Method and system for rapidly detecting residual magnetism error of current transformer

Abstract

The invention discloses a current transformer residual magnetism error rapid detection method and system. The method comprises the steps that a high-precision power frequency current source and a high-precision direct current source are connected with a detected current transformer in parallel; working parameters of the high-precision power frequency current source and the high-precision direct current source are set through a control unit; based on the working parameters, power frequency current and direct current of rated percentage are generated through the high-precision power frequency current source and the high-precision direct current source respectively; the power frequency current and the direct current are applied to the primary side of the detected current transformer at the same time, the power frequency current and the transformer secondary current of the detected current transformer are obtained through a diverter, and the power frequency current and the transformer secondary current are preprocessed through a signal sampling preprocessing unit; and analyzing a difference value between the power frequency current and the secondary current of the transformer through an error calculation unit, and determining an error of the detected current transformer based on the difference value.

Description

Technical Field

[0001] The present invention relates to the field of electrical measurement technology, and more specifically, to a method and system for quickly detecting residual magnetism error of a current transformer. Background Art

[0002] When a short circuit occurs in the power system, due to the hysteresis characteristics of the core material of the current transformer, the short circuit current will generate residual magnetism in the core. The residual magnetism is not easy to eliminate during the daily operation of the current transformer, which will change the working hysteresis loop of the current transformer, causing the current transformer to be unable to correctly transmit electrical signals. As an important device for electric energy metering, the current transformer will exceed the limit requirements under the influence of residual magnetism, resulting in the loss of accuracy and fairness in electric energy metering. There are a huge number of current transformers in the power system, with more than 40 million. Ensuring that the current transformer does not exceed the error tolerance due to the influence of residual magnetism is of great significance to ensuring the fairness and justice of electric energy trade. At present, the national metrological verification regulations JJG 1189.3-2022 "Measuring transformers Part 3: Power current transformers", the State Grid Enterprise Standard Q / GDW 10572.1-2020 "Technical Specifications for Measuring Transformers Part 1: Low Voltage Current Transformers", and the State Grid Enterprise Standard Q / GDW 10572.2-2023 "Technical Specifications for Measuring Transformers Part 1: 10kV~35kV Current Transformers" stipulate that residual magnetism error detection must be carried out before the current transformer is put into operation. However, since the residual magnetism error detection involves DC magnetization and demagnetization, the wiring is complex and the operation process is cumbersome, the existing human and material resources cannot meet the residual magnetism error detection needs before the full current transformer is put into operation.

[0003] Therefore, it is necessary to develop a method that can quickly detect the residual magnetism error of the current transformer, simplify the detection cost of the current transformer error before commissioning, and ensure that the transformer metering performance is qualified before commissioning. Summary of the invention

[0004] The technical solution of the present invention provides a method and system for quickly detecting residual magnetism error of a current transformer, so as to solve the problem of how to quickly detect residual magnetism error of a current transformer.

[0005] In order to solve the above problems, the present invention provides a method for quickly detecting residual magnetism error of a current transformer, the method comprising:

[0006] Connecting a high-precision industrial frequency current source and a high-precision DC current source in parallel with the current transformer to be measured;

[0007] Setting the working parameters of the high-precision power frequency current source and the high-precision DC current source by a control unit; based on the working parameters, generating a rated percentage of the power frequency current and the DC current by the high-precision power frequency current source and the high-precision DC current source respectively;

[0008] Applying the power frequency current and the direct current simultaneously on the primary side of the current transformer under test, respectively obtaining the power frequency current and the transformer secondary current of the current transformer under test through a shunt, and preprocessing the power frequency current and the transformer secondary current through a signal sampling preprocessing unit;

[0009] The difference between the power frequency current and the transformer secondary current is analyzed by an error calculation unit, and the error of the current transformer under test is determined based on the difference.

[0010] Preferably, the step of setting the operating parameters of the high-precision power frequency current source and the high-precision direct current source by the control unit further includes:

[0011] The control unit controls the start and stop, current increase and current decrease of the high-precision power frequency current source and the high-precision DC current source;

[0012] The control unit is used to control the start and stop, data display and difference result of the error calculation unit.

