proportional conversion capability of the current is lost, so that the transmission characteristic of the magnetic saturation region cannot be calibrated by using the calibration coefficient obtained by the non-magnetic saturation region.
In view of the above problems, the present application provides a calibration method for current transformers, which extracts a plurality of groups of current sensors, controls the temperature rise of a magnetic ring of each group of current transformers, collects secondary side output currents when different preset currents are input by each group of current sensors, constructs a transmission characteristic matrix of the current transformers, determines an interpolation expression of the secondary side output currents and the percentage of turns, and calibrates a preset transmission characteristic curve according to the percentage of turns and the interpolation expression. The application considers the change of two factors, namely the magnetic ring temperature rise of the current transformer and the secondary side output current change of different preset currents input by different current sensors, 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.
The method of calibrating the current transformer is described below in connection with specific embodiments.
Fig. 1 shows a flowchart of a method for calibrating a current transformer according to an embodiment of the present application. The calibration method of the current transformer comprises the following steps:
s110, constructing a transmission characteristic matrix of the current transformer, and determining a mapping relation between secondary side output current and turn percentage of the current transformer according to the transmission characteristic matrix.
In one embodiment, as shown in fig. 2, the method for constructing the transmission characteristic matrix of the current transformer includes the following steps:
and S111, sampling the target overall including a plurality of current transformers to obtain a plurality of groups of current transformers with different coil turns.
In the embodiment of the application, the plurality of current transformers of the target overall are from different batches and have the differences of magnetic core characteristics, windings and the like. The magnetic core material and manufacturing process of the current transformer have different batches of differences which affect the characteristics of magnetic permeability, loss and the like, for example, magnetic cores of different batches may have certain fluctuation in magnetic permeability, which can cause the magnitude and waveform of secondary side output current to be different under the same primary side input current. The winding process of the windings and the different batch differences of materials can also have an effect on the performance of the current transformer. For example, the uneven thickness of the enameled wire, the different arrangement and tightness of the winding, etc. may cause the variation of the parameters such as the resistance, inductance, etc. of the winding, and further affect the transformation ratio of the current transformer.
In one embodiment, the primary winding of the current transformer is a through current carrying conductor, i.e., the number of turns of the primary winding of the current transformer is 1. The calibration method of the current transformer comprises the steps of setting rated turns and sampling proportion, and extracting a plurality of groups of current transformers according to the number of turns of the secondary side coil of the current transformer based on the set rated turns and sampling proportion. For example, the application samples the current transformer according to different secondary coil turns, and the rated turns areSampling proportion is + -1%,±2%,±3%The number of turns of the secondary coil can be extracted as、(1±1%)、(1±2%)、(1±3%)The sampling ratio can be enlarged or reduced according to the requirement of the 7 groups of current transformers.
And S112, leading different preset currents into the primary sides of each group of current transformers, and collecting the secondary side output currents of each group of current transformers.
In one embodiment, the primary side input current of each group of current transformers is equal to the input preset current, and the calibration method of the current transformers further comprises the step of controlling the temperature rise of the magnetic rings of each group of current transformers so as to enable each group of current transformers to be input with different preset currents under the same magnetic ring temperature rise, wherein the magnetic ring temperature rise is the change of the magnetic ring temperature in unit time.
It can be understood that the application equivalent the current transformer used for the circuit breaking device into a black box magnetic system influenced by electric parameters and magnetic parameters to embody the transmission characteristics from the primary side input current to the secondary side output current, constructs a transmission characteristic matrix of the current transformer by actually measuring the response of the black box magnetic system to the electric parameters or the magnetic parameters, and extracts a non-saturation region calibration method and a saturation region calibration method from the transmission characteristic matrix. The application selects the change of the number of turns of the coil to represent the change of the electric parameter, and the change of the magnetic permeability of the magnetic ring to represent the change of the magnetic parameter. The number of turns of the coil of the current transformer is a function of the length of the coil, the width of the coil and the diameter of the coil, the resistance and inductance of the coil are a function of the number of turns of the coil, the resistivity of the lead, the length of the coil, the width of the coil and the diameter of the coil, and the number of turns of the coil is a comprehensive representation of the electrical parameters of the coil, so that the change of the number of turns of the coil is selected to represent the change of the electrical parameters. The magnetic permeability of the magnetic ring has sensitivity to temperature rise, a certain mapping relation exists, and the magnetic ring has little individual difference in structural size, so that the change of the magnetic permeability of the magnetic ring is selected to reflect the change of magnetic parameters.
