CN108899871B - A kind of recognition methods of excitation surge current, device and computer-readable medium - Google Patents
A kind of recognition methods of excitation surge current, device and computer-readable medium Download PDFInfo
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- CN108899871B CN108899871B CN201810440367.3A CN201810440367A CN108899871B CN 108899871 B CN108899871 B CN 108899871B CN 201810440367 A CN201810440367 A CN 201810440367A CN 108899871 B CN108899871 B CN 108899871B
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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
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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
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Abstract
The embodiment of the invention provides a kind of recognition methods of excitation surge current, device and computer-readable mediums, it is related to the technical field of transformer, it include: the sampled data for obtaining the difference current a cycle of transformer, and sampled data is normalized, obtain target data, wherein, the value of data is being preset in value range in target data；The change rate data of target data are calculated, and predict target sinusoidal data based on change rate data；The sinusoidal coefficients of difference current are determined in conjunction with change rate data and the target sinusoidal data；Whether the difference current that transformer is determined based on sinusoidal coefficients is excitation surge current.When the present invention is solved using conventional method identification excitation surge current, the technical issues of such as excitation surge current waveform interval angle disappears, can judge by accident in the higher situation of fault current secondary harmonic component.
Description
Technical field
The present invention relates to the technical fields of transformer, more particularly, to a kind of recognition methods of excitation surge current, device and meter
Calculation machine readable medium.
Background technique
The identification of excitation surge current is the advantageous guarantee that transformer differential protection correctly acts.
Excitation surge current is identified frequently with interrupted angle principle and second order harmonics principle in engineering at present.Interval angle deceleration method by
The limitation of TA (current transformer) saturation and hardware, recognition effect is unsatisfactory in practical applications.Since long range high pressure is defeated
The secondary harmonic component of the presence of electric line distribution capacity and reactive power compensator, fault current obviously increases, and due to the modern times
The utilization of transformer core new material leads to secondary harmonic brake method more so that the secondary harmonic component of excitation surge current reduces
It is easy to appear erroneous judgement.
In recent years, the method for following several identification excitation surge currents is had also been proposed.Distributed wave is run on the basis of histogram
Feature identifies excitation surge current, and this method principle is simple, calculation amount is small, sensitivity is good, but anti-interference ability is not strong, full in TA
The criterion can fail with when, to cause to judge by accident.Fundamental wave and secondary is fitted using Prony (Pu Luoni algorithm) algorithm
The energy type of harmonic wave distinguishes excitation surge current and fault current by comparing the ratio of fundamental wave energy and second harmonic energy, but
When there are D.C. magnetic biasing and TA saturation, second harmonic energy is very big, and this method can fail.With the rapid hair of computer technology
Exhibition, there are also some new theory methods such as: mathematical morphology, neural network, wavelet transformation, but such method is to hardware requirement
Height is realized complicated.
In view of the above problems, not proposing fully effective solution also.
Summary of the invention
In view of this, the purpose of the present invention is to provide a kind of recognition methods of excitation surge current, device and computer-readable
Medium, when solving using conventional method identification excitation surge current, in the disappearance of such as excitation surge current waveform interval angle, fault current two
The technical issues of being judged by accident in the higher situation of subharmonic content.
A kind of recognition methods of excitation surge current is provided according to embodiments of the present invention, which comprises obtains transformer
Difference current a cycle sampled data, and the sampled data is normalized, obtains target data,
In, the value of data is in default value range in the target data；The change rate of the target data is calculated, and is based on institute
It states change rate data and calculates target sinusoidal data, wherein target sinusoidal data makes reference to the change rate data, is used for conduct
The reference data of the change rate data, so that the change rate data are compared with the target sinusoidal data；In conjunction with institute
It states change rate data and the target sinusoidal data determines the sinusoidal coefficients of the difference current；It is determined based on the sinusoidal coefficients
The difference current of the transformer is the excitation surge current or fault current.