[0013] Preferably, the power frequency current and the transformer secondary current are preprocessed by a signal sampling preprocessing unit, including:

[0014] The signal sampling preprocessing unit isolates, filters and performs A / D conversion processing on the acquired power frequency current and the transformer secondary current.

[0015] Preferably, the power frequency current and the transformer secondary current are input into the error calculation unit through channel 1 and channel 2 respectively.

[0016] Based on another aspect of the present invention, the present invention provides a current transformer residual magnetism error rapid detection system, the system comprising: a high-precision power frequency current source, a high-precision DC current source, a shunt, a control unit and a sampling preprocessing unit;

[0017] The high-precision power frequency current source and the high-precision DC current source are connected in parallel with the current transformer under test;

[0018] The control unit is used to set the working parameters of the high-precision power frequency current source and the high-precision DC current source; based on the working parameters, the high-precision power frequency current source and the high-precision DC current source are used to generate a rated percentage of the power frequency current and the DC current respectively;

[0019] Applying the power frequency current and the direct current simultaneously on the primary side of the current transformer under test, respectively obtaining the power frequency current and the transformer secondary current of the current transformer under test through a shunt, and preprocessing the power frequency current and the transformer secondary current through a signal sampling preprocessing unit;

[0020] The error calculation unit is used to analyze the difference between the power frequency current and the transformer secondary current, and determine the error of the measured current transformer based on the difference.

[0021] Preferably, the control unit is used to set the working parameters of the high-precision power frequency current source and the high-precision DC current source, and is also used to:

[0022] The control unit controls the start and stop, current increase and current decrease of the high-precision power frequency current source and the high-precision DC current source;

[0023] The control unit is used to control the start and stop, data display and difference result of the error calculation unit.

[0024] Preferably, the power frequency current and the transformer secondary current are preprocessed by a signal sampling preprocessing unit, including:

[0025] The signal sampling preprocessing unit isolates, filters and performs A / D conversion processing on the acquired power frequency current and the transformer secondary current.

[0026] Preferably, the power frequency current and the transformer secondary current are input into the error calculation unit through channel 1 and channel 2 respectively.

[0027] Based on another aspect of the present invention, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is used to execute a method for quickly detecting residual magnetism error of a current transformer.

[0028] Based on another aspect of the present invention, the present invention provides an electronic device, the electronic device comprising: a processor and a memory; wherein,

[0029] The memory is a memory for storing instructions executable by the processor;

[0030] The processor is used to read the executable instructions from the memory and execute the instructions to implement a method for quickly detecting residual magnetism errors of current transformers.

[0031] The technical solution of the present invention provides a method and system for rapid detection of residual magnetism error of a current transformer, wherein the method includes: connecting a high-precision power frequency current source and a high-precision direct current source in parallel with the current transformer to be measured; setting the working parameters of the high-precision power frequency current source and the high-precision direct current source through a control unit; based on the working parameters, generating rated percentage power frequency current and direct current respectively through the high-precision power frequency current source and the high-precision direct current source; applying power frequency current and direct current simultaneously on the primary side of the current transformer to be measured, obtaining the power frequency current and the transformer secondary current of the current transformer to be measured respectively through a shunt, and preprocessing the power frequency current and the transformer secondary current through a signal sampling preprocessing unit; analyzing the difference between the power frequency current and the transformer secondary current through an error calculation unit, and determining the error of the current transformer to be measured based on the difference. The technical solution of the present invention provides a method and system for rapid detection of residual magnetism error of a current transformer, based on the equivalent principle of the working state of the iron core magnetization curve, simplifies the test process of residual magnetism error detection, reduces time and labor costs, and greatly improves the efficiency of residual magnetism error detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0033] Figure 1 A flow chart of a method for rapid detection of residual magnetism error of a current transformer according to a preferred embodiment of the present invention;

[0034] Figure 2 A schematic diagram of a magnetization curve of a current transformer according to a preferred embodiment of the present invention; and

[0035] Figure 3 It is a principle structure diagram of a current transformer residual magnetism error rapid detection system according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0036] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0037] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0038] Figure 1 The present invention is a flowchart of a method for rapid detection of residual magnetism error of a current transformer according to a preferred embodiment of the present invention.

