CN107887886B - A kind of improved triple-frequency harmonics stator grounding ratio criterion - Google Patents
A kind of improved triple-frequency harmonics stator grounding ratio criterion Download PDFInfo
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- CN107887886B CN107887886B CN201710981354.2A CN201710981354A CN107887886B CN 107887886 B CN107887886 B CN 107887886B CN 201710981354 A CN201710981354 A CN 201710981354A CN 107887886 B CN107887886 B CN 107887886B
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- frequency harmonics
- neutral point
- generator terminal
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Protection Of Generators And Motors (AREA)
Abstract
The invention discloses a kind of improved triple-frequency harmonics stator grounding ratio criterions, the extracting method of triple-frequency harmonics is realized using 10Hz as fundamental extraction 150Hz component in the criterion, pass through this method, the injection source of 20Hz is all filtered out as 2 subharmonic of 10Hz, the extraction of 150Hz component is not influenced by 20Hz component, and 150Hz component can be extracted accurately；In the criterion when neutral point 150Hz component is less than 0.2V, if not latch-up protection when the mutation of generator terminal 150Hz component is greater than 0.2V, neutral point PT broken string and neutral point low-impedance earthed system failure nearby can be correctly distinguished.
Description
Technical field
The present invention relates to a kind of improved triple-frequency harmonics stator grounding ratio criterions, belong to relay protection of power system neck
Domain.
Background technique
Neutral point is not directly grounded when large-scale generator, phase modifier etc. synchronize motor operation at present.It is fixed when occurring
When sub- ground fault, since earth current is smaller, the current differential protection for the configuration of these synchronous motors cannot be sensitive
Ground reflects this kind of failure.In order to reflect that Stator ground fault, synchronous motor generally configure individual stator ground fault protection, match at present
There are two types of types for the stator ground fault protection set, and one is fundamental wave zero-pressure stator ground fault protections and triple-frequency harmonics stator ground fault protection structure
At 100% stator ground fault protection；Another kind is injected type stator ground protection.Triple-frequency harmonics stator ground fault protection ratio criterion
It is one kind of triple-frequency harmonics stator ground fault protection, as the supplement of fundamental wave zero-pressure stator ground fault protection, leans on weakly acidic pH for protecting
Stator ground fault protection near point.
The triple-frequency harmonics used in ratio criterion at present is by extracting using 50Hz as the Fu Shi algorithm of fundamental wave.Do not having
Have inside the unit using injected type stator ground protection, this method does not have any problems.But using injected type stator
Inside the unit of ground protection, since the frequency in injection source is not that (country's injected type stator connects at present for the integral frequency harmonizing wave of 50Hz
Ground protection is substantially 20Hz), there are biggish errors for the method for tradition extraction triple-frequency harmonics.In addition, when neutral point PT breaks
When, ratio criterion malfunction in order to prevent, at present protection is considered neutral when judging that neutral point voltage is less than some value
Point PT broken string, directly locking ratio criterion.Erroneous judgement is neutrality when this method will lead to low-impedance earthed system near neutral point
Point PT broken string, leads to ratio criterion tripping.
Summary of the invention
In order to solve the above-mentioned technical problems, the present invention provides a kind of improved triple-frequency harmonics stator grounding ratio criterions.
In order to achieve the above object, the technical scheme adopted by the invention is that:
A kind of improved triple-frequency harmonics stator grounding ratio criterion, including,
Using 10Hz as fundamental wave, the 150Hz component of generator terminal and neutral point is extracted；
The ratio of computer terminal 150Hz component and neutral point 150Hz component, judges whether it is greater than the ratio calibration of adjusting
Value meets if it is greater than Ratio Conditions are then judged to, is otherwise judged to Ratio Conditions and is unsatisfactory for；
Judge whether generator terminal 150Hz component is less than voltage threshold, if it is less than being then judged to the small item of generator terminal third-harmonic component
Part meets, and is otherwise judged to the small condition of generator terminal third-harmonic component and is unsatisfactory for；
Judge whether neutral point 150Hz component is less than voltage threshold, if it is less than being then judged to neutral point third-harmonic component
Small condition meets, and is otherwise judged to the small condition of neutral point third-harmonic component and is unsatisfactory for；
Judge whether generator terminal 150Hz component is greater than voltage threshold relative to the Sudden Changing Rate before N1ms, if it is greater than voltage
The duration of threshold value is greater than N2ms, then is judged to generator terminal sudden change conditions satisfaction, is greater than adjusting if it is less than the time of voltage threshold
Time definite value add N3ms, then be judged to generator terminal sudden change conditions and be unsatisfactory for；
If the small condition of neutral point third-harmonic component meets and generator terminal sudden change conditions are unsatisfactory for or generator terminal is humorous three times
The small condition of wave component meets, then is judged to barring condition satisfaction, is otherwise judged to barring condition and is unsatisfactory for；
If Ratio Conditions meet and the barring condition ungratified duration is greater than the time definite value of adjusting, it is judged to
Triple-frequency harmonics stator grounding ratio criterion meets, protection act；
If the duration that Ratio Conditions are unsatisfactory for or barring condition meets is greater than N4ms, it is judged to triple-frequency harmonics stator
Ground connection ratio criterion is unsatisfactory for, and protection is failure to actuate.