Further, the sampled data of the difference current a cycle of transformer is obtained, and the sampled data is carried out
Normalized, obtaining target data includes: being normalized to the sampled data got, obtains the first processing
Data, wherein the value of data is in [- a in the first processing data0,a0] in range；Calculate the first processing data
Maximum value, minimum value and average value；According to formulaAnd formula
The first processing data are translated, obtain second processing data, wherein amaxFor the maximum value, aminFor it is described most
Small value, a0For the average value, x is translational movement；The second processing data are normalized again, obtain the mesh
Mark data.
Further, the change rate for calculating the target data obtains the change rate data, and is based on the change rate
Data predict that target sinusoidal data includes: to pass through formulaDerivation is carried out to the target data, is obtained described
Change rate data, wherein i=1,2 ..., N-1, k [i] they are the change rate data,For the target data, the π f of ω=2,
F is fundamental frequency, and Δ T is the sampling interval of the sampled data, and N is the data amount check in the sampled data；Described in calculating
Sequential value corresponding to the maximum value of the maximum value of change rate data and the change rate data；By formula j [i]=
kmax* the target sinusoidal data is calculated in sin (2* π * (i-1)/(N-1)+θ), wherein i=1,2 ..., N-1, kmaxFor
The maximum value of the change rate data, j [i] are the target sinusoidal data, and θ is used for the k as i=mmaxWith sinusoidal data j [m]
It is equal, wherein m is the sequential value.
Further, the sinusoidal system of the difference current is determined in conjunction with the change rate data and the target sinusoidal data
Number includes: to pass through formulaThe sinusoidal coefficients of the difference current are calculated, wherein S
For the sinusoidal coefficients, kiFor the change rate data, jiFor the target sinusoidal data, wherein i=1,2 ..., N-1, Δ T
For the sampling interval of the sampled data, N is the data amount check in the sampled data.
Further, determine that the difference current of the transformer is the excitation surge current or event based on the sinusoidal coefficients
If barrier electric current includes: that the sinusoidal coefficients are less than preset threshold, it is determined that the difference current is the fault current；If
The sinusoidal coefficients are greater than or equal to the preset threshold, it is determined that the difference current is the excitation surge current.
A kind of identification device of excitation surge current is additionally provided according to embodiments of the present invention, and described device includes: data processing
Unit, the sampled data of the difference current a cycle for obtaining transformer, and place is normalized to the sampled data
Reason, obtains target data, wherein the value of data is in default value range in the target data；Computing unit, based on
The change rate for calculating the target data obtains change rate data, and calculates target sinusoidal data based on the change rate data,
In, target sinusoidal data is for the reference data as the change rate data, so that the change rate data and the target
Sinusoidal data compares change rate data；First determination unit, for sinusoidal in conjunction with the change rate data and the target
Data determine the sinusoidal coefficients of the difference current；Second determination unit, for determining the transformation based on the sinusoidal coefficients
The difference current of device is the excitation surge current or fault current.
Further, the data processing unit includes: the first normalization module, for the hits got
According to pretreatment is normalized, the first processing data are obtained, wherein the value of data is in [- a in the first processing data0,
a0] in range；First computing module, for calculating maximum value, minimum value and the average value of the first processing data；Translate mould
Block, for according to formulaAnd formulaTo first processing
Data are translated, and obtain second processing data, wherein amaxFor the maximum value amax、aminIt for the minimum value and is a0Institute
State average value；Second normalization module obtains the number of targets for the second processing data to be normalized
According to.
Further, the computing unit includes: derivation module, for passing through formulaTo the target
Data carry out derivation, obtain the change rate data, wherein and i=1,2 ..., N-1, k [i] they are the change rate data,
For the target data, the π of ω=2 f, f are fundamental frequency, and Δ T is the sampling interval of the sampled data, and N is the hits
Data amount check in；Second computing module, for calculating the maximum value and the change rate data of the change rate data
Maximum value corresponding to sequential value；Third computing module, for passing through formula j [i]=kmax*sin(2*π*(i-1)/(N-1)
+ θ) the target sinusoidal data is calculated, wherein i=1,2 ..., N-1, kmaxFor the maximum value of the change rate data, j
[i] is the target sinusoidal data, and θ is used for the k as i=mmaxIt is equal with sinusoidal data j [m], wherein m is the sequential value.