[0039] The present invention provides a method for quickly detecting residual magnetism error of a current transformer, which improves detection efficiency while meeting the requirements of residual magnetism error detection, and meets the requirement of completing residual magnetism error detection during arrival acceptance before commissioning of the current transformer.

[0040] The present invention provides a method for quickly detecting residual magnetism error of a current transformer, the purpose of which is to change the problem that the detection technology of residual magnetism error performance of the current transformer is complicated and the operation is inconvenient, and the efficiency of residual magnetism error detection is improved while ensuring the detection accuracy of residual magnetism error of the current transformer.

[0041] The common method for detecting residual magnetism error of current transformer in the present invention is: before error detection, a DC power supply is used to magnetize the transformer core to ensure that residual magnetism still exists in the core after the transformer is powered off, the purpose of which is to change the working point of the transformer when it is working, as follows Figure 2 As shown, when there is no residual magnetism in the core, the transformer is magnetized along hysteresis loop 1 in the steady state of power frequency; when there is residual magnetism in the core, it runs along transient hysteresis loop 2. Compared with the steady state hysteresis loop 1, when the transformer core is magnetized along hysteresis loop 2, its working point changes, and the magnetic permeability also changes accordingly, resulting in a change in the error of the current transformer. Therefore, by detecting the error change of the transformer before and after magnetization, it can be determined whether the transformer's ability to resist the influence of residual magnetism meets the relevant standard technical requirements. That is, in the method of residual magnetism error detection, the focus is on changing the magnetization curve of the transformer from the steady state magnetization curve to magnetization along the transient magnetization curve.

[0042] The invention applies a certain amount of direct current to the transformer at the same time when the rated percentage of the power frequency current is applied once and the error is measured, so that the transformer core has a direct current bias magnetization, and the core magnetization state is changed, so that the core magnetized along the steady-state magnetization curve under normal power frequency current excitation is changed to magnetized along the transient excitation curve, and the equivalent effect is achieved with the change of the core magnetization state after the conventional direct current magnetization method. The error of the current transformer is measured under the condition of power frequency and direct current superposition, and the error of the current transformer under the condition of residual magnetism can be measured, and the residual magnetism variation can be obtained by comparing with the error under the condition of no direct current superposition.

[0043] Since DC current is used to apply DC bias magnetization and change the working state of the iron core, it is only necessary to add the corresponding DC power supply to the transformer once, and there is no need to disconnect the transformer once according to the conventional test method. The wiring on the secondary side is changed and the DC power supply is used for magnetization. The wiring is convenient, so it can greatly simplify the test operation process and save the time for wire disassembly and assembly. When carrying out automatic detection of current transformers on the calibration line, the magnetization process and the time spent on changing the wiring are greatly shortened, and the rapid automatic detection of residual magnetism errors can be achieved.

[0044] like Figure 1 As shown, the present invention provides a method for quickly detecting residual magnetism error of a current transformer, the method comprising:

[0045] Step 101: connecting a high-precision power frequency current source and a high-precision DC current source in parallel with a current transformer under test;

[0046] Step 102: Setting operating parameters of the high-precision power frequency current source and the high-precision DC current source through a control unit; based on the operating parameters, generating a rated percentage of power frequency current and DC current through the high-precision power frequency current source and the high-precision DC current source respectively;

[0047] Step 103: applying a power frequency current and a direct current to the primary side of the current transformer under test at the same time, obtaining the power frequency current and the transformer secondary current of the current transformer under test respectively through a shunt, and preprocessing the power frequency current and the transformer secondary current through a signal sampling preprocessing unit;

[0048] Step 104: Analyze the difference between the power frequency current and the transformer secondary current through an error calculation unit, and determine the error of the current transformer under test based on the difference.

[0049] Preferably, the operating parameters of the high-precision power frequency current source and the high-precision DC current source are set by the control unit, and further include:

[0050] The start and stop, current increase and current decrease of the high-precision industrial frequency current source and the high-precision DC current source are controlled by the control unit;

[0051] The control unit controls the start and stop, data display and difference results of the error calculation unit.

[0052] Preferably, the power frequency current and the transformer secondary current are preprocessed by a signal sampling preprocessing unit, including:

[0053] The signal sampling preprocessing unit isolates, filters and performs A / D conversion processing on the acquired power frequency current and transformer secondary current.

