CN109444672A - One kind automatically tracking line selection device for low current and selection method - Google Patents
One kind automatically tracking line selection device for low current and selection method Download PDFInfo
- Publication number
- CN109444672A CN109444672A CN201811621494.XA CN201811621494A CN109444672A CN 109444672 A CN109444672 A CN 109444672A CN 201811621494 A CN201811621494 A CN 201811621494A CN 109444672 A CN109444672 A CN 109444672A
- Authority
- CN
- China
- Prior art keywords
- phase
- current
- ground
- zero
- controllable impedance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000010187 selection method Methods 0.000 title claims abstract description 16
- 230000007935 neutral effect Effects 0.000 claims abstract description 55
- 230000005611 electricity Effects 0.000 claims description 4
- 230000003111 delayed effect Effects 0.000 claims description 3
- 230000001629 suppression Effects 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 7
- 229940100688 oral solution Drugs 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 6
- 239000003990 capacitor Substances 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 239000004020 conductor Substances 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 208000025274 Lightning injury Diseases 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 239000013598 vector Substances 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses one kind to automatically track line selection device for low current and selection method, it is characterized in that: neutral point is arranged in the system of small current neutral grounding mode, setting can automatically track the controllable impedance of adjustment between neutral point and ground, and the maximum value of controllable impedance is configured according to system nominal voltage；Controllable impedance is to carry out tracking adjustment according to system voltage-to-ground or according to the electric current of controllable impedance.The present invention keeps the zero-sequence current of faulty line maximum and reaches the judgement precision of route selection electric current, and accurate judgement faulty line, route selection is not influenced by arc suppression coil；And can apply to judge faulty line when small resistance grounding system high resistance ground, eliminate the protection's dead-zone of neutral grounding by small resistance system.
Description
Technical field
The present invention relates to electrical protection apparatus, more particularly for the choosing of single-phase grounded malfunction in grounded system of low current
Line apparatus and selection method, it can also be used to the route selection of neutral point low values of resistors earthed system single-phase high-impedance.
Background technique
Small current line selection timely and accurately determines that earth-return circuit is the quick basis for excluding singlephase earth fault and small electricity
Flow the core function of route selection.But choosing is often falsely dropped and leaked to current line selection apparatus, and effect is unsatisfactory, route selection accuracy rate
It is relatively low.
Small Electric Current Earthing And Routing Device has had been subjected to the replacement of technology innovation several times since the 1980s comes out,
The accuracy of route selection is also being continuously improved, but the higher problem of False Rate is still had in practical implementation.
The fault current of single-phase earthing is related with system voltage, capacitance to earth, fault point impedance ground, and a certain kind is transported
System under line mode, system voltage and capacitance to earth are determining, impedance ground of the fault current of system with fault point
Size is related, and the more big then neutral point voltage of the impedance ground of fault point is smaller, therefore fault current, with regard to smaller, fault current is smaller
Route selection is more difficult to, this is the difficult point for being difficult to go beyond of small current line selection, and simultaneity factor occurs resonance and causes to judge by accident when " Xuhanting oral solution "
Route selection.
In addition, single-phase high-impedance makes singlephase earth fault route in neutral point low values of resistors earthed system
Electric current be less than protection seting value, cause microcomputer complex protection that can not cut off faulty line, form protection's dead-zone.
Summary of the invention
The present invention is to provide one kind to avoid above-mentioned existing deficiencies in the technology and automatically track small current line selection
Device and selection method, setting automatically tracks impedance between property point and ground in systems, according to the size of fault point impedance ground
Adjustment is automatically tracked, keep the zero-sequence current of faulty line maximum and reaches the judgement precision of route selection electric current, accurate judgement fault wire
Road, route selection are not influenced by arc suppression coil；And can apply to judge faulty line when small resistance grounding system high resistance ground, it eliminates
The protection's dead-zone of neutral grounding by small resistance system.
The present invention adopts the following technical scheme that in order to solve the technical problem
The present invention, which automatically tracks the characteristics of line selection device for low current, is: being arranged in the system of small current neutral grounding mode neutral
Point, setting can automatically track the controllable impedance Z of adjustment between the neutral point and groundT, the controllable impedance ZTMaximum value
ZTMIt is configured according to system nominal voltage；The controllable impedance ZTIt is according to system voltage-to-ground or according to the controllable resistance
Anti- ZTElectric current INCarry out tracking adjustment, the controllable impedance ZTAdjusting range in 0≤ZT≤ZTMBetween.
