CN109884466A - A kind of distribution earthing wire-selecting method recognizing double negative-sequence current vector correlation features - Google Patents
A kind of distribution earthing wire-selecting method recognizing double negative-sequence current vector correlation features Download PDFInfo
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Abstract
The invention discloses a kind of distribution earthing wire-selecting methods for recognizing double negative-sequence current vector correlation features, comprising: 1. calculate the instantaneous difference of three-phase increment current and two-phase increment current in real time；2. transient condition verification three-phase increment current whether there is the scalar relationship characteristic of double negative-sequence currents, decide whether to start earthing wire-selecting program；3. time transient state examines three-phase increment current to whether there is the scalar relationship characteristic of double negative-sequence currents, the monitored whether doubtful ground path of route is determined；4. transient state examines three-phase increment current to whether there is the vector correlation feature of double negative-sequence currents after, recognizes and confirms true and false single-phase earthing.Through emulation and simulated experiment verifying, this method is suitable for all types of distribution lines and the earthing wire-selecting and the true and false of bus are grounded identification.
Description
Technical field
The present invention relates to power distribution network single-phase grounding selecting methods, recognize double negative-sequence current vector correlations more particularly to a kind of
The earthing wire-selecting method of feature.
Background technique
There is following problems for existing distribution earthing wire-selecting method:
1, stable status zero-sequence current value and power direction comparison method can be used for earth-free distribution and low resistance grounding distribution
Line-to-ground route selection；But in resonance grounding distribution, stable state zero of the same power source bus difference branched line in ground fault
Sequence current amplitude is close, zero sequence power direction is identical, this is just difficult to differentiate between ground path and sound circuit.
2, zero-sequence current Instantaneous Comparison Method and difference of phase currents bootstrapping selection method, solve resonant earthed system
The earthing wire-selecting problem of radial line, but not can solve the earthing wire-selecting problem of Electromagnetic coupling route.
3, it is based on voltage and current Sudden Changing Rate derivative polarity comparison, document thinks can to distinguish the single-phase of route and bus
Ground connection, but analysis of simulation experiment illustrate, three-phase voltage Sudden Changing Rate be all residual voltage instantaneous value, Earth Phase jump-value of current be
It is grounded increment current instantaneous value, for the two when any section of distribution is grounded, derivative polarity is all on the contrary, therefore being difficult to differentiate between mother
The single-phase earthing of line or route.
4, Low frequency signal injection method single phase earth fault detection technology is preferable for the detection effect of low-impedance earthed system, but is not suitable for
Senior middle school hinders single-phase earthing, and signal injection device is pressed in need to increasing, and not only there is low-frequency current impacts, but also brings in newly-increased and press
The safety management risk of equipment and the trouble of engineering construction.
5, very high using the earthing detection sensitivity of wavelet analysis, but easily judge wrong report by accident in the fluctuation of load.
6, traveling wave grounded line selection and fault locating technology is suitable for cable run or corresponding within km in the application of distribution line
Extend the offline ranging of joint line, but is unsuitable for application on site；Not only because distribution direct-to-ground capacitance is too big to its attenuation, more because of row
The medium-high frequency resonance current wave that wave signal is simultaneously produced is flooded.
In summary earthing wire-selecting method, also because pseudo- earth current of distribution in the presence of operation and operating process is harmonious
Vibration voltage and current signal and judge wrong report by accident；Particularly with the earthing wire-selecting method using instantaneous voltage current signal, institute is impacted
It stands in the breach.
Summary of the invention
Goal of the invention: being directed to the above-mentioned prior art, and the distribution for providing a kind of double negative-sequence current vector correlation features of identification connects
Ground selection method, for the true single-phase earthing in all distribution sections of the upper limit and following resistance value, can it is automatic, accurate, sensitive,
Quickly and reliably select whether ground path；It, can and for various pseudo- earth currents appeared in operation and operating process
Correctly it is recognized as non-single-phase-to-ground current.