[0054] Preferably, the power frequency current and the transformer secondary current are input into the error calculation unit through channel 1 and channel 2 respectively.

[0055] The high-precision power frequency current source and the high-precision DC current source of the present invention are connected to the current transformer under test in parallel, and the rated percentage of the power frequency current and a certain DC current are applied according to the parameters set by the control host, so that the current transformer is excited by the power frequency current + DC current at the same time. The DC current causes the transformer core to produce a bias magnetic effect, which is equivalent to simulating the residual magnetic effect in the core; the power frequency current is the normal working current of the transformer, and the transformer error can be obtained by comparing the difference between the standard power frequency current and the transformer secondary current.

[0056] The high-precision shunt of the present invention, together with the signal sampling preprocessing unit and the error calculation unit, completes the collection, preprocessing and error calculation of the primary and secondary current signals of the transformer. Generally, the transformer error detection is realized by the difference measurement method. The standard transformer and the tested current transformer are excited by the same signal, and the difference in the secondary signals of the two is compared to obtain the error. In the present invention, the tested current transformer is excited by a mixed power frequency current + direct current. If the difference measurement method is adopted, the standard transformer should be excited by the power frequency current alone. The wiring is complicated and cumbersome, and it is inconvenient to implement. Therefore, a shunt is used as a signal sampling unit to avoid the use of a standard transformer. The main application scenario of the present invention is mainly for laboratory or assembly line detection of current transformers. Only the test part needs to be replaced, and frequent disassembly and assembly of other parts is not required. Using a shunt as a signal sampling unit is the simplest, most convenient and economical technical solution.

[0057] The signal sampling preprocessing unit of the present invention is the pre-processing part of the error calculation. Affected by power supply fluctuations, external interference, etc., the voltage signal obtained on the shunt needs isolation, filtering, A / D conversion and other links before it can be used for error calculation by the back end.

[0058] The main functions of the control unit of the present invention are as follows: 1) completing the parameter setting of the industrial frequency current source and the DC current source, and controlling their start and stop, current increase and decrease; 2) controlling the start and stop of the signal preprocessing and error calculation unit, and displaying relevant data and error results.

[0059] The invention provides a method for rapid detection of residual magnetism error of a current transformer, which is based on the working state equivalence principle of the core magnetization curve, simplifies the test process of residual magnetism error detection, reduces time and labor costs, and greatly improves the efficiency of residual magnetism error detection.

[0060] Figure 3 It is a principle structure diagram of a current transformer residual magnetism error rapid detection system according to a preferred embodiment of the present invention.

[0061] like Figure 3 As shown, the present invention provides a current transformer residual magnetism error rapid detection system, the system comprises: a high-precision power frequency current source, a high-precision DC current source, a shunt, a control unit and a sampling preprocessing unit;

[0062] A high-precision industrial frequency current source and a high-precision DC current source are connected in parallel with the current transformer to be measured;

[0063] The control unit is used to set the working parameters of the high-precision power frequency current source and the high-precision DC current source; based on the working parameters, the high-precision power frequency current source and the high-precision DC current source are used to generate the rated percentage of the power frequency current and the DC current respectively;

[0064] Applying power frequency current and direct current simultaneously on the primary side of the current transformer under test, obtaining the power frequency current and the transformer secondary current of the current transformer under test respectively through a shunt, and preprocessing the power frequency current and the transformer secondary current through a signal sampling preprocessing unit;

[0065] The error calculation unit is used to analyze the difference between the power frequency current and the transformer secondary current, and determine the error of the measured current transformer based on the difference.

[0066] The present invention builds a current transformer residual magnetism error rapid detection system, the system mainly includes: a high-precision industrial frequency current source, a high-precision DC current source, a high-precision shunt, a signal sampling and preprocessing unit, an error calculation unit, a control unit, a signal connecting line with a shielding effect, etc.

[0067] Preferably, the control unit is used to set the working parameters of the high-precision power frequency current source and the high-precision DC current source, and is also used to:

[0068] The start and stop, current increase and current decrease of the high-precision industrial frequency current source and the high-precision DC current source are controlled by the control unit;

[0069] The control unit controls the start and stop, data display and difference results of the error calculation unit.

