CN111025189A - Low-current grounding line selection CT test system and test method - Google Patents
Low-current grounding line selection CT test system and test method Download PDFInfo
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- CN111025189A CN111025189A CN202010018391.5A CN202010018391A CN111025189A CN 111025189 A CN111025189 A CN 111025189A CN 202010018391 A CN202010018391 A CN 202010018391A CN 111025189 A CN111025189 A CN 111025189A
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Abstract
The present disclosure provides a small current grounding line selection CT test system and method, comprising a signal generation module configured to generate a current signal with a set amplitude and frequency; a signal processing module configured to perform filtering processing on the generated current signal; a signal output module configured to pass the processed signal through the CT under test effectively; and the low-current grounding line selection equipment acquires the detection value of the tested CT. The method can solve the problems that in a low-current grounding line selection system and other electric power systems, due to the fact that CT polarity is installed incorrectly and CT performance is poor, line selection is incorrect or interference is caused to line selection.
Description
Technical Field
The disclosure belongs to the technical field of power equipment, and relates to a small-current grounding line selection CT test system and a test method.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
In an electric power system, especially in a 3 kV-35 kV electric power system, a low-current grounding mode is generally adopted, although the power supply reliability is improved, the fault characteristics are not obvious when a fault occurs, so that the line selection is difficult, and the problem is basically solved by the wide application of the low-current grounding line selection system. The line selection criterion of the low-current grounding line selection system mainly comprises the following steps: the method includes a steady-state phasor method, a transient state method, a characteristic quantity method and the like, wherein the methods all depend on the acquisition of zero sequence Current, and the direction and the magnitude of the zero sequence Current are the key for correctly judging and selecting a grounding loop, so that the requirement that the polarity of a Current transformer (CT for short) must be correctly arranged when zero sequence Current detection is carried out is required, and the performance of the CT must meet the requirement. In other power systems, there are many application scenarios similar to the low-current grounding line selection system, which require a CT to collect current.
According to the inventor, the phenomenon that the CT polarity is installed incorrectly and the CT performance does not reach the standard due to complex reasons such as field operation and the like is caused, so that the line selection of the low-current grounding line selection system is inaccurate, and other electric power systems using the CT to acquire line current are problematic, and if the problems are not solved, the low-current grounding line selection system or other systems using the CT to acquire current are extremely difficult.
Disclosure of Invention
The present disclosure provides a low-current grounding line selection CT test system and a test method to solve the above problems, and the present disclosure can solve the problems of incorrect line selection or interference to line selection due to incorrect CT polarity installation and poor CT performance in a low-current grounding line selection system and other power systems.
According to some embodiments, the following technical scheme is adopted in the disclosure:
a small current grounding line selection CT test system and a test method thereof comprise:
a signal generation module configured to generate a current signal having a set amplitude and frequency;
a signal processing module configured to perform filtering processing on the generated current signal;
a signal output module configured to pass the processed signal through the CT under test effectively;
and the low-current grounding line selection equipment acquires the detection value of the tested CT.
As an alternative embodiment, the signal generation module comprises a time-base circuit that generates a unidirectional rectangular current pulse signal of constant amplitude, fixed frequency and duty cycle equal to a set value (preferably between 10% and 30%).
As an alternative embodiment, the signal processing module includes a filter circuit to process the current signal generated by the signal generating module.
As an alternative embodiment, the signal output module includes a single-control switch and a transistor, and the single-control switch controls the transistor to output the analog current signal.
As an alternative embodiment, the low-current grounding line selection device can normally monitor and display waveforms.
The test method based on the system comprises the following steps:
a lead penetrates through a CT to be tested to simulate the current of a field feeder line, and the lead penetrates through the CT in the same way as the field feeder line;
and checking signals displayed by the device by combining a low-current grounding line selection system device or other power system devices to judge whether the CT polarity is connected and the CT performance meets the requirements.
As an alternative embodiment, the amplitude attenuation and frequency variation of the current waveform displayed by the low-current grounding line selection device are maintained within a reasonable range in consideration of the objective condition influence of signal attenuation and line impedance, and if the amplitude attenuation and frequency variation exceed the reasonable range, the measured CT performance does not reach the standard or other adverse influence factors need to be eliminated.
As an alternative embodiment, the waveform direction of the unidirectional square wave displayed by the low-current grounding line selection device should be consistent with the unidirectional rectangular current pulse signal (the duty ratio is preferably between 10% and 30%) generated by the signal generation module, and if the waveform direction is inconsistent with the unidirectional rectangular current pulse signal, the CT polarity installation is reversed.
