CN112904265B - Second winding open circuit detection circuit of zero sequence current transformer - Google Patents
Second winding open circuit detection circuit of zero sequence current transformer Download PDFInfo
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- CN112904265B CN112904265B CN202110291192.6A CN202110291192A CN112904265B CN 112904265 B CN112904265 B CN 112904265B CN 202110291192 A CN202110291192 A CN 202110291192A CN 112904265 B CN112904265 B CN 112904265B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/54—Testing for continuity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/72—Testing of electric windings
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- Engineering & Computer Science (AREA)
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- Measurement Of Current Or Voltage (AREA)
Abstract
The invention relates to a second winding open circuit detection circuit of a zero sequence current transformer, which comprises: the zero-sequence current transformer comprises a busbar through core, a first winding and a second winding; the AD measurement conditioning module is coupled with the first winding and used for collecting current signals of the first winding of the zero-sequence current transformer; the pulse excitation module is coupled with the second winding and provides a pulse excitation signal for the second winding; the AD measurement conditioning module comprises a sampling resistor coupled with a first winding of the zero sequence current transformer and a signal monitoring unit, and the signal monitoring unit monitors a sampling value of the sampling resistor in real time; the pulse excitation module comprises a single chip microcomputer for outputting square wave signals to the second winding, and the single chip microcomputer is coupled with the second winding; the square wave frequency output by the single chip microcomputer is larger than the sampling frequency of the zero sequence current transformer.
Description
Technical Field
The invention relates to an electronic circuit technology, in particular to a second winding open circuit detection circuit of a zero sequence current transformer.
Background
In the existing circuit design of the circuit breaker, the current transformer plays an important role in the operation of the whole circuit breaker. The main function of the current transformer is to monitor the corresponding current, and when the normal value of the current running deviates, the current transformer can perform corresponding treatment measures, such as disconnecting a breaker or transmitting fault current to a server. However, if an abnormality occurs during the operation of the existing zero sequence current transformer, the detection mode is usually a serial connection type, and the serial connection type needs to be correspondingly shielded from interference, so that the overall cost is high, and therefore, how to design a detection circuit not only has low cost, but also can ensure the correctness of the detection result, which becomes a technical problem to be solved urgently.
Disclosure of Invention
In order to solve the technical problem, the zero sequence current transformer is included;
the method comprises the following steps:
the zero sequence current transformer comprises a busbar through core, a first winding and a second winding;
the AD measurement conditioning module is coupled with the first winding and used for collecting current signals of the first winding of the zero-sequence current transformer;
the pulse excitation module is coupled with the second winding and provides a pulse excitation signal for the second winding;
the AD measurement conditioning module comprises a sampling resistor coupled with a first winding of the zero sequence current transformer and a signal monitoring unit, and the signal monitoring unit monitors a sampling value of the sampling resistor in real time;
the pulse excitation module comprises a single chip microcomputer for outputting square wave signals to the second winding, and the single chip microcomputer is coupled with the second winding;
the square wave frequency output by the single chip microcomputer is greater than the sampling frequency of the zero sequence current transformer;
when the measurement is normal, the output of the pulse excitation module is 0, when the abnormality needs to be detected, the singlechip outputs a square wave to the second winding, and a theoretical sampling increment value can be calculated according to the output value of the pulse excitation and the proportion of the first winding and the second winding;
and subtracting the sampling initial value from the sampling initial value to obtain an actual sampling incremental value after the signal monitoring unit records the sampling initial value before the singlechip outputs the square wave, and finally comparing the theoretical sampling incremental value with the actual sampling incremental value to judge whether the secondary winding of the zero-sequence transformer is open circuit or not.
The sampling frequency of the zero sequence current transformer is 50HZ, and the square wave signal output by the single chip microcomputer is 60-70 HZ.
After the circuit structure is sampled, when abnormality needs to be detected, the output pulse of the single chip microcomputer is used for exciting the second winding, and the second winding is superposed on the first winding, so that the sampling resistor on the first winding can simultaneously acquire the pulse excitation signal of the second winding and the output current signal of the secondary winding. And because the sampling resistor is always in a monitored state, the monitoring value under the current condition is observed firstly before the square wave is sent out, and after the square wave is sent out, the square wave signal of the second winding can be superposed on the sampling resistor of the first winding due to the working mechanism of the winding, at the moment, the monitoring value under the current condition is observed again, and the monitoring values observed twice are utilized for comparison to obtain incremental data, and the incremental data is compared with a theoretical value to judge whether the secondary winding of the zero-sequence transformer is open circuit or not.
And because the square wave frequency output by the pulse excitation module is greater than the sampling frequency of the zero sequence current transformer, the technical problem that when the sampling frequency of the pulse excitation module is consistent with the sampling frequency of the current transformer, the two frequencies are mutually superposed to cause inaccurate measuring results is solved, and finally, the detected superposed value is analyzed to judge whether the second winding of the zero sequence current transformer is broken.
Drawings
Fig. 1 is a schematic diagram of the circuit of the present invention.
Detailed Description
The device comprises a first winding S1, a second winding S2, an AD conditioning measuring module T1 and a pulse excitation module T2.
As shown in fig. 1, the zero sequence current transformer of the present invention includes a bus bar feedthrough, a first winding S1 and a second winding S2;
the AD measurement conditioning module is coupled with the first winding S1 and used for collecting current signals of the first winding S1 of the zero-sequence current transformer; a pulse excitation module T2 coupled to the second winding S2 and providing a pulse excitation signal to the second winding S2;
the AD measurement conditioning module comprises a sampling resistor coupled with a first winding S1 of the zero sequence current transformer and a signal monitoring unit, and the signal monitoring unit monitors the sampling value of the sampling resistor in real time;
the pulse excitation module T2 comprises a single chip microcomputer for outputting square wave signals to the second winding S2, and the single chip microcomputer is coupled with the second winding S2;
the square wave frequency output by the single chip microcomputer is greater than the sampling frequency of the zero sequence current transformer;
when the measurement is normal, the output of the pulse excitation module T2 is 0, when the abnormality needs to be detected, the singlechip outputs square waves to the second winding S2, and according to the output value of the pulse excitation and the proportion of the first winding S1 and the second winding S2, a theoretical sampling increment value can be calculated;
and subtracting the sampling initial value from the sampling initial value to obtain an actual sampling incremental value after the signal monitoring unit records the sampling initial value before the singlechip outputs the square wave, and finally comparing the theoretical sampling incremental value with the actual sampling incremental value to judge whether the secondary winding of the zero-sequence transformer is open circuit or not.
The sampling frequency of the zero sequence current transformer is 50HZ, and the square wave signal output by the single chip microcomputer is 60-70 HZ.
After the circuit structure is sampled, when abnormality needs to be detected, the output pulse of the single chip microcomputer is used for exciting the second winding S2, and the output pulse is superposed on the first winding S1, so that the sampling resistor on the first winding S1 can simultaneously acquire the pulse excitation signal of the second winding S2 and the output current signal of the secondary winding. And because the sampling resistor is always in a monitored state, the monitoring value under the current condition is observed firstly before the wave of the transmitting party, and after the wave of the transmitting party, the square wave signal of the second winding S2 is superposed on the sampling resistor of the first winding S1 due to the working mechanism of the winding, at the moment, the monitoring value under the current condition is observed again, and the monitoring values observed twice are utilized for comparison to obtain incremental data, and the incremental data is compared with a theoretical value to judge whether the secondary winding of the zero-sequence transformer is open circuit or not.
And because the square wave frequency output by the pulse excitation module T2 is greater than the sampling frequency of the zero sequence current transformer, the technical problem that when the sampling frequency of the pulse excitation module T2 is consistent with the sampling frequency of the current transformer, the two frequencies are mutually superposed to cause inaccurate measuring results is solved, and finally, the detected superposed value is analyzed to judge whether the second winding S2 of the zero sequence current transformer is broken.
