CN104134972A - Method for preventing trailing current of current transformer from influencing circuit breaker failure protection - Google Patents
Method for preventing trailing current of current transformer from influencing circuit breaker failure protection Download PDFInfo
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- CN104134972A CN104134972A CN201410281034.2A CN201410281034A CN104134972A CN 104134972 A CN104134972 A CN 104134972A CN 201410281034 A CN201410281034 A CN 201410281034A CN 104134972 A CN104134972 A CN 104134972A
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Abstract
The invention discloses a method for preventing trailing current of a current transformer from influencing circuit breaker failure protection. The method comprises the steps of judging the trailing current of the current transformer, including judging zero passage of a sampling point and judging current decrease to determine whether the trailing current of the current transformer exists at present, then allowing a failure protection circuit breaker to act after the original fixed failure protection action time plus short time delay if the trailing current of the current transformer exists at present, and allowing the failure protection circuit breaker to act in accordance with the original fixed time if the trailing current of the current transformer does not exist at present. The method achieves effective identification of the trailing current of the current transformer, and reduces a misjudgment rate of the trailing current of the current transformer; if the trailing current of the current transformer is not identified, no time delay is required; if current of the current transformer is judged to be in a trailing state, failure action time increase does not much influence a power system; and contradiction of failure protection action rapidity and reliability is solved.
Description
Technical field
The present invention relates to a kind of method of current transformer hangover electric current on breaker fail protection impact that prevent, belong to power system automation technology field.
Background technology
Due to the development of power grid construction, the dynamic stabiltiy limit of southern mesh portions 500kV transformer station only has 300ms left and right, therefore requires malfunctioning switch protection responsiveness to accelerate, and original failure protection time definite value need to be tapered to 200ms by 300ms.But failure protection malfunction is worried again in too short time delay, especially when switch does not excise fault when zero passage at electric current, likely cause current transformer (being called for short CT) hangover.The electric current that CT flows through after circuit breaker is opened can not be reduced to zero at once, but presents the feature of attenuating dc component, and common this phenomenon is referred to as CT hangover.If be left intact in this situation, the current value that protective device calculates must be greater than failure protection definite value in the short time, easily causes failure protection malfunction.In relaying protection work in the past, if failure protection time definite value is larger, can escape CT hangover time, if in the situation that failure protection time definite value reduces, CT hangover electric current will exert an influence to breaker fail protection.So-called breaker fail protection; refer in the time that electric power system is broken down; tripping operation pulse is sent in the protection action of fault element and circuit breaker miss operation utilizes the protection of fault element, moves in other the relevant circuit breaker excision fault being connected on same bus with the shorter time limit.In the time that CT trails, fault element may not return, if do not taken measures, and breaker fail protection malfunction, very serious according to moving consequence.
At present relevant CT hangover is considered less both at home and abroad on the impact of failure protection; normally utilize failure protection time setting to escape CT hangover time; but in the time that the moving steady time of system does not allow, need to shorten in failure protection time definite value situation, just there will be the difficulty of adjusting.
Summary of the invention
The deficiency existing for prior art, the object of the invention is to provide a kind of method of current transformer hangover electric current on breaker fail protection impact that prevent, has solved the contradiction of failure protection action rapidity and reliability, has reduced the impact on electric power system.
To achieve these goals, the present invention realizes by the following technical solutions:
A kind of method of current transformer hangover electric current on breaker fail protection impact that prevent of the present invention, specifically comprises following step:
(1) current transformer hangover electric current judgement: comprise that the judgement of sampled point zero passage and electric current reduce judgement, thereby determine the current current transformer hangover electric current that whether exists;
(2) after current transformer hangover electric current has judged, have current transformer hangover electric current if current, failure protection moves increase short time delay in original failure protection definite value operate time after again; If do not have current transformer hangover electric current current, failure protection circuit breaker moves according to original failure protection definite value operate time.
Above-mentioned sampled point zero passage determination methods is as follows:
If current sample is 50Hz ideal waveform,, in a wave period, the time of continuous three zero crossings of current sample is 20ms;
If current sample is current transformer hangover electric current, not zero passage of current sample;
Therefore sampled point zero passage criterion is set: if the time of continuous three zero crossings of current sample, between 17.5ms～22.5ms, does not currently exist current transformer hangover electric current, otherwise have current transformer hangover electric current.