[0070] Preferably, the power frequency current and the transformer secondary current are preprocessed by a signal sampling preprocessing unit, including:

[0071] The signal sampling preprocessing unit isolates, filters and performs A / D conversion processing on the acquired power frequency current and transformer secondary current.

[0072] Preferably, the power frequency current and the transformer secondary current are input into the error calculation unit through channel 1 and channel 2 respectively.

[0073] The present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is used to execute a method for quickly detecting residual magnetism error of a current transformer.

[0074] The present invention provides an electronic device, the electronic device comprising: a processor and a memory; wherein:

[0075] Memory, a memory for storing processor executable instructions;

[0076] The processor is used for reading executable instructions from a memory and executing the instructions to implement a method for quickly detecting residual magnetism error of a current transformer.

[0077] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0078] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0079] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0080] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0081] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0082] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0083] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0084] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of the means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

Claims

1. A method for quickly detecting residual magnetism error of a current transformer, the method comprising: Connecting a high-precision industrial frequency current source and a high-precision DC current source in parallel with the current transformer to be measured; Setting the working parameters of the high-precision power frequency current source and the high-precision DC current source by a control unit; based on the working parameters, generating a rated percentage of the power frequency current and the DC current by the high-precision power frequency current source and the high-precision DC current source respectively; Applying the power frequency current and the direct current simultaneously on the primary side of the current transformer under test, respectively obtaining the power frequency current and the transformer secondary current of the current transformer under test through a shunt, and preprocessing the power frequency current and the transformer secondary current through a signal sampling preprocessing unit; The difference between the power frequency current and the transformer secondary current is analyzed by an error calculation unit, and the error of the current transformer under test is determined based on the difference.

2. The method according to claim 1, wherein the step of setting the operating parameters of the high-precision power frequency current source and the high-precision DC current source by a control unit further comprises: The control unit controls the start and stop, current increase and current decrease of the high-precision power frequency current source and the high-precision DC current source; The control unit is used to control the start and stop, data display and difference result of the error calculation unit.

3. The method according to claim 1, wherein the power frequency current and the transformer secondary current are preprocessed by a signal sampling preprocessing unit, comprising: The signal sampling preprocessing unit isolates, filters and performs A / D conversion processing on the acquired power frequency current and the transformer secondary current.

4. According to the method of claim 1, the power frequency current and the transformer secondary current are input into the error calculation unit through channel 1 and channel 2 respectively.

5. A current transformer residual magnetism error rapid detection system, the system comprising: High-precision power frequency current source, high-precision DC current source, shunt, control unit and sampling preprocessing unit; The high-precision power frequency current source and the high-precision DC current source are connected in parallel with the current transformer under test; The control unit is used to set the working parameters of the high-precision power frequency current source and the high-precision DC current source; based on the working parameters, the high-precision power frequency current source and the high-precision DC current source are used to generate a rated percentage of the power frequency current and the DC current respectively; Applying the power frequency current and the direct current simultaneously on the primary side of the current transformer under test, respectively obtaining the power frequency current and the transformer secondary current of the current transformer under test through a shunt, and preprocessing the power frequency current and the transformer secondary current through a signal sampling preprocessing unit; The error calculation unit is used to analyze the difference between the power frequency current and the transformer secondary current, and determine the error of the measured current transformer based on the difference.

6. The system according to claim 5, wherein the control unit is used to set the working parameters of the high-precision power frequency current source and the high-precision DC current source, and is also used to: The control unit controls the start and stop, current increase and current decrease of the high-precision power frequency current source and the high-precision DC current source; The control unit is used to control the start and stop, data display and difference result of the error calculation unit.

7. The system according to claim 5, wherein the power frequency current and the transformer secondary current are preprocessed by a signal sampling preprocessing unit, comprising: The signal sampling preprocessing unit isolates, filters and performs A / D conversion processing on the acquired power frequency current and the transformer secondary current.

8. The system according to claim 5, wherein the power frequency current and the transformer secondary current are input into the error calculation unit through channel 1 and channel 2 respectively.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 4.

10. An electronic device, characterized in that: The electronic device comprises: a processor and a memory; wherein, The memory is a memory for storing instructions executable by the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 4.

Images