CN116224210A - Current transformer verification system and method in AC/DC coexisting environment - Google Patents
Current transformer verification system and method in AC/DC coexisting environment Download PDFInfo
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Abstract
The invention discloses a system and a method for checking a current transformer in an alternating current-direct current coexistence environment. The system at least comprises a programmable power supply and a standard AC/DC current transformer CT 02 Program-controlled load Z B DC current transformer CT of the test X And an error measurement device; wherein the programmable power supply is used for outputting a power frequency alternating current signal, a direct current signal and/or a sine half-wave signal and loading the signals to the standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a); the error measuring device is used for measuring the current transformer CT according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a function of the error of (a). The invention can accurately and efficiently realize the error of the DC-resistant current transformer under the condition of power frequency alternating current signals, DC current signals and/or sine half-wave signalsThe insulation test can be tested, and the metering performance and the insulation performance of the network-access DC current transformer can be guaranteed.
Description
Technical Field
The invention relates to the technical field of current transformers, in particular to a system and a method for checking a current transformer in an alternating current-direct current coexistence environment.
Background
The current transformer is installed on a power line in an AC/DC coexisting environment and has a DC magnetic bias resistance function. Since a certain dc component may exist in the ac current of the power grid, the dc half wave is the most typical ac condition with dc component, in which case the current transformer becomes the most severely misaligned. In addition, the error data of the existing low-voltage current transformer under the alternating current condition meets the 0.2S requirement, but the error data of the existing low-voltage current transformer is completely misaligned when in the direct current half-wave, which is tens of times of the 0.2S level error limit value. The error has serious influence on the metering of the current transformer, and the use requirement of an actual application scene can not be met well in practice, so that the current transformer is required to be subjected to error measurement and verification under the conditions of alternating current superposition of direct current components and direct current half waves; however, the existing verification methods mostly have the defects of low efficiency and low precision, so that hidden troubles of safety and measurement misalignment of the current transformer in an alternating current-direct current coexisting environment can be caused.
Disclosure of Invention
The invention aims to solve the technical problem of providing a system and a method for checking a current transformer in an alternating current-direct current coexisting environment, which can accurately and efficiently realize the error of the anti-direct current transformer under the condition of a power frequency alternating current signal, a direct current signal and/or a sine half-wave signal, can also test an insulation test, and can ensure the metering performance and the insulation performance of the network-access anti-direct current transformer.
In order to solve the above technical problems, as one aspect of the present invention, a current transformer calibration system in an ac/dc coexisting environment is provided, which at least includes a programmable power supply, a standard ac/dc universal current transformer CT 02 Program-controlled load ZB and detected DC-resistant transformer CT X And an error measurement device; wherein:
a standard AC/DC universal current transformer CT is connected in series between two DC output ends of the programmable power supply 02 Primary winding of (1) and detected DC current transformer CT X A standard AC/DC universal current transformer CT is connected in series between two power frequency current output ends of the programmable power supply 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
standard AC/DC universal current transformer CT 02 Two ends of the secondary winding of the transformer are respectively and correspondingly electrically connected with one group of secondary current terminals of the error measuring device, and the detected DC current transformer CT X One end of the secondary winding of the (B) is electrically connected with one of the other group of secondary current terminals of the error measuring device, and the detected DC current transformer CT X The other end of the secondary winding of the error measuring device is electrically connected with the other one of the other group of secondary current terminals of the error measuring device through a program-controlled load ZB;
wherein the programmable power supply is used for outputting a power frequency alternating current signal, a direct current signal and/or a sinusoidal half-wave signal and loading the signals into a standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
the error measuring device is used for measuring the current transformer CT according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a function of the error of (a).
Preferably, the error measurement device comprises two signal preprocessing circuits and a digital signal processing circuit;
one of the signalsTwo signal input ends of the preprocessing circuit are respectively connected with a standard alternating current-direct current universal current transformer CT 02 Two ends of the secondary winding of the other signal preprocessing circuit are correspondingly and electrically connected with the two ends of the detected DC current transformer CT respectively X The two ends of the secondary winding are correspondingly and electrically connected, and the output ends of the two signal preprocessing circuits are respectively and electrically connected with the input ends of the digital signal processing circuits;
the signal preprocessing circuit is used for the standard AC/DC current transformer CT 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X Amplifying, filtering and analog-to-digital converting the analog signal to be tested, which is output by the secondary winding of the transformer, to obtain a standard digital signal and a digital signal to be tested respectively;
the digital signal processing circuit is used for respectively carrying out sampling analysis on the standard digital signal and the tested digital signal and calculating to obtain a ratio difference and a phase difference.