The present invention, which automatically tracks the characteristics of low-current line selection method, is, using it is described automatically track line selection device for low current by
As under type carries out route selection:
When single-phase earthing occurs for phase any one in system:
For non-fault line: with UNIndicate system neutral voltage, XCiIndicate the capacitance to earth on i-th line road,Table
Show the phase voltage of failure phase, then in non-fault line i-th outlet zero-sequence current ICiAre as follows:
For faulty line: indicating the number of outgoing of system, i ∈ (1, M), X with MCExpression system capacitance to earth, ZGIt indicates
Fault point impedance ground, then the zero-sequence current I of faulty lineGAre as follows:
ICIt is the faulty line zero-sequence current I characterized by formula (3)GIn capacitance current；
INIt is the investment controllable impedance Z characterized by formula (4)TIn the electric current that faulty line generates；
For fault point impedance ground ZG: with UФIndicate failure phase-to-ground voltage,Then failure
Point ground impedance ground ZGSuch as formula (5) or such as formula (6):
|ZG|=| XCtgθ/3| (6)
Using one of following four kinds of criterions, or the combination of any criterion, carry out the judgement of faulty line:
Criterion one: when single-phase earthing occurs for system, putting into has the controllable impedance Z for determining valueT, can described in the investment
Control impedance ZTPeriod, criterion are as follows: the zero-sequence current of faulty line is the maximum value of all outlet zero-sequence currents, and faulty line
Zero-sequence current is greater than IN；
Criterion two: when single-phase earthing occurs for system, the controllable impedance Z is put intoT, and put into the controllable impedance ZTIt
Afterwards, implement the primary controllable impedance ZTAdjustment, criterion are as follows: in the controllable impedance ZTAdjustment before and after, zero in all outlets
The maximum outlet of sequence current change quantity is faulty line；
Criterion three: when single-phase earthing occurs for system, putting into has the controllable impedance Z for determining valueT, criterion are as follows: throwing
Enter the controllable impedance ZTFront and back, the maximum outlet of zero-sequence current variable quantity is faulty line in all outlets；
Criterion four: when single-phase earthing occurs for system, the controllable impedance Z is exitedT, criterion are as follows: exiting the controllable resistance
Anti- ZTFront and back, the maximum outlet of zero-sequence current variable quantity is faulty line in all outlets.
The present invention automatically tracks the characteristics of low-current line selection method and lies also in: the controllable impedance ZTBasis as follows
System voltage-to-ground carries out tracking adjustment:
When single-phase earthing occurs for phase any in system A, B, C three-phase, is calculated according to formula (5) or formula (6) and obtain fault point
Impedance ground ZGValue be ZG1, set INAdjustment target value be INK, then controllable impedance ZTAdjusted value ZT1Are as follows:
By the controllable impedance ZTTracking adjustment is ZT1。
The present invention automatically tracks the characteristics of low-current line selection method and lies also in: the controllable impedance ZTBy the INCarry out with
Track adjustment: first by the controllable impedance ZTIt is set as maximum value ZTM, with most when system operates normally or after single-phase earthing
Big value ZTMIt is put into；When single-phase earthing occurs, the zero-sequence current of faulty line is IG1, I is setGAdjustment target value be IGK,
Work as IG1< TGKWhen, reduce controllable impedance ZTValue, until IG1≥IGK。
The present invention, which automatically tracks the characteristics of low-current line selection method, is, using it is described automatically track line selection device for low current by
As under type carries out route selection:
When single-phase earthing occurs for phase any one in system, failure phase-to-ground voltage UΦPhase lag behind neutral point over the ground
Voltage UN90 ° of phase, in the controllable impedance ZTWhen not putting into, the zero-sequence current I of faulty lineGEqual to capacitance current IC,
Such as formula (7):
XCFor the capacitance to earth of system, (- 1/XC) show the zero-sequence current I of faulty lineGPhase lag behind neutral point pair
Ground voltage UN90 ° of phase, therefore failure phase-to-ground voltage UΦWith the zero-sequence current I of faulty lineGPhase is identical；
Set criterion are as follows: in the controllable impedance ZTWhen there is no input coefficient, zero-sequence current and failure phase in all outlets
Voltage-to-ground UΦThe identical outlet of phase is zero-sequence current delayed phase neutral point voltage-to-ground in faulty line or all outlets
UN90 ° of phase of outlet be faulty line.
Faulty line zero-sequence current IGWith failure phase-to-ground voltage UФPhase is identical to be referred to: faulty line zero-sequence current IGWith
Failure phase-to-ground voltage UΦSampled value zero passage simultaneously, and reach maximum value simultaneously；
Faulty line zero-sequence current IGLag neutral point voltage-to-ground UN90 ° of phase refer to: faulty line zero-sequence current IG
Sampled value zero passage when, neutral point voltage-to-ground UNSampled value absolute value | UN| it is maximum value.
The present invention automatically tracks the characteristics of line selection device for low current and lies also in: when resonance occurs for system, the controllable resistance
Anti- ZTWith maximum value ZTMInvestment, for eliminating system resonance.
The present invention automatically tracks the characteristics of line selection device for low current and lies also in: when occur can described in single-phase earthing investment for system
Control impedance ZTAfterwards, the maximum phase of electric current is system single-phase earth fault phase in grounding transformer, for carrying out system single-phase earthing
The judgement of failure phase.
The present invention automatically tracks the characteristics of line selection device for low current and lies also in: in neutral point low values of resistors earthed system
In, by the neutral ground low values of resistors the low values of resistors in system is considered as controllable impedance ZT, single-phase height is occurring
When resistance ground connection zero-sequenceprotection failure, implement faulty line route selection using the low values of resistors.