Technical solution: a kind of distribution earthing wire-selecting method recognizing double negative-sequence current vector correlation features, including walk as follows
It is rapid:
Step 1: ground monitor calculates three-phase increment current instantaneous value and the instantaneous difference of two-phase increment current in real time；
Step 2: transient condition verification three-phase increment current whether there is the scalar relationship characteristic in double negative-sequence current vector correlations,
Decide whether to start earthing wire-selecting program；
Step 3: in secondary transient state, three-phase increment current being examined to whether there is the scalar relationship in double negative-sequence current vector correlations
Feature determines the monitored whether doubtful ground path of route；
Step 4: in rear transient state, three-phase increment current being examined to whether there is the scalar relationship characteristic and phase of double negative-sequence currents
Relationship characteristic recognizes and confirms true and false single-phase earthing.
Further, in the step 1, the real-time computing technique of the three-phase increment current instantaneous value is iAk-iAk-2N=
iAIk、iBk-iBk-2N=iBIk、iAk-iAk-2N=iCIk；The real-time computing technique of the instantaneous difference of two-phase increment current is iAIk-
iBIk=iABIk、iBIk-iCIk=iBCIk、iCIk-iAIk=iCAIk；Wherein, the k in every electric current subscript indicates to occur from doubtful ground connection
Moment starts the sampling number calculated, and A, B, C, which are respectively indicated, to be belonged to A phase, B phase and C phase, AI, BI, CI by mark electric current and respectively indicate
A phase, B phase and C phase are belonged to by mark increment current, ABI, BCI, CAI, which are respectively indicated, belongs to AB, BC by mark two-phase increment current difference
With CA phase, N is the sampling number of every power frequency period.
Further, the step 2 includes: that preparatory adjusting transient state increment current crosses limit value iset；When ground monitor is examined
Test | iAIk| > isetAnd | iABIk| > 2 | iBIk| and | iCAIk| > 2 | iCIk| or | iBIk| > isetAnd | iBCIk| > 2 | iCIk|
And | iABIk| > 2 | iAIk| or | iCIk| > isetAnd | iCAIk| > 2 | iAIk| and | iBCIk| > 2 | iBIk| criterion set up
When, it decides that monitored route is corresponding and A phase or B phase or the doubtful ground connection of C phase has occurred, determine starting route selection process；Otherwise it returns
Return main program.
Further, the step 3 includes: that preparatory time transient state increment current of adjusting crosses limit value Iset1；Ground monitor
I is taken in secondary transient state respectivelyAIk、iBIk、iCIkAnd iABIk、iBCIk、iCAIkHalf cycle instantaneous value calculate three split-phase increment currents
Subtranient value IAI1、IBI1、ICI1With the secondary transient state difference I of two-phase increment currentABI1、IABI1、ICAI1, when inspection is arrived | IAI1| >
Iset1And | IABI1| > 2 | IBI1| and | ICAI1| > 2 | ICI1| or | IBI1| > Iset1And | IBCI1| > 2 | ICI1| and | IABI1| > 2 |
IAI1|, or | ICI1| > Iset1And | ICAI1| > 2 | IAI1| and | IBCI1| > 2 | IBI1| criterion set up when, decide that and supervised
Survey line road is corresponding to have occurred A phase or B phase or the doubtful ground connection of C phase, determines starting true and false ground connection identification process；Otherwise main journey is returned
Sequence.