Extract the 150Hz component of generator terminal and neutral point respectively using Fu Shi algorithm.
The range of voltage threshold is 0.1V ~ 0.3V.
Voltage threshold is 0.2V.
N1=100。
N2=20。
N3=200。
N4=100。
Advantageous effects of the invention: the extracting method of triple-frequency harmonics is using 10Hz as fundamental extraction in the 1, present invention
150Hz component is come what is realized, in this way, the injection source of 20Hz is all filtered out as 2 subharmonic of 10Hz, 150Hz divides
The extraction of amount is not influenced by 20Hz component, and 150Hz component can be extracted accurately；2, when neutral point 150Hz component in the present invention
When less than 0.2V, if not latch-up protection when the mutation of generator terminal 150Hz component is greater than 0.2V, it is disconnected can correctly to distinguish neutral point PT
Low-impedance earthed system failure near line and neutral point.
Detailed description of the invention
Fig. 1 is flow chart of the invention.
Specific embodiment
The invention will be further described below in conjunction with the accompanying drawings.Following embodiment is only used for clearly illustrating the present invention
Technical solution, and not intended to limit the protection scope of the present invention.
In microcomputer protective relay device, data acquisition and processing (DAP) be all it is discrete, in Microcomputer Protection be applicable in it is discrete
A specific embodiment of the invention is described, microcomputer protecting device adjusting cans be compared to rate definite value and time definite value, micro- for mode
Each sampled point of machine protective device takes improved triple-frequency harmonics stator grounding ratio criterion, as shown in Figure 1, including following step
It is rapid:
1) using 10Hz as fundamental wave, the 150Hz component of generator terminal and neutral point is extracted respectively using Fu Shi algorithm.
2) ratio of computer terminal 150Hz component and neutral point 150Hz component, judges whether it is greater than the ratio calibration of adjusting
Value meets if it is greater than Ratio Conditions are then judged to, is otherwise judged to Ratio Conditions and is unsatisfactory for.
3) judge whether generator terminal 150Hz component is less than voltage threshold, the range of voltage threshold is 0.1V ~ 0.3V, optimal value
All use 0.2V as voltage threshold for 0.2V(or less), meet if it is less than the small condition of generator terminal third-harmonic component is then judged to,
Otherwise the small condition of generator terminal third-harmonic component is judged to be unsatisfactory for.
4) judge whether neutral point 150Hz component is less than 0.2V, neutral point third-harmonic component is small if it is less than being then judged to
Condition meets, and is otherwise judged to the small condition of neutral point third-harmonic component and is unsatisfactory for.
5) judge whether generator terminal 150Hz component is greater than 0.2V relative to the Sudden Changing Rate before N1ms, N1=100, if it is greater than
The duration of 0.2V is greater than N2ms, and N2=20 are then judged to generator terminal sudden change conditions satisfaction, is greater than if it is less than the time of 0.2V whole
Fixed time definite value adds N3ms, and N3=200 are then judged to generator terminal sudden change conditions and are unsatisfactory for.
If 6) the small condition of neutral point third-harmonic component meet and generator terminal sudden change conditions be unsatisfactory for or generator terminal three times
The small condition of harmonic component meets, then is judged to barring condition satisfaction, is otherwise judged to barring condition and is unsatisfactory for.
If 7) Ratio Conditions meet and the barring condition ungratified duration be greater than adjusting time definite value when, sentence
For triple-frequency harmonics stator grounding ratio criterion satisfaction, protection act；If Ratio Conditions be unsatisfactory for or barring condition meet
Duration is greater than N4ms, and N4=100 are judged to triple-frequency harmonics stator grounding ratio criterion and are unsatisfactory for, and protection is failure to actuate.
In above-mentioned improved triple-frequency harmonics stator grounding ratio criterion, the extracting method of triple-frequency harmonics is mentioned by fundamental wave of 10Hz
150Hz component is taken to realize, in this way, the injection source of 20Hz is all filtered out as 2 subharmonic of 10Hz, 150Hz
The extraction of component is not influenced by 20Hz component, and 150Hz component can be extracted accurately.