In one embodiment, the application realizes the consistent change of the magnetic permeability of the magnetic ring of each group of current transformers by controlling the consistent temperature rise of the magnetic ring of each group of current transformers. According to the application, a temperature sensor is arranged near the magnetic ring of each group of current transformers, and the temperature change of the magnetic ring is monitored in real time. When the temperature change of the magnetic ring is too large, the temperature rise of the magnetic ring is regulated through a feedback mechanism, for example, a radiating fin or a fan can be used for helping the magnetic ring to radiate heat, the temperature of the magnetic ring is reduced, and the temperature rise of the magnetic ring is changed.
In another embodiment, the primary side of the sampled current transformer is respectively fed with preset currents of 1In, 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In and 21In, corresponding secondary side output currents are obtained through AD sampling, and the temperature rise of the magnetic ring is controlled before each AD sampling, so that the temperature rise of the magnetic ring is consistent with the temperature rise of the magnetic ring corresponding to 1 In.
S113, constructing a transmission characteristic matrix according to the primary side input current and the secondary side output current of each group of current transformers.
In one embodiment, the rows of the transmission characteristic matrix represent the secondary side output currents of each group of current transformers that are fed with the same preset current, and the columns of the transmission characteristic matrix represent the secondary side output currents of the same current transformer that are fed with different preset currents.
In one embodiment, when 1In is 125A,For 2500, a transmission characteristic matrix of the current transformer is constructed by actually measuring the primary side input current and the secondary side output current, for example, when the primary sides of 7 groups of current transformers are respectively supplied with preset currents of 1In, 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In and 21In, the transmission characteristic matrix is a matrix of 11 rows and 7 columns, and the element of the first row and the first column of the transmission characteristic matrix represents that the number of turns of the secondary side coil is (1-3%)The secondary side outputs current when the preset current 1In is introduced, and the elements of the first row and the second column represent that the number of turns of the secondary side coil is (1-2%)The secondary side outputs current when the preset current 1In is introduced, and the elements In the first column of the second row represent that the number of turns of the secondary side coil is (1-3%)The secondary side outputs current when the preset current 3In is introduced, and so on, and the transmission characteristic matrix is as follows:
In one embodiment, the calibration method of the current transformer respectively determines linear equation sets corresponding to the same preset current of each group of current transformers based on a transmission characteristic matrix, and solves each linear equation set to determine interpolation expressions of secondary side output currents and turn percentages corresponding to different preset currents according to solutions of each linear equation set.
In one embodiment, the interpolation expression is set as The linear equation set corresponding to each primary side input current can be extracted from the transmission characteristic matrix, and the linear equation set corresponding to the primary side input current 1In is as follows:
According to the linear equation, determining a determinant corresponding to the coefficient matrix, and solving the coefficient matrix determinant to obtain the following formula: When the matrix determinant of the coefficient is not zero, the equation set has a unique solution, and the equation set solution is obtained by solving: ,,,,,, . When the preset current of 1In is fed into the primary side, the interpolation expression of the output current of the secondary side and the percentage of turns is as follows:
。
Similarly, interpolation expressions of the corresponding secondary side output current and the turn percentage at 3In, 4In, 5In, 6In, 7In, 8In, 10In, 12In, 16In, and 21In can be obtained by the transmission characteristic matrix.
S120, constructing a preset transmission characteristic curve of each current transformer.
In one embodiment, fig. 3 shows a schematic diagram of a preset transmission characteristic curve, the calibration method of the current transformer takes the average value of the secondary output currents of the current transformers of each group 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 primary input current and the average value of the secondary output current.
S130, calculating the turn percentage of the primary side input current corresponding to the unsaturated region when each current transformer is connected with a preset transmission characteristic curve.
In one embodiment, the application introduces each current transformer into the primary side input current corresponding to the unsaturated zone of the preset transmission characteristic curve to obtain the secondary side output current of each current transformer, calculates the number of turns of the secondary side coil of each current transformer according to the current ratio formula of the current transformers, and calculates the percentage of turns of each current transformer according to the percentage formula of turns. It can be understood that if the primary side input current of the current transformer is too large, the proportional conversion capability of the current is lost, so that the calculation of the turns percentage of the current transformer is inaccurate, and therefore, the application can accurately calculate the turns percentage of each current transformer by inputting the current transformer into the primary side input current corresponding to the unsaturated region of the preset transmission characteristic curve. The current ratio formula is as follows:, The current is input to the primary side of the current transformer, The current is output for the secondary side 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 side coil of the current transformer. The percentage formula of the turns is,Is rated as a turn number.