Further, the step 4 includes:
Step 4.1: transient state ground connection phase current crosses limit value I after adjusting in advance respectivelyset2Limit is crossed with phase increment current is perfected
Definite value Iset3, and two limit value θ excessively for perfecting phase increment current phase difference are adjusted in advanceset；
Step 4.2: ground monitor takes i in rear transient state respectivelyAIk、iBIk、iCIkAnd iABIk、iBCIk、iCAIkHalf cycle it is instantaneous
Value calculates the rear transient value I of three-phase increment currentAI2、IBI2、ICI2With the rear transient state difference I of two-phase increment currentABI2、IBCI2、
ICAI2, when detecting | IAI2| > Iset2And | IABI2| > 2 | IBI1| and | ICAI2| > 2 | ICI1| or | IBI2| > Iset2And | IBCI2|
> 2 | ICI1| and | IABI2| > 2 | IAI1|, or | ICI2| > Iset2And | ICAI2| > 2 | IAI1| and | IBCI2| > 2 | IBI1| criterion item
When part is set up, A phase or B phase has occurred for the monitored route correspondence of preliminary judgement or C phase is grounded；Otherwise determine that increment current is puppet
Earth current；
Step 4.3: examining again whether big with the increment current magnitude that perfects one of phase corresponding to preliminary judgement Earth Phase
In the criterion definite value of phase calculation: | IAI2| > Iset3Or | IBI2| > Iset3Or | ICI2| > Iset3；If being not more than criterion definite value, just
Determine that A phase or B phase or the true ground connection of C phase of high value has occurred in monitored route；If more than criterion definite value, then calculates and connect
Two phase differences perfected between phase increment current corresponding to ground phase are θBI-θCI=θBCIOr θCI-θAI=θCAIOr
θAI-θBI=θABI；When detecting θBCI> θsetOr θCAI> θseOr θABI> θsetCriterion set up when, determine that and supervised
The true ground connection of the corresponding A phase that the design following resistance value of the upper limit has occurred in survey line road or B phase or C phase；Otherwise it is determined as pseudo- ground connection
Electric current；Wherein, θAI、θBI、θCIRespectively A, B, C phase increment current phase, θABI、θBCI、θCAIRespectively θAIAnd θBI、θBIAnd θCI、
θCIAnd θAIPhase difference.
Further, the subtranient value of calculated three-phase increment current and rear transient value are all half cycle area integral value, or
For half cycle area integral mean value, or amplitude or virtual value for the conversion of half cycle area integral.
The utility model has the advantages that the present invention compared with existing earthing wire-selecting method, has following basic effect:
One, using in the relatively large transient state of signal strength, secondary transient state three-phase increment current as signal source；It is single using reflection
The scalar optimized relation feature of double negative-sequence currents of phase ground path earth current constitutive relations feature, so that criterion is sensitive
Degree, discrimination precision and coverage area significantly improve；It is allowed to be suitable for various all sections of structure distribution under different voltages phase
The single-phase earthing of the design upper limit and following resistance value that are occurred.
Secondly, using the optimization feature of double negative-sequence current scalar relationships in rear transient state increment current, be combined double negative
Sequence electric current can recognize true and false list of the various doubtful earth currents within design accuracy in the feature for perfecting equal value same-phase
Mutually it is grounded.
Thirdly, the present invention be applicable not only to the single-phase earthing of continuity and the full power frequency period wave of noncontinuity, can also be applicable in
In periodicity or the single-phase earthing of the non-complete cycle power frequency wave of aperiodicity；So that drawing by environment, weather and by reasons such as heat ageings
It plays electric leakage caused by insulation damages and ground connection being capable of early detection.
Detailed description of the invention
Fig. 1 is implementation flow chart of the invention.
Fig. 2 is the distribution network model figure of application case of the present invention.
Fig. 3 is the simulated current waveform diagram that 5k Ω ground connection occurs in operation with closed ring route G point C phase for Fig. 2 isolated neutral system；Figure
In 3: iP00、iR11、iR21、iB31The respectively earth current of bus, operation with closed ring route and other parallel branch.
Fig. 4 is the analytic process polar plot that earth current is analyzed to negative-sequence current in pairs.
Fig. 5 occurs 5k Ω in operation with closed ring route G point C phase for network distribution transformer neutral by arc extinction coil grounding system and connects
The Digital Simulation figure on ground；In Fig. 5: iP00、iR11、iR21、iB31、iXHQRespectively bus, operation with closed ring route, other parallel branch
With the earth current of arc suppression coil.
Fig. 6 be when neutral point resonant earthed system operation with closed ring route occur G point C phase 1k Ω resistance eutral grounding when, ground connection
Phase and the difference current simulation waveform perfected between the double negative-sequence current vectors of phase.
Specific embodiment
Further explanation is done to the present invention with reference to the accompanying drawing.