Compared with the prior art, the invention has the advantages that:
1, present invention firstly provides adjustment route selection is automatically tracked according to fault point impedance ground size, make the zero of faulty line
Sequence electric current is maximum and reaches the precision that electric current judgement is sentenced in route selection, accurate judgement faulty line；Overcome prior art zero-sequence current
Signal it is small and can not accurate route selection the shortcomings that；
2, controllable impedance proposed by the present invention, maximum value are arranged according to system nominal voltage, make controllable impedance in failure
The electric current that point generates is moderate, does not cause the destruction of failure point insulating；
3, the calculating formula for the fault point impedance ground that the present invention provides, the adjustment for controllable impedance resistance provide foundation；
4, the present invention carries out route selection by any combination to four kinds of line selection modes under controllable impedance, effectively improves route selection
Accuracy rate；
5, controllable impedance can implement adjustment calculating according to system voltage-to-ground in the method for the present invention, in a certain method of operation
Under, fault point impedance ground is corresponded with identical voltage-to-ground, any one in three phase-to-ground voltage of system and neutral point voltage
A voltage can calculate fault point impedance ground；And give simultaneously controllable impedance can itself electric current adjustment calculating side
Method simplifies calculation method, is convenient for quick response；
6, the invention proposes judge failure phase capacitance current and faulted phase voltage same-phase, failure phase capacitor with sampled value
The selection method of 90 ° of neutral point voltage-to-ground phase after current hysteresis provides new selection method and improves route selection accuracy rate.
7, in the method for the present invention, controllable impedance Z is put intoTTo eliminate system resonance, and the phenomenon that eliminate " Xuhanting oral solution ", gram
Taken Xuhanting oral solution falsely drops line mistake；
8, the method for the present invention can accurate judgement single-phase earthing failure phase, be conducive to turning for accident analysis and fault current
It moves；
9, it is can also be applied to small resistance grounding system, carries out faulty line judgement for single-phase high resistance ground, disappear
Except the protection's dead-zone of neutral grounding by small resistance system.
Detailed description of the invention
Line selection device for low current schematic diagram is automatically tracked in Fig. 1 present invention；
Fig. 2 is three phase-to-ground voltage polar plot of single-phase earthing；
Specific embodiment
Line selection device for low current is automatically tracked in the present embodiment is: being arranged in the system of small current neutral grounding mode neutral
Point, setting can automatically track the controllable impedance Z of adjustment between neutral point and groundT, controllable impedance ZTMaximum value ZTMAccording to being
System voltage rating is configured；Controllable impedance ZTIt is according to system voltage-to-ground or according to controllable impedance ZTElectric current INCarry out with
Track adjustment, controllable impedance ZTAdjusting range in 0≤ZT≤ZTMBetween.
Controllable impedance ZTMaximum value ZTMIt is arranged according to system nominal voltage, such as voltage rating 10kV system, maximum value ZTM
300 Ω are set as, neutral point power-frequency voltage is up to 5.77kV when single phase metal is grounded, then controllable impedance ZTTo faulty line
And the maximum current of fault point injection is 19.2A, it is sufficient to meet the electric current of route selection needs.But with fault point impedance ground
Become larger, the voltage of neutral point decreases, controllable impedance ZTAlso just become smaller to faulty line injection, it is necessary to adjust controllable impedance ZT
Value so that injection faulty line and the electric current of fault point injection reach certain value and meet the needs of accurate route selection.
Controllable impedance ZTIt can be the assembly of inductance, capacitor, resistance, can also be resistor, can also be capacitor etc..
It is to utilize to automatically track line selection device for low current by such as lower section that low-current line selection method is automatically tracked in the present embodiment
Formula carries out route selection: when single-phase earthing occurs for phase any one in system:
For non-fault line: with UNIndicate system neutral voltage, XCiIndicate the capacitance to earth on i-th line road,Table
Show the phase voltage of failure phase, then in non-fault line i-th outlet zero-sequence current ICiAre as follows:
Wherein UA+UB+UC=3UN, so
For faulty line: indicating the number of outgoing of system, i ∈ (1, M), X with MCExpression system capacitance to earth, ZGIt indicates
Fault point impedance ground, then the zero-sequence current I of faulty lineGAre as follows:
ICIt is the faulty line zero-sequence current I characterized by formula (3)GIn capacitance current；
INIt is the investment controllable impedance Z characterized by formula (4)TIn the electric current that faulty line generates；
ICThe sum of all outlet capacitance currents are equal to, and current direction is opposite:
Cause are as follows:
So
That is: occur the faulty line of single-phase earthing capacity current be equal to all non-fault lines capacitive capacitance current it
With, and current direction is on the contrary, the size of capacitance current and the voltage of neutral point are proportional.
We find out simultaneously from formula (1) and (3): system neutral voltage UNIt is lower, then faulty line and non-faulting line
Zero-sequence current in road is then smaller；System capacitance to earth XCBigger, i.e., system capacitive current is smaller, then the capacitor electricity of faulty line
Stream is then smaller, and the smaller route selection difficulty of capacitance current is bigger.
