CN1057646C - Virtual third harmonic blocking method for transformer microcomputer protection - Google Patents
Virtual third harmonic blocking method for transformer microcomputer protection Download PDFInfo
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- CN1057646C CN1057646C CN97109270A CN97109270A CN1057646C CN 1057646 C CN1057646 C CN 1057646C CN 97109270 A CN97109270 A CN 97109270A CN 97109270 A CN97109270 A CN 97109270A CN 1057646 C CN1057646 C CN 1057646C
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- Prior art keywords
- locking information
- time
- virtual
- harmonic
- differential protection
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Abstract
The present invention relates to a virtual third harmonic locking method for the microcomputer protection of transformers, which comprises the steps that a sampling value of the first half industrial frequency period is obtained after failure happens, and a half period signal is orderly moved and is used as a sampling value of the next half industrial frequency period after signs are changed. When U3/U1 is more than a set value, locking information is transmitted once. A sampling point is orderly shifted, and the processes are repeated for m times. If the locking information does not exist in m times, differential protection trip is allowed. If the locking information exists in m times, calculation is prolonged after m times. When the processes are prolonged and repeated subsequently, if the locking information does not exist in m times continuously, the differential protection trip is allowed. The method of the present invention is suitable for power transformers with symmetric harmonics, asymmetric harmonics and various capacity and winding connecting modes, and has the advantages that action is swift, excitation surges can not result in wrong action, etc.
Description
When the invention belongs to power transformer generation internal fault, need be by the virtual third harmonic blocking method of rapidly that failure removal is the used transformer microcomputer protection of protective relaying device.
Need be during power transformer generation internal fault by protective relaying device rapidly with failure removal, with the minimizing accident extent of damage.The relaying protection of power transformer mainly is made of differential protection, and it can not have time-delay ground excision fault.But, for the differential protection that guarantees power transformer correctly, reliably, work selectively, must overcome two major obstacles, promptly 1. the appearance of the transient state magnetizing inrush current of transformer does not cause differential protection misoperation, the mistake locking of the discriminating element that is subjected to when yet not making transformer generation internal fault shoving and tripping; When 2. being short-circuited fault in the transformer outside, unlikely so the time unsymmetrical current that can take place and cause differential protection misoperation.But when internal fault, the technical measures taked of essential factor and reduce the sensitivity of the action of protective device not.
In the prior art magnetizing inrush current problem being adopted maximum technology both at home and abroad is " second harmonic locking " method, secondly is " interval angle differentiation " method, and large-scale power transformer is then required to realize " dualization " with the different technologies scheme.Second harmonic blocking method of the prior art has following deficiency: 1. internal short-circuit can produce second harmonic temporarily with the locking of differential protection mistake because of resonance when there is electric capacity the outside; 2. to commonly used
/ delta connection power transformer can produce " symmetry harmonic wave ", and second harmonic is seriously reduced, and loses blocking function, makes the differential protection delay tripping.
The present invention is directed to the deficiencies in the prior art, propose a kind of employing virtual third harmonic blocking method, to solve the problem that power trans-former protection produces misoperation and mistake locking.
The main flow process of the method applied in the present invention is: get the sampled value that first half power frequency period in back takes place fault, with this half period sampled value along move and reindexing as the sampled value (seeing shown in the dotted line in the accompanying drawing 2,3) of later half power frequency period.Again with the virtual complete all signals of the common composition of preceding half cycle signal.Get the triple-frequency harmonics U in the complete period information
3And first-harmonic value U
1, work as U
3/ U
1Send locking information once during greater than the brake percentage B that adjusts (B can select) between 0.20～0.25.With sampled point of half cycle sampling window forwards (each sampled point can be 15 °～45 ° electrical degrees usually), repeat said process.When said process Repeated m time (m=3～5), if in m time completely without locking information, then allow differential protection to trip; If locking information is arranged more than once in m time, the computing of then postponing after m time is postponed during the repetition said process follow-up, meets continuous m no locking information and then allows differential protection to trip.
When magnetizing inrush current decays to seldom, when above-mentioned criterion is not enough to move, mainly reliably brake by the differential protection assurance of band brake characteristic itself.
Virtual third harmonic blocking method of the present invention is applicable to the humorous asymmetry harmonic wave that involves of symmetry simultaneously; Be applicable to various amount of capacity, the power transformer of electric pressure and winding connection mode.Have be swift in motion (operate time of protection is no longer than 18 milliseconds), external fault and magnetizing inrush current of internal fault and can not cause advantages such as misoperation.
Accompanying drawing 1: the main flow chart of this method;
Accompanying drawing 2: asymmetric shoving and virtual waveform;
Accompanying drawing 3: symmetry is shoved and virtual waveform.