And S140, calibrating the corresponding preset transmission characteristic curves according to the turn percentage and the mapping relation of the corresponding current transformers, and obtaining the transmission characteristic curve of each calibrated current transformer.
In an embodiment, the application calculates secondary side output current of each current transformer with different preset currents according to the turn percentage and interpolation expression of each current transformer, takes the calculated secondary side output current and primary side input current as points in a transmission characteristic curve to adjust a preset transmission characteristic curve, and constructs a calibrated transmission characteristic curve according to the calculated secondary side output current and corresponding primary side input current.
In an embodiment, when a current transformer primary side is fed with preset current 1in, the preset current 1in is 125A, corresponding secondary side output current is 48.65mA obtained through AD sampling, the corresponding secondary side output current is substituted into a current ratio formula to calculate the number of turns of the secondary side coil, the corresponding secondary side output current and the corresponding number of turns percentage are substituted into a turns percentage formula to calculate the number of turns percentage to be 2.76%, interpolation expressions of the corresponding secondary side output current and the number of turns percentage are substituted into different preset currents, the dynamically calibrated secondary side output current is calculated, a dynamically calibrated transmission characteristic curve is obtained based on the calculated secondary side output current and the corresponding primary side input current, calibration of the preset transmission characteristic curve is achieved, and the dynamically calibrated transmission characteristic curve is shown in fig. 4.
The present application also provides a calibration system 200 of a current transformer, as shown in fig. 5, and the calibration system 200 of the current transformer exemplarily includes:
the relation mapping module 210 is configured to construct a transmission characteristic matrix of the current transformer, so as to determine a mapping relation between the secondary side output current and the percentage of turns of the current transformer according to the transmission characteristic matrix.
A preset curve construction module 220, configured to construct a preset transmission characteristic curve of each current transformer.
The curve calibration module 230 is configured to calculate a turn percentage of the primary input current corresponding to the unsaturated region when each current transformer is connected to the preset transmission characteristic curve, and calibrate the corresponding preset transmission characteristic curve according to the turn percentage and the mapping relationship of the corresponding current transformer, so as to obtain a transmission characteristic curve of each calibrated current transformer.
The application also provides a circuit breaker which can be a vacuum circuit breaker, a universal circuit breaker, a plastic shell circuit breaker, an electric leakage circuit breaker and the like. The circuit breaker device comprises a current transformer, and the circuit breaker device calibrates the transmission characteristic curve of the current transformer by adopting the calibration method of the current transformer in the embodiment.
In an embodiment, after the transmission characteristic curve of the current transformer in the circuit breaking device is calibrated, when the circuit breaking device passes through a certain unknown working current, the corresponding secondary side output current is obtained through AD sampling, and the unknown working current can be reversely determined through a mapping relation by combining the transmission characteristic curve after dynamic calibration, so that the need of executing a protection function is confirmed. When the unknown working current exceeds the set overcurrent protection action value, the circuit breaking device is used for breaking the circuit so as to protect equipment and personnel. The circuit breaker is also used for measuring primary side input current and secondary side output current by using a current transformer, and when the difference value between the primary side input current and the secondary side output current exceeds a set differential protection action value, the differential protection device acts. The circuit breaker also has other protection functions, such as under-voltage protection, overvoltage protection, leakage protection and the like.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The apparatus embodiments described above are merely illustrative, for example, of the flow diagrams and block diagrams in the figures, which illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, functional modules or units in various embodiments of the application may be integrated together to form a single part, or the modules may exist alone, or two or more modules may be integrated to form a single part.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored on a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a smart phone, a personal computer, a server, a network device, or the like) to perform all or part of the steps of the method of the embodiments of the present application.
The foregoing is merely illustrative embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about variations or substitutions within the technical scope of the present application, and the application should be covered.
Claims (9)
1. A method of calibrating a current transformer, comprising:
constructing a transmission characteristic matrix of the current transformer, and determining a mapping relation between secondary side output current and turn percentage of the current transformer according to the transmission characteristic matrix;
constructing a preset transmission characteristic curve of each current transformer;
Calculating the turn percentage of the primary side input current corresponding to the unsaturated zone of each current transformer when the preset transmission characteristic curve is fed in;
Calibrating the corresponding preset transmission characteristic curves according to the turn percentage and the mapping relation of the corresponding current transformers to obtain transmission characteristic curves of the calibrated current transformers;
The construction of the transmission characteristic matrix of the current transformer comprises the following steps:
sampling a target overall comprising a plurality of current transformers to obtain a plurality of groups of current transformers with different coil turns;
Different preset currents are led into the primary sides of each group of current transformers, and the secondary side output currents of each group of current transformers are collected;
Constructing the transmission characteristic matrix according to the primary side input current and the secondary side output current of each group of current transformers;
The rows of the transmission characteristic matrix represent secondary side output currents when the current transformers of each group are fed with the same preset current, and the columns of the transmission characteristic matrix represent secondary side output currents when the current transformers of each group are fed with different preset currents;
the percentage formula of the turns is ,For a nominal number of turns,Is the number of turns of the secondary coil.
