CN1614845A - 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 PDF

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Publication number
CN1614845A
CN1614845A CN 200410084758 CN200410084758A CN1614845A CN 1614845 A CN1614845 A CN 1614845A CN 200410084758 CN200410084758 CN 200410084758 CN 200410084758 A CN200410084758 A CN 200410084758A CN 1614845 A CN1614845 A CN 1614845A
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China
Prior art keywords
current
transformer
zero
maximum
sequence
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CN 200410084758
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Chinese (zh)
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CN100350705C (en
Inventor
徐习东
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Zhejiang University ZJU
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Zhejiang University ZJU
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Priority to CNB2004100847584A priority Critical patent/CN100350705C/en
Publication of CN1614845A publication Critical patent/CN1614845A/en
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Publication of CN100350705C publication Critical patent/CN100350705C/en
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Abstract

The method includes following steps: the maximum value of three phase current at Y0 side of transformer are used to build up rate break component; when the rate value is less than setting value, the break signal is outputted to break the rate differential protection of relating transformer. The invention can avoid miss -protection caused by ground fault of Y0 side when error of three-phase current transformer is disagreeing.

Description

A kind of maximum current zero sequence braking method that prevents malfunction for tranformer protection
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, when rate value during less than setting value K, the output brake signal is braked the transformer ratio differential protection;
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 0Side zero-sequence current (being the 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, when rate value during less than setting value, the output brake signal is braked the transformer ratio differential protection; 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 c) be 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 o) be Y 0Side zero-sequence current (being the three-phase current sum) (K) is setting value.
2. according to claim 1. a kind of maximum current zero sequence braking method that prevents malfunction for tranformer protection is characterized in that: setting value (K) is 0<K<2/3.
CNB2004100847584A 2004-12-02 2004-12-02 Maximum current zero sequence braking method for preventing transformer protection malfunction Expired - Fee Related CN100350705C (en)

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)

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CN1614845A true CN1614845A (en) 2005-05-11
CN100350705C CN100350705C (en) 2007-11-21

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Cited By (1)

* Cited by examiner, † Cited by third party
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

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100424955C (en) * 2002-08-26 2008-10-08 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

Cited By (1)

* Cited by examiner, † Cited by third party
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

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Publication number Publication date
CN100350705C (en) 2007-11-21

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