Compared with the prior art, the beneficial effect of this disclosure is:
1. the method solves the problems that the CT polarity which is easy to appear in the process of installing the CT in a small-current grounding line selection system and other electric power systems is reversed to cause line selection inaccuracy and the like.
2. The method solves the problem that the CT performance is unqualified and the system is adversely affected easily in the process of installing the CT in the low-current grounding line selection system and other electric power systems.
3. The battery pack has the advantages of simple structure, stable output, small volume of the embodiment and capability of being used by being circularly charged by combining the battery.
4. The low-current grounding line selection system is used by combining with low-current grounding line selection system equipment which is used by a large amount of equipment of a power system, the test effect is good, and the reliability of the test result is high.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this disclosure.
Fig. 1 is a schematic circuit diagram of a signal generation module, a signal processing module, and a signal output module of the present embodiment;
fig. 2 is a longitudinal sectional view of the signal generation module, the signal processing module, and the signal output module of the present embodiment.
The specific implementation mode is as follows:
the present disclosure is further described below with reference to the accompanying drawings.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Low current ground connection route selection CT test system includes:
the device comprises a signal generating module, a signal processing module, a signal output module and low-current grounding line selection equipment. Wherein:
the signal generation module is used for generating a current signal. The LM555CM time-base circuit is used as a core to generate a forward rectangular current pulse signal with stable amplitude, fixed frequency and duty ratio equal to 20 percent, the forward rectangular current pulse signal replaces a feed line current signal in practice, and the amplitude and the frequency of the signal can be set according to requirements.
The signal processing module is used for processing the signal generated by the signal generating module. The signal generated by the signal generating module needs to be filtered, so that the output signal is more stable, and a stable output signal plays an important role in CT test of the system.
The signal output module provides a connection mode of the test system and the tested CT. Through the signal output module, the signal effectively passes through the tested CT and can be acquired by the low-current grounding line selection equipment.
The low current grounding line selection equipment is used for connecting the CT display waveform, and other devices which can be connected with the CT display waveform can be used for the disclosure.
The method for testing the low-current grounding line selection CT test system provided by the embodiment sequentially executes the following steps:
the method comprises the following steps: and generating a current signal through the signal generation module. The module will generate a positive rectangular current pulse signal with stable amplitude, fixed frequency and duty ratio equal to 20%, the frequency and size of the waveform can be changed according to actual needs to obtain the best test effect, and the output of the waveform must be stable and known to test the performance and polarity of the tested CT.
Step two: the signal processing module ensures that the signal generated in the first step is stable. And capacitors are connected in parallel at two ends of the signal generating circuit for filtering processing so as to obtain a good signal output effect.
Step three: the signal output module passes the generated signal through the tested CT in the following mode: the direction in which the conductor 1 passes coincides with the direction of the field feeder current. And after the CT senses a current signal, the signal is displayed by using low-current grounding line selection equipment.
Step four: considering the influence of objective conditions such as signal attenuation, line impedance and the like, the amplitude attenuation and frequency change of the current waveform displayed by the low-current grounding line selection equipment are maintained within the range required by the actual requirement, and if the amplitude attenuation and frequency change exceed the range, the performance of the tested CT does not reach the standard or other adverse influence factors exist and need to be eliminated.
Step five: the direction of the waveform displayed by the low-current grounding line selection device should be consistent with the direction of the positive rectangular current pulse signal with the duty ratio equal to the set value (preferably between 10% and 30%) generated by the signal generation module. When the current pulse signal generated by the signal generating module is in the positive direction, the waveform displayed by the low-current grounding line selection equipment is also in the positive direction, and if the current pulse signal is not in the positive direction, the CT polarity installation is incorrect.
As an exemplary embodiment, the low current grounding selection CT test system comprises:
the device comprises a signal generating module, a signal processing module, a signal output module and a low-current grounding line selection device. Fig. 1 is a schematic diagram of a circuit for signal generation, signal processing and signal output. Wherein:
1. the battery V1 and LM555CM constitute a signal generating module, and the module is used for generating a positive rectangular current pulse signal with stable amplitude, fixed frequency and duty ratio equal to 20 percent, and the signal generating module replaces a feed line current signal in practice, and the amplitude and the frequency of the signal can be set according to requirements. The capacitors C1, C2, C3 and the resistor R10 form a simple signal processing module for processing the signal generated by the signal generating module. The signal generated by the signal generating module needs to be filtered, so that the output signal is more stable.
