CN105552838B - Transformer zero-seguence differential protection algorithm based on the identification of standardized graphics similarity mode - Google Patents
Transformer zero-seguence differential protection algorithm based on the identification of standardized graphics similarity mode Download PDFInfo
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- CN105552838B CN105552838B CN201610109112.XA CN201610109112A CN105552838B CN 105552838 B CN105552838 B CN 105552838B CN 201610109112 A CN201610109112 A CN 201610109112A CN 105552838 B CN105552838 B CN 105552838B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
- H02H7/045—Differential protection of transformers
- H02H7/0455—Differential protection of transformers taking into account saturation of current transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0092—Details of emergency protective circuit arrangements concerning the data processing means, e.g. expert systems, neural networks
Abstract
Based on the transformer zero-seguence differential protection algorithm of standardization Hausdorff shape similarity match cognizations, sequence is entered with self-produced zero-sequence current and neutral conductor TA electric currents to transformer zero-seguence differential protection using standardization Hausdorff distance algorithms and carries out wave-form similarity match cognization.Under guarantee and traditional zero sequence differential protection identical protection domain and anti-transition resistance capabilities might, the malfunction of traditional zero sequence differential protection caused by recovery inrush after external earth-fault elimination can be effectively prevented, and it is with the obvious advantage in terms of quick-action.
Description
Technical field
A kind of transformer zero-seguence differential protection algorithm based on the identification of standardized graphics similarity mode of the present invention, is related to change
Depressor zero sequence differential protection field.
Background technology
Generally, transformer zero-seguence differential protection has the stronger anti-ability of shoving and higher accuracy.Due to homodyne not
The size of balanced balanced current has dependency relation with zero sequence differential protection both ends size of current, therefore modified zero sequence is differential in recent years
Preservation tactics can all set up rate restraint criterion to ensure accuracy.
But still there are multiple 500kV and 220kV transformers that single-phase earthing transient fault or outside single-phase occurs in outside
After earth fault is removed, the report of transformer zero-seguence differential protection malfunction, the action of such zero sequence differential protection belongs to it
Protection external area error is bypassed the immediate leadership malfunction.In fact, by live recording report analysis, at the time of zero sequence differential protection malfunction often not
Be in the failure duration, but after Failure elimination a period of time.Because for content ratio braking characteristic
For zero sequence differential protection, its stalling current has a certain degree of decline after Failure elimination, and stopping power reduces；And due to
There is saturated characteristic in transformer core, can produce recovery inrush in voltage recovery process after Failure elimination, such to shove
TA biasing saturation may be caused in protective current transformer, (TA) through cumulative effect after a while, deteriorate Transfer characteristic
And cause the rising of false difference current.
Fig. 1 is the situation of change of transformer zero-sequence current after failure generation and failure removal.Failure occurred at the 1s moment,
Cut off after 0.05s.As can be seen that in the transient state evolutionary process after failure occurs and cuts off, zero-sequence current amplitude significantly increases,
And substantially biased to a direction.When transformer is in normal operating condition, the amplitude of zero-sequence current is simultaneously little, therefore in order to protect
Measurement accuracy is demonstrate,proved, neutral conductor TA anti-saturation ability is generally below three-phase inlet wire TA.Therefore when zero-sequence current is substantially asymmetric,
The cumulative effect of remanent magnetism can cause the magnetic linkage of TA iron cores gradually to be biased to some direction, may finally cause the unidirectional saturations of TA.
And for the higher protection without configuring secondary harmonic brake of this sensitivity of zero sequence differential protection, neutral conductor TA list
The Transfer characteristic error come to saturated zone is possible to introduce malfunction risk.On the other hand, for three-phase inlet wire TA, due to gushing
Accounting of the flow component in total current is simultaneously little, thus the DC component in electric current cause inlet wire TA reach needed for saturation when
Between, it is long much to reach saturation required time than neutral conductor TA.And in view of the damping effect and TA iron of transformer iron core itself
The damping effect of core, the duration of inrush current phenomenon is insufficient to allow three-phase inlet wire TA to reach saturation under normal circumstances, therefore typically recognizes
The change of three-phase inlet wire TA Transfer characteristic will not be caused for failure removal recovery inrush.
