CN100350705C - Maximum current zero sequence braking method for preventing transformer protection malfunction - Google Patents
Maximum current zero sequence braking method for preventing transformer protection malfunction Download PDFInfo
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- CN100350705C CN100350705C CNB2004100847584A CN200410084758A CN100350705C CN 100350705 C CN100350705 C CN 100350705C CN B2004100847584 A CNB2004100847584 A CN B2004100847584A CN 200410084758 A CN200410084758 A CN 200410084758A CN 100350705 C CN100350705 C CN 100350705C
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- current
- transformer
- electric current
- maximum
- zero sequence
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Abstract
The present invention discloses a maximum electric current zero sequence braking method for preventing the malfunction protection for transformers; a ratio braking element is composed of the maximum value of a three-phase electric current at the Y0 side of a transformer and a zero sequence electric current; when a ratio value is smaller than a definite value, a braking signal is output to stop the differential protection for transformer ratios. The application of the proposal only collects the three-phase electric current with a power supply at the Y0 side, and uses the ratio braking element composed of the maximum value of a three-phase electric current and the zero sequence electric current at the side, which can thoroughly avoid the malfunction of differential protection for transformers caused by an external grounding fault at the Y0 side when the errors of a three-phase electric current transformer are not consistent and can prevent the malfunction of differential protection for transformers, caused by the zero sequence electric current resulting in differential unbalance electric currents under the condition of other non-internal faults.
Description
Technical field
The present invention relates to a kind of relay protection method of power system, particularly a kind of maximum current zero sequence braking method that prevents malfunction for tranformer protection.
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.In number of patent application is 200410016305.8 " branch that prevents the transformer differential protection malfunction differs the stream method ", recently differentiate Y by differential current and zero-sequence current
0The method of lateral areas external ground fault can overcome above-mentioned defective, but differential current is gathered complexity.
Summary of the invention
The technical problem to be solved in the present invention is the Y that exists in the existing transformer differential protection technology
0Side three-phase current transform method can not be eliminated the influence of zero-sequence current fully, and a kind of maximum current zero sequence braking method that prevents malfunction for tranformer protection is provided, and uses transformer Y
0Maximum in the three-phase current of side and this side zero-sequence current component ratio braking member, when rate value during less than setting value K, the output brake signal is braked the transformer ratio differential protection.Advantage of the present invention is, relies on maximum and this side zero-sequence current component ratio braking member in the one-sided three-phase current, in the time of just 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 maximum current zero sequence braking method that prevents malfunction for tranformer protection is characterized in that: use transformer Y
0Maximum in the three-phase current of side and this side zero-sequence current component ratio braking member are worked as Y
0During less than setting value K, brake the transformer ratio differential protection by the output brake signal divided by the rate value of this side zero-sequence current value for the maximum of side three-phase current;
The foundation of maximum current zero sequence braking is:
(I
a、I
b、I
c)max/3I
o＜K
I in the formula
a, I
b, I
cBe respectively transformer Y
0The three-phase current of side, (I
a, I
b, I
c) max is transformer Y
0Maximum in the three-phase current of side, 3I
oBe Y
0The side zero-sequence current, i.e. three-phase current sum, setting value K is 0＜K＜1.
With prior art relatively, the invention has the beneficial effects as follows to have proposed first in traditional transformer differential protection, add a kind of transformer Y that uses
0Maximum in the three-phase current of side and this side zero-sequence current component ratio braking member, when rate value during less than setting value, the output brake signal is braked the transformer ratio differential protection.Use this programme, only need to gather the Y that power supply is arranged
0The three-phase current of side, with maximum and this side zero-sequence current component ratio braking member in the three-phase current, in the time of just 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.
Description of drawings
Below in conjunction with accompanying drawing to the specific embodiment of the present invention further detailed description.
Fig. 1 is for realizing a kind of circuit block diagram that prevents the maximum current zero sequence braking element of malfunction for tranformer protection of the present invention.
Embodiment
Embodiment 1:
A kind of maximum current zero sequence braking method that prevents malfunction for tranformer protection, this method can be achieved by a kind of circuit of the maximum current zero sequence braking element of malfunction for tranformer protection that prevents of Fig. 1.This element is made of filter 11～14, maximizing circuit 2, multiplier 3 and comparator 4, and the input of its median filter 11～13 is input transformer Y respectively
0The three-phase current instantaneous value signal i of side
a, i
b, i
c, its output connects three inputs of maximizing circuit 2 respectively; The input input transformer Y of filter 14
0The zero-sequence current instantaneous value signal 3i of side
o, an input of its output termination multiplier 3; Another input input setting value K=0.5 of multiplier 3, the negative input end of its output termination comparator 4; The positive input terminal of comparator 4 is connected with the output of maximum value circuit 2, its output output three-phase brake signal.Positive input terminal signal in comparator is less than the negative input end signal, and comparator exports 0, and declaring has district's external ground fault, and output three-phase brake signal is braked the transformer ratio differential protection, prevents the transformer differential protection malfunction; Otherwise comparator output 1 allows the differential protection action.Use this programme, only need to gather the Y that power supply is arranged
0The three-phase current of side, with maximum and this side zero-sequence current component ratio braking member in the three-phase current, in the time of just 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.
Claims (2)
1. a maximum current zero sequence braking method that prevents malfunction for tranformer protection is characterized in that: use transformer Y
0The maximum of the three-phase current of side and this side zero-sequence current component ratio braking member are worked as Y
0During less than setting value K, brake the transformer ratio differential protection by the output brake signal divided by the rate value of this side zero-sequence current value for the maximum of side three-phase current; The foundation of maximum current zero sequence braking is:
(I
a、I
b、I
c)max/3I
o＜K
I in the formula
a, I
b, I
cBe respectively transformer Y
0The three-phase current of side, (I
a, I
b, I
c) max is transformer Y
0Maximum in the three-phase current of side, 3I
oBe Y
0The side zero-sequence current, i.e. three-phase current sum, K is a setting value.
2. a kind of maximum current zero sequence braking method that prevents malfunction for tranformer protection according to claim 1 is characterized in that: setting value K is 0＜K＜2/3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100847584A CN100350705C (en) | 2004-12-02 | 2004-12-02 | Maximum current zero sequence braking method for preventing transformer protection malfunction |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100847584A CN100350705C (en) | 2004-12-02 | 2004-12-02 | Maximum current zero sequence braking method for preventing transformer protection malfunction |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1614845A CN1614845A (en) | 2005-05-11 |
| CN100350705C true CN100350705C (en) | 2007-11-21 |
Family
ID=34765972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004100847584A Expired - Fee Related CN100350705C (en) | 2004-12-02 | 2004-12-02 | Maximum current zero sequence braking method for preventing transformer protection malfunction |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100350705C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104852354A (en) * | 2015-06-04 | 2015-08-19 | 南京南瑞继保电气有限公司 | Adaptive-slope transformer zero-sequence differential protection method and device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN1419327A (en) * | 2002-10-24 | 2003-05-21 | 南京南瑞继保电气有限公司 | Generator industrial-frequency variation equantity rate difference protection method |
-
2004
- 2004-12-02 CN CNB2004100847584A patent/CN100350705C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN1419327A (en) * | 2002-10-24 | 2003-05-21 | 南京南瑞继保电气有限公司 | Generator industrial-frequency variation equantity rate difference protection method |
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| Publication number | Publication date |
|---|---|
| CN1614845A (en) | 2005-05-11 |
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|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20071121 Termination date: 20101202 |