Preferably, the device further comprises an insulation resistance tester, and a tested anti-DC current transformer CT X The primary winding and the secondary winding are electrically connected at two ends of the insulation resistance tester after being connected in series.
Preferably, the device further comprises a power frequency withstand voltage tester, and two ends of the power frequency withstand voltage tester are respectively connected with the tested DC current transformer CT X One end of the primary winding of (1) and the other end corresponding to the secondary winding, and the detected DC current transformer CT X One end of primary winding of (C) and grounding bottom plate or tested DC current transformer CT X Is electrically connected to the ground plate.
The invention also provides a method for checking the current transformer in the AC/DC coexisting environment, which is characterized by comprising the following steps:
step S1, outputting a power frequency alternating current signal by a programmable power supply and loading the power frequency alternating current signal to a standard alternating current/direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S2, according to a preset zero-crossing pulse clock signal, the error measuring device time-sharing pairs standard AC/DC universal current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of (2) is sampled and is based on the standard AC/DC current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a power frequency error of (2);
step S3, the programmable power supply outputs a power frequency alternating current signal and a direct current signal and loads the power frequency alternating current signal and the direct current signal to a standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S4, according to a preset zero-crossing pulse clock signal, the error measuring device time-sharing pairs standard AC/DC universal current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of (2) is sampled and is based on the standard AC/DC current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X A power frequency current superposition direct current component error;
step S5, outputting a sine half-wave signal by the programmable power supply and loading the sine half-wave signal to a standard AC/DC universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S6, the error measuring device time-sharing pairs standard alternating current-direct current universal current transformer CT according to a preset zero-crossing pulse clock signal 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X Sampling the current output by the secondary winding of the standard AC/DC universal current transformer CT02 and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a sinusoidal half-wave error of (c).
Preferably, in steps S2 to S6, the error measuring device is based on a standard ac/dc universal current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The method comprises the steps of determining a power frequency error, a power frequency current superposition direct current component error or a sine half-wave error by the current output by the secondary winding, and specifically comprises the following steps:
the signal preprocessing circuit is used for standard AC/DC current transformer CT 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X Amplifying, filtering and analog-to-digital converting the analog signal to be tested, which is output by the secondary winding of the transformer, to obtain a standard digital signal and a digital signal to be tested respectively;
the digital signal processing circuit is used for respectively carrying out sampling analysis on the standard digital signal and the tested digital signal, and calculating to obtain the power frequency ratio difference and the phase difference, and the power frequency current superposition direct current component ratio difference and the phase difference or the sine half-wave ratio difference and the phase difference.
Preferably, before the error measurement is performed, the method further comprises the following steps:
CT (computed tomography) of DC-resistant current transformer to be detected X The primary winding and the secondary winding of the transformer are electrically connected at two ends of an insulation resistance tester after being connected in series, and the transformer is used for resisting direct current to be tested X And performing insulation test, and entering a subsequent error testing step after the insulation test is qualified.
Preferably, before the error test after the insulation test, the method further comprises the following steps:
two ends of the power frequency withstand voltage tester are respectively connected with the tested DC current transformer CT in sequence X One end of the primary winding of (1) and the other end corresponding to the secondary winding, and the detected DC current transformer CT X One end of primary winding of (C) and grounding bottom plate or tested DC current transformer CT X One end of the secondary winding of the transformer is electrically connected with the grounding bottom plate, and is subjected to voltage withstand test, and after the voltage withstand test is qualified, the subsequent error testing step is carried out.
The embodiment of the invention has the following beneficial effects:
the invention provides an AC/DC commonCurrent transformer verification system and method under storage environment, power frequency alternating current signal, direct current signal and/or sine half-wave signal are output through program controlled power supply switching, and are loaded to standard alternating current/direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X So that the current transformer CT can be used for the current according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is accurately determined to be detected to resist the CT X The error of the power supply output power supply, the standard device and the error checking device are not required to be replaced for different error checking by adopting a unified interface, so that the workload is reduced, and the efficiency is greatly improved.