2. And opening the single-control switch J1, and controlling the triode Q1 to output the analog current signal.
3. In the figure, terminals 1 and 2 provide a connection mode of the test system and the device to be tested for the signal output module. Through the signal output module, the signal is effectively passed through the tested CT, so that the signal can be collected by the low-current grounding line selection equipment.
The method for testing the low-current grounding line selection CT test system provided by the embodiment sequentially executes the following steps:
as shown in fig. 2:
1. after the switch (4) is turned on, the indicator lamp (3) is turned on to indicate that the equipment starts to work, and the circuit board (5) controls current output;
2. the LM555CM time base circuit (9) outputs a current signal with the size of 10mA and the frequency of 50Hz on the lead (1) by supplying power through the batteries (6) and (7), and the signal is set to be finished as required in design due to the consideration of portability;
3. the lead (1) penetrates through a field CT (11) and is connected with the lead (2) to simulate field feeder current, and the penetrating direction of the lead (1) is consistent with the direction of the field feeder current;
4. and checking signals displayed by the device by combining a low-current grounding line selection system device or other power system devices to judge whether the CT polarity is connected and the CT performance meets the requirements. Considering the influence of objective conditions such as signal attenuation, line impedance and the like, the amplitude attenuation and frequency change of the current waveform displayed by the low-current grounding line selection equipment are maintained in a reasonable range, and if the amplitude attenuation and frequency change exceed the range, the performance of the tested CT does not reach the standard or other adverse influence factors need to be eliminated. The direction of the waveform displayed by the low-current grounding line selection equipment is consistent with the direction of the unidirectional square wave generated by the signal generation module, and if the direction of the waveform is not consistent, the installation of the CT polarity is reversed.
5, (8) is a power management board, and (10) is a charging port;
the low-current grounding line selection CT test system provided by the embodiment generates current signals based on the LM555CM time-base circuit, and can conveniently test the performance and installation polarity of various CTs by combining with low-current grounding line selection equipment or other electric system equipment capable of displaying secondary side current signals of the CTs after processing.
As will be appreciated by one skilled in the art, embodiments of the present disclosure may be provided as a method, system, or computer program product. Accordingly, the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present disclosure 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 so forth) having computer-usable program code embodied therein.
The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams 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.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (7)
1. A small current grounding line selection CT test system is characterized in that: the method comprises the following steps:
a signal generation module configured to generate a current signal having a set amplitude, frequency, and duty cycle;
a signal processing module configured to perform filtering processing on the generated current signal;
a signal output module configured to pass the processed signal through the CT under test effectively;
and the low-current grounding line selection equipment acquires the detection value of the tested CT.
2. The small current grounding line selection CT test system as claimed in claim 1, wherein: the signal generation module comprises a time base circuit, and the time base circuit generates and generates a forward rectangular current pulse signal which is stable in amplitude, fixed in frequency and equal to a set value in duty ratio.
3. The small current grounding line selection CT test system as claimed in claim 1, wherein: the signal processing module comprises a filter circuit to process the current signal generated by the signal generating module.
4. The small current grounding line selection CT test system as claimed in claim 1, wherein: the signal output module comprises a single control switch and a triode which are sequentially connected, and the single control switch controls the triode to output the analog current signal.
5. Method of operating a system according to any of claims 1-4, characterized in that: the method comprises the following steps:
a lead connecting system and a tested CT are utilized to simulate the field feeder current, and the mode that a connecting lead penetrates through the tested CT is the same as the mode of the field feeder current;
and checking signals displayed by the device by combining a low-current grounding line selection system device or other power system devices to judge whether the CT polarity is connected and the CT performance meets the requirements.
6. The method of operation of claim 5, wherein: considering the objective condition influence of signal attenuation and line impedance, the amplitude attenuation and frequency variation of the current waveform displayed by the small-current grounding line selection equipment are maintained in a reasonable range, and if the amplitude attenuation and frequency variation exceed the range, the performance of the tested CT does not reach the standard or other adverse influence factors need to be eliminated.
7. The method of operation of claim 5, wherein: the direction of the waveform displayed by the low-current grounding line selection equipment is consistent with the direction of the unidirectional rectangular pulse signal generated by the signal generation module, and if the direction of the waveform is inconsistent, the installation of the CT polarity is reversed.
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