As shown in Figure 1, a kind of distribution earthing wire-selecting method for recognizing double negative-sequence current vector correlation features, including walk as follows
It is rapid:
Step 1: ground monitor calculates three-phase increment current and the instantaneous difference of two-phase increment current in real time；In subsequent step
In, it takes positive difference to be respectively greater than two for two and takes positive deduction item instantaneous value and 2 times of subtranient value of scalar relationship characteristic, together with two
A same-phase relationship characteristic for perfecting phase increment current is subsequent survey process all as double negative-sequence current vector correlation features
The data foundation for recognizing double negative-sequence current vector correlation features is provided.
This step, the real-time computing technique of three-phase increment current instantaneous value are iAk-iAk-2N=iAIk、iBk-iBk-2N=iBIk、
iAk-iAk-2N=iCIk；The real-time computing technique of the instantaneous difference of two-phase increment current is iAIk-iBIk=iABIk、iBIk-iCIk=iBCIk、
iCIk-iAIk=iCAIk；Wherein, the k in the subscript of each tense electric current indicates the sampling calculated since occurring the moment for doubtful ground connection
Number, A, B, C, which are respectively indicated, belongs to A phase, B phase and C phase by mark electric current, and AI, BI, CI, which are respectively indicated, belongs to A by mark increment current
Phase, B phase and C phase, ABI, BCI, CAI, which are respectively indicated, belongs to AB, BC and CA phase by mark increment current difference, and N is every power frequency period
Sampling number.
By taking the 10kV distribution of Fig. 2 as an example, if the wherein relatively total capacitance including cyclization route branched line containing ring network cabinet
Value is 20 μ F；Other parallel lines are 60 μ F per relatively total capacitance value；Arc suppression coil inductance is designed as by 10% overcompensation degree
38mH.If when the network closed loop route operation with closed ring G point have occurred C phase 5k Ω transition resistance ground connection, then P00 shown in Fig. 2,
The monitoring point R11, R21, B31 measures increment current data.
Step 2: transient condition verification three-phase increment current whether there is the scalar relationship characteristic in double negative-sequence current vector correlations,
Decide whether to start earthing wire-selecting program.Specific step is as follows for this step packet:
Adjusting transient state increment current crosses limit value i in advanceset.When ground monitor inspection is arrived | iAIk| > isetAnd | iABIk|
> 2 | iBIk| and | iCAIk| > 2 | iCIk| or | iBIk| > isetAnd | iBCIk| > 2 | iCIk| and | iABIk| > 2 | iAIk| or |
iCIk| > isetAnd | iCAIk| > 2 | iAIk| and | iBCIk| > 2 | iBIk| criterion when setting up, decide that monitored route is corresponding
A phase or B phase or the doubtful ground connection of C phase has occurred, determines starting route selection process；Otherwise main program is returned.
In the present embodiment, iset=0.6A；The ground monitor of P00, R11, R21 point is all examined respectively and is arrived | iCIk| > iset
And | iCAIk| > 2 | iAIk| and | iBCIk| > 2 | iBIk| transient criterion condition set up, meet double negative-sequence current transient state vector correlations
In scalar relationship characteristic, with regard to qualitative discrimination be monitored route occur the doubtful ground connection of C phase, and determine start route selection process.And B31
The detection of point does not meet these criterions, does not just start route selection process.
Step 3: in secondary transient state, three-phase increment current being examined to whether there is the scalar relationship in double negative-sequence current vector correlations
Feature determines the monitored whether doubtful ground path of route.Specific step is as follows for this step packet:
Time transient state increment current is adjusted in advance crosses limit value Iset1；Ground monitor takes i in secondary transient state respectivelyAIk、iBIk、
iCIkAnd iABIk、iBCIk、iCAIkHalf cycle instantaneous value, using half cycle area integral method calculate three split-phase increment currents secondary transient state
Value IAI1、IBI1、ICI1With the secondary transient state difference I of two-phase increment currentABI1、IABI1、ICAI1, as half cycle area integral value.Work as inspection
Test | IAI1| > Iset1And | IABI1| > 2 | IBI1| and | ICAI1| > 2 | ICI1| or | IBI1| > Iset1And | IBCI1| > 2 | ICI1| and
|IABI1| > 2 | IAI1|, or | ICI1| > Iset1And | ICAI1| > 2 | IAI1| and | IBCI1| > 2 | IBI1| criterion set up when,
It decides that monitored route is corresponding and A phase or B phase or the doubtful ground connection of C phase has occurred, determine starting true and false ground connection identification process；It is no
Then return to main program.Wherein, 1 in every electric current subscript indicates time transient state.