Since when low-impedance earthed system there is mutation in generator terminal 150Hz component near neutral point, and 150Hz points when neutral point PT broken string
There is no mutation for amount, this feature are based on, in improved triple-frequency harmonics stator grounding ratio criterion, when neutral point 150Hz component is small
When 0.2V, if not latch-up protection when the mutation of generator terminal 150Hz component is greater than 0.2V, neutral point PT broken string can be correctly distinguished
With low-impedance earthed system failure near neutral point.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, without departing from the technical principles of the invention, several improvement and deformations can also be made, these improvement and deformations
Also it should be regarded as protection scope of the present invention.
Claims (8)
1. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion, it is characterised in that: including,
Using 10Hz as fundamental wave, the 150Hz component of generator terminal and neutral point is extracted；
The ratio of computer terminal 150Hz component and neutral point 150Hz component, judges whether it is greater than the ratio definite value of adjusting, such as
Fruit, which is greater than, is then judged to Ratio Conditions satisfaction, is otherwise judged to Ratio Conditions and is unsatisfactory for；
Judge whether generator terminal 150Hz component is less than voltage threshold, it is full if it is less than the small condition of generator terminal third-harmonic component is then judged to
Foot, is otherwise judged to the small condition of generator terminal third-harmonic component and is unsatisfactory for；
Judge whether neutral point 150Hz component is less than voltage threshold, if it is less than being then judged to the small item of neutral point third-harmonic component
Part meets, and is otherwise judged to the small condition of neutral point third-harmonic component and is unsatisfactory for；
Judge whether generator terminal 150Hz component is greater than voltage threshold relative to the Sudden Changing Rate before N1ms, if it is greater than voltage threshold
Duration be greater than N2ms, then be judged to generator terminal sudden change conditions satisfaction, if it is less than voltage threshold time be greater than adjusting when
Between definite value add N3ms, then be judged to generator terminal sudden change conditions and be unsatisfactory for；
If the small condition of neutral point third-harmonic component meets and generator terminal sudden change conditions are unsatisfactory for or generator terminal triple-frequency harmonics point
It measures small condition to meet, is then judged to barring condition satisfaction, is otherwise judged to barring condition and is unsatisfactory for；
If Ratio Conditions meet and the barring condition ungratified duration is greater than the time definite value of adjusting, it is judged to three times
Harmonic wave stator grounding ratio criterion meets, protection act；
If the duration that Ratio Conditions are unsatisfactory for or barring condition meets is greater than N4ms, it is judged to triple-frequency harmonics stator grounding
Ratio criterion is unsatisfactory for, and protection is failure to actuate.
2. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion according to claim 1, feature
It is: extracts the 150Hz component of generator terminal and neutral point respectively using Fu Shi algorithm.
3. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion according to claim 1, feature
Be: the range of voltage threshold is 0.1V ~ 0.3V.
4. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion according to claim 3, feature
It is: voltage threshold 0.2V.
5. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion according to claim 1, feature
It is: N1=100.
6. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion according to claim 1, feature
It is: N2=20.
7. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion according to claim 1, feature
It is: N3=200.
8. a kind of method based on improved triple-frequency harmonics stator grounding ratio criterion according to claim 1, feature
It is: N4=100.
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| CN201710981354.2A CN107887886B (en) | 2017-10-20 | 2017-10-20 | A kind of improved triple-frequency harmonics stator grounding ratio criterion |
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| CN201710981354.2A CN107887886B (en) | 2017-10-20 | 2017-10-20 | A kind of improved triple-frequency harmonics stator grounding ratio criterion |
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| CN107887886B true CN107887886B (en) | 2019-02-26 |
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| CN110488136B (en) * | 2019-08-12 | 2021-11-30 | 河海大学 | Rotor one-point grounding fault detection method of phase modulator excitation system |
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| CN100373729C (en) * | 2005-01-14 | 2008-03-05 | 北京四方继保自动化股份有限公司 | Stator grounding protection with combined third harmonic dynamic alignment criterion and voltage ratio criterion |
| CN103091595B (en) * | 2012-07-23 | 2015-09-02 | 南京南瑞继保电气有限公司 | The method of discrimination that a kind of generator terminal voltage mutual inductor once breaks |
| CN105655977B (en) * | 2016-03-23 | 2017-12-26 | 南京国电南自电网自动化有限公司 | Earthing protection method for stator based on third harmonic voltage variable quantity differential principle |
| CN107240905B (en) * | 2017-08-03 | 2018-11-23 | 南京国电南自电网自动化有限公司 | A kind of third harmonic voltage earthing protection method for stator |
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