Further, first determination unit includes: the 4th computing module, for passing through formulaThe sinusoidal coefficients of the difference current are calculated, wherein S is the sinusoidal coefficients,
kiFor the change rate data, jiFor the target sinusoidal data, wherein i=1,2 ..., N-1, Δ T are the sampled data
Sampling interval, N be the sampled data in data amount check.
A kind of calculating of non-volatile program code that can be performed with processor is additionally provided according to embodiments of the present invention
Machine readable medium, said program code make the processor execute the recognition methods of above-mentioned excitation surge current.
In embodiments of the present invention, firstly, obtaining the sampled data of the difference current a cycle of transformer, and to sampling
Data are normalized, and obtain target data, wherein the value of data is in default value range in target data；Its
It is secondary, the change rate of target data is calculated, obtains change rate data, and calculate target sinusoidal data based on change rate data；Then,
The sinusoidal coefficients of difference current are determined in conjunction with change rate data and the target sinusoidal data；Finally, being determined based on sinusoidal coefficients
The difference current of transformer is excitation surge current or fault current.The present invention, which is solved, identifies excitation surge current using conventional method
When, it can be judged by accident in the disappearance of such as excitation surge current waveform interval angle, the higher situation of fault current secondary harmonic component
Technical problem.
Detailed description of the invention
It, below will be to specific in order to illustrate more clearly of the specific embodiment of the invention or technical solution in the prior art
Embodiment or attached drawing needed to be used in the description of the prior art be briefly described, it should be apparent that, it is described below
Attached drawing is some embodiments of the present invention, for those of ordinary skill in the art, before not making the creative labor
It puts, is also possible to obtain other drawings based on these drawings.
Fig. 1 is a kind of flow chart of the recognition methods of excitation surge current according to an embodiment of the present invention；
Fig. 2 is the waveform diagram of the excitation surge current of the transformer provided according to embodiments of the present invention；
Fig. 3 is the waveform diagram of the fault current of the transformer provided according to embodiments of the present invention；
Fig. 4 is the waveform diagram of the excitation surge current after the normalized provided according to embodiments of the present invention；
Fig. 5 is the derivative wave-form and target sine of the excitation surge current after the normalized provided according to embodiments of the present invention
The schematic diagram of data；
Fig. 6 is the schematic diagram of the sinusoidal coefficients of the excitation surge current after the normalized provided according to embodiments of the present invention；
Fig. 7 is the waveform diagram of the fault current after the normalized provided according to embodiments of the present invention；
Fig. 8 is the derivative wave-form and target sine of the fault current after the normalized provided according to embodiments of the present invention
The schematic diagram of data；
Fig. 9 is the schematic diagram of the sinusoidal coefficients of the fault current after the normalized provided according to embodiments of the present invention；
Figure 10 is a kind of schematic diagram of the excitation surge current experimental system provided according to embodiments of the present invention；
The three-phase difference current waveform diagram that Figure 11 is the QF1 closing moment that provides according to embodiments of the present invention when being 0.02s；
Figure 12 is the schematic diagram of the sinusoidal coefficients of three-phase difference current in the embodiment of the present invention；
Figure 13 is three-phase difference current waveform diagram when three-phase shortcircuit ground fault occurring in the embodiment of the present invention；
Figure 14 is the sinusoidal coefficients of three-phase difference current when three-phase shortcircuit ground fault occurring in the embodiment of the present invention
Schematic diagram；
Figure 15 is the waveform diagram after the excitation surge current that interval angle disappears in the embodiment of the present invention is normalized；
Figure 16 is the derivative wave-form for the excitation surge current that the interval angle after being normalized in the embodiment of the present invention disappears
The waveform diagram of figure and target sinusoidal data；
Figure 17 is the sinusoidal coefficients for the excitation surge current that the interval angle after being normalized in the embodiment of the present invention disappears
Schematic diagram；
Figure 18 is the fault current after being normalized when secondary harmonic component is 15% in the embodiment of the present invention
Waveform diagram；
Figure 19 is the fault current that the secondary harmonic component after being normalized in the embodiment of the present invention is 15%
The waveform diagram of derivative wave-form figure and target sinusoidal data；
Figure 20 is the fault current that the secondary harmonic component after being normalized in the embodiment of the present invention is 15%
The schematic diagram of sinusoidal coefficients；
Figure 21 is the schematic diagram of the sinusoidal coefficients of the excitation surge current and fault current after noise is added in the embodiment of the present invention；
Figure 22 is a kind of schematic diagram of the identification device of the excitation surge current provided according to embodiments of the present invention；
Figure 23 is the schematic diagram of a kind of electronic equipment provided according to embodiments of the present invention.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with attached drawing to the present invention
Technical solution be clearly and completely described, it is clear that described embodiments are some of the embodiments of the present invention, rather than
Whole embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art are not making creative work premise
Under every other embodiment obtained, shall fall within the protection scope of the present invention.