In the present embodiment, Iset1=0.6A；The monitor inspection of P00, R11, R21 point is arrived | ICI1| > Iset1And | ICAI1| >
2|IAI1| and | IBCI1| > 2 | IBI1| criterion set up, meet the scalar relationship in double negative-sequence currents time transient state vector correlations
Feature just all determines that the doubtful ground connection of C phase has occurred in monitored route, determines starting true and false ground connection identification process.
Step 4: in rear transient state, three-phase increment current being examined to whether there is the scalar relationship characteristic and phase of double negative-sequence currents
Relationship characteristic recognizes and confirms true and false single-phase earthing.Specific step is as follows for this step packet:
Step 4.1: transient state ground connection phase current crosses limit value I after adjusting in advance respectivelyset2Limit is crossed with phase increment current is perfected
Definite value Iset3, and two limit value θ excessively for perfecting phase increment current phase difference are adjusted in advanceset.In the present embodiment, Iset2=
0.6A, Iset3=0.4A, θset=20 °.
Step 4.2: ground monitor takes i in rear transient state respectivelyAIk、iBIk、iCIkAnd iABIk、iBCIk、iCAIkHalf cycle it is instantaneous
Value calculates the rear transient value I of three split-phase increment currents using half cycle area integral methodAI2、IBI2、ICI2With two-phase increment current
Rear transient state difference IABI2、IBCI2、ICAI2, as half cycle area integral value.When detecting | IAI2| > Iset2And | IABI2| > 2 |
IBI1| and | ICAI2| > 2 | ICI1| or | IBI2| > Iset2And | IBCI2| > 2 | ICI1| and | IABI2| > 2 | IAI1|, or | ICI2| >
Iset2And | ICAI2| > 2 | IAI1| and | IBCI2| > 2 | IBI1| criterion when setting up, preliminary judgement is monitored the corresponding hair of route
It has given birth to A phase or B phase or C phase is grounded；Otherwise determine that increment current is pseudo- earth current.Wherein, 2 tables in every electric current subscript
Show rear transient state.
In the present embodiment, the ground monitor of P00, R11, R21 point is all detected | ICI2| > Iset2And | ICAI2| > 2 | IAI1
| and | IBCI2| > 2 | IBI1| criterion set up, meet the scalar relationship characteristic after double negative-sequence currents in transient state vector correlation,
Route is monitored with regard to preliminary judgement C phase has occurred and is grounded.
Step 4.3: examining again whether big with the increment current magnitude that perfects one of phase corresponding to preliminary judgement Earth Phase
In the criterion definite value of phase calculation: | IAI2| > Iset3Or | IBI2| > Iset3Or | ICI2| > Iset3；If being not more than criterion definite value, just
Determine that A phase or B phase or the true ground connection of C phase of high value has occurred in monitored route；If more than criterion definite value, then calculates and connect
Two phase differences perfected between phase increment current corresponding to ground phase are θBI-θCI=θBCIOr θCI-θAI=θCAIOr
θAI-θBI=θABI；When detecting θBCI> θsetOr θCAI> θseOr θABI> θsetCriterion set up when, determine that and supervised
The true ground connection of the corresponding A phase that the design following resistance value of the upper limit has occurred in survey line road or B phase or C phase；Otherwise it is determined as pseudo- ground connection
Electric current；Wherein, θAI、θBI、θCIRespectively A, B, C phase increment current phase, θABI、θBCI、θCAIRespectively θAIAnd θBI、θBIAnd θCI、
θCIAnd θAIPhase difference.
In the present embodiment, i.e., for | IAI2| > Iset3Criterion, P00 point sets up, which directly confirms that C phase occurs
True ground connection；R11, R21 point are invalid, then continue phase identification.R11, R21 point monitor detect | θABI| > θset
Criterion set up, determine that the true ground connection of corresponding C phase that high value has occurred of monitored route.Due to P00, R11, R21
The present position of point monitor, can be confirmed that true C phase, which has occurred, with operation with closed ring line loop in bus is grounded.Again because all
Pseudo- earth current does not comply with the criterion of these rear transient state, therefore adds bright these and reflect double negative-sequence current vector correlation features
Criterion have anti-error discriminating function.
It should be noted that the subtranient value of calculated three-phase increment current and rear transient value are all half cycle area integral
Value, or be half cycle area integral mean value, or be the amplitude or virtual value of the conversion of half cycle area integral.
The present invention has anti-error identification and raising route selection precision and correct because compared with other existing earthing wire-selecting methods
The clear superiority of rate, can cover the single-phase earthing in all sections of all types of distributions, therefore can be widely applied.
Related notion explanation
1, increment current
The general name of the increased current segment in point being monitored.Increment current is after being identified, and when confirmation, it has short-circuit electricity
Fault component electric current or earth current can be called when flowing the perhaps characteristic attribute of earth current.
2, three tense increment current
After phase fault or single-phase earthing, the increment current detected by selected three tenses.
Transient state increment current: phase fault or the increment of sample electric current at single-phase earthing generation moment.
Secondary transient current: the increment current calculated in phase fault or the second half of the cycle of single-phase earthing generation.
Transient current afterwards: institute in the second half of the cycle of second power frequency period after phase fault or single-phase earthing occur
The increment current of measuring and calculating.
Emulation and simulated experiment are shown, check of genuineness single-phase earthing and are improved the accuracy of earthing wire-selecting, at least need
Use the increment current of three above tense.
3, double negative-sequence currents
In Fig. 2: as neutral point switch S0When disjunction, distribution is isolated neutral system；Work as S0When closure, distribution is power supply transformation
The resonant earthed system of device neutral by arc extinction coil grounding.In isolated neutral system C phase G point ground connection, in P00 bus
Three-phase increment current observed by power supply monitoring point flows into the earth, and divides from power transformer, C phase line, ground connection transition resistance
A and B relatively capacitor, A and B phase line and power transformer are not flowed into from the earth.It can be seen that the transition resistance that C phase is grounded
It has been respectively communicated with CA phase and BC phase two mutually increment current circuit.I in the three-phase increment current such as Fig. 3 of the monitoring point P00P00
Shown in simulated current waveform.For the constitutive relations feature for disclosing the circuit three-phase increment current, using the vector analysis side of Fig. 4
Method: wherein Fig. 1 a~1c and Fig. 1 d~1f with using the phase in the circuit CA, BC respectively increment current, in conjunction with the symmetrical components electricity before ground connection
Stream is analyzed using negative sequence component method.
In Fig. 4:The respectively symmetrical load current vector of A, B, C；Respectively A,
B, the current phasor of C phase direct measuring；Respectively A, B, C phase are grounded increment current vector；The respectively current phasor of A, B, C phase direct measuring；Respectively A is symmetrical negative
The current phasor for carrying current phasor and direct measuring rotates clockwise 120 ° respectively；Respectively B is symmetrical
120 ° of the rotation counterclockwise respectively of the current phasor of load current vector sum direct measuring；Respectively the 1st, 2 group of negative phase-sequence system
3 times of C phase negative-sequence current vectors in system；In respectively the 1st, 2 group of negative phase-sequence system
A, B, C phase negative-sequence current vector.
By the analysis result of Fig. 4 as it can be seen that isolated neutral system power supply monitoring point, the substantive characteristics electric current of single-phase earthing,
It is the resultant current of two negative phase-sequence vector systems, referred to as double negative-sequence currents.Thus it defines: when single-phase earthing occurs, at two
Between ungrounded phase and Earth Phase under the action of line voltage, respectively in the ground connection transition of the direct-to-ground capacitance of ungrounded phase and Earth Phase
Two negative phase-sequence system powers that resistance loop is generated and synthesized simultaneously are called double negative-sequence currents.The vector of double negative-sequence currents closes
It is feature are as follows: 1. the increment current of Earth Phase is always twice of the sound mutually electric current；2. the two anti-phase position；3. two strong
Full phase increment current equivalence same-phase.
4, the optimization relationship characteristic of double negative-sequence current vectors
When power transformer neutral by arc extinction coil grounding shown in Fig. 2 is when closing the switch, selected monitoring point is in G point
The three-phase increment current simulation waveform that C phase is grounded is as shown in Figure 5.Wherein, the monitoring point R11 Earth Phase increases relative to phase is perfected
It is more out greatly to measure electric current, wherein double negative-sequence current component accountings are obvious.And in the monitoring point P00 and R21, perfect phase and Earth Phase
Increment current is all smaller in the difference of the area integral of each tense, so that double negative-sequence current vector correlations of three-phase increment current are special
Levy unobvious show；But because double negative-sequence currents still exist with the distribution mode in isolated neutral system at this time, therefore to three-phase increment
Electric current carries out following optimization processing.
According to the vector correlation feature of double negative-sequence currents, such as in secondary transient state, Earth Phase increment current I " is takenCGIR11Respectively
Perfect phase increment current I " with twoAGIR11、I″BGIR11Seek vector difference I "CAIR111、I″CBIR11Processing method:
I″CGIR11-I″AGIR11=I "CAIR111、I″CGIR11-I″BGIR11=I "CBIR111
By the processing of this formula, following effect is obtained: 1. three characteristics of the middle term zero sequence resonance current equivalence same-phase, Earth Phase
The influence of zero sequence resonance current is eliminated with the vector difference algorithm for perfecting phase increment current；2. because of Earth Phase and pair for perfecting phase
The difference of negative-sequence current antiphase, the two vector is the sum of scalar, to improve the sensitivity that inequality criterion compares；3. two
The feature for perfecting phase increment current equivalence same-phase remains unchanged.
These optimization processing effects are high-visible by the difference current simulation waveform of Fig. 6.As a result, in the methods of the invention,
The preferentially vector correlation feature by this after optimization processing, as double negative-sequence current vector correlation features.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (6)
1. a kind of distribution earthing wire-selecting method for recognizing double negative-sequence current vector correlation features, which is characterized in that including walking as follows
It is rapid:
Step 1: ground monitor calculates three-phase increment current instantaneous value and the instantaneous difference of two-phase increment current in real time；
Step 2: transient condition verification three-phase increment current whether there is the scalar relationship characteristic in double negative-sequence current vector correlations, determine
Whether earthing wire-selecting program is started；
Step 3: in secondary transient state, the scalar relationship for examining three-phase increment current to whether there is in double negative-sequence current vector correlations is special
Sign determines the monitored whether doubtful ground path of route；
Step 4: in rear transient state, three-phase increment current being examined to whether there is the scalar relationship characteristic and phase relation of double negative-sequence currents
Feature recognizes and confirms true and false single-phase earthing.
2. the distribution earthing wire-selecting method according to claim 1 for recognizing double negative-sequence current vector correlation features, feature
It is, in the step 1, the real-time computing technique of the three-phase increment current instantaneous value is iAk-iAk-2N=iAIk、iBk-iBk-2N
=iBIk、iAk-iAk-2N=iCIk；The real-time computing technique of the instantaneous difference of two-phase increment current is iAIk-iBIk=iABIk、iBIk-
iCIk=iBCIk、iCIk-iAIk=iCAIk；Wherein, the k in every electric current subscript indicates the calculating since occurring the moment for doubtful ground connection
Sampling number, A, B, C, which are respectively indicated, belongs to A phase, B phase and C phase by mark electric current, and AI, BI, CI are respectively indicated by mark increment current category
In A phase, B phase and C phase, ABI, BCI, CAI, which are respectively indicated, belongs to AB, BC and CA phase by mark two-phase increment current difference, and N is every work
The sampling number in frequency period.
3. the distribution earthing wire-selecting method according to claim 2 for recognizing double negative-sequence current vector correlation features, feature
It is, the step 2 includes: that preparatory adjusting transient state increment current crosses limit value iset；When ground monitor inspection is arrived | iAIk| >
isetAnd | iABIk| > 2 | iBIk| and | iCAIk| > 2 | iCIk| or | iBIk| > isetAnd | iBCIk| > 2 | iCIk| and | iABIk| > 2 |
iAIk| or | iCIk| > isetAnd | iCAIk| > 2 | iAIk| and | iBCIk| > 2 | iBIk| criterion set up when, decide that and supervised
Survey line road is corresponding to have occurred A phase or B phase or the doubtful ground connection of C phase, determines starting route selection process；Otherwise main program is returned.