In investment controllable impedance ZTPeriod, in the zero-sequence current that faulty line generates:
Wherein, ZJFor substation ground impedance, requirements of the national standard is not more than 4 ohm, for several hundred ohm of ZTIt can neglect
Slightly disregard；The capacitance to earth of simultaneous faults route is much larger than ZG, the impedance when in parallel with fault point impedance ground after be approximately equal to therefore
Barrier point impedance ground ZG.Therefore:
For fault point impedance ground ZG, then fault point ground impedance ground ZGSuch as formula (5) or such as formula (6): flowing through fault point
Electric current be equal to UΦ/ZG, it is faulty line zero-sequence current IGIn capacitance current IC, UΦFor failure phase-to-ground voltage, therefore:
So the impedance ground Z of fault pointGAre as follows:
Referring to fig. 2, in faulted phase voltageFailure phase-to-ground voltage UΦ, neutral point voltage-to-ground UNThree vectors are constituted
Right angled triangle in, θ is faulted phase voltageWith neutral point voltage-to-ground UNAngle, therefore
So the impedance ground Z of fault pointGIt again can be with are as follows:
For the system under certain method of operationIt is known, as long as Z can be calculated according to system neutral voltageG
Value.It can be obtained by formula (6):
Such as Fig. 2, UΦ、UNForm right angle triangle,It is known that by UΦU can be extrapolatedN, can also be by UNIt extrapolates
UΦ, therefore: when singlephase earth fault, three phase-to-ground voltages, neutral point voltage, fault point impedance ground/system capacitance to earth are
Which type of Z is complete corresponding relationship, there isG/XCValue, just there is corresponding system voltage-to-ground, only it is to be understood that any one system
Voltage-to-ground can derive other voltage-to-ground, and can shift out impedance ground value onto, and can extrapolate ground connection electricity
The size of capacitance current, I in table onemaxFor system maximum capacitor electric current, the characteristic relation between them is shown in Table one.
One: 10kV Fault feature of single phase earthing relation table of table
| UΦ | 0 | 993 | 1955 | 2858 | 3674 | 4378 | 4950 | 5180 | 5371 | 5521 | 5629 | 5671 | 5606 |
| UN | 5770 | 5543 | 5371 | 4950 | 4378 | 3674 | 2858 | 2416 | 1955 | 1479 | 993 | 894 | 795 |
| ZG/XC | 0 | 0,06 | 0,12 | 0,19 | 0,28 | 0,4 | 0,58 | 0,71 | 0,92 | 1,24 | 1,89 | 2,11 | 2,35 |
| IC/Imax | 1,00 | 0,96 | 0,93 | 0,86 | 0,76 | 0,64 | 0,50 | 0,42 | 0,34 | 0,26 | 0,17 | 0,15 | 0,14 |
As can be seen from Table I, the capacitance current of faulty line with grounding point impedance ground increase, faulty line
Capacitance current reduces, and faulty line judgement is more difficult, and the investment of controllable impedance provides condition, accurate judgement for faulty line judgement
Faulty line.
Using one of following four kinds of criterions, or the combination of any criterion, carry out the judgement of faulty line:
Criterion one: when single-phase earthing occurs for system, putting into has the controllable impedance Z for determining valueT, in investment controllable impedance ZT
Period, criterion are as follows: the zero-sequence current of faulty line is the maximum value of all outlet zero-sequence currents, and the zero-sequence current of faulty line
Greater than IN；
Because of IG=IN+ICFor vector sum, and INWith ICAngle is less than 90 degree, so IGAmplitude be greater than INWith ICAmplitude.
Criterion two: when single-phase earthing occurs for system, controllable impedance Z is put intoT, and in investment controllable impedance ZTLater, implement one
Secondary controllable impedance ZTAdjustment, criterion are as follows: in controllable impedance ZTAdjustment before and after, zero-sequence current variable quantity is maximum in all outlets
Outlet be faulty line；
Controllable impedance ZTAdjustment change when, it is clear that the electric current of formula (1) will not change, therefore non-fault line electric current
It is constant；The zero-sequence current of formula (2) faulty line changes, and variable quantity is formula (4), so controllable impedance ZTAdjustment change
It is faulty line that zero-sequence current, which changes maximum outlet,.
Criterion three: when single-phase earthing occurs for system, putting into has the controllable impedance Z for determining valueT, criterion are as follows: can putting into
Control impedance ZTFront and back, the maximum outlet of zero-sequence current variable quantity is faulty line in all outlets；
Similarly, controllable impedance Z is exitedTWhen, the zero-sequence current of faulty line changes maximum, therefore zero-sequence current variation is maximum
Outlet be faulty line.
In Fig. 1, XCFor system impedance, XCiFor the capacitance to earth on i-th line road, UNFor system neutral voltage, ZTIt is controllable
Impedance, ZGFor fault point impedance ground, UA、UB、UCFor the voltage-to-ground of system A, B, C three-phase, Ua、Ub、UcFor system A, B, C tri-
The phase voltage of phase, N are the number of outgoing of system, ICi、ICia、ICib、ICicThe zero-sequence current and A, B, C phase of respectively i-th outlet
Capacitive earth current, IG、ICGa、ICGb、ICGc, it is the zero-sequence current and A, B, C relatively capacitance current of faulty line, INIt is controllable
Impedance ZTElectric current, IJA、IJB、IJCFor the three-phase current of grounding transformer J, QS, KD are breaker, and J is grounding transformer, and K is
Controllable impedance ZTFling-cut switch, M is system busbar, i ∈ (1, N).
Criterion four: when single-phase earthing occurs for system, controllable impedance Z is exitedT, criterion are as follows: exiting controllable impedance ZTBefore
Afterwards, the maximum outlet of zero-sequence current variable quantity is faulty line in all outlets.
Similarly, controllable impedance Z is exitedTWhen, the zero-sequence current of faulty line changes maximum, therefore zero-sequence current variation is maximum
Outlet be faulty line.
