CN100377461C - Maximum differential flow brake device for preventing voltage transformer differential protection unwanted operation - Google Patents
Maximum differential flow brake device for preventing voltage transformer differential protection unwanted operation Download PDFInfo
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- CN100377461C CN100377461C CNB2004100162784A CN200410016278A CN100377461C CN 100377461 C CN100377461 C CN 100377461C CN B2004100162784 A CNB2004100162784 A CN B2004100162784A CN 200410016278 A CN200410016278 A CN 200410016278A CN 100377461 C CN100377461 C CN 100377461C
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- differential protection
- differential
- input
- comparator
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Abstract
The present invention relates to a maximum differential flow braking device for preventing the unwanted operation of differential protection for transformers; a ratio braking element is composed of the maximum value of a three-phase differential electric current in the differential protection for transformers and a zero-sequence differential electric current at a y<o> side. An external grounding fault is judged at the y<o> side; when the ratio value of the maximum value of a differential electric current to the zero-sequence differential electric current is smaller than a setting value K, a comparator outputs 0; the external grounding fault is judged, and a three-phase differential protection outlet is locked; or the comparator outputs 1; three-phase differential protection is allowed to act. The proposal 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 consistent, 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 protection equipment for transformer, particularly a kind of maximum difference stream brake apparatus that prevents the transformer differential protection malfunction.
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; By shoving and the overexcitation braking member, promptly, discern magnetizing inrush current and overexcitation electric current simultaneously, reach the purpose of differentiating internal fault by analyzing the waveform or the harmonic content of differential current.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; ratio brake element, the braking member that shoves can not reliably be braked this; especially very little even be under zero the situation at transformer opposite side load 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 purpose of this invention is to provide a kind of maximum difference stream brake apparatus that prevents the transformer differential protection malfunction, by maximum and Y with the three-phase differential current in the transformer differential protection
0The zero-sequence current component ratio braking member of side when the rate value of differential current maximum and zero-sequence current during less than setting value K, is judged to Y
0Lateral areas external ground fault, the outlet of locking three-phase differential protection.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, and the correct operation of differential protection under the zone of influence internal fault situation not.
A kind of maximum difference stream brake apparatus that prevents the transformer differential protection malfunction; this device circuit structure as shown in Figure 1; it is characterized in that: this device is made of first to the 3rd filter 11～13 and the 4th filter 14, maximizing circuit 2, multiplier 3, comparator 4, wherein the three-phase differential current instantaneous value signal i of the input of first to the 3rd filter 11～13 difference input transformer differential protection formation
Da, i
Db, i
Dc, the input input transformer Y of the 4th filter 14
0Side zero-sequence current instantaneous value signal 3i
0An input of its output termination multiplier 3, another input input setting value K of multiplier 3, the negative input end of its output termination comparator 4, three inputs of maximizing circuit 2 connect the output of first to the 3rd filter 11～13 respectively, the positive input terminal of its output termination comparator 4, the output output three-phase brake signal of comparator 4.When the positive input terminal signal of comparator 4 less than the negative input end signal, comparator 4 outputs 0 are judged to district's external ground fault, locking three-phase differential protection outlet, otherwise comparator 4 outputs 1 allow the action of three-phase differential protection.Arrive under the same side, the same no-load voltage ratio situation in differential current and the equal reduction of zero-sequence current, setting value K is 0＜K＜1/3; The filtering characteristic of first to fourth filter 11～14 is identical.
With prior art relatively, advantage of the present invention is maximum and the Y that has proposed first to set up in traditional transformer differential protection with the three-phase differential current in the transformer differential protection
0The zero-sequence current component ratio braking member of side, when the rate value of differential current maximum and zero-sequence current during less than setting value K, comparator output 0; be judged to district's external ground fault; the outlet of locking three-phase differential protection, otherwise comparator output 1 then allow the action of three-phase differential protection.The advantage of using this programme 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; 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 the circuit block diagram that prevents the maximum difference stream brake apparatus of transformer differential protection malfunction.
Embodiment
Embodiment 1:
A kind of maximum difference stream brake apparatus that prevents the transformer differential protection malfunction; its circuit constitutes as shown in Figure 1; when the positive input terminal signal of comparator 4 less than the negative input end signal; comparator 4 outputs 0; be judged to district's external ground fault; the outlet of locking three-phase differential protection, otherwise comparator 4 outputs 1 allow the action of three-phase differential protection.Arrive under the same side, the same no-load voltage ratio situation in differential current and the equal reduction of zero-sequence current, setting value K gets 0.1.The advantage of this device 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, and the correct operation of differential protection under the zone of influence internal fault situation not.
Claims (3)
1. maximum difference stream brake apparatus that prevents the transformer differential protection malfunction; it is characterized in that: this device is made of first to the 3rd filter (11～13) and the 4th filter (14), maximizing circuit (2), multiplier (3), comparator (4), wherein the three-phase differential current instantaneous value signal (i of the input of first to the 3rd filter (11～13) difference input transformer differential protection formation
Da, i
Db, i
Dc), the input input transformer Y of the 4th filter (14)
0Side zero-sequence current instantaneous value signal (3i
0); an input of its output termination multiplier (3); another input input setting value K of multiplier (3); the negative input end of comparator (4) is connected with the output of multiplier (3), and three inputs of maximizing circuit (2) connect the output of first to the 3rd filter (11～13) respectively, the positive input terminal of its output termination comparator (4); when comparator (4) exports 0; the outlet of locking three-phase differential protection, comparator (4) output 1 o'clock, open three-phase differential protection outlet.
2. device according to claim 1 is characterized in that: under the same side, same no-load voltage ratio situation, setting value K is 0＜K＜1/3 in differential current and the equal reduction of zero-sequence current.
3. device according to claim 1 is characterized in that: the filtering characteristic of first to fourth filter (11～14) is identical.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100162784A CN100377461C (en) | 2004-02-13 | 2004-02-13 | Maximum differential flow brake device for preventing voltage transformer differential protection unwanted operation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100162784A CN100377461C (en) | 2004-02-13 | 2004-02-13 | Maximum differential flow brake device for preventing voltage transformer differential protection unwanted operation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1558485A CN1558485A (en) | 2004-12-29 |
| CN100377461C true CN100377461C (en) | 2008-03-26 |
Family
ID=34351793
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004100162784A Expired - Fee Related CN100377461C (en) | 2004-02-13 | 2004-02-13 | Maximum differential flow brake device for preventing voltage transformer differential protection unwanted operation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100377461C (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN2687916Y (en) * | 2004-02-13 | 2005-03-23 | 浙江大学 | Maximum different-current brake device for preventing transformer differential protection from being malfunction |
-
2004
- 2004-02-13 CN CNB2004100162784A patent/CN100377461C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN2687916Y (en) * | 2004-02-13 | 2005-03-23 | 浙江大学 | Maximum different-current brake device for preventing transformer differential protection from being malfunction |
Non-Patent Citations (1)
| Title |
|---|
| 多判据综合的变压器差动保护. 杨经超等.电网技术，第27卷第10期. 2003 * |
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| Publication number | Publication date |
|---|---|
| CN1558485A (en) | 2004-12-29 |
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| C10 | Entry into substantive examination | ||
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20080326 Termination date: 20110213 |