Fig. 2 is the difference current of the front and rear zero sequence differential protection for considering TA Transfer characteristics of failure removal, transformer Y sides three-phase
The difference of self-produced zero-sequence current and neutral current., it is apparent that do not broken down inside zero sequence differential protection, it is actual
In the case that zero sequence difference current is 0, magnetic bias of the recovery inrush on neutral conductor TA accumulates serious shadow after failure removal
The accuracy of zero sequence variate electric current is rung.The peak value of zero sequence difference current fluctuation is considerable, and zero sequence differential protection will be caused to miss
It is dynamic.Also, it is obvious that by taking traditional zero sequence differential protection than width tripping characteristic as an example, by improving rate restraint criterion
The modes such as action current, restraint coefficient or action slope over 10, can not there is the generation for eliminating such zero sequence differential protection malfunction.Cause
This is, it is necessary to consider to build the zero sequence differential protection strategy based on new principle.
The content of the invention
For the global feature of transformer inside and outside failure zero sequence differential protection both sides current waveform, the present invention provides a kind of
Based on the transformer zero-seguence differential protection algorithm of standardized graphics similarity mode identification, shape similarity recognizer is a kind of
Compare the overall permanence of two waveforms and be not limited to the algorithm that some small range features influence, it is differential that the algorithm can improve zero sequence
The ability of anti-sampled value missing and anti-TA saturations is protected, recovery inrush gives zero sequence differential protection after effectively solving Failure elimination
The malfunction risk problem brought.
The technical solution adopted in the present invention is：
Based on the transformer zero-seguence differential protection algorithm of standardized graphics similarity mode identification, comprise the following steps：
Step 1：Transformer neutral conductor TA measurement zero-sequence current sequences I is obtained under certain sample raten0(k) transformation, is gathered
Device Y sides three-phase TA measures current sequence and is added to form self-produced zero-sequence current sequence by three-phase current in zero sequence differential protection
Arrange Iself0(k), make the difference to form zero sequence difference current sequence using self-produced zero-sequence current sequence and neutral conductor zero-sequence current sequence
Idiff(k), wherein k ∈ { 1,2,3 ..., n }, n are sampling number in a cycle；
Step 2：Judge 3In0>IREFWhether set up, wherein IREFFor the reference value of transformer neutral current；If setting up
Start the present invention and carry protection algorism, to step 3；Otherwise return and persistently the inequality is differentiated；
Step 3：Judge Idiff>IsetWhether set up, wherein IsetFor zero sequence difference current IdiffThreshold setting valve；If into
It is vertical then to step 4；Otherwise calculate and terminate, return to step 2；
Step 4：To self-produced zero-sequence current sequence Iself0And neutral conductor zero-sequence current sequence I (k)n0(k), it is standardized
Processing, obtains the maximum and minimum value in the two current sequences, i.e. max (I respectively in a cycleself0), max
(In0), min (Iself0) and min (In0), following computing is made to two time current sequences respectively：
Respectively obtain Iself0And I (k)n0(k) standardization sequence Iself0' (k) and In0'(k)。
The formula (1), (2) and (3) according to the formula present invention solves Iself0' (k) and In0' (k) Hausdorff away from
From sequence H；
Step 5：Judge H>HsetWhether set up, wherein HsetFor the standardization self-produced zero-sequence current of three-phase and the standardization neutral conductor
The threshold setting valve of Hausdorff distances between zero-sequence current；If so, then zero sequence differential protection acts；Otherwise calculate and terminate,
Return to step 2.
Using standardization Hausdorff distance algorithms to transformer zero-seguence differential protection self-produced zero-sequence current and the neutral conductor
TA electric currents enter sequence and carry out wave-form similarity match cognization.
A kind of transformer zero-seguence differential protection algorithm based on the identification of standardized graphics similarity mode of the present invention, technology effect
Fruit is as follows：
1:Hausdorff distance algorithms are not related to projection of the signal from time domain to frequency domain, therefore the setting of time window can be with
It is more flexible.The Hausdorff of 1/4 cycle time window is used between the time is calculated as 1/3 to the 1/2 of the DFT calculating times, this
Scheme rapidity is good.
2：What inventive algorithm considered is the uniformity of waveform global feature, and to the time domain alignment and sample rate of sampled point
Uniformity it is not strictly necessary that, on the premise of existing sample devices is changed without, differential protection scope and plan can be realized
Flexible arrangement slightly.
3：Inventive algorithm compares overall waveform, and the loss of individual data point, has no effect in difference current sample sequence
Its judgement to figure global feature, there is very strong anti-loss of data ability, better than real-time sampling differential algorithm.