In the invention, the standard AC/DC universal current transformer CT can be respectively subjected to the signal preprocessing circuit 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X The analog signal to be detected output by the secondary winding is amplified, filtered and subjected to analog-to-digital conversion, so that on one hand, detection can be more accurate, and on the other hand, the digital signal processing circuit is convenient for carrying out sampling analysis processing on the standard digital signal and the digital signal to be detected, and an accurate error detection result is obtained.
In the invention, the insulation resistance tester is adopted, so that the tested DC current transformer CT can be tested X The insulation performance between the primary winding and the secondary winding is detected, and the CT of the detected DC-resistant current transformer is ensured X The insulation performance of the alloy meets the set requirements.
In the invention, the tested DC-resistant current transformer CT can be tested by arranging the power frequency withstand voltage tester X Between one end of the primary winding and the secondary winding, the tested anti-DC current transformer CT X Between the primary winding of (C) and the grounding bottom plate, and the tested DC-resistant transformer CT X The voltage resistance between the secondary winding and the ground meets the set requirement.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are required in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that it is within the scope of the invention to one skilled in the art to obtain other drawings from these drawings without inventive faculty.
FIG. 1 is a schematic diagram of an embodiment of a current transformer verification system in an AC/DC coexisting environment according to the present invention;
fig. 2 is a schematic diagram of a main flow of an embodiment of a current transformer verification method in an ac/dc coexisting environment according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
Referring to fig. 1, a schematic structural diagram of an embodiment of a current transformer verification system in an ac/dc coexisting environment according to the present invention is shown; in this embodiment, the current transformer verification system in the ac/dc coexisting environment includes a programmable power supply 1, a standard ac/dc universal current transformer CT 02 Program-controlled load ZB and detected DC-resistant transformer CT X And an error measuring apparatus 2, wherein:
a standard AC/DC universal current transformer CT is connected in series between two DC output ends of the program-controlled power supply 1 02 Primary winding L of (2) 1 、L 2 And the tested DC-resistant current transformer CT X Primary winding P of (2) 1 、P 2 A standard AC/DC universal current transformer CT is connected in series between two power frequency current output ends of the programmable power supply 02 Primary winding L of (2) 1 、L 2 And the tested DC-resistant current transformer CT X Primary winding P of (2) 1 、P 2 Standard AC/DC universal current transformer CT 02 Two ends K of secondary winding of (2) 1 、K 2 Respectively with one group of secondary current terminals I of the error measuring device 01 、I 02 Corresponding electrical connectionThe CT of the DC current transformer is connected with the tested X Is arranged at one end S of the secondary winding 1 One of the other set of secondary current terminals of the error measuring device X1 Electric connection, tested DC current transformer CT X The other end S of the secondary winding of (2) 2 By a programmable load Z B With another one of the other sets of secondary current terminals of the error-measuring device X2 Electrically connecting;
specifically, the programmable power supply is used for outputting a power frequency alternating current signal, a direct current signal and/or a sinusoidal half-wave signal and loading the signals into a standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
the error measuring device is used for measuring the current transformer CT according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a function of the error of (a).
The current transformer verification system in the AC/DC coexisting environment outputs a power frequency AC signal, a DC current signal and/or a sinusoidal half-wave signal through switching of a programmable power supply and loads the power frequency AC signal, the DC current signal and/or the sinusoidal half-wave signal to a standard AC/DC universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X So that the current transformer CT can be used for the current according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is accurately determined to be detected to resist the CT X The error of the power supply output power supply, the standard device and the error checking device are not required to be replaced for different error checking by adopting a unified interface, so that the workload is reduced, and the efficiency is greatly improved.
In one or more embodiments of the present invention, the error measurement device includes two signal preprocessing circuits and a digital signal processing circuit, wherein two signal input ends of one signal preprocessing circuit are respectively connected with a standard AC/DC universal current transformer CT 02 Two ends K of secondary winding of (2) 1 、K 2 The two signal input ends of the other signal preprocessing circuit are respectively connected with the detected DC current transformer CT correspondingly X Two ends S of the secondary winding of (2) 1 、S 2 The inner corresponding electric connection, the output ends of the two signal preprocessing circuits are respectively and electrically connected with the input ends of the digital signal processing circuits;
the signal preprocessing circuit is used for the standard AC/DC current transformer CT 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X Amplifying, filtering and analog-to-digital converting the analog signal to be tested, which is output by the secondary winding of the transformer, to obtain a standard digital signal and a digital signal to be tested respectively;
the digital signal processing circuit is used for respectively carrying out sampling analysis on the standard digital signal and the tested digital signal and calculating to obtain a ratio difference and a phase difference.
