CN1558490A

CN1558490A - Integrated difference stream brake device for preventing voltage transformer differential protection unwanted operation by utilizing fault components

Info

Publication number: CN1558490A
Application number: CNA200410016284XA
Authority: CN
Inventors: 徐习东
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2004-02-13
Filing date: 2004-02-13
Publication date: 2004-12-29
Anticipated expiration: 2024-02-13
Also published as: CN100350695C

Abstract

The invention discloses an integrated difference stream brake device for preventing voltage transformer differential protection unwanted operation by utilizing fault components, wherein the base wave positive sequence current or negative sequence current of the three-phase difference currents in the transformer differential protection constitute ratio braking element with the zero-sequence current on the Y0 side, when the ratio of the differential current variation and the zero-sequence current variation is smaller than a setting value K, the comparator outputs 0, the Y0 lateral area outer ground fault is determined, the three-phase differential protection exit is locked, otherwise the comparator 7 outputs 1, and the corresponding differential protection actuations are allowed. The advantages of the invention are, the transformer differential protection accidental operation resulted from ground fault outside the Y0 lateral area when the errors of the three-phase current transformer are in inconformity, and without influencing the correct actuation of the differential protection under the circumstance of in-area faults.

Description

Utilize fault component to prevent the comprehensive poor stream brake apparatus of transformer differential protection malfunction

Technical field

The present invention relates to a kind of protection equipment for transformer, particularly a kind of comprehensive poor stream brake apparatus that utilizes fault component to prevent 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 comprehensive poor stream brake apparatus that utilizes fault component to prevent the transformer differential protection malfunction, by fundamental positive sequence sudden change amount or first-harmonic negative phase-sequence sudden change amount and zero-sequence current sudden change amount component ratio braking member with the three-phase differential current in the transformer differential protection, when the rate value of the sudden change amount of fundamental positive sequence sudden change amount or first-harmonic negative phase-sequence sudden change amount and zero-sequence current during less than setting value K, be judged to district's 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 comprehensive poor stream brake apparatus that utilizes fault component to prevent the transformer differential protection malfunction; this device circuit constitutes as shown in Figure 1; it is characterized in that: this device is made of memory 11～14, subtracter 21～24, fundamental positive sequence pass filter 3, filter 4, filter 5, multiplier 6, comparator 7, wherein the three-phase differential current instantaneous value signal i of the positive input terminal of the input of memory 11～13 and subtracter 21～23 difference input transformer differential protection formation _Da, i _Db, i _DcThe negative input end of subtracter 21～23 connects the output of memory 11～13 respectively, its output is connected with three inputs of fundamental positive sequence pass filter 3 respectively, the output of the input termination fundamental positive sequence pass filter 3 of filter 4, the positive input terminal of its output and comparator 7 joins, and the positive input terminal of the input of memory 14 and subtracter 24 is input transformer Y respectively ₀Side zero-sequence current instantaneous value signal 3i _oThe negative input end of subtracter 24 connects the output of memory 14, its output is connected with the input of filter 5, an input of the output termination multiplier 6 of filter 5, another input input setting value K of multiplier 6, the negative input end of its output termination comparator 7, comparator 7 output three-phase brake signals.First-harmonic phase sequence pass filter 3 is the fundamental positive sequence pass filter, perhaps is the first-harmonic negative sequence filter.Arrive the same side in differential current and the equal reduction of zero-sequence current, under the same no-load voltage ratio situation, setting value K is 0＜K＜1.When comparator 7 positive input terminal signals less than the negative input end signal, comparator 7 output 0 is judged to district's external ground fault, locking three-phase differential protection outlet, otherwise comparator 7 outputs 1 allow the action of three-phase differential protection.

With prior art relatively, advantage of the present invention is that the ratio that has proposed to set up the sudden change amount of a kind of positive sequence first-harmonic sudden change amount of three-phase differential current or negative phase-sequence first-harmonic sudden change amount and zero-sequence current first in traditional transformer differential protection constitutes braking member, when the rate value of the sudden change amount of fundamental positive sequence sudden change amount or first-harmonic negative phase-sequence sudden change amount and zero-sequence current during less than setting value K, be judged to district's external ground fault, the outlet of locking three-phase differential protection; 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 a kind of comprehensive poor stream brake apparatus circuit block diagram that utilizes fault component to prevent the transformer differential protection malfunction.

Embodiment

A kind of comprehensive poor stream brake apparatus that utilizes fault component to prevent the transformer differential protection malfunction; this device circuit constitutes as shown in Figure 1; present embodiment first-harmonic phase sequence pass filter 3 adopts the fundamental positive sequence pass filter; arrive the same side in differential current and the equal reduction of zero-sequence current; under the same no-load voltage ratio situation, setting value K is 0.8.When comparator 7 positive input terminal signals less than the negative input end signal, comparator 7 output 0 is judged to district's external ground fault, locking three-phase differential protection outlet, otherwise comparator 7 outputs 1 allow the action of three-phase differential protection.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

1. comprehensive poor stream brake apparatus that utilizes fault component to prevent the transformer differential protection malfunction; it is characterized in that: this device is made of memory (11～14), subtracter (21～24), first-harmonic phase sequence pass filter (3), filter (4), filter (5), multiplier (6), comparator (7), wherein the three-phase differential current instantaneous value signal (i of the positive input terminal of the input of memory (11～13) and subtracter (21～23) difference input transformer differential protection formation _Da, i _Db, i _Dc), the negative input end of subtracter (21～23) connects the output of memory (11～13) respectively, its output is connected with three inputs of first-harmonic phase sequence pass filter (3) respectively, the output of the input termination first-harmonic phase sequence pass filter (3) of filter (4), the positive input terminal of its output and comparator (7) joins, the positive input terminal input transformer Y of the input of memory (14) and subtracter (24) ₀Side zero-sequence current instantaneous value signal (3i _o), the negative input end of subtracter (24) connects the output of memory (14), the input of its output and filter (5) joins, an input of the output termination multiplier (6) of filter (5), another input input setting value (K) of multiplier (6), the negative input end of its output termination comparator (7), comparator (7) output three-phase brake signal.

2. device according to claim 1 is characterized in that: first-harmonic phase sequence pass filter (3) is the fundamental positive sequence pass filter, perhaps is the first-harmonic negative sequence filter.

3. device according to claim 1 is characterized in that: to the same side, under the same no-load voltage ratio situation, setting value (K) is 0＜K＜1 in differential current and the equal reduction of zero-sequence current.