4. the distribution earthing wire-selecting method according to claim 2 for recognizing double negative-sequence current vector correlation features, feature
It is, the step 3 includes: that preparatory time transient state increment current of adjusting crosses limit value Iset1；Ground monitor is respectively in secondary transient state
Take iAIk、iBIk、iCIkAnd iABIk、iBCIk、iCAIkHalf cycle instantaneous value calculate the subtranient value I of three split-phase increment currentsAI1、
IBI1、ICI1With the secondary transient state difference I of two-phase increment currentABI1、IABI1、ICAI1, when inspection is arrived | IAI1| > Iset1And | IABI1| > 2 |
IBI1| and | ICAI1| > 2 | ICI1| or | IBI1| > Iset1And | IBCI1| > 2 | ICI1| and | IABI1| > 2 | IAI1|, or | ICI1| >
Iset1And | ICAI1| > 2 | IAI1| and | IBCI1| > 2 | IBI1| criterion when setting up, decide that monitored route is corresponding and occur
A phase or B phase or the doubtful ground connection of C phase determine starting true and false ground connection identification process；Otherwise main program is returned.
5. the distribution earthing wire-selecting method according to claim 2 for recognizing double negative-sequence current vector correlation features, feature
It is, the step 4 includes:
Step 4.1: transient state ground connection phase current crosses limit value I after adjusting in advance respectivelyset2Limit value is crossed with phase increment current is perfected
Iset3, and two limit value θ excessively for perfecting phase increment current phase difference are adjusted in advanceset；
Step 4.2: ground monitor takes i in rear transient state respectivelyAIk、iBIk、iCIkAnd iABIk、iBCIk、iCAIkHalf cycle instantaneous value come
Calculate the rear transient value I of three-phase increment currentAI2、IBI2、ICI2With the rear transient state difference I of two-phase increment currentABI2、IBCI2、ICAI2,
When detecting | IAI2| > Iset2And | IABI2| > 2 | IBI1| and | ICAI2| > 2 | ICI1| or | IBI2| > Iset2And | IBCI2| > 2 |
ICI1| and | IABI2| > 2 | IAI1|, or | ICI2| > Iset2And | ICAI2| > 2 | IAI1| and | IBCI2| > 2 | IBI1| criterion at
Immediately, A phase or B phase has occurred in the monitored route correspondence of preliminary judgement or C phase is grounded；Otherwise determine that increment current is pseudo- ground connection
Electric current；
Step 4.3: examining whether be greater than phase with the increment current magnitude for perfecting one of phase corresponding to preliminary judgement Earth Phase again
The criterion definite value that position calculates: | IAI2| > Iset3Or | IBI2| > Iset3Or | ICI2| > Iset3；If being not more than criterion definite value, determine that
The A phase of high value has occurred in monitored route or B phase or C phase are really grounded；If more than criterion definite value, then calculate and Earth Phase
Two corresponding phase differences perfected between phase increment current are θBI-θCI=θBCIOr θCI-θAI=θCAIOr θAI-θBI
=θABI；When detecting θBCI> θsetOr θCAI> θseOr θABI> θsetCriterion set up when, determine that monitored route
The true ground connection of the corresponding A phase that the design following resistance value of the upper limit has occurred or B phase or C phase；Otherwise it is determined as pseudo- earth current；Its
In, θAI、θBI、θCIRespectively A, B, C phase increment current phase, θABI、θBCI、θCAIRespectively θAIAnd θBI、θBIAnd θCI、θCIAnd θAI
Phase difference.
6. the distribution earthing wire-selecting method according to claim 4 or 5 for recognizing double negative-sequence current vector correlation features, special
Sign is that the subtranient value of calculated three-phase increment current and rear transient value are all half cycle area integral value, or is half cycle area
Integral mean value, or amplitude or virtual value for the conversion of half cycle area integral.
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