4：Inventive algorithm ensures and traditional zero sequence differential protection identical protection domain and anti-transition resistance ability premise
Under, it can effectively prevent outside singlephase earth fault from eliminating the malfunction of zero sequence differential protection caused by recovery inrush, have higher
Reliability.
Brief description of the drawings
The invention will be further described with reference to the accompanying drawings and examples：
Fig. 1 is the situation of change figure of transformer zero-sequence current after failure generation described in background technology and failure removal.
Fig. 2 is the difference current of the front and rear zero sequence differential protection for considering TA Transfer characteristics of failure removal described in background technology
Figure.
Fig. 3 is that the self-produced zero sequence of three-phase current measures zero sequence with the neutral conductor under typical transformer troubles inside the sample space operating mode of the invention
The oscillogram of electric current.
Fig. 4 is that the self-produced zero-sequence current of three-phase and the neutral conductor are electric under recovery inrush operating mode after the external fault of the present invention eliminates
Flow oscillogram.
Fig. 5 is the zero sequence differential protection new algorithm flow based on Hausdorff shape similarity match cognizations of the present invention
Figure.
The standardization of self-produced zero-sequence current and neutral conductor TA electric currents when Fig. 6 is the inside singlephase earth fault of the present invention
Hausdorff distance maps.
Fig. 7 is that the external fault of the present invention recovers the standardization of self-produced zero-sequence current and neutral conductor TA electric currents under operating mode
Hausdorff distance maps.
Embodiment
As shown in figure 5, the transformer zero-seguence differential protection algorithm based on the identification of standardized graphics similarity mode, including with
Lower step：
Step 1：Transformer neutral conductor TA measurement zero-sequence current sequences I is obtained under certain sample raten0(k) transformation, is gathered
Device Y sides three-phase TA measures current sequence and is added to form self-produced zero-sequence current sequence by three-phase current in zero sequence differential protection
Arrange Iself0(k), make the difference to form zero sequence difference current sequence using self-produced zero-sequence current sequence and neutral conductor zero-sequence current sequence
Idiff(k), wherein k ∈ { 1,2,3 ..., n }, n are sampling number in a cycle；
Step 2：Judge 3In0>IREFWhether set up, wherein IREFFor the reference value of transformer neutral current；If setting up
Start the present invention and carry protection algorism, to step 3；Otherwise return and persistently the inequality is differentiated；
Step 3：Judge Idiff>IsetWhether set up, wherein IsetFor zero sequence difference current IdiffThreshold setting valve；If into
It is vertical then to step 4；Otherwise calculate and terminate, return to step 2；
Step 4：To self-produced zero-sequence current sequence Iself0And neutral conductor zero-sequence current sequence I (k)n0(k), it is standardized
Processing, obtains the maximum and minimum value in the two current sequences, i.e. max (I respectively in a cycleself0), max
(In0), min (Iself0) and min (In0), following computing is made to two time current sequences respectively：
Respectively obtain Iself0And I (k)n0(k) standardization sequence Iself0' (k) and In0'(k)。
The formula (1), (2) and (3) according to the formula present invention solves Iself0' (k) and In0' (k) Hausdorff away from
From sequence H；
Step 5：Judge H>HsetWhether set up, wherein HsetFor the standardization self-produced zero-sequence current of three-phase and the standardization neutral conductor
The threshold setting valve of Hausdorff distances between zero-sequence current；If so, then zero sequence differential protection acts；Otherwise calculate and terminate,
Return to step 2.
1st, transformer troubles inside the sample space and zero sequence differential protection current characteristic during Removal of external faults recovery inrush：
For zero sequence differential protection, although internal fault and Recovery Inrush After Clearance of External Faults can produce
Larger zero sequence difference stream, it can not ensure to make a distinction by the amplitude of difference stream on the premise of sensitivity and accuracy at the same time, but
The factor of phase angle difference is allowed for, the falseness difference stream that internal fault difference stream and Recovery Inrush After Clearance of External Faults trigger is in shape
Very big difference is showed in state.
Fig. 3 is the ripple that the self-produced zero sequence of three-phase current measures zero-sequence current with the neutral conductor under typical transformer troubles inside the sample space operating mode
Shape figure.Failure is arranged to A phase ground short circuits, and short-circuit resistance is 5 Ω.It can be seen that, on the one hand, internal fault has larger difference
Stream；On the other hand, phase difference during internal fault between self-produced zero-sequence current and neutral current is very big, and the numerical value of phase angle difference exists
180 ° or so.From topological angle analysis, only in the way of tradition makees difference, if to ensure the accuracy of protection act,
Inevitably lose certain sensitivity.And for the recovery inrush after Removal of external faults, although self-produced zero sequence
Also considerable difference flows between electric current and neutral current, but the ripple of the waveform of self-produced zero-sequence current itself and neutral current
Shape shows and the different topology feature of internal fault.
Fig. 4 is the self-produced zero-sequence current of three-phase and neutral current waveform under recovery inrush operating mode after external fault elimination
Figure.As can be seen that the difference current numerical value of zero sequence differential protection is also more considerable, if only passing through the ratio of traditional zero sequence differential protection
Width tripping characteristic inevitably causes the decline of protection sensitivity to distinguish recovery inrush operating mode after external fault eliminates.Together
When because the phase difference between self-produced zero sequence and neutral point current is close to 0, therefore than phase tripping characteristic to stalling current coefficient
Self-adaptive sites strategy can not play a role in such a scenario.
To sum up, not only difference is very big between self-produced zero-sequence current and neutral point measurement electric current during power transformer interior fault, phase
For angular difference also close to 180 °, shape similarity is very low；And after external fault elimination under recovery inrush operating mode between two electric currents
Difference in magnitude is larger, but phase angle difference very little, and figure has very high similarity.Therefore shape similarity match cognization can be introduced
Algorithm construction zero sequence differential protection new algorithm.
2nd, Hausdorff distance algorithms：
Hausdorff distance algorithms are matching degrees between a kind of reflection targeted graphical and template graphics Edge Feature Points
Algorithm.Hausdorff distances are that one kind of similarity degree is measured between describing two groups of point sets, and it is distance between two point sets
A kind of form of Definition：Assuming that have two groups of point set A={ a1 ..., ap }, B={ b1 ..., bq }, then between the two point sets
Hausdorff distance definitions are：
H (A, B)=max (h (A, B), h (B, A)) (1)
Wherein：
H (A, B)=max (a ∈ A) min (b ∈ B) ‖ a-b ‖ (2)
H (B, A)=max (b ∈ B) min (a ∈ A) ‖ b-a ‖ (3)
| | | | it is the conventional Euclidean normal forms in normal form, common engineering between point set A and B point set.
Found in formula (2) first to each point (such as ai) in point set A compared with all click-through row distances in all set B
For the nearest point bj of ai：||ai-bj||≤||ai-bk| | (1≤k≤q and k ≠ j), | | ai-bj| | as correspond to ai points most
Small distance, h (A, B) are the maximum of the minimum range at all set A midpoints, referred to as from point set A to the unidirectional of point set B collection
Hausdorff distances.The higher value that the Hausdorff distances of formula (1) are one-way distance h (A, B) and h (B, A), it has measured two
Maximum mismatch degree between individual point set.
3rd, adaptability the characteristics of Hausdorff distance algorithms and to differential protection demand：
The algorithm obtained compared to the point-by-point comparison difference applied in conventional differential protection algorism, Hausdorff distances are calculated
Method has the characteristics that：
First：Hausdorff distance algorithms can unrestricted choice data window length according to demand.Traditional protection algorism one
As use Fourier algorithm, conventional has all-round Fourier algorithm and half cycle Fourier algorithm.But both algorithms all need
The length for ensureing time window is the integral multiple of current half.In relay protection engineer applied in practice, this time window is special
At least 10ms delay when property causes handling failure signal, and time window length can not be flexibly set according to demand.
And Hausdorff distance algorithms are not related to projection of the signal from time domain to frequency domain, therefore the setting of time window can be with more flexible.
When realizing different defencive functions, the Preservation tactics based on Hausdorff distance algorithms set more convenient；
Second：Hausdorff distance algorithms are influenceed smaller by sample frequency.Conventional Fourier algorithm is adopted to protection device
The requirement of sample frequency is higher, if protection device sample rate is too low, signal can be caused inaccurate in the projection of frequency domain.This
Outside, traditional real-time sampling time domain differential protection needs the sample frequency strict conformance of differential protection both sides, and needs accurate
Error during calibration pair, limit the flexibility of differential protection deployment.And Hausdorff distance algorithms are more examined when calculating
Consider be global feature uniformity, and the uniformity of the time domain alignment and sample rate to sampled point it is not strictly necessary that,
On the premise of being changed without existing sample devices, differential protection scope and the flexible arrangement of strategy can be realized, improves new protection side
The compatibility of case；
3rd：Hausdorff distance algorithms have anti-loss of data ability.The loss of individual data point often causes reality
When the failure of sampling differential algorithm.But for Hausdorff distance algorithms, have no effect on it and figure global feature is sentenced
It is disconnected.
Current data is after being gathered by sensor, existing in the form of two-dimentional point set.Therefore electric current is considered as one
It is individual using the time as abscissa, size of current be ordinate discrete-time series, each current data point is equivalent to figure
Some characteristic point.And Hausdorff distance algorithms exactly reflect between targeted graphical and template graphics Edge Feature Points
Algorithm with degree, directly it can be calculated using these extracted good characteristic points.Meanwhile in view of relay protection has speed
Dynamic property demand, the Hausdorff distance calculating times of a quarter cycle arrive half for DFT calculates the time 1/3rd
Between, further embody its adaptability to relay protection quick-action demand.
4th, the transformer zero-seguence differential protection new algorithm based on standardization Hausdorff shape similarity match cognizations：
The similarity of figure has not only been weighed in view of original Hausdorff Graph Distances algorithm, while can also have been weighed
Amplitude information between two figures.Therefore, in order to weaken difference in magnitude to Hausdorff distance calculate influence, it is necessary to from
Production zero-sequence current waveform is pre-processed with neutral point measurement current waveform.
Assuming that the self-produced zero-sequence current sequence that zero sequence differential protection measures is Iself0(k), neutral conductor TA measurements electricity
Stream sequence is In0(k), wherein k ∈ { 1,2,3 ..., n }.So that all-wave Hausdorff distances calculate as an example, it is assumed that each self-contained n
Two current sequences of individual point are all a complete fundamental frequency cycles, i.e. time series span is 20ms.Obtain respectively first this two
Maximum and minimum value in individual current sequence, i.e. max (Iself0), max (In0), min (Iself0) and min (In0).Respectively to two
Individual time current sequence makees following computing：
Wherein Iself0' (k) and In0' (k) be respectively Iself0And I (k)n0(k) standardization sequence.By formula (4) and formula
(5) processing, the all-round signal of self-produced zero-sequence current and the neutral conductor TA measurement electric current waited ratio be converted to amplitude be 0~1 it
Between time series, the amplitude characteristic of primary current signal is almost no longer considered in Hausdorff distances calculate.Easily see
Go out, after standardization, the Hausdorff distance ranges of any two figure are necessarily the subset of [0,1].
Current waveform after standardization can utilize Hausdorff shape similarity matching algorithms, draw this
Standardization Hausdorff distances in the range of time window between two waveforms.The time window is constantly slided backward, can be obtained
One Hausdorff is apart from array.Changed using the waveform of the array, and rational threshold value H is setset, can effectively differentiate
Each operating mode of troubles inside the sample space, and can correctly identify that the various TA saturations including recovery inrush after external fault elimination are led
The falseness difference stream of cause.With reference to traditional difference current criterion, zero sequence differential protection performance can be effectively improved.
Therefore Protection criteria could be arranged to：
Wherein IREFFor the reference value of neutral current, IsetFor zero sequence difference current IdiffThreshold value, HsetFor standardization
The threshold value of Hausdorff distances between the self-produced zero-sequence current of three-phase and standardization neutral conductor zero-sequence current.
Zero sequence differential relaying algorithm flow based on standardization Hausdorff shape similarity match cognizations is as shown in Figure 5.
To the zero sequence of inside transformer singlephase earth fault shown in Fig. 3 differential protection self-produced zero-sequence current and neutral conductor TA electricity
Stream carries algorithm using the present invention and carries out the calculating of H values, as a result such as Fig. 6.It is restorative after being eliminated to transformer external fault shown in Fig. 4
Self-produced zero-sequence current is standardized Hausdorff distances with neutral conductor TA electric currents and calculated under operating mode of shoving, as a result such as Fig. 7.
(Hset takes 0.7)
It can be seen that：
1., it is clear that internally failure occurs before and after, zero sequence differential protection both ends electric current by standardization it
Between Hausdorff distances jumped to from close to 0 close to 1, crossed 0.7 threshold value.Protection can export, being capable of positive positive motion
Make.
2., under the influence of recovery inrush after serious external fault eliminates, zero sequence differential protection both ends electric current
Hausdorff distances also reach far away 0.7 threshold value, so, zero sequence differential protection new algorithm proposed by the present invention has very
The high anti-ability of shoving.