Embodiment one:
According to embodiments of the present invention, a kind of embodiment of the recognition methods of excitation surge current is provided, it should be noted that In
The step of process of attached drawing illustrates can execute in a computer system such as a set of computer executable instructions, also,
It, in some cases, can be to be different from shown in sequence execution herein although logical order is shown in flow charts
The step of out or describing.
Fig. 1 is a kind of flow chart of the recognition methods of excitation surge current according to an embodiment of the present invention, as shown in Fig. 1, the party
Method includes the following steps:
Step S102 obtains the sampled data of the difference current a cycle of transformer, and carries out normalizing to sampled data
Change processing, obtains target data, wherein the value of data is in default value range in target data；
Step S104 calculates the change rate of target data, obtains change rate data, and calculate target based on change rate data
Sinusoidal data, wherein target sinusoidal data is for the reference data as the change rate data, so that the change rate data
It is compared with the target sinusoidal data；
Step S106 determines the sinusoidal coefficients of difference current in conjunction with change rate data and target sinusoidal data；
Step S108 determines that the difference current of transformer is excitation surge current or fault current based on sinusoidal coefficients.
In embodiments of the present invention, firstly, obtaining the sampled data of the difference current a cycle of transformer, and to sampling
Data are normalized, and obtain target data, wherein the value of data is in default value range in target data；Its
It is secondary, the change rate of target data is calculated, obtains change rate data, and calculate target sinusoidal data based on change rate data；Then,
The sinusoidal coefficients of difference current are determined in conjunction with change rate data and the target sinusoidal data；Finally, being determined based on sinusoidal coefficients
The difference current of transformer is excitation surge current or fault current.The present invention, which is solved, identifies excitation surge current using conventional method
When, it can be judged by accident in the disappearance of such as excitation surge current waveform interval angle, the higher situation of fault current secondary harmonic component
Technical problem.
In an optional embodiment, step S102 obtains the hits of the difference current a cycle of transformer
According to, and the sampled data is normalized, obtaining target data includes following steps:
Pretreatment is normalized to the sampled data got in step S1021, obtains the first processing data, wherein the
The value of data is in [- a in one processing data0,a0] in range；
Step S1022 calculates maximum value, minimum value and the average value of the first processing data；
Step S1023, according to formulaAnd formulaTo
One processing data are translated, and obtain second processing data, wherein amaxFor maximum value, aminFor minimum value, a0For average value, x
For translational movement；
Step S1024 is normalized second processing data, obtains target data.
In embodiments of the present invention, sampled data is the N point of difference current uniform sampling in a cycle T of transformer
Data, it is assumed that the discrete sampling data are array [ai], i=1,2 ..., N, the sampling interval are Δ T, and Δ T=T/N.
Specifically, firstly, to array [ai] pretreatment is normalized, it obtains that pretreated array is normalized
[ai], that is, obtain above-mentioned first processing data；Pretreated array [a is normalized secondly, askingi] maximum value amax, most
Small value aminWith average value a0, that is, calculate maximum value, minimum value and the average value of above-mentioned first processing data, wherein amax=
max([ai]), amin=min ([ai]), a0=(amax-amin)/2；Then, according to formulaWith
FormulaFirst processing data are translated, second processing data are obtained, whereinAs
Second processing data, x are translational movement；Finally, to second processing dataIt is normalized, obtains target dataWherein,It should be noted that second processing dataThe purpose being normalized is
Make target dataValue in the range of [- 1,1].