In specific implementation, controllable impedance ZTTracking adjustment is carried out according to system voltage-to-ground as follows:
When single-phase earthing occurs for phase any in system A, B, C three-phase, is calculated according to formula (5) or formula (6) and obtain fault point
Impedance ground ZGValue be ZG1, set INAdjustment target value be INK, then controllable impedance ZTAdjusted value ZT1Are as follows:
By controllable impedance ZTTracking adjustment is ZT1。
Referring to Fig. 1, if 8 microfarad of 10kV system direct-to-ground capacitance, system capacitive reactance XC=398 Ω, capacitance current Imax=
43.2A, when singlephase earth fault occurs for system, B phase-to-ground voltage UΦ=UB=4378V, neutral point voltage UN=3674V, root
It is calculated according to formula (5) and obtains fault point impedance ground ZG1:
It is calculated according to formula (4) and obtains controllable impedance ZTAdjusted value ZT1, INAdjustment target value be INK=15A
By controllable impedance ZTTracking adjustment is 134 Ω, implements route selection in throwing, retreating system.We can also be by counting in advance
The correspondence table of the similar table one of calculating searches the worth Z out for corresponding to table according to correspondingT1, carry out tracking adjustment controllable impedance ZT。
In specific implementation, or by controllable impedance ZTBy INCarry out tracking adjustment: first by controllable impedance ZTIt is set as maximum value
ZTM, with maximum value Z when system operates normally or after single-phase earthingTMIt is put into；When single-phase earthing occurs, faulty line
Zero-sequence current be IG1, I is setGAdjustment target value be IGK, work as IG1< IGKWhen, reduce controllable impedance ZTValue, until IG1≥
IGK。
If 10kV system is electric over the ground, 3 microfarads, system capacitive reactance XC=1061 Ω, capacitance current Imax=16.2A,If: ZTM=800 Ω, IGK=12A puts into controllable impedance Z when normal operation or after single-phase earthing generationT, certain
Singlephase earth fault occurs for a period of time etching system A phase: failure phase-to-ground voltage UΦ=5371V, neutral point voltage UN=1955V, root
Table one obtains IC1=0.34 × Imax=0.42 × 16.2=6.8A, | ZG1|=0.71 × XC=753 Ω, according to formula (4) faulty line
In capacitance current IN1=5770/ (800+753)=3,72A, it is clear that IG1=IC1+IN1< 6.8+3,72 < 12A are unsatisfactory for wanting
Seek IG1≥IGK；Adjust ZTMFor 300 Ω, it is unsatisfactory for IG1≥IGK；Continue adjustment adjustment ZTMFor 50 Ω, I at this timeN1=5770/ (50+
753)=7,19A, meet IG1≥IGK。
In specific implementation, it also can use and automatically track line selection device for low current and carry out route selection as follows:
When single-phase earthing occurs for phase any one in system, failure phase-to-ground voltage UΦPhase lag behind neutral point over the ground
Voltage UN90 ° of phase, in controllable impedance ZTWhen not putting into, the zero-sequence current I of faulty lineGEqual to capacitance current IC, such as formula
(7):
XCFor the capacitance to earth of system, (- 1/XC) show the zero-sequence current I of faulty lineGPhase lag behind neutral point pair
Ground voltage UN90 ° of phase, therefore failure phase-to-ground voltage UΦWith the zero-sequence current I of faulty lineGPhase is identical, if it is B phase
Single-phase earthing U occursΦFor UB, i.e. the capacitance current I of faulty lineCWith failure phase-to-ground voltage UBWaveform it is consistent, amplitude is not
Together.
Set criterion are as follows: in controllable impedance ZTZero-sequence current and failure be relatively when not having input coefficient, in all outlets
Voltage UΦThe identical outlet of phase is zero-sequence current delayed phase neutral point voltage-to-ground U in faulty line or all outletsN's
The outlet that 90 ° of phase is faulty line.
Faulty line zero-sequence current IGWith failure phase-to-ground voltage UΦPhase is identical to be referred to: faulty line zero-sequence current IGWith
Failure phase-to-ground voltage UΦSampled value zero passage and reach maximum value simultaneously simultaneously；
Faulty line zero-sequence current IGLag neutral point voltage-to-ground UN90 ° of phase refer to: faulty line zero-sequence current IG
Sampled value zero passage when, the capacitance current I of faulty lineCU when zero passageNPositive maximum or negative maximum, therefore neutral point pair
Ground voltage UNSampled value absolute value | UN| it is maximum value.
In specific implementation, there can also be following different application mode:
When resonance occurs for system, controllable impedance ZTWith maximum value ZTMInvestment, for eliminating system resonance.When system occurs
When resonance, controllable impedance Z is put intoTSystem parameter is changed, resonance cannot maintain to eliminate resonance, and " Xuhanting oral solution " is that PT resonance is made
At the voltage signal similar with singlephase earth fault, make one to take for that single-phase earthing occurs, put into controllable impedance ZTAfter eliminate
The problem of resonance, " Xuhanting oral solution " phenomenon will disappear, " Xuhanting oral solution " mistake route selection would not also occur, therefore putting into can
Control impedance ZT" Xuhanting oral solution " phenomenon can be eliminated.
Single-phase earthing often judges failure phase by accident, puts into controllable impedance ZTThe electric current of front and back, the failure phase of grounding transformer exists
Change maximum in its three-phase current, in controllable impedance ZTThe electric current of the input time failure phase of transformer indirectly be also it is maximum, because
This puts into controllable impedance Z when single-phase earthing occurs for systemTAfterwards, the maximum phase of electric current is the event of system single-phase earthing in grounding transformer
Hinder phase, for carrying out the judgement of system single-phase earth fault phase.