3., carry out for single-phase earthing in transformer area under 0~150 Ω transition resistance operating modes and double earthfault situation
Checking, the results showed that with the rise of transition resistance, the amplitude of neutral conductor TA electric currents and the amplitude of zero sequence difference current can reduce.
Until transition resistance rises to 140 Ω, traditional zero sequence differential protection and the present invention carry zero sequence differential protection new algorithm just all because
For neutral current amplitude too it is small can not starting protection calculate fail.So based on standardization Hausdorff figure phase knowledge and magnanimity
The zero sequence differential protection new algorithm of match cognization has and traditional zero sequence differential protection identical on the premise of sensitivity is ensured
The anti-transition resistance ability of troubles inside the sample space.
4., the single-phase winding different weight percentage wire turn ground fault condition of transformer is verified, the results showed that only work as
Short dot position is less than 20%, and new algorithm proposed by the invention just can be because neutral point zero-sequence current be less than protection triggering threshold
Value is unable to starting protection and calculates and fail.And traditional zero sequence differential protection equally short dot be less than 20% when because of differential electricity
Stream causes protection not start less than threshold value.Therefore, the present invention carries the protection domain and tradition of zero sequence differential protection new algorithm
Zero sequence differential relaying algorithm is identical.
Transformer zero-seguence differential protection of the present invention based on standardization Hausdorff shape similarity match cognizations is newly calculated
Method, under guarantee and traditional zero sequence differential protection identical protection domain and anti-transition resistance capabilities might, can effectively it prevent outer
The malfunction of traditional zero sequence differential protection caused by recovery inrush after portion's earth fault eliminates, and advantage is bright in terms of quick-action
It is aobvious.
Claims (1)
1. the transformer zero-seguence differential protection algorithm based on the identification of standardized graphics similarity mode, it is characterised in that including following
Step：
Step 1：Transformer neutral conductor TA measurement zero-sequence current sequences I is obtained under certain sample raten0(k) transformer Y sides, are gathered
Three-phase TA measures current sequence and is added to form self-produced zero-sequence current sequence by three-phase current in zero sequence differential protection
Iself0(k), make the difference to form zero sequence difference current sequence I using self-produced zero-sequence current sequence and neutral conductor zero-sequence current sequencediff
(k), wherein k ∈ { 1,2,3 ..., n }, n are sampling number in a cycle；
Step 2：Judge 3In0>IREFWhether set up, wherein IREFFor the reference value of transformer neutral current；Start if setting up
The present invention carries protection algorism, to step 3；Otherwise return and persistently the inequality is differentiated；
Step 3：Judge Idiff>IsetWhether set up, wherein IsetFor zero sequence difference current IdiffThreshold setting valve；If setting up
To step 4；Otherwise calculate and terminate, return to step 2；
Step 4：To self-produced zero-sequence current sequence Iself0And neutral conductor zero-sequence current sequence I (k)n0(k), it is standardized,
Obtain the maximum and minimum value in the two current sequences, i.e. max (I respectively in a cycleself0), max (In0), min
(Iself0) and min (In0), following computing is made to two time current sequences respectively：
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Solve Iself0' (k) and In0' (k) Hausdorff distance sequences H；
Step 5：Judge H>HsetWhether set up, wherein HsetFor the standardization self-produced zero-sequence current of three-phase and standardization neutral conductor zero sequence
The threshold setting valve of Hausdorff distances between electric current；If so, then zero sequence differential protection acts；Otherwise calculate and terminate, return
Step 2.
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| CN108110737B (en) * | 2017-11-28 | 2019-06-25 | 酒泉钢铁(集团)有限责任公司 | 6-10kV isolated neutral system casing zero sequence optical differential protective relaying device |
| CN108923398B (en) * | 2018-07-23 | 2019-08-20 | 国网浙江省电力有限公司电力科学研究院 | A kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure |
| CN110261706B (en) * | 2019-07-22 | 2020-09-29 | 西南交通大学 | Power transmission line fault detection method based on neighborhood distance |
| CN110829371B (en) * | 2019-11-09 | 2021-08-03 | 天津大学 | Magnetizing inrush current identification method based on waveform similarity of circular current and zero sequence current |
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| CN111276938B (en) * | 2019-11-25 | 2021-11-16 | 国网宁夏电力有限公司 | New zero sequence differential protection criterion of converter transformer based on waveform correlation analysis |
| CN112054482B (en) * | 2020-08-06 | 2022-05-06 | 三峡大学 | Converter transformer zero sequence differential protection anti-misoperation method based on DTW algorithm |
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