In another optional embodiment, step S104 calculates the change rate of target data, obtains change rate number
According to, and included the following steps: based on change rate data prediction target sinusoidal data
Step S1041, passes through formulaDerivation is carried out to target data, obtains change rate data, wherein
I=1,2 ..., N-1, k [i] are change rate data,For target data, the π of ω=2 f, f are fundamental frequency, and Δ T is hits
According to sampling interval, N be sampled data in data amount check；
Step S1042 calculates sequential value corresponding to the maximum value of change rate data and the maximum value of change rate data；
Step S1043 passes through formula j [i]=kmax* the positive chord number of target is calculated in sin (2* π * (i-1)/(N-1)+θ)
According to, wherein i=1,2 ..., N-1, kmaxFor the maximum value of change rate data, j [i] is target sinusoidal data, and θ is for working as i=m
When, kmaxIt is equal with sinusoidal data j [m], wherein m is sequential value.
In embodiments of the present invention, target data is being obtainedAfterwards, firstly, passing through formulaTo target
DataDerivation is carried out, is obtainedChange rate data k [i]；Then, the maximum value k of change rate data k [i] is calculatedmax
And sequential value m corresponding to the maximum value of change rate data；Finally, passing through formula j [i]=kmax*sin(2*π*(i-1)/
(N-1)+θ) target sinusoidal data j [i] is calculated.
In an optional embodiment, step S108 is determined differential in conjunction with change rate data and target sinusoidal data
The sinusoidal coefficients of electric current include the following steps:
Step S1081, passes through formulaThe sinusoidal coefficients of difference current are calculated,
Wherein, S is sinusoidal coefficients, kiFor change rate data, jiFor target sinusoidal data, wherein i=1,2 ..., N-1, Δ T are sampling
The sampling interval of data, N are the data amount check in sampled data.
In embodiments of the present invention, after target sinusoidal data j [i] is calculated, pass through formulaThe sinusoidal coefficients S of difference current is calculated, it should be noted that formulaIn, the molecule of sinusoidal coefficients S is actual current waveform (that is, above-mentioned difference current) and pre-
The absolute value of the difference of sinusoidal waveform (that is, above-mentioned target sinusoidal data) area is surveyed, denominator is the area of actual current waveform.
In another optional embodiment, step S108, the difference current for determining transformer based on sinusoidal coefficients is
It is no to include the following steps: for excitation surge current
Step S1081, if sinusoidal coefficients are less than preset threshold, it is determined that difference current is fault current；
Step S1082, if sinusoidal coefficients are greater than or equal to preset threshold, it is determined that difference current is excitation surge current.
In embodiments of the present invention, since the waveform of the fault current of inside transformer is in sinuso sine protractor, derivative wave-form
It is in still sinuso sine protractor, the sinusoidal coefficients of calculated fault current are smaller, and there are interval angles, peaked wave in excitation surge current waveform
Deng the calculated sinusoidal coefficients of institute are larger, thus identify excitation surge current and failure so that whether sinusoidal coefficients exceed preset threshold
Electric current is the method for effectively identification excitation surge current.Below by inside transformer excitation surge current and fault current do and have
The introduction of body.
Fig. 2 is the waveform diagram of the excitation surge current of the transformer provided according to embodiments of the present invention.
In embodiments of the present invention, when transformer drops or restores normal process in transformer external area error excision voltage
In, since magnetic flux cannot be mutated, occur aperiodic transient state component in magnetic flux, makes transformer core full together with iron core remanent magnetism
With.Simultaneously as voltage is alternation, thus transformer core periodically enters saturation region and exits full in one cycle
The area and.Assuming that the iron core remanent magnetism of transformer is Φr, nominal operation magnetic flux is Φm, pass through public affairs under simplified iron core magnetization characteristic
FormulaExcitation surge current i can be obtainedu., wherein θ=ω t+ α, θ1=arccos
(cosα+kr-ks), kr=Φr/Φm, ks=Φs/Φm.As shown in Fig. 2, containing non-stationary wave crest and largely in excitation surge current
Aperiodic component, and there is interruption between waveform.