It is as follows that above-mentioned electric current reduces determination methods:
Failure protection is preserved current current-mode value as save value after starting a wave period; in the time that the time delay of failure protection definite value operate time meets; again judge the size of current current-mode value; if judge the save value that current current-mode value is less than 0.2 times; illustrate that fault after-current obviously reduces; currently there is not current transformer hangover electric current, otherwise have current transformer hangover electric current.
In step (2), be 100ms because electric power system setting time is differential, for ensure that reliability prevents from moving with other elements simultaneously, so the time of the short time delay that failure protection increases is 50ms.
The present invention has realized effective identification of current transformer hangover electric current, and utilizes the judgement of sampled point zero passage and electric current to reduce judgement, has reduced the False Rate of current transformer hangover electric current; In the time that current transformer hangover electric current fails to identify, illustrate that fault current is larger, do not need to increase time delay, in the time differentiating current transformer electric current in hangover state, illustrate that fault current is less, increase malfunctioning operate time little to effect on power system, failure protection processing scheme adaptability is high; Circuit breaker adopts after method of the present invention; in the time that failure protection tapers to 160ms by 300ms operate time; also can not produce failure protection misoperation because current transformer trails, and there will not be failure protection tripping, solve the contradiction of failure protection action rapidity and reliability.
Brief description of the drawings
Fig. 1 is failure protection elemental motion logic;
Action logic when Fig. 2 is the hangover of failure protection current transformer.
Embodiment
For technological means, creation characteristic that the present invention is realized, reach object and effect is easy to understand, below in conjunction with embodiment, further set forth the present invention.
Method of the present invention comprises current transformer hangover electric current identification and the processing method of failure protection in the time that current transformer trails.
The method combines the feature of current sample waveform and Fourier algorithm result.The recognition methods of current transformer hangover comprises two parts: 1, cyclic variation does not appear in the polarity of current waveform sampled point.2, the amplitude of electric current Fourier result of calculation has variation tendency from large to small.In the time that current waveform meets above two conditions, differentiate current electric current and be the CT waveform that trails, not normal AC wave shape.
The concrete methods of realizing of current transformer hangover electric current identification is as follows:
(1) sampled point zero passage criterion:
After starting, drops into breaker fail protection sampled point zero passage criterion.When current sample point is by just becoming negative or becoming timing by negative, think sampled point zero passage.If determine the time of continuous three zero crossings of current sample between 17.5ms～22.5ms, think normal current waveform, not hangover electric current, otherwise think that this electric current is in the current transformer state that trails.
(2) electric current reduces criterion:
After breaker fail protection starts, drop into electric current and reduce criterion.Failure protection is preserved current current-mode value after starting 20ms; in the time that the time delay of failure protection relay setting meets; again differentiate the size of current current-mode value; if the save value that current electric current is greater than 0.2 times; think that current electric current is not in current transformer hangover state, otherwise be judged to be current electric current in the current transformer state that trails.
The processing method of failure protection in the time that current transformer trails is as follows:
In the time adopting said method to identify current transformer electric current and do not trail, according to failure protection according to the time definite value action of adjusting, otherwise automatically to exporting after failure protection time relay time delay 50ms.As a comparison, list basic failure protection logic (referring to Fig. 1), and the failure protection action logic (referring to Fig. 2) that provides of this programme.
The present invention has realized effective identification of current transformer hangover electric current, and utilizing the judgement of sampled point zero passage and electric current to reduce judgement combines, in the time that arbitrary criterion meets, think that current transformer does not exist hangover electric current, reduce the False Rate of current transformer hangover electric current; In the time that current transformer hangover electric current fails to identify, illustrate that fault current is larger, do not need to increase time delay, in the time differentiating current transformer electric current in hangover state, illustrate that fault current is less, increase malfunctioning operate time little to effect on power system, failure protection processing scheme adaptability is high; Circuit breaker adopts after method of the present invention; in the time that failure protection tapers to 160ms by 300ms operate time; also can not produce failure protection misoperation because current transformer trails, and there will not be failure protection tripping, solve the contradiction of failure protection action rapidity and reliability.
More than show and described general principle of the present invention and principal character and advantage of the present invention.The technical staff of the industry should understand; the present invention is not restricted to the described embodiments; that in above-described embodiment and specification, describes just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.