In small resistance grounding system, the current in resistance property that when single-phase earthing flows through fault point is larger, generally in 400-600A
In range, it is possible to determine the no-load voltage ratio of zero sequence current mutual inductor according to the action message of zero-sequenceprotection is ensured.Because zero sequence is protected
The setting valve of shield is greater than the maximum capacitive earth current of single feedback line in substation, in the general zero-sequenceprotection of Central Substations
Action value should adjust 40A, and the transition resistance over the ground of such fault point is protected when being greater than 150 Ω because zero sequence is not achieved in fault current
The action value of shield can make " zero-sequenceprotection failure ", and zero-sequenceprotection ability can when the transition resistance over the ground in fault point is less than 140 Ω
By movement.If the pole tower ground resistance of 10kv overhead transmission line is that 30 Ω flow through fault loop when line insulator lightning stroke flashover
Resistive fault current up to 100A or more, then be superimposed with the capacitance current of system and meet the sensitivity of zero-sequenceprotection and do not ask
Topic.If the landing but generation overhead transmission line single-phase transmission line breaks, especially present overhead transmission line generally use insulated conductor, and
Due to lightning stroke or to tree abrasion single-phase insulated conductor breakage landing most easily occurs for insulated conductor, and due to not having at landing of breaking
Earthing or grounding means, the impedance ground of conducting wire over the ground are through transition resistance eutral grounding, and impedance ground depends on what conducting wire was contacted with the earth
The contact situation of length, the soil resistivity of pick-up point and conducting wire with the earth.And insulated conductor breakage, the exposed length of general conducting wire
Spend it is small, land fault point soil resistivity it is higher when or conducting wire with greatly contact unreliable when, can all fault point be caused to be grounded
Impedance is higher, the small requirement that can not meet zero-sequence current sensitivity of fault current, the zero-sequenceprotection of system will " failure ", failure
Route does not trip.In addition, the earth current that also will cause fault point is small when fault point impedance ground is higher, accordingly even when zero
The small 40A of setting valve of sequence protection, also can not solve the safety problem of fault point using zero-sequenceprotection come disengagement failure feeder line.
Thus low resistance grounding mode can not solve the broken string landing of overhead transmission line single-phase transmission line to personal safety risk problem.
Therefore, by neutral ground low values of resistors low in system in neutral point low values of resistors earthed system
Value resistor is considered as controllable impedance ZT, when single-phase high resistance ground zero-sequenceprotection failure occurs, implement event using low values of resistors
Hinder route selection.Fault current is less than the protection's dead-zone of protection seting value when eliminating single-phase high-impedance.
Claims (8)
1. one kind automatically tracks line selection device for low current, it is characterized in that: neutral point is set in the system of small current neutral grounding mode,
Setting can automatically track the controllable impedance Z of adjustment between the neutral point and groundT, the controllable impedance ZTMaximum value ZTMRoot
It is configured according to system nominal voltage；The controllable impedance ZTIt is according to system voltage-to-ground or according to the controllable impedance ZT's
Electric current INCarry out tracking adjustment, the controllable impedance ZTAdjusting range in 0≤ZT≤ZTMBetween.
2. one kind automatically tracks low-current line selection method, characterized in that using automatically tracking small current line selection described in claim 1
Device carries out route selection as follows:
When single-phase earthing occurs for phase any one in system:
For non-fault line: with UNIndicate system neutral voltage, XCiIndicate the capacitance to earth on i-th line road,Indicate event
Hinder phase phase voltage, then in non-fault line i-th outlet zero-sequence current ICiAre as follows:
ICi=3UN/XCi (1)
For faulty line: indicating the number of outgoing of system, i ∈ (1, M), X with MCExpression system capacitance to earth, ZGIndicate failure
Impedance ground is put, then the zero-sequence current I of faulty lineGAre as follows:
ICIt is the faulty line zero-sequence current I characterized by formula (3)GIn capacitance current；
INIt is the investment controllable impedance Z characterized by formula (4)TIn the electric current that faulty line generates；
For fault point impedance ground ZG: with UΦIndicate failure phase-to-ground voltage,Then fault point
Impedance ground ZGSuch as formula (5) or such as formula (6):
ZG=-UΦXC/3UN (5)
|ZG|=| XCtgθ/3| (6)
Using one of following four kinds of criterions, or the combination of any criterion, carry out the judgement of faulty line:
Criterion one: when single-phase earthing occurs for system, putting into has the controllable impedance Z for determining valueT, put into the controllable resistance
Anti- ZTPeriod, criterion are as follows: the zero-sequence current of faulty line is the maximum value of all outlet zero-sequence currents, and the zero sequence of faulty line
Electric current is greater than IN；
Criterion two: when single-phase earthing occurs for system, the controllable impedance Z is put intoT, and put into the controllable impedance ZTLater, real
Apply the primary controllable impedance ZTAdjustment, criterion are as follows: in the controllable impedance ZTAdjustment before and after, zero sequence electricity in all outlets
The stream maximum outlet of variable quantity is faulty line；
Criterion three: when single-phase earthing occurs for system, putting into has the controllable impedance Z for determining valueT, criterion are as follows: described in investment
Controllable impedance ZTFront and back, the maximum outlet of zero-sequence current variable quantity is faulty line in all outlets；
Criterion four: when single-phase earthing occurs for system, the controllable impedance Z is exitedT, criterion are as follows: exiting the controllable impedance ZT's
Front and back, the maximum outlet of zero-sequence current variable quantity is faulty line in all outlets.