2. The method for calibrating a current transformer according to claim 1, wherein when different preset currents are applied to the primary sides of each group of current transformers, the method further comprises:
And controlling the temperature rise of the magnetic rings of each group of current transformers so as to enable each group of current transformers to be fed with different preset currents under the same temperature rise of the magnetic rings.
3. The method for calibrating a current transformer according to claim 1, wherein a primary coil of the current transformer is a through current carrying conductor, and the sampling is performed on a target population including a plurality of current transformers to obtain a plurality of groups of current transformers with different coil turns, including:
And extracting a plurality of groups of current transformers according to the number of turns of the secondary side coil of the current transformers based on the set rated number of turns and the sampling proportion.
4. The method of calibrating a current transformer according to claim 1, wherein said constructing a preset transmission characteristic curve for each of said current transformers comprises:
Taking the average value of the secondary side output currents of the current transformers of the groups corresponding to the same primary side input current, and obtaining the average value of the secondary side output currents corresponding to each primary side input current;
and constructing the preset transmission characteristic curve according to the average value of the primary side input current and the secondary side output current.
5. The method for calibrating a current transformer according to claim 1, wherein determining a mapping relationship between secondary side output current and percentage of turns of the current transformer according to the transmission characteristic matrix comprises:
Based on the transmission characteristic matrix, respectively determining a linear equation set corresponding to the current transformer of each group fed with the same preset current;
And solving each linear equation set to determine interpolation expressions of the secondary side output current and the turn percentage corresponding to different preset currents according to the solution of each linear equation set.
6. The method for calibrating a current transformer according to claim 5, wherein calculating the percentage of turns of the primary input current of each current transformer corresponding to the unsaturated zone by the preset transmission characteristic curve comprises:
inputting current to the primary side of each current transformer corresponding to the unsaturated zone of the preset transmission characteristic curve, and obtaining secondary side output current of each current transformer;
and calculating the number of turns of the secondary side coil of each current transformer according to a current ratio formula of the current transformers, and calculating the percentage of turns of each current transformer according to a percentage of turns formula.
7. The method of calibrating a current transformer according to claim 6, wherein said calibrating the corresponding preset transmission characteristic according to the percentage of turns and the mapping relationship for the current transformer comprises:
calculating secondary side output currents of different preset currents fed by each current transformer according to the turn percentage of each current transformer and the interpolation expression;
and constructing the calibrated transmission characteristic curve according to the calculated secondary side output current and the corresponding primary side input current.
8. A calibration system for a current transformer, comprising:
The relation mapping module is used for constructing a transmission characteristic matrix of the current transformer so as to determine the mapping relation between the secondary side output current of the current transformer and the percentage of turns according to the transmission characteristic matrix;
The construction of the transmission characteristic matrix of the current transformer comprises the following steps:
sampling a target overall comprising a plurality of current transformers to obtain a plurality of groups of current transformers with different coil turns;
Different preset currents are led into the primary sides of each group of current transformers, and the secondary side output currents of each group of current transformers are collected;
Constructing the transmission characteristic matrix according to the primary side input current and the secondary side output current of each group of current transformers;
The rows of the transmission characteristic matrix represent secondary side output currents when the current transformers of each group are fed with the same preset current, and the columns of the transmission characteristic matrix represent secondary side output currents when the current transformers of each group are fed with different preset currents;
the percentage formula of the turns is ,For a nominal number of turns,Turns of the secondary coil;
the preset curve construction module is used for constructing a preset transmission characteristic curve of each current transformer;
And the curve calibration module is used for calculating the turn percentage of the primary side input current corresponding to the unsaturated zone of each current transformer when the preset transmission characteristic curve is fed, and calibrating the corresponding preset transmission characteristic curve according to the turn percentage and the mapping relation of the corresponding current transformer to obtain the transmission characteristic curve of each calibrated current transformer.
9. A circuit interrupting device comprising a current transformer, the circuit interrupting device calibrating a transmission characteristic of the current transformer using the calibration method of the current transformer according to any one of claims 1-7.
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| JP5430725B1 (en) * | 2012-09-03 | 2014-03-05 | 株式会社近計システム | Waveform processing device |
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