Claims (4)
1. prevent the method for current transformer hangover electric current on breaker fail protection impact, it is characterized in that, specifically comprise following step:
(1) current transformer hangover electric current judgement: comprise that the judgement of sampled point zero passage and electric current reduce judgement, thereby determine the current current transformer hangover electric current that whether exists;
(2) after current transformer hangover electric current has judged, have current transformer hangover electric current if current, failure protection moves increase short time delay in original failure protection definite value operate time after again; If do not have current transformer hangover electric current current, failure protection circuit breaker moves according to original failure protection definite value operate time.
2. the method for current transformer hangover electric current on breaker fail protection impact that prevent according to claim 1, is characterized in that,
Described sampled point zero passage determination methods is as follows:
If current sample is 50Hz ideal waveform,, in a wave period, the time of continuous three zero crossings of current sample is 20ms;
If current sample is current transformer hangover electric current, not zero passage of current sample;
Therefore sampled point zero passage criterion is set: if the time of continuous three zero crossings of current sample, between 17.5ms～22.5ms, does not currently exist current transformer hangover electric current, otherwise have current transformer hangover electric current.
3. the method for current transformer hangover electric current on breaker fail protection impact that prevent according to claim 1, is characterized in that,
It is as follows that described electric current reduces determination methods:
Failure protection is preserved current current-mode value as save value after starting a wave period; in the time that the time delay of failure protection definite value operate time meets; again judge the size of current current-mode value; if judge the save value that current current-mode value is less than 0.2 times; illustrate that fault after-current obviously reduces; currently there is not current transformer hangover electric current, otherwise have current transformer hangover electric current.
4. according to the method for current transformer hangover electric current on breaker fail protection impact that prevent described in claims 1 to 3 any one, it is characterized in that,
In step (2), be 100ms because electric power system setting time is differential, for ensure that reliability prevents from moving with other elements simultaneously, so the time of the short time delay that failure protection increases is 50ms.
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| CN201410281034.2A CN104134972B (en) | 2014-06-20 | 2014-06-20 | A kind of method preventing current transformer tail currents from breaker fail protection being affected |
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Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104977452A (en) * | 2014-12-22 | 2015-10-14 | 中国南方电网有限责任公司 | Failure protection mutual inductor tail current detection method |
| CN105866511A (en) * | 2016-05-27 | 2016-08-17 | 国电南瑞科技股份有限公司 | Method for recognizing trailing currents based on adjacent sampling point specific values of current wave forms |
| CN105914714A (en) * | 2016-05-16 | 2016-08-31 | 国电南瑞科技股份有限公司 | Method based on current waveform recognition for preventing failure protection maloperation of circuit breaker |
| CN105929217A (en) * | 2016-05-12 | 2016-09-07 | 国电南瑞科技股份有限公司 | Method for discriminating tail current in ineffective protection based on DC component blocking |
| CN105954563A (en) * | 2016-05-16 | 2016-09-21 | 国电南瑞科技股份有限公司 | Method of identifying tail current based on current derivative and differential current zero-crossing |
| CN106451369A (en) * | 2015-08-13 | 2017-02-22 | 中国电力科学研究院 | Current transformer tail current truncation method in failure protection |
| CN106451328A (en) * | 2016-11-22 | 2017-02-22 | 长园深瑞继保自动化有限公司 | Adaptive breaker failure protection method |
| WO2017059655A1 (en) * | 2015-10-08 | 2017-04-13 | 南京南瑞继保电气有限公司 | Method for detecting transformer tail current |
| CN107221915A (en) * | 2017-05-17 | 2017-09-29 | 南京南瑞继保电气有限公司 | A kind of method of dc circuit breaker failure protection |
| CN108695823A (en) * | 2018-06-26 | 2018-10-23 | 南京南瑞继保电气有限公司 | A kind of differential protection blocking method of series transformer tail currents |
| CN109888750A (en) * | 2019-03-25 | 2019-06-14 | 国电南瑞科技股份有限公司 | A kind of shortening site failure protection time delay of action method and system |
| CN111505435A (en) * | 2020-04-10 | 2020-08-07 | 三峡大学 | Current transformer trailing current identification method based on Frechet distance algorithm |
| CN111797699A (en) * | 2020-06-10 | 2020-10-20 | 积成软件有限公司 | Method for identifying fault-removal CT trailing waveform |
| CN112072610A (en) * | 2020-08-06 | 2020-12-11 | 许继集团有限公司 | Breaker failure protection optimization method and system based on comprehensive difference |
| CN114400622A (en) * | 2021-12-28 | 2022-04-26 | 北京四方继保工程技术有限公司 | Circuit breaker failure protection optimization method and system based on current waveform recognition |
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| CN104977452A (en) * | 2014-12-22 | 2015-10-14 | 中国南方电网有限责任公司 | Failure protection mutual inductor tail current detection method |
| CN106451369A (en) * | 2015-08-13 | 2017-02-22 | 中国电力科学研究院 | Current transformer tail current truncation method in failure protection |
| CN106451369B (en) * | 2015-08-13 | 2019-03-08 | 中国电力科学研究院 | A kind of chopping current mutual inductor tail currents method in failure protection |
| WO2017059655A1 (en) * | 2015-10-08 | 2017-04-13 | 南京南瑞继保电气有限公司 | Method for detecting transformer tail current |
| CN106569163A (en) * | 2015-10-08 | 2017-04-19 | 南京南瑞继保电气有限公司 | Method for detecting trailing amount of transformer |
| CN105929217A (en) * | 2016-05-12 | 2016-09-07 | 国电南瑞科技股份有限公司 | Method for discriminating tail current in ineffective protection based on DC component blocking |
| CN105929217B (en) * | 2016-05-12 | 2019-01-08 | 国电南瑞科技股份有限公司 | A kind of failure protection current tail method of discrimination based on DC component locking |
| CN105914714A (en) * | 2016-05-16 | 2016-08-31 | 国电南瑞科技股份有限公司 | Method based on current waveform recognition for preventing failure protection maloperation of circuit breaker |
| CN105954563A (en) * | 2016-05-16 | 2016-09-21 | 国电南瑞科技股份有限公司 | Method of identifying tail current based on current derivative and differential current zero-crossing |
| CN105914714B (en) * | 2016-05-16 | 2018-06-29 | 国电南瑞科技股份有限公司 | The method for preventing breaker fail protection malfunction based on current waveform identification |
| CN105954563B (en) * | 2016-05-16 | 2018-09-28 | 国电南瑞科技股份有限公司 | The method for identifying tail currents based on electric current derivation and difference current zero crossing |
| CN105866511A (en) * | 2016-05-27 | 2016-08-17 | 国电南瑞科技股份有限公司 | Method for recognizing trailing currents based on adjacent sampling point specific values of current wave forms |
| CN106451328A (en) * | 2016-11-22 | 2017-02-22 | 长园深瑞继保自动化有限公司 | Adaptive breaker failure protection method |
| CN106451328B (en) * | 2016-11-22 | 2018-11-13 | 长园深瑞继保自动化有限公司 | Adaptive breaker fail protection method |
| CN107221915A (en) * | 2017-05-17 | 2017-09-29 | 南京南瑞继保电气有限公司 | A kind of method of dc circuit breaker failure protection |
| CN108695823A (en) * | 2018-06-26 | 2018-10-23 | 南京南瑞继保电气有限公司 | A kind of differential protection blocking method of series transformer tail currents |
| CN109888750A (en) * | 2019-03-25 | 2019-06-14 | 国电南瑞科技股份有限公司 | A kind of shortening site failure protection time delay of action method and system |
| CN109888750B (en) * | 2019-03-25 | 2021-07-06 | 国电南瑞科技股份有限公司 | Method and system for shortening in-place failure protection action time delay |
| CN111505435A (en) * | 2020-04-10 | 2020-08-07 | 三峡大学 | Current transformer trailing current identification method based on Frechet distance algorithm |
| CN111505435B (en) * | 2020-04-10 | 2022-02-08 | 三峡大学 | Current transformer trailing current identification method based on Frechet distance algorithm |
| CN111797699A (en) * | 2020-06-10 | 2020-10-20 | 积成软件有限公司 | Method for identifying fault-removal CT trailing waveform |
| CN112072610A (en) * | 2020-08-06 | 2020-12-11 | 许继集团有限公司 | Breaker failure protection optimization method and system based on comprehensive difference |
| CN112072610B (en) * | 2020-08-06 | 2022-10-04 | 许继集团有限公司 | Breaker failure protection optimization method and system based on comprehensive difference |
| CN114400622A (en) * | 2021-12-28 | 2022-04-26 | 北京四方继保工程技术有限公司 | Circuit breaker failure protection optimization method and system based on current waveform recognition |
| CN114400622B (en) * | 2021-12-28 | 2024-05-10 | 北京四方继保工程技术有限公司 | Circuit breaker failure protection optimization method and system based on current waveform identification |
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