3. according to claim 2 automatically track low-current line selection method, it is characterized in that: the controllable impedance ZTBy as follows
Mode carries out tracking adjustment according to system voltage-to-ground:
When single-phase earthing occurs for phase any in system A, B, C three-phase, is calculated according to formula (5) or formula (6) and obtain fault point ground connection
Impedance ZGValue be ZG1, set INAdjustment target value be INK, then controllable impedance ZTAdjusted value ZT1Are as follows:
By the controllable impedance ZTTracking adjustment is ZT1。
4. according to claim 2 automatically track low-current line selection method, it is characterized in that: the controllable impedance ZTBy described
INCarry out tracking adjustment: first by the controllable impedance ZTIt is set as maximum value ZTM, connect when system operates normally or single-phase
With maximum value Z behind groundTMIt is put into；When single-phase earthing occurs, the zero-sequence current of faulty line is IG1, I is setGAdjustment target
Value is IGK, work as IG1< IGKWhen, reduce controllable impedance ZTValue, until IG1≥IGK。
5. one kind automatically tracks low-current line selection method, characterized in that using automatically tracking small current line selection described in claim 1
Device carries out route selection as follows:
When single-phase earthing occurs for phase any one in system, failure phase-to-ground voltage UΦPhase lag behind neutral point voltage-to-ground
UN90 ° of phase, in the controllable impedance ZTWhen not putting into, the zero-sequence current I of faulty lineGEqual to capacitance current IC, such as formula
(7):
IG=IC=-3UN/XC=(- 1/XC)3UN (7)
XCFor the capacitance to earth of system, (- 1/XC) show the zero-sequence current I of faulty lineGPhase to lag behind neutral point electric over the ground
Press UN90 ° of phase, therefore failure phase-to-ground voltage UΦWith the zero-sequence current I of faulty lineGPhase is identical；
Set criterion are as follows: in the controllable impedance ZTWhen not having input coefficient, zero-sequence current and failure are relatively electric in all outlets
Press UΦThe identical outlet of phase is zero-sequence current delayed phase neutral point voltage-to-ground U in faulty line or all outletsNPhase
The outlet of 90 ° of position is faulty line.
Faulty line zero-sequence current IGWith failure phase-to-ground voltage UΦPhase is identical to be referred to: faulty line zero-sequence current IGWith failure
Phase-to-ground voltage UΦSampled value zero passage simultaneously, and reach maximum value simultaneously；
Faulty line zero-sequence current IGLag neutral point voltage-to-ground UN90 ° of phase refer to: faulty line zero-sequence current IGAdopt
When sample value zero passage, neutral point voltage-to-ground UNSampled value absolute value | UN| it is maximum value.
6. according to claim 1 automatically track line selection device for low current, it is characterized in that: when resonance occurs for system, institute
State controllable impedance ZTWith maximum value ZTMInvestment, for eliminating system resonance.
7. according to claim 1 automatically track line selection device for low current, it is characterized in that: being thrown when single-phase earthing occurs for system
Enter the controllable impedance ZTAfterwards, the maximum phase of electric current is system single-phase earth fault phase in grounding transformer, for carrying out system
The judgement of singlephase earth fault phase.
8. according to claim 1 automatically track line selection device for low current, it is characterized in that: being connect in neutral point low values of resistors
In ground system, by the neutral ground low values of resistors the low values of resistors in system is considered as controllable impedance ZT, occurring
When single-phase high resistance ground zero-sequenceprotection failure, implement faulty line route selection using the low values of resistors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811621494.XA CN109444672A (en) | 2018-12-28 | 2018-12-28 | One kind automatically tracking line selection device for low current and selection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811621494.XA CN109444672A (en) | 2018-12-28 | 2018-12-28 | One kind automatically tracking line selection device for low current and selection method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN109444672A true CN109444672A (en) | 2019-03-08 |
Family
ID=65540348
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811621494.XA Pending CN109444672A (en) | 2018-12-28 | 2018-12-28 | One kind automatically tracking line selection device for low current and selection method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109444672A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109921405A (en) * | 2019-04-24 | 2019-06-21 | 南京泰润电力工程有限公司 | A kind of earthing method of medium voltage network neutral point |
| CN111381129A (en) * | 2020-03-05 | 2020-07-07 | 华中科技大学 | Ground fault line and type identification method and device based on ultralow frequency signal |
| CN111880110A (en) * | 2019-04-15 | 2020-11-03 | 山东大学 | Single-phase earth fault disappearance judgment method and system for neutral point non-effective earthing system |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1591033A (en) * | 2003-08-26 | 2005-03-09 | 陈昌鹏 | Method for small current grounding selecting wire and fault positioning |
| CN101598761A (en) * | 2009-07-29 | 2009-12-09 | 江苏省电力公司常州供电公司 | Fault line selection method for small electric current grounding system of distribution network |
| CN102520314A (en) * | 2011-11-23 | 2012-06-27 | 北京天能继保电力科技有限公司 | Detection system and detection method for single-phase grounding fault line selection in small current grounding system |
