CN113671233A - Method for judging operation condition of secondary circuit based on harmonic characteristics of current transformer - Google Patents
Method for judging operation condition of secondary circuit based on harmonic characteristics of current transformer Download PDFInfo
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- CN113671233A CN113671233A CN202110869311.1A CN202110869311A CN113671233A CN 113671233 A CN113671233 A CN 113671233A CN 202110869311 A CN202110869311 A CN 202110869311A CN 113671233 A CN113671233 A CN 113671233A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
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Abstract
The invention discloses a method for judging the operation condition of a secondary circuit based on the harmonic characteristics of a current transformer, which comprises the following steps of firstly, measuring the secondary current of the secondary circuit of the current transformer; and then, judging whether the current on the secondary winding side of the current transformer is reduced simultaneously according to the multiple harmonic wave amplitude in the secondary current, if the current reduction characteristic is met, judging that the secondary circuit of the current transformer is open-circuited, and if the current reduction characteristic is not met, judging that the current transformer is saturated. The invention comprehensively judges the operation condition of the secondary circuit of the current transformer aiming at the difference of harmonic characteristics when the secondary circuit of the current transformer is open-circuited, thereby comprehensively monitoring the operation state of the current transformer in real time.
Description
Technical Field
The invention belongs to the field of operation monitoring of current transformers.
Background
The current transformer is widely used in power systems, and has the function of converting large current of a primary system into small current of a secondary system according to a certain proportion for measuring, metering, relay protection and automation devices. The secondary side of the current transformer must not be opened, and once the current transformer is opened, serious influence can be caused. In actual work, the possibility of secondary open circuit of the current transformer exists, for example, the open circuit is caused by the reasons of looseness, overheating or burning due to oxidation, or faults in maintenance work and the like after the transition terminal of the secondary circuit is oxidized.
Disclosure of Invention
Aiming at the defects of the prior art, the technical problem to be solved by the invention is to provide a method for judging the operation condition of a secondary circuit based on the harmonic characteristics of a current transformer, which can comprehensively monitor the operation state of the current transformer in real time and accurately judge whether the current transformer is open-circuited in the secondary circuit.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for judging the operation status of a secondary circuit based on the harmonic characteristics of a current transformer,
firstly, measuring the secondary current of a secondary loop of a current transformer;
and then, judging whether the current on the secondary winding side of the current transformer is reduced simultaneously according to the multiple harmonic wave amplitude in the secondary current, if the current reduction characteristic is met, judging that the secondary circuit of the current transformer is open-circuited, and if the current reduction characteristic is not met, judging that the current transformer is saturated.
Preferably, the third harmonic fluctuation amplitude I3 in the second current is measured, if the third harmonic fluctuation amplitudes I3 are all greater than 5%, the fifth harmonic fluctuation amplitude I5 in the second current is measured, and if the fifth harmonic fluctuation amplitudes I5 are all greater than 1%, the next measurement is performed.
The invention comprehensively judges the operation condition of the secondary circuit of the current transformer aiming at the difference of harmonic characteristics when the secondary circuit of the current transformer is open-circuited, thereby comprehensively monitoring the operation state of the current transformer in real time. Compared with the prior art, its obvious advantage is:
1) the method for judging the operation condition of the secondary circuit based on the harmonic characteristics of the current transformer solves the problem that the operation condition of the secondary circuit of the current transformer is difficult to detect;
2) the invention discloses detailed steps of a method for judging the operation condition of a secondary circuit based on the harmonic characteristics of a current transformer, which is simple and easy to implement and can ensure that whether the secondary circuit is open or not can be judged accurately by adopting the method when the current transformer operates.
The following detailed description of the present invention will be provided in conjunction with the accompanying drawings.
Drawings
The invention is further described with reference to the accompanying drawings and the detailed description below:
fig. 1 is a flowchart of a method for determining an operating condition of a secondary circuit based on harmonic characteristics of a current transformer.
Fig. 2 is a harmonic variation diagram of a method for determining an operating condition of a secondary circuit based on a harmonic characteristic of a current transformer.
Fig. 3 is a schematic structural diagram of an apparatus for determining an operating condition of a secondary circuit based on a harmonic characteristic of a current transformer.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention comprehensively judges the operation condition of the secondary circuit of the current transformer aiming at the difference of harmonic characteristics when the secondary circuit of the current transformer is open-circuited, thereby comprehensively monitoring the operation state of the current transformer in real time.
Referring to fig. 1 and 2, the present invention discloses a method for determining the operating condition of a secondary circuit based on the harmonic characteristics of a current transformer, which comprises:
firstly, installing a secondary current detection module of the current transformer in the residual winding of the current transformer;
and then measuring the secondary current by using a current transformer secondary loop current detection module.
Measuring third harmonic wave amplitude I in secondary current3If the third harmonic fluctuation amplitude I3And if the content is more than 5 percent, the next measurement is carried out.
Measuring the fifth harmonic fluctuation amplitude I in the secondary current5If the fifth harmonic fluctuation amplitude I5And if the content is more than 1%, the next measurement is carried out.
And judging whether the current on the secondary winding side of the current transformer is reduced simultaneously. And if the current reduction characteristics are met (referring to the existing standard), judging that the secondary circuit of the current transformer is open-circuited. And if the current reduction characteristic is not satisfied, judging that the current transformer is saturated.
As shown in fig. 3, a device for determining the operating condition of a secondary circuit based on the harmonic characteristics of a current transformer includes a single chip 1, an analog/digital conversion module 2, a current signal interface 3, a display module 4, a sampling resistor 5, a power module 6, and a key module 7. The current signal is acquired through a current signal interface and a resistor, converted by an analog-digital sensor and then input into a single chip microcomputer for decomposition and judgment, and finally a judgment result is output. The input of the power supply module is a 12V rechargeable battery, and the output of the power supply module is 5V and 24V. The conversion from 12V to 5V is realized by an LM2576 chip, and the conversion from 12V to 24V is realized by an MC34063 chip.
The invention can comprehensively diagnose the operation state of the secondary circuit of the high-voltage current transformer by detecting and analyzing the harmonic characteristics in the secondary current of the current transformer so as to find and process open circuits in the secondary circuit in time, avoid potential safety hazards and power supply accidents caused by the fault of the current transformer and ensure the safe and stable operation of an electric power system. The method has higher popularization and practicability in the field of current transformer state monitoring.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that the invention is not limited thereto, and may be embodied in other forms without departing from the spirit or essential characteristics thereof. Any modification which does not depart from the functional and structural principles of the present invention is intended to be included within the scope of the claims.
Claims (2)
1. A method for judging the operation condition of a secondary circuit based on the harmonic characteristics of a current transformer is characterized in that: firstly, measuring the secondary current of a secondary loop of a current transformer;
and then, judging whether the current on the secondary winding side of the current transformer is reduced simultaneously according to the multiple harmonic wave amplitude in the secondary current, if the current reduction characteristic is met, judging that the secondary circuit of the current transformer is open-circuited, and if the current reduction characteristic is not met, judging that the current transformer is saturated.
2. The method for judging the operating condition of the secondary circuit based on the harmonic characteristics of the current transformer as claimed in claim 1, wherein: measuring the third harmonic fluctuation amplitude I3 in the secondary current, if the third harmonic fluctuation amplitudes I3 are all larger than 5%, measuring the fifth harmonic fluctuation amplitude I5 in the secondary current, and if the fifth harmonic fluctuation amplitudes I5 are all larger than 1%, performing the next measurement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110869311.1A CN113671233B (en) | 2021-07-30 | 2021-07-30 | Method for judging operation condition of secondary circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110869311.1A CN113671233B (en) | 2021-07-30 | 2021-07-30 | Method for judging operation condition of secondary circuit |
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| CN113671233A true CN113671233A (en) | 2021-11-19 |
| CN113671233B CN113671233B (en) | 2023-12-15 |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102967792A (en) * | 2012-11-19 | 2013-03-13 | 北京交通大学 | System and method for monitoring open-circuit faults of secondary circuit of current transformer in traction substation |
| KR20130039475A (en) * | 2011-10-12 | 2013-04-22 | 한국전력공사 | Over current relay for diagnosing open condition of current transformer secondary circuit and method thereof |
| US20140306716A1 (en) * | 2011-11-04 | 2014-10-16 | Abb Research Ltd | Methods for detecting an open current transformer |
| CN108132426A (en) * | 2018-02-13 | 2018-06-08 | 国网江苏省电力有限公司无锡供电分公司 | Current transformer circuit supervision fail Alarm Detector |
| KR102104835B1 (en) * | 2019-11-04 | 2020-04-27 | 중원 주식회사 | Gis for 29kv with prevention apparatus for secondary circuit opening of current transformer |
| CN111880118A (en) * | 2020-08-05 | 2020-11-03 | 广州东方电科自动化有限公司 | Connection fault detection circuit of current transformer |
-
2021
- 2021-07-30 CN CN202110869311.1A patent/CN113671233B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20130039475A (en) * | 2011-10-12 | 2013-04-22 | 한국전력공사 | Over current relay for diagnosing open condition of current transformer secondary circuit and method thereof |
| US20140306716A1 (en) * | 2011-11-04 | 2014-10-16 | Abb Research Ltd | Methods for detecting an open current transformer |
| CN102967792A (en) * | 2012-11-19 | 2013-03-13 | 北京交通大学 | System and method for monitoring open-circuit faults of secondary circuit of current transformer in traction substation |
| CN108132426A (en) * | 2018-02-13 | 2018-06-08 | 国网江苏省电力有限公司无锡供电分公司 | Current transformer circuit supervision fail Alarm Detector |
| KR102104835B1 (en) * | 2019-11-04 | 2020-04-27 | 중원 주식회사 | Gis for 29kv with prevention apparatus for secondary circuit opening of current transformer |
| CN111880118A (en) * | 2020-08-05 | 2020-11-03 | 广州东方电科自动化有限公司 | Connection fault detection circuit of current transformer |
Non-Patent Citations (3)
| Title |
|---|
| CHRISTIAN LAURANO 等: "A Simple Method for Compensating Harmonic Distortion in Current Transformers: Experimental Validation", 《SENSORS》, pages 1 - 19 * |
| 侯战斌 等: "电流互感器二次侧接入状态在线监测装置技术", 《科技和产业》, vol. 20, no. 4, pages 181 - 185 * |
| 龚成: "CT二次回路断线情况下变压器保护应用分析", 《机电信息》, no. 429, pages 40 - 41 * |
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