The standard AC/DC current transformer CT can be respectively subjected to signal preprocessing circuit 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X The analog signal to be detected output by the secondary winding is amplified, filtered and subjected to analog-to-digital conversion, so that on one hand, detection can be more accurate, and on the other hand, the digital signal processing circuit is convenient for carrying out sampling analysis processing on the standard digital signal and the digital signal to be detected, and an accurate error detection result is obtained.
It should be noted that in practice, before the detection, the appearance of the current transformer needs to be checked, including the assembly quality, the surface treatment of the parts, the nameplate, the connection terminals and other appearance items specified by the technical conditions of the product. Visual inspection is adopted to check whether the appearance, the mark and the like are qualified, and vernier calipers, straightedge and the like are used for measuring whether the size meets the requirements.
Optionally, in one or more embodiments of the present invention, the current transformer verification system in an ac-dc coexisting environment further includes an insulation resistance tester, and the detected dc current transformer CT X The primary winding and the secondary winding are electrically connected at two ends of the insulation resistance tester after being connected in series.
By adopting the insulation resistance tester, the DC current transformer CT can be resisted to the detected X The insulation performance between the primary winding and the secondary winding is detected, and the CT of the detected DC-resistant current transformer is ensured X The insulation performance of the alloy meets the set requirements.
Specifically, an insulating resistance meter with the working voltage of 500V and the measurement error of less than +/-10% is adopted for test, and the two meters are directly and electrically connected to a tested DC-resistant current transformer CT X Is arranged between the primary winding and the secondary winding.
In addition, in practice, it is also necessary to measure the CT of the tested DC transformer X An insulation resistance between the secondary winding and the grounded metal casing. The results of the test need to meet the following requirements:
the insulation resistance of the primary winding and the secondary winding is not lower than 100MΩ; the insulation resistance of the secondary winding to the grounded metal shell is not lower than 30MΩ.
Optionally, in one or more embodiments of the present invention, the current transformer verification system in an ac/dc coexisting environment further includes a power frequency withstand voltage tester, two ends of the power frequency withstand voltage tester are respectively connected with the detected dc-resistant current transformer CT X One end of the primary winding of (1) and the other end corresponding to the secondary winding, and the detected DC current transformer CT X One end of primary winding of (C) and grounding bottom plate or tested DC current transformer CT X Is electrically connected to the ground plate. The tested DC current transformer CT can be tested by arranging a power frequency withstand voltage tester X Between one end of the primary winding and the secondary winding, the tested anti-DC current transformer CT X Between the primary winding of (C) and the grounding bottom plate, and the tested DC-resistant transformer CT X The voltage resistance between the secondary winding and the grounding bottom plate meets the set requirement.
In practice, the withstand voltage test method comprises the following steps:
using a withstand voltage tester with output voltage of 0-4.5 kV and error of less than +/-3% to test, and after the test voltage rises to a specified value, continuing for 1min, wherein the test result meets the following requirements:
the primary winding (or the surface of the casing which may be in contact with the primary conductor) has a power frequency withstand voltage of 3kV to the secondary winding and to the ground plate.
Fig. 2 is a schematic diagram of a main flow of an embodiment of a current transformer verification method in an ac/dc coexisting environment according to the present invention. In this embodiment, the method is implemented by using the current transformer verification system in the ac/dc coexisting environment described in fig. 1, and specifically includes the following steps:
step S1, outputting a power frequency alternating current signal by a programmable power supply and loading the power frequency alternating current signal to a standard alternating current/direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S2, according to a preset zero-crossing pulse clock signal, the error measuring device time-sharing pairs standard AC/DC universal current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of (2) is sampled and is based on the standard AC/DC current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a power frequency error of (2);
step S3, the programmable power supply outputs a power frequency alternating current signal and a direct current signal and loads the power frequency alternating current signal and the direct current signal to a standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S4, according to a preset zero-crossing pulse clock signal, the error measuring device time-sharing pairs standard AC/DC universal current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of (2) is sampled and is based on the standard AC/DC current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X A power frequency current superposition direct current component error;
step S5, programmable power supplyOutputting a sine half-wave signal, and loading the sine half-wave signal to a primary winding of a standard AC/DC universal current transformer CT02 and a detected DC-resistant current transformer CT X Primary windings of (a);
step S6, the error measuring device time-sharing pairs standard alternating current-direct current universal current transformer CT according to a preset zero-crossing pulse clock signal 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of (2) is sampled and is based on the standard AC/DC current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a sinusoidal half-wave error of (c).
According to the checking method of the current transformer in the AC/DC coexisting environment, the power frequency AC signal, the DC current signal and/or the sine half-wave signal are output through switching of the programmable power supply and are loaded to the standard AC/DC universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X So that the current transformer CT can be used for the current according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is accurately determined to be detected to resist the CT X The error of the power supply output power supply, the standard device and the error checking device are not required to be replaced for different error checking by adopting a unified interface, so that the workload is reduced, and the efficiency is greatly improved.
In one or more embodiments of the invention, the error measurement device is based on a standard AC/DC current transformer CT 02 The specific implementation of the power frequency error, the power frequency current superposition direct current component error or the sine half-wave error determined by the current output by the secondary winding of the detected direct current transformer CTX and the current output by the secondary winding of the detected direct current transformer CTX is as follows:
the signal preprocessing circuit is used for standard AC/DC current transformer CT 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X Is tested mould of secondary winding outputAmplifying, filtering and analog-to-digital converting the analog signal to obtain a standard digital signal and a tested digital signal respectively;
the digital signal processing circuit is used for respectively carrying out sampling analysis on the standard digital signal and the tested digital signal, and calculating to obtain the power frequency ratio difference and the phase difference, and the power frequency current superposition direct current component ratio difference and the phase difference or the sine half-wave ratio difference and the phase difference.
The standard AC/DC current transformer CT can be respectively subjected to signal preprocessing circuit 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X The analog signal to be detected output by the secondary winding is amplified, filtered and subjected to analog-to-digital conversion, so that on one hand, detection can be more accurate, and on the other hand, the digital signal processing circuit is convenient for carrying out sampling analysis processing on the standard digital signal and the digital signal to be detected, and an accurate error detection result is obtained.
Optionally, in one or more embodiments of the present invention, before performing the error measurement, the method further includes the steps of:
CT (computed tomography) of DC-resistant current transformer to be detected X The primary winding and the secondary winding of the transformer are electrically connected at two ends of an insulation resistance tester after being connected in series, and the transformer is used for resisting direct current to be tested X And performing insulation test, and entering a subsequent error testing step after the insulation test is qualified.
By adopting the insulation resistance tester, the DC current transformer CT can be resisted to the detected X The insulation performance between the primary winding and the secondary winding is detected, and the CT of the detected DC-resistant current transformer is ensured X The insulation performance of the alloy meets the set requirements.
Optionally, in one or more embodiments of the present invention, before performing the post-insulation test error test, the method further includes the steps of:
two ends of the power frequency withstand voltage tester are respectively connected with the tested DC current transformer CT in sequence X One end of the primary winding of (1) and the other end corresponding to the secondary winding, and the detected DC current transformer CT X One end of primary winding of (a) and a grounding bottom plate or a detected DC-resistant current transformerCT X One end of the secondary winding of the transformer is electrically connected with the grounding bottom plate, and is subjected to voltage withstand test, and after the voltage withstand test is qualified, the subsequent error testing step is carried out.
The tested DC current transformer CT can be tested by arranging a power frequency withstand voltage tester X Between one end of the primary winding and the secondary winding, the tested anti-DC current transformer CT X Between the primary winding of (C) and the grounding bottom plate, and the tested DC-resistant transformer CT X The voltage resistance between the secondary winding and the grounding bottom plate meets the set requirement.
The embodiment of the invention has the following beneficial effects:
the invention provides a system and a method for checking a current transformer in an alternating current-direct current coexisting environment, which are used for outputting a power frequency alternating current signal, a direct current signal and/or a sinusoidal half-wave signal through switching of a programmable power supply and loading the power frequency alternating current signal, the direct current signal and/or the sinusoidal half-wave signal to a standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X So that the current transformer CT can be used for the current according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is accurately determined to be detected to resist the CT X The error of the power supply output power supply, the standard device and the error checking device are not required to be replaced for different error checking by adopting a unified interface, so that the workload is reduced, and the efficiency is greatly improved.
In the invention, the standard AC/DC universal current transformer CT can be respectively subjected to the signal preprocessing circuit 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X The analog signal to be detected output by the secondary winding is amplified, filtered and subjected to analog-to-digital conversion, so that on one hand, detection can be more accurate, and on the other hand, the digital signal processing circuit is convenient for carrying out sampling analysis processing on the standard digital signal and the digital signal to be detected, and an accurate error detection result is obtained.
In the present invention, the insulation resistance tester is used to resist the detected objectDC current transformer CT X The insulation performance between the primary winding and the secondary winding is detected, and the CT of the detected DC-resistant current transformer is ensured X The insulation performance of the alloy meets the set requirements.
In the invention, the tested DC-resistant current transformer CT can be tested by arranging the power frequency withstand voltage tester X Between one end of the primary winding and the secondary winding, the tested anti-DC current transformer CT X Between the primary winding of (C) and the grounding bottom plate, and the tested DC-resistant transformer CT X The voltage resistance between the secondary winding and the grounding bottom plate meets the set requirement.
It will be apparent to those skilled in the art that embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above disclosure is only a preferred embodiment of the present invention, and it is needless to say that the scope of the invention is not limited thereto, and therefore, the equivalent changes according to the claims of the present invention still fall within the scope of the present invention.
Claims (8)
1. A current transformer verification system in an AC/DC coexisting environment is characterized by at least comprising a programmable power supply and a standard AC/DC universal current transformer CT 02 Program-controlled load Z B DC current transformer CT of the test X And an error measurement device; wherein:
the standard AC/DC universal current transformer CT is connected in series between two DC output ends of the programmable power supply 02 Primary winding of (C) and the detected DC-resistant transformer CT X The standard AC/DC universal current transformer CT is connected in series between two power frequency current output ends of the programmable power supply 02 Primary winding of (C) and the detected DC-resistant transformer CT X Primary windings of (a);
the standard AC/DC universal current transformer CT 02 Two ends of the secondary winding of the error measuring device are respectively and correspondingly electrically connected with one group of secondary current terminals of the error measuring device, and the detected DC-resistant current transformer CT X One end of the secondary winding of the error measuring device is electrically connected with one of the other group of secondary current terminals of the error measuring device, and the detected DC-resistant current transformer CT X Through the other end of the secondary winding of the program-controlled load Z B Electrically connected to another one of the other set of secondary current terminals of the error measurement device;
wherein the programmable power supply is used for outputting a power frequency alternating current signal, a direct current signal and/or a sine half-wave signal and loading the signals to the standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
the error measuring device is used for measuring the current transformer CT according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a function of the error of (a).
2. The system of claim 1, wherein the error measurement device comprises two signal preprocessing circuits and a digital signal processing circuit;
two signal input ends of one signal preprocessing circuit are respectively connected with the standard alternating current-direct current universal current transformer CT 02 Two ends of the secondary winding of the other signal preprocessing circuit are correspondingly and electrically connected with the two ends of the detected DC current transformer CT respectively X The two ends of the secondary winding are correspondingly and electrically connected, and the output ends of the two signal preprocessing circuits are respectively and electrically connected with the input ends of the digital signal processing circuits;
the signal preprocessing circuit is used for processing the standard AC/DC current transformer CT 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X Amplifying, filtering and analog-to-digital converting the analog signal to be tested, which is output by the secondary winding of the transformer, to obtain a standard digital signal and a digital signal to be tested respectively;
the digital signal processing circuit is used for respectively carrying out sampling analysis on the standard digital signal and the tested digital signal and calculating to obtain a ratio difference and a phase difference.
3. The system of claim 2, further comprising an insulation resistance tester, said tested anti-dc current transformer CT X The primary winding and the secondary winding are electrically connected at two ends of the insulation resistance tester after being connected in series.
4. The system of claim 3, further comprising a power frequency withstand voltage tester, two ends of the power frequency withstand voltage tester being respectively connected with the tested DC transformer CT X One end of the primary winding of the transformer is corresponding to the other end of the secondary winding, and the detected DC-resistant current transformer CT X One end of the primary winding of (2) and a grounding bottom plate or the tested DC-resistant current transformer CT X Is electrically connected to the ground plate.