| CN102798795A (en) * | 2012-08-14 | 2012-11-28 | 大连电力勘察设计院有限公司 | Method capable of realizing low-current route selection and fault location |
| CN107064733A (en) * | 2017-03-15 | 2017-08-18 | 长沙理工大学 | Power distribution network flexible ground device single-phase earth fault line selection and arc extinguishing method |
| CN108548986A (en) * | 2018-06-01 | 2018-09-18 | 南京南瑞继保电气有限公司 | A kind of high resistance ground detecting system of small current neutral grounding system, device and method |
| CN209280851U (en) * | 2018-12-28 | 2019-08-20 | 张安斌 | One kind automatically tracking line selection device for low current |
-
2018
- 2018-12-28 CN CN201811621494.XA patent/CN109444672A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1591033A (en) * | 2003-08-26 | 2005-03-09 | 陈昌鹏 | Method for small current grounding selecting wire and fault positioning |
| CN101598761A (en) * | 2009-07-29 | 2009-12-09 | 江苏省电力公司常州供电公司 | Fault line selection method for small electric current grounding system of distribution network |
| CN102520314A (en) * | 2011-11-23 | 2012-06-27 | 北京天能继保电力科技有限公司 | Detection system and detection method for single-phase grounding fault line selection in small current grounding system |
| CN102798795A (en) * | 2012-08-14 | 2012-11-28 | 大连电力勘察设计院有限公司 | Method capable of realizing low-current route selection and fault location |
| CN107064733A (en) * | 2017-03-15 | 2017-08-18 | 长沙理工大学 | Power distribution network flexible ground device single-phase earth fault line selection and arc extinguishing method |
| CN108548986A (en) * | 2018-06-01 | 2018-09-18 | 南京南瑞继保电气有限公司 | A kind of high resistance ground detecting system of small current neutral grounding system, device and method |
| CN209280851U (en) * | 2018-12-28 | 2019-08-20 | 张安斌 | One kind automatically tracking line selection device for low current |
Non-Patent Citations (2)
| Title |
|---|
| 刘良玉;: "浅谈10kV电网中性点经小电阻接地自动跟踪补偿消弧装置", 小水电, no. 04, 22 August 2006 (2006-08-22), pages 149 - 150 * |
| 杨帆;杨涛;尹华山;: "消弧补偿自动跟踪及选线技术在工程中的研究与应用", 电子技术与软件工程, no. 05, 1 March 2015 (2015-03-01), pages 149 - 150 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111880110A (en) * | 2019-04-15 | 2020-11-03 | 山东大学 | Single-phase earth fault disappearance judgment method and system for neutral point non-effective earthing system |
| CN111880110B (en) * | 2019-04-15 | 2021-08-27 | 山东大学 | Single-phase earth fault disappearance judgment method and system for neutral point non-effective earthing system |
| CN109921405A (en) * | 2019-04-24 | 2019-06-21 | 南京泰润电力工程有限公司 | A kind of earthing method of medium voltage network neutral point |
| CN111381129A (en) * | 2020-03-05 | 2020-07-07 | 华中科技大学 | Ground fault line and type identification method and device based on ultralow frequency signal |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2446283B1 (en) | Method for identifying type of fault on power line | |
| CN108594071B (en) | Single-phase earth fault detection method for neutral point small-resistance earth distribution network | |
| CN209280851U (en) | One kind automatically tracking line selection device for low current | |
| CN106443349B (en) | A kind of high resistance earthing fault localization method and system | |
| CN109444672A (en) | One kind automatically tracking line selection device for low current and selection method | |
| CN103592571A (en) | Method for achieving single-phase earth fault line selection of small current grounding system | |
| CN101540499B (en) | Fast line selection tripping device for medium resistance grounding for urban distribution network and line selection method | |
| CN104914391A (en) | Distribution network single-phase grounding fault simulation and positioning performance test platform and method | |
| CN113484672B (en) | Small-resistance grounding system single-phase grounding fault protection method based on ground wire current | |
| CN2521811Y (en) | Shunt resistance type autoamtic tracking arc suppression compensating & select switch | |
| CN110879330A (en) | Power distribution network single-phase earth fault development situation discrimination method based on zero sequence volt-ampere curve area | |
| CN110336251A (en) | A kind of small resistance grounding system ground fault centralization new protective method | |
| CN112433175A (en) | Ungrounded system fault line selection method utilizing zero sequence current multiplication characteristic | |
| Altonen et al. | Performance of modern fault passage indicator concept in compensated MV-networks | |
| CN113258544A (en) | Compensation type intelligent resistance ground fault processing method | |
| Balcerek et al. | Centralized substation level protection for determination of faulty feeder in distribution network | |
| CN107516877B (en) | Small resistance grounding system failure protecting device, system and method | |
| CN112986862B (en) | Power distribution network fault indicator sensitivity improving method based on neutral point resistance control | |
| CN110535116A (en) | A kind of arc extinction cabinet and small current neutral grounding system | |
| CN109245068A (en) | A kind of neutral grounding mode conversion equipment | |
| CN112039031B (en) | Differentiation processing and fault area isolation method for single-phase earth fault of power distribution network | |
| Venkata et al. | Advanced and adaptive protection for active distribution grid | |
| CN114977091A (en) | Grounding fault isolation method for neutral point arc suppression coil and medium resistance grounding power grid | |
| CN110687389B (en) | Method for measuring key parameters of transfer grounding device and judging arc extinction of fault point | |
| CN104849616B (en) | Based on virtual power comparison principle distribution fault line selection method for single-phase-to-ground fault |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |