CN100367604C - Transformer longitudinal error protecting method with zero sequence ratio brake - Google Patents
Transformer longitudinal error protecting method with zero sequence ratio brake Download PDFInfo
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- CN100367604C CN100367604C CNB2004100847620A CN200410084762A CN100367604C CN 100367604 C CN100367604 C CN 100367604C CN B2004100847620 A CNB2004100847620 A CN B2004100847620A CN 200410084762 A CN200410084762 A CN 200410084762A CN 100367604 C CN100367604 C CN 100367604C
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- transformer
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Abstract
The present invention discloses a method for the longitudinal error protection of a transformer with zero sequence ratio brake. Brake current containing zero sequence current of the phase is formed by the method that brake current representing through current in the longitudinal differential protection of a common transformer carries out weighting summation with the zero sequence current at the Y0 side of the transformer, and the brake current containing zero sequence current is used for forming a brake element in the phase ratio with the differential current of the corresponding phase. When the differential current is larger than the brake current containing zero sequence current and is larger than the smallest operation current, operation signals of the brake element in the corresponding phase ratio are output. When the proposal is applied, the mis-operation of the differential protection of the transformer because of a grounding fault outside a Y0 side zone can be completely avoided under the condition that the errors of a three-phase current mutual inductor are inconsistent.
Description
Technical field
The present invention relates to a kind of relay protection method of power system, particularly a kind of transformer longitudinal error protecting method with zero sequence ratio brake.
Background technology
Present Power Transformer Longitudinal Differential Protection is made of elements such as differential quick-break, percentage differential, magnetizing inrush current detection, overexcitation detections; according to the DL/T 684-1999 in People's Republic of China's power industry standard " the high-rating generator transformer relay protecting is adjusted and is calculated guide rule "; the transformer differential protection block diagram as shown in Figure 1, Differential Current Protection Principle wiring example is as shown in Figure 2.Usually utilize current transformer to Y
0The side three-phase current carries out the conversion of Y/ Δ, to eliminate the influence of zero-sequence current.Obviously, after the conversion, each electric current has not comprised the zero-sequence component in the primary current, these electric currents are behind intermediate current instrument transformer TAM1～TAM6 balancing, each phase current addition of the same name obtains the three-phase differential current, Wd is a differential coil, and phase current of the same name carries out the alternate manner combination and obtains the three-phase system streaming current, and Wres1～Wres3 is each side restraining coil.As seen, differential current that obtains thus and stalling current all do not comprise the zero-sequence component in the primary current.
When implementing longitudinal difference protection, also there is Y
0The side current transformer is the situation of complete star-like wiring, at this moment, often in protective device to Y
0Side three-phase secondary current carries out the conversion of Y/ Δ, perhaps with Y
0Side three-phase secondary current deducts zero-sequence current respectively and simultaneously Δ side secondary current is carried out Δ/Y conversion, eliminates the influence of zero-sequence current by above-mentioned conversion.By these conversion and behind each side balancing, the stalling current that obtains by the differential current that obtains with famous prime minister's addition and by other combination does not comprise the zero-sequence component in the primary current equally.As: the vector by calculating phase current of the same name with obtain this differential current mutually; Maximum by asking for phase current of the same name or obtain this phase stalling current by the weighted sum of calculating phase current magnitude of the same name, its stalling current can only be represented the size of through current.
When transformer at Y
0Side generating region external ground fault and when having only this side that power supply is arranged, Y
0Very big zero-sequence fault electric current will appear in side, but the fault-free electric current passes through transformer.At this moment, work as Y
0When side threephase current transformer error was inconsistent, the zero-sequence current that equates at the primary side three-phase was after the threephase current transformer conversion, and secondary current is unequal, above-mentioned traditional Y
0Side three-phase current transform method can not be eliminated the influence of zero-sequence current fully, will produce unsymmetrical current at differential circuit.Because this moment, the fault-free electric current passed through transformer, the stalling current that obtains by above-mentioned conventional method is very little, can not surpass the preceding stalling current of fault, as long as differential unsymmetrical current surpasses differential threshold, transformer differential protection is with malfunction.Obviously, by Y
0Side zero-sequence fault electric current causes that unsymmetrical current has been left in the basket in the ratio brake element of traditional longitudinal difference protection, promptly do not have corresponding stalling current that it is braked in the ratio brake element, thereby may cause the transformer differential protection misoperation.