5. A method for checking a current transformer in an ac/dc coexisting environment, which is characterized by comprising the steps of:
step S1, outputting a power frequency alternating current signal by a programmable power supply and loading the power frequency alternating current signal to a standard alternating current/direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S2, the error measuring device time-sharing the standard AC/DC universal current transformer CT according to a preset zero-crossing pulse clock signal 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X Sampling the current output by the secondary winding of (2) and obtaining a current transformer CT according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a power frequency error of (2);
step S3, the programmable power supply outputs a power frequency alternating current signal and a direct current signal and loads the power frequency alternating current signal and the direct current signal to a standard alternating current-direct current universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S4, the error measuring device time-sharing the standard AC/DC universal current transformer CT according to a preset zero-crossing pulse clock signal 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X Sampling the current output by the secondary winding of (2) and obtaining a current transformer CT according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X A power frequency current superposition direct current component error;
step S5, outputting a sine half-wave signal by the programmable power supply and loading the sine half-wave signal to a standard AC/DC universal current transformer CT 02 Primary winding of (1) and detected DC current transformer CT X Primary windings of (a);
step S6, the error measuring device time-sharing the standard AC/DC universal current transformer CT according to a preset zero-crossing pulse clock signal 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X Sampling the current output by the secondary winding of (2) and obtaining a current transformer CT according to the standard AC/DC 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The current output by the secondary winding of the transformer is used for determining the detected DC-resistant current transformer CT X Is a sinusoidal half-wave error of (c).
6. The method of claim 5, wherein in steps S2 to S6, the error measurement device is based on the standard ac/dc current transformer CT 02 The current output by the secondary winding of (1) and the detected DC-resistant current transformer CT X The method comprises the steps of determining a power frequency error, a power frequency current superposition direct current component error or a sine half-wave error by the current output by the secondary winding, and specifically comprises the following steps:
the signal preprocessing circuit is used for the standard AC/DC universal current transformer CT 02 Standard analog signal or detected DC-resistant current transformer CT output by secondary winding of (C) X Amplifying, filtering and analog-to-digital converting the analog signal to be tested, which is output by the secondary winding of the transformer, to obtain a standard digital signal and a digital signal to be tested respectively;
and the digital signal processing circuit is used for respectively carrying out sampling analysis on the standard digital signal and the tested digital signal, and calculating to obtain the power frequency ratio difference and the phase difference, and the power frequency current superposition direct current component ratio difference and the phase difference or the sine half-wave ratio difference and the phase difference.
7. The method of claim 6, further comprising the step of, prior to performing the error measurement:
CT (computed tomography) of DC-resistant current transformer to be detected X The primary winding and the secondary winding of the transformer are electrically connected at two ends of an insulation resistance tester after being connected in series, and the transformer is used for resisting direct current to be tested X Performing insulation test, and entering subsequent error measurement after the insulation test is qualifiedAnd (5) testing.
8. The method of claim 7, further comprising the step of, prior to performing the post-insulation test error test:
two ends of the power frequency withstand voltage tester are respectively connected with the tested DC current transformer CT in sequence X One end of the primary winding of the transformer is corresponding to the other end of the secondary winding, and the detected DC-resistant current transformer CT X One end of the primary winding of (2) and a grounding bottom plate or the tested DC-resistant current transformer CT X One end of the secondary winding of the transformer is electrically connected with the grounding bottom plate, and is subjected to voltage withstand test, and after the voltage withstand test is qualified, the subsequent error testing step is carried out.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500534A (en) * | 2023-06-27 | 2023-07-28 | 国网天津市电力公司营销服务中心 | DBI type current transformer DC resistance detection device and method |
| CN116755020A (en) * | 2023-07-06 | 2023-09-15 | 浙江天际互感器股份有限公司 | Anti-direct current transformer half-wave error detection system and method based on harmonic comparison method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116500534A (en) * | 2023-06-27 | 2023-07-28 | 国网天津市电力公司营销服务中心 | DBI type current transformer DC resistance detection device and method |
| CN116755020A (en) * | 2023-07-06 | 2023-09-15 | 浙江天际互感器股份有限公司 | Anti-direct current transformer half-wave error detection system and method based on harmonic comparison method |
| CN116755020B (en) * | 2023-07-06 | 2024-05-10 | 浙江天际互感器股份有限公司 | Harmonic comparison method-based half-wave error detection method for anti-direct current transformer |
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