Claims (2)
1. A second winding circuit break detection circuit of a zero sequence current transformer is characterized in that:
the method comprises the following steps:
the zero sequence current transformer comprises a busbar through core, a first winding and a second winding;
the AD measurement conditioning module is coupled with the first winding and used for collecting current signals of the first winding of the zero-sequence current transformer;
the pulse excitation module is coupled with the second winding and provides a pulse excitation signal for the second winding;
the AD measurement conditioning module comprises a sampling resistor coupled with a first winding of the zero sequence current transformer and a signal monitoring unit, and the signal monitoring unit monitors a sampling value of the sampling resistor in real time;
the pulse excitation module comprises a single chip microcomputer for outputting square wave signals to the second winding, and the single chip microcomputer is coupled with the second winding;
the square wave frequency output by the single chip microcomputer is greater than the sampling frequency of the zero sequence current transformer;
when the measurement is normal, the output of the pulse excitation module is 0, when the abnormality needs to be detected, the singlechip outputs a square wave to the second winding, and a theoretical sampling increment value can be calculated according to the output value of the pulse excitation and the proportion of the first winding and the second winding;
and subtracting the sampling initial value from the sampling initial value to obtain an actual sampling incremental value after the signal monitoring unit records the sampling initial value before the singlechip outputs the square wave, and finally comparing the theoretical sampling incremental value with the actual sampling incremental value to judge whether the secondary winding of the zero-sequence transformer is open circuit or not.
2. The second winding open circuit detection circuit of the zero sequence current transformer according to claim 1, characterized in that: the sampling frequency of the zero sequence current transformer is 50HZ, and the square wave signal output by the single chip microcomputer is 60-70 HZ.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110291192.6A CN112904265B (en) | 2021-03-18 | 2021-03-18 | Second winding open circuit detection circuit of zero sequence current transformer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110291192.6A CN112904265B (en) | 2021-03-18 | 2021-03-18 | Second winding open circuit detection circuit of zero sequence current transformer |
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| CN112904265A CN112904265A (en) | 2021-06-04 |
| CN112904265B true CN112904265B (en) | 2022-05-13 |
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Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5687870A (en) * | 1979-12-20 | 1981-07-16 | Masaji Nakajima | Improvement of disconnection detecting system |
| CN201184891Y (en) * | 2008-01-11 | 2009-01-21 | 俞盛荣 | Detection module for short/open circuit of current mutual inductor secondary circuit |
| CN106338704A (en) * | 2015-07-14 | 2017-01-18 | 重庆龙源科技产业发展有限公司 | Real-time detection device suitable for failure and electricity larceny prevention of metering current transformer |
| CN109991563B (en) * | 2018-01-02 | 2020-12-29 | 常熟开关制造有限公司(原常熟开关厂） | Current transformer disconnection detection method and measurement device |
| CN209946348U (en) * | 2019-03-22 | 2020-01-14 | 吴琼 | Portable CT return circuit detection device that opens a way |
| CN110794355B (en) * | 2019-10-21 | 2021-11-16 | 许继集团有限公司 | Bus current transformer disconnection identification method, differential protection method and device |
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Inventor after: Xu Xiaofeng Inventor after: Zheng Chao Inventor after: Sun Bochen Inventor after: Guo Zhangle Inventor after: Zhao Sheng Inventor before: Sun Bochen Inventor before: Guo Zhangle Inventor before: Zheng Chao Inventor before: Xu Xiaofeng Inventor before: Zhao Sheng |
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Address after: Room 402-410, 4th floor, incubator building 14, Wenzhou National University Science Park, 75 Fengfang Road, Ouhai Economic Development Zone, Wenzhou City, Zhejiang Province 325000 Patentee after: Zhejiang juchuang Intelligent Technology Co.,Ltd. Address before: Room 402-410, 4th floor, incubator building 14, Wenzhou National University Science Park, 75 Fengfang Road, Ouhai Economic Development Zone, Wenzhou City, Zhejiang Province 325000 Patentee before: Zhejiang juchuang Intelligent Technology Co.,Ltd. |
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