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 transformer longitudinal error protecting method with zero sequence ratio brake is provided, by stalling current and the transformer Y that represents through current in the typical transformer longitudinal difference protection
0The side zero-sequence current is weighted the summation formation, and this contains the stalling current of zero-sequence current mutually, with this stalling current that contains zero-sequence current mutually with this mutually differential current constitute this phase ratio braking member, when differential current during, export the actuating signal of corresponding phase ratio braking member greater than the stalling current that contains zero-sequence current and greater than minimum working current.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 transformer longitudinal error protecting method with zero sequence ratio brake is characterized in that: by a certain phase stalling current and the transformer Y in the three-phase of representing through current in the transformer differential protection
0The side zero-sequence current is weighted summation and constitutes the stalling current that contains zero-sequence current; constitute this phase ratio braking criterion with this differential current mutually in this stalling current that contains zero-sequence current and the transformer differential protection; when this phase differential current contains the stalling current of zero-sequence current mutually greater than this and during greater than minimum working current; export the actuating signal of this phase ratio braking member, the operating criterion of band zero sequence ratio brake criterion is:
I
d＞K
Z×I
z+K
0×3I
0
I in the formula Chinese style
d, I
zFor the differential current of any phase in the transformer differential protection three-phase with represent this stalling current of through current mutually, 3I
0Be Y
0The side zero-sequence current, K
ZBe ratio brake coefficient, its value is 0＜K
Z＜1, K
0Be the zero-sequence braking coefficient, arrive under the situation of the same side K at zero-sequence current and three-phase differential current, the reduction of three-phase system streaming current
0Value is 0＜K
0＜1/3.
With prior art relatively, the invention has the beneficial effects as follows and proposed first in the stalling current of the ratio brake element of traditional transformer longitudinal difference protection, to add the zero-sequence braking electric current.By stalling current and the transformer Y that represents through current
0The side zero-sequence current is weighted the summation formation, and this contains the stalling current of zero-sequence current mutually, constitutes this phase ratio braking member with this stalling current that contains zero-sequence current with corresponding differential current mutually.When differential current during, export the actuating signal of this phase ratio braking member greater than the stalling current that contains zero-sequence current and greater than minimum working current.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 situation; the transformer differential protection misoperation that the differential unsymmetrical current that zero-sequence current causes causes, and the correct operation of longitudinal difference protection under the zone of influence internal fault situation not.
Description of drawings
Below in conjunction with accompanying drawing to the specific embodiment of the present invention further detailed description.
Fig. 1 is existing transformer differential protection block diagram.
Fig. 2 is existing transformer differential protection key wiring diagram.
Fig. 3 is for realizing the circuit block diagram of a kind of transformer differential protection ratio brake element with zero-sequence braking of the present invention.
Fig. 4 is for realizing the another kind of circuit block diagram of being with the transformer differential protection ratio brake element of zero-sequence braking of the present invention.
Embodiment
Embodiment 1:
A kind of transformer longitudinal error protecting method, this method with zero sequence ratio brake can be by Fig. 3 a kind of circuit block diagram of the transformer differential protection ratio brake element with zero-sequence braking be achieved.This element is made of multiplier A1, B1, C1,01, adder A3, B3, C3 and comparator A4, B4, C4.Wherein multiplier A1, B1, C1 input represent in the input transformer longitudinal difference protection respectively through current through filtered stalling current signal I
Za, I
Zb, I
Zc, another input input ratio brake coefficient K
Z=0.5, its output connects the input of adder A3, B3, C3 respectively; An input input transformer Y of multiplier 01
0Side is through filtered zero sequence current signal 3I
0, another input input zero-sequence braking COEFFICIENT K
0=0.15, its output connects another input of adder A3, B3, C3 respectively; The positive input terminal of comparator A4, B4, C4 is imported respectively through filtered three-phase differential current signal I
Da, I
Db, I
Dc, negative input end is connected with the output of adder A3, B3, C3 respectively, and its output is exported the percentage differential actuating signal of A, B, C phase respectively.When differential current when containing the stalling current of zero-sequence current, comparator is exported the percentage differential actuating signal of corresponding phase.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 situation; the transformer differential protection misoperation that the vertical poor unsymmetrical current that zero-sequence current causes causes, and the correct operation of longitudinal difference protection under the zone of influence internal fault situation not.
Embodiment 2:
A kind of transformer longitudinal error protecting method, this method with zero sequence ratio brake can be by Fig. 4 the circuit of transformer differential protection ratio brake element of another kind band zero-sequence braking be achieved.This element is made of subtracter A11, B12, C13, multiplier A21, B22, C23,02, adder A31, B32, C33, A41, B42, C43 and comparator A51, B52, C53.Wherein the positive input terminal of subtracter A11, B12, C13 respectively the input transformer longitudinal difference protection the representative through current through filtered stalling current signal I
Za, I
Zb, I
Zc, the braking keen current value I in the negative input end difference input transformer longitudinal difference protection
Reso=1.2 * I
n, I
nFor converting the transformer rated current of this side; The input of multiplier A21, B22, C23 connects the output of subtracter A11, B12, C13 respectively, and another input is imported percentage differential broken line slope S=0.5 respectively, and its output connects the input of adder A31, B32, C33 respectively; Another input of adder A31, B32, C33 is imported minimum working current value I respectively
Op.min=0.4 * I
n, its output is connected with the input of adder A41, B42, C43 respectively; An input input transformer Y of multiplier 02
0Side is through filtered zero sequence current signal 3I
0, another input input zero-sequence braking COEFFICIENT K
0=0.2, its output connects another input of adder A41, B42, C43 respectively; The positive input terminal of comparator A51, B52, C53 is imported respectively through filtered three-phase differential current signal I
Da, I
Db, I
Dc, negative input end is connected with the output of adder A41, B42, C43 respectively, and its output is exported the percentage differential actuating signal of A, B, C phase respectively.When differential current when containing the stalling current of zero-sequence current, comparator is exported the percentage differential actuating signal of corresponding phase.Use this programme, can realize the only situation of initial point of percentage differential broken line, i.e. ratio brake coefficient Kz=S * (1-I
Reso/ Iz)+I
Op.min/ Iz, ratio brake coefficient Kz changes with stalling current; In the time of also 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 situation; the transformer differential protection misoperation that the vertical poor unsymmetrical current that zero-sequence current causes causes, and the correct operation of longitudinal difference protection under the zone of influence internal fault situation not.
Claims (3)
1. the transformer longitudinal error protecting method with zero sequence ratio brake is characterized in that: by a certain phase stalling current and the transformer Y in the three-phase of representing through current in the transformer differential protection
0The side zero-sequence current is weighted summation and constitutes the stalling current that contains zero-sequence current, constitute this phase ratio braking criterion with this stalling current that contains zero-sequence current with this differential current mutually, when differential current during greater than the stalling current that contains zero-sequence current and greater than minimum working current, export the actuating signal of this phase ratio braking criterion, the operating criterion of band zero sequence ratio brake criterion is:
I
d＞K
Z×I
z+K
0×3I
0
I in the formula
d, I
zFor the differential current of any phase in the transformer differential protection three-phase with represent this stalling current of through current mutually, 3I
0Be Y
0The side zero-sequence current, K
ZBe ratio brake coefficient, K
0Be the zero-sequence braking coefficient.
2. method according to claim 1 is characterized in that: ratio brake coefficient K
ZValue be 0＜K
Z＜1.
3. method according to claim 1 is characterized in that: in zero-sequence current and three-phase differential current, the reduction of three-phase system streaming current under the situation of the same side, the zero-sequence braking COEFFICIENT K
0Setting range is 0＜K
0＜1/3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100847620A CN100367604C (en) | 2004-12-02 | 2004-12-02 | Transformer longitudinal error protecting method with zero sequence ratio brake |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100847620A CN100367604C (en) | 2004-12-02 | 2004-12-02 | Transformer longitudinal error protecting method with zero sequence ratio brake |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1783612A CN1783612A (en) | 2006-06-07 |
| CN100367604C true CN100367604C (en) | 2008-02-06 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004100847620A Expired - Fee Related CN100367604C (en) | 2004-12-02 | 2004-12-02 | Transformer longitudinal error protecting method with zero sequence ratio brake |
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| Country | Link |
|---|---|
| CN (1) | CN100367604C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110943433A (en) * | 2019-11-25 | 2020-03-31 | 广东电网有限责任公司 | Zero sequence differential protection method and device for grounding transformer |
Citations (3)
| 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 |
| US6356421B1 (en) * | 1999-11-29 | 2002-03-12 | Schweitzer Engineering Labs., Inc. | System for power transformer differential protection |
| 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
- 2004-12-02 CN CNB2004100847620A patent/CN100367604C/en not_active Expired - Fee Related
Patent Citations (3)
| 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 |
| US6356421B1 (en) * | 1999-11-29 | 2002-03-12 | Schweitzer Engineering Labs., Inc. | System for power transformer differential protection |
| 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 |
Non-Patent Citations (1)
| Title |
|---|
| 差动保护比率制动整定中动作电流与制动系数等关系分析. 庄伟民.继电器，第28卷第9期. 2000 * |
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| Publication number | Publication date |
|---|---|
| CN1783612A (en) | 2006-06-07 |
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