Be further described below in conjunction with the principle of accompanying drawing the said virtual third harmonic blocking method of the present invention.
What accompanying drawing 1 was given is the main flow chart of realizing this method; What accompanying drawing 2,3 provided is asymmetric and symmetrical shoving and their pairing virtual waveform.Solid line in accompanying drawing 2,3 is represented original waveform, and dotted line is represented virtual waveform.The method applied in the present invention is to get the sampled value that first half power frequency period in back takes place fault, the signal of second half is along moving and changing its positive and negative symbol with preceding half period sampled value, sampled value (seeing shown in the dotted line in the accompanying drawing 2,3) as later half power frequency period, after handling like this, get the triple-frequency harmonics value U in the complete period information
3And first-harmonic value U
1Compare, work as U
3/ U
1Send locking information once greater than 0.20～0.25 o'clock, with sampled point of half cycle sampling window forwards (such as 30 ° of electrical degrees), get the triple-frequency harmonics value U in the complete period information more then
3And first-harmonic value U
1Compare, promptly repeat said process.As repeat said process m time (m=3～5), and in m time completely without locking information, then allow differential protection tripping operation; If more than having once in m time locking information is arranged, the computing of then postponing after m time is postponed during the repetition said process follow-up, meets continuous m no locking information and then allows differential protection to trip.
Claims (1)
1. a virtual third harmonic blocking method that is used for transformer microcomputer protection is:
A, the sampled value of getting first half power frequency period in fault generation back;
B, with this half period signal along moving and changing its positive and negative number sampled value as later half power frequency period;
C, get the triple-frequency harmonics U in the virtual complete period information that step a, b constitute
3And first-harmonic value U
1
D, work as U
3/ U
1Send locking information once during greater than the brake percentage of adjusting;
E, with sampled point of half cycle sampling window forwards;
F, repetition said process;
G, repeat said process m time, m=3～5 time;
H, if in m time completely without locking information, then allow differential protection to trip;
I, if locking information is arranged, the computing of then after m time, postponing more than once in m time;
J, in the follow-up repetition said process of postponing, meet continuous m no locking information and then allow differential protection tripping operation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97109270A CN1057646C (en) | 1997-10-15 | 1997-10-15 | Virtual third harmonic blocking method for transformer microcomputer protection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97109270A CN1057646C (en) | 1997-10-15 | 1997-10-15 | Virtual third harmonic blocking method for transformer microcomputer protection |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1187704A CN1187704A (en) | 1998-07-15 |
| CN1057646C true CN1057646C (en) | 2000-10-18 |
Family
ID=5171075
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN97109270A Expired - Fee Related CN1057646C (en) | 1997-10-15 | 1997-10-15 | Virtual third harmonic blocking method for transformer microcomputer protection |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1057646C (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100350696C (en) * | 2004-02-13 | 2007-11-21 | 浙江大学 | Negative sequence synthesized brake device for preventing multiple-branch voltage transformer differential protection unwanted operation |
| CN100350700C (en) * | 2004-02-13 | 2007-11-21 | 浙江大学 | Phase-splitting difference stream method for preventing multiple-branch voltage transformer differential protection unwanted operation by utilizing fault components |
| CN100367600C (en) * | 2004-02-13 | 2008-02-06 | 浙江大学 | Phase-splitting integrated zero-sequence brake method for preventing multiple-branch voltage transformer differential protection unwanted operation |
| CN100392934C (en) * | 2004-02-13 | 2008-06-04 | 浙江大学 | Phase-splitting difference stream method for preventing voltage transformer differential protection unwanted operation by utilizing fault components |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1141097A (en) * | 1994-01-06 | 1997-01-22 | 施耐德电器公司 | Device for differentially protecting a power transformer |
-
1997
- 1997-10-15 CN CN97109270A patent/CN1057646C/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1141097A (en) * | 1994-01-06 | 1997-01-22 | 施耐德电器公司 | Device for differentially protecting a power transformer |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100350696C (en) * | 2004-02-13 | 2007-11-21 | 浙江大学 | Negative sequence synthesized brake device for preventing multiple-branch voltage transformer differential protection unwanted operation |
| CN100350700C (en) * | 2004-02-13 | 2007-11-21 | 浙江大学 | Phase-splitting difference stream method for preventing multiple-branch voltage transformer differential protection unwanted operation by utilizing fault components |
| CN100367600C (en) * | 2004-02-13 | 2008-02-06 | 浙江大学 | Phase-splitting integrated zero-sequence brake method for preventing multiple-branch voltage transformer differential protection unwanted operation |
| CN100392934C (en) * | 2004-02-13 | 2008-06-04 | 浙江大学 | Phase-splitting difference stream method for preventing voltage transformer differential protection unwanted operation by utilizing fault components |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1187704A (en) | 1998-07-15 |
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| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |