CN100388581C - Phase-splitting differential flow method for preventing voltage transformer differential protection unwanted operation - Google Patents
Phase-splitting differential flow method for preventing voltage transformer differential protection unwanted operation Download PDFInfo
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- CN100388581C CN100388581C CNB2004100163058A CN200410016305A CN100388581C CN 100388581 C CN100388581 C CN 100388581C CN B2004100163058 A CNB2004100163058 A CN B2004100163058A CN 200410016305 A CN200410016305 A CN 200410016305A CN 100388581 C CN100388581 C CN 100388581C
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- Prior art keywords
- differential
- current
- phase
- differential protection
- transformer
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- 230000004224 protection Effects 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 13
- 230000007257 malfunction Effects 0.000 claims abstract description 18
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
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Abstract
The present invention relates to a phase-splitting differential flow method for preventing the unwanted operation of differential protections for transformers; ratio braking elements are respectively composed of three-phase differential electric currents i<da>, i<db>, i<dc> in the differential protection for transformers and zero-sequence electric currents 3i<o> at the y<o> side of the transformer. When a ratio value is smaller than a definite value K, a corresponding differential electric current is judged to be an error current caused by an external fault; the differential protection for a corresponding phase ratio is stopped to prevent the malfunction of the differential protection for transformers. The method has the advantages that the present invention can thoroughly avoid the unwanted operation of differential protection for transformers, caused by the external grounding fault at the y<o> side when the errors of a three-phase electric current transformer are not same, and has no influence on the correct action of differential protection for internal faults.
Description
Technical field
The present invention relates to a kind of transformer protection method, particularly a kind of branch of transformer differential protection malfunction that prevents differs the stream method.
Background technology
Existing power transformer differential protection device by the ratio brake element, promptly by the ratio of differential current and through current, is discerned external area error and troubles inside the sample space; Simultaneously,, promptly, discern magnetizing inrush current and overexcitation electric current, reach the purpose of differentiating internal fault by analyzing the waveform or the harmonic content of differential current by shoving and the overexcitation braking member.To Y
0The power transformer of/Δ wiring is for preventing Y
0Lateral areas external ground fault zero-sequence current causes differential protection malfunction, extensively adopts Y at present
0The side three-phase current carries out the method for conversion, eliminates the influence of zero-sequence current.But work as Y
0Side threephase current transformer error is inconsistent, and transformer is only at the Y that external area error takes place
0When side has power supply, can not eliminate Y by conventional method
0The influence of the zero-sequence current that lateral areas external ground fault causes; bigger differential unsymmetrical current will be had; the ratio brake element, shove and the overexcitation braking member can not reliably be braked this; especially very little even be under zero the situation at the transformer load electric current; ratio brake element, the braking member that shoves can not be braked this; as long as error current surpasses threshold, transformer differential protection is with malfunction.
Summary of the invention
The object of the present invention is to provide a kind of branch of transformer differential protection malfunction that prevents to differ the stream method, with the three-phase differential current I in the transformer differential protection
Da, I
Db, I
DcRespectively with transformer Y
0Side zero-sequence current 3I
oThe component ratio braking member, when rate value during less than setting value K, declaring corresponding phase differential current is the error current that external area error causes, corresponding phase ratio differential protection is braked, and prevents the transformer differential protection malfunction.Advantage of the present invention is, in the time of can avoiding the threephase current transformer error inconsistent fully, and Y
0The transformer differential protection malfunction that lateral areas external ground fault causes.
A kind of branch of transformer differential protection malfunction that prevents differs the stream method, it is characterized in that: with the three-phase differential current I in the transformer differential protection
Da, I
Db, I
DcRespectively with transformer Y
0Side zero-sequence current 3I
oThe component ratio braking member, when rate value during less than setting value K, declaring corresponding phase differential current is the error current that external area error causes, exports the brake signal of corresponding phase, and corresponding phase ratio differential protection is braked;
Declaring corresponding phase differential current is the error current that external area error causes, the foundation of phase-splitting braking is:
I
da/3I
o＜K
I
db/3I
o＜K
I
dc/3I
o＜K
I in the formula
Da, I
Db, I
DcBe respectively the three-phase differential current, 3I
oBe Y
0Side zero-sequence current, K are setting value, arrive the same side at zero-sequence current and the reduction of three-phase differential current, and under the situation of same no-load voltage ratio, setting value K is 0＜K＜1/3.
With prior art relatively; advantage of the present invention is to have proposed first in traditional transformer differential protection; add a kind of with the three-phase differential current respectively with zero-sequence current component ratio braking member; when rate value during less than setting value K; declaring corresponding phase differential current is the error current that external area error causes; corresponding phase ratio differential protection is braked, prevented the transformer differential protection malfunction.Use this programme, in the time of can avoiding the threephase current transformer error inconsistent fully, Y
0The transformer differential protection malfunction that lateral areas external ground fault causes; also can prevent under other non-internal fault situations; the transformer differential protection misoperation that the differential unsymmetrical current that zero-sequence current causes causes, and the correct operation of differential protection under the zone of influence internal fault situation not.
Description of drawings
Fig. 1 is for realizing a kind of circuit block diagram that prevents the phase-splitting brake apparatus of transformer differential protection malfunction of the present invention.
Embodiment
Embodiment 1
A kind of branch of transformer differential protection malfunction that prevents differs the stream method, and this method can be achieved by a kind of circuit of the phase-splitting brake apparatus of transformer differential protection malfunction that prevents of Fig. 1.This device is made of filter 11～14, multiplier 2, comparator 31～33, and the input of its median filter 11～13 is A, B, the C three-phase differential current instantaneous value signal i of the formation of input transformer differential protection respectively
Da, i
Db, i
Dc, the input input transformer Y of filter 14
oSide zero-sequence current instantaneous value signal 3i
oAn input of its output termination multiplier 2, another input input setting value K of multiplier 2, the negative input end of comparator 31～33 is connected with the output of multiplier 2, its positive input terminal connects the output of filter 11～13 respectively, and comparator 31～33 is exported the brake signal of A, B, C phase respectively.Positive input terminal signal in comparator 31～33 is less than the negative input end signal, comparator output 0, declaring corresponding phase differential current is the error current that external area error causes, exports corresponding phase brake signal, corresponding phase ratio differential protection is braked, prevented the transformer differential protection malfunction; Otherwise comparator output 1 allows corresponding phase differential protection action.Arrive under the situation of the same side, same no-load voltage ratio in differential current and the equal reduction of zero-sequence current, setting value K is 0.1.The advantage of using this method is to avoid Y fully
0The transformer differential protection malfunction that lateral areas external ground fault causes, and the correct operation of differential protection under the zone of influence internal fault situation not.
Claims (1)
1. a branch that prevents the transformer differential protection malfunction differs the stream method, it is characterized in that: with the three-phase differential current I in the transformer differential protection
Da, I
Db, I
DcRespectively with transformer Y
0Side zero-sequence current 3I
oThe component ratio braking member, when rate value during less than setting value K, declaring corresponding phase differential current is the error current that external area error causes, exports the brake signal of corresponding phase, and corresponding phase ratio differential protection is braked, and prevents the transformer differential protection malfunction;
Declaring corresponding phase differential current is the error current that external area error causes, the foundation of phase-splitting braking is:
I
da/3I
o＜K
I
db/3I
o＜K
I
dc/3I
o＜K
I in the formula
Da, I
Db, I
DcBe respectively the three-phase differential current, 3I
oBe Y
0Side zero-sequence current, K are setting value, arrive the same side at zero-sequence current and the reduction of three-phase differential current, and under the situation of same no-load voltage ratio, setting value K is 0＜K＜1/3.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100163058A CN100388581C (en) | 2004-02-13 | 2004-02-13 | Phase-splitting differential flow method for preventing voltage transformer differential protection unwanted operation |
| PCT/CN2005/000194 WO2005078886A1 (en) | 2004-02-13 | 2005-02-16 | A zero-sequence current braking method for power transformer differential protection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100163058A CN100388581C (en) | 2004-02-13 | 2004-02-13 | Phase-splitting differential flow method for preventing voltage transformer differential protection unwanted operation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1558511A CN1558511A (en) | 2004-12-29 |
| CN100388581C true CN100388581C (en) | 2008-05-14 |
Family
ID=34351819
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004100163058A Expired - Fee Related CN100388581C (en) | 2004-02-13 | 2004-02-13 | Phase-splitting differential flow method for preventing voltage transformer differential protection unwanted operation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100388581C (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1047887C (en) * | 1994-01-06 | 1999-12-29 | 施耐德电器公司 | Device for differentially protecting a power transformer |
| CN1402400A (en) * | 2002-08-26 | 2003-03-12 | 南京南瑞继保电气有限公司 | Variable slope differential ratio protection method |
-
2004
- 2004-02-13 CN CNB2004100163058A patent/CN100388581C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1047887C (en) * | 1994-01-06 | 1999-12-29 | 施耐德电器公司 | Device for differentially protecting a power transformer |
| CN1402400A (en) * | 2002-08-26 | 2003-03-12 | 南京南瑞继保电气有限公司 | Variable slope differential ratio protection method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1558511A (en) | 2004-12-29 |
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