Fig. 3 is the waveform diagram of the fault current of the transformer provided according to embodiments of the present invention.
In embodiments of the present invention, when disregarding coil-block of transformer, the transformer model based on equivalent instantaneous inductor
Meet equationWherein, u is winding terminal voltage；idFor spill current；L is equivalent instantaneous inductor.By equationIt can
Know, the waveform variation characteristic of fault current is determined by winding terminal voltage and equivalent instantaneous inductor, and voltage is held only to occur in failure
Moment can mutate, and remain unchanged later.Iron core will not be saturated when due to power transformer interior fault, magnetizing inductance and each
Winding leakage inductance can be assumed that as constant, therefore equivalent instantaneous inductor is also constant, then fault current is also keeping power frequency just substantially
String characteristic, as shown in Figure 3.
Fig. 4 is the waveform diagram of the excitation surge current after the normalized provided according to embodiments of the present invention.
Fig. 5 is the derivative wave-form and target sine of the excitation surge current after the normalized provided according to embodiments of the present invention
The schematic diagram of data.Fig. 6 is showing for the sinusoidal coefficients of the excitation surge current after the normalized provided according to embodiments of the present invention
It is intended to.Fig. 7 is the waveform diagram of the fault current after the normalized provided according to embodiments of the present invention.Fig. 8 is according to this hair
The derivative wave-form of fault current after the normalized that bright embodiment provides and the schematic diagram of target sinusoidal data.Fig. 9 is root
According to the schematic diagram of the sinusoidal coefficients of the fault current after normalized provided in an embodiment of the present invention.
In embodiments of the present invention, such as Fig. 7, Fig. 8, shown in Fig. 9, since transformer fault current waveform is in sinuso sine protractor,
Thus it is normalized rear waveform is still in sinuso sine protractor (i.e. waveform diagram shown in Fig. 7), derivative wave-form (i.e. Fig. 8
Shown in waveform 3) and target sinusoidal data (waveform 4 i.e. shown in fig. 8) be also in sinuso sine protractor, thus obtained failure electricity
The sinusoidal coefficients of stream are smaller, as shown in figure 9, the sinusoidal coefficients range of fault current is generally between 0~0.2；And excitation surge current
There are interval angle, peaked wave (i.e. waveform diagram shown in Fig. 4), derivative wave-form (i.e. waveform 1 shown in Fig. 5) is distorted,
The substantial deviation sinuso sine protractor compared with target sinusoidal data (i.e. waveform 2 shown in Fig. 5), thus obtained excitation surge current is just
String coefficient value is larger, and as shown in Figure 6, the sinusoidal coefficients range of excitation surge current is generally between 3~6, just with fault current
The difference of string coefficient is larger.Thus it can divide excitation surge current and failure electricity with effective district by the way that the preset threshold of sinusoidal coefficients is rationally arranged
Stream, it should be noted that in embodiments of the present invention, the preset threshold of setting is 0.8.
The recognition methods to excitation surge current provided in an embodiment of the present invention is come in difference with a specific embodiment below
In the case of implementation result do specific description.
Figure 10 is a kind of schematic diagram of the excitation surge current experimental system provided according to embodiments of the present invention.As shown in Figure 10,
Em, En are power supply, and QF1, QF2 are breaker.Simulink is one of MATLAB Visual Simulation Tools, In
The electric system with bilateral electric current two-winding transformer as shown in Figure 10 is constructed in Simulink.
In embodiments of the present invention, by Simulink simulation analysis can proper appearance following several situations when, the present invention
The recognition methods of excitation surge current provided by embodiment still can accurately identify excitation surge current.
(1) when transformer during no-load closing, as shown in figure 11, be QF1 closing moment shown in Figure 10 be 0.02s when
Three-phase difference current waveform diagram, wherein ia, ib, icRespectively in three-phase difference current.Figure 12 is the sine of three-phase difference current
The schematic diagram of coefficient.As shown in figure 12, SaCorrespond to i in Figure 11aSinusoidal coefficients, SbCorrespond to i in Figure 11bSinusoidal coefficients,
ScCorrespond to i in Figure 11cSinusoidal coefficients.As shown in Figure 12, the either waveform or asymmetry of symmetry excitation surge current
The waveform of excitation surge current, corresponding to sinusoidal coefficients it is larger, thus still may be used using method provided in an embodiment of the present invention
Effectively to identify excitation surge current.
(2) as 0.02s, three-phase shortcircuit ground fault occurs for the low-pressure side of transformer, is that three-phase occurs as shown in figure 13
Three-phase difference current waveform diagram when short circuit grounding failure, wherein i shown in Figure 13a, ib, icThe respectively differential electricity of three-phase
In stream.Figure 14 is the schematic diagram of the sinusoidal coefficients of three-phase difference current when three-phase shortcircuit ground fault occurs.As shown in figure 14,
SaCorrespond to i in Figure 13aSinusoidal coefficients, SbCorrespond to i in Figure 13bSinusoidal coefficients, ScCorrespond to i in Figure 13cSinusoidal system
Number.As shown in figure 14, sinusoidal coefficients corresponding to three-phase fault electric current are smaller, and sinusoidal coefficients are below the embodiment of the present invention
In preset threshold 0.8, thus still can effectively identify excitation surge current using method provided in an embodiment of the present invention.
(3) when transformer during no-load closing, under the influence of the factors such as aperiodic component and remanent magnetism, in fact it could happen that electric current is mutual
Sensor TA saturation, causes the interval angle of excitation surge current waveform to disappear.By Simulink simulation analysis it is found that Figure 15 is interruption
Angle disappear excitation surge current be normalized after waveform diagram, Figure 16 is that the interval angle after being normalized disappears
The derivative wave-form figure of excitation surge current and the waveform diagram of target sinusoidal data, Figure 17 are that the interval angle after being normalized disappears
Excitation surge current sinusoidal coefficients schematic diagram.Wherein, the waveform 1 in Figure 16 is derivative wave-form figure, and waveform 2 is the positive chord number of target
According to waveform diagram.Such as Figure 15, Figure 16, shown in Figure 17, in the case where the interval angle of excitation surge current waveform disappears, excitation surge current
Sinusoidal coefficients are still higher than the preset threshold 0.8 in the embodiment of the present invention, thus using method provided in an embodiment of the present invention according to
It so can effectively identify excitation surge current.
(4) when the secondary harmonic component of fault current is higher, with the continuous increase of power transformer capacity, due to length
Presence apart from transmission line of electricity distribution capacity and reactive compensation capacitor, when severe internal failure occurs, resonance may make failure
Secondary harmonic component obviously increases in electric current, may cause the correct movement that secondary harmonic brake device prevents differential protection, makes
At tripping.
By Simulink simulation analysis it is found that Figure 18 be secondary harmonic component be 15% when be normalized after
The waveform diagram of fault current, Figure 19 are the derivative waves for the fault current that the secondary harmonic component after being normalized is 15%
The waveform diagram of shape figure and target sinusoidal data, Figure 20 are the failure electricity that the secondary harmonic component after being normalized is 15%
The schematic diagram of the sinusoidal coefficients of stream.Wherein, the waveform 1 in Figure 19 is derivative wave-form figure, and waveform 2 is the waveform of target sinusoidal data
Figure.Such as Figure 18, Figure 19, shown in Figure 20, contain higher second harmonic in fault current, that is, above-mentioned secondary harmonic component is 15%
In the case where, sinusoidal coefficients are below the preset threshold 0.8 in the embodiment of the present invention, thus are provided using the embodiment of the present invention
Method still can effectively identify excitation surge current.
(5) white noise of 40db is added, in the current waveform of Simulink analogue system to examine the embodiment of the present invention
The anti-interference ability of the recognition methods of the excitation surge current of offer.By Simulink simulation analysis it is found that Figure 21 is that noise is added
The schematic diagram of the sinusoidal coefficients of excitation surge current and fault current afterwards.Wherein, the waveform 1 in Figure 21 is the sinusoidal system of excitation surge current
Several schematic diagrames, the waveform 2 in Figure 21 are the schematic diagram of the sinusoidal coefficients of fault current.As shown in figure 21, it after noise being added, encourages
Magnetic shoves and still differs larger with the sinusoidal coefficients of fault current, thus can still be had using method provided in an embodiment of the present invention
Effect identification excitation surge current.
In embodiments of the present invention, firstly, obtaining the sampled data of the difference current a cycle of transformer, and to sampling
Data are normalized, and obtain target data, wherein the value of data is in default value range in target data；Its
It is secondary, the change rate of target data is calculated, obtains change rate data, and calculate target sinusoidal data based on change rate data；Then,
The sinusoidal coefficients of difference current are determined in conjunction with change rate data and the target sinusoidal data；Finally, being determined based on sinusoidal coefficients
The difference current of transformer is excitation surge current or fault current.The present invention, which is solved, identifies excitation surge current using conventional method
When, it can be judged by accident in the disappearance of such as excitation surge current waveform interval angle, the higher situation of fault current secondary harmonic component
Technical problem.
Embodiment two:
The embodiment of the invention also provides a kind of identification device of excitation surge current, the identification device of the excitation surge current is mainly used
In the recognition methods for executing the excitation surge current that above content of the embodiment of the present invention provides, encourage below provided in an embodiment of the present invention
The identification device that magnetic shoves does specific introduction.
Figure 22 is a kind of schematic diagram of the identification device of the excitation surge current provided according to embodiments of the present invention, such as Figure 22 institute
Showing, the identification device of the excitation surge current mainly includes data processing unit 10, computing unit 20, the first determination unit 30, and second
Determination unit 40, in which:
Data processing unit 10, the sampled data of the difference current a cycle for obtaining transformer, and to hits
According to being normalized, target data is obtained, wherein the value of data is in default value range in target data；
Computing unit 20 obtains change rate data, and pre- based on change rate data for calculating the change rate of target data
Survey target sinusoidal data, wherein target sinusoidal data is for the reference data as the change rate data, so that the variation
Rate data and the target sinusoidal data compare change rate data；
First determination unit 30, for combining change rate data and target sinusoidal data to determine the sinusoidal system of difference current
Number；
Second determination unit 40, for determining that the difference current of transformer is excitation surge current or failure based on sinusoidal coefficients
Electric current.
In embodiments of the present invention, firstly, obtaining the sampled data of the difference current a cycle of transformer, and to sampling
Data are normalized, and obtain target data, wherein the value of data is in default value range in target data；Its
It is secondary, the change rate of target data is calculated, obtains change rate data, and calculate target sinusoidal data based on change rate data；Then,
The sinusoidal coefficients of difference current are determined in conjunction with change rate data and the target sinusoidal data；Finally, being determined based on sinusoidal coefficients
The difference current of transformer is excitation surge current or fault current.The present invention, which is solved, identifies excitation surge current using conventional method
When, it can be judged by accident in the disappearance of such as excitation surge current waveform interval angle, the higher situation of fault current secondary harmonic component
Technical problem.
Optionally, data processing unit 10 includes: the first normalization module, for the sampled data got into
Row normalization pretreatment, obtains the first processing data, wherein the value of data is in [- a in the first processing data0,a0] model
In enclosing；First computing module, for calculating maximum value, minimum value and the average value of the first processing data；Translation module is used
According to formulaAnd formulaTo it is described first processing data into
Row translation, obtains second processing data, wherein amaxFor the maximum value amax、aminIt for the minimum value and is a0It is described average
Value；Second normalization module obtains the target data for the second processing data to be normalized.
Optionally, computing unit 20 includes: derivation module, for passing through formulaTo the target data
Derivation is carried out, the change rate data are obtained, wherein i=1,2 ..., N-1, k [i] they are the change rate data,For institute
Target data is stated, the π of ω=2 f, f are fundamental frequency, and Δ T is the sampling interval of the sampled data, and N is in the sampled data
Data amount check；Second computing module, maximum value and the change rate data for calculating the change rate data are most
The corresponding sequential value of big value；Third computing module, for passing through formula j [i]=kmax*sin(2*π*(i-1)/(N-1)+θ)
The target sinusoidal data is calculated, wherein i=1,2 ..., N-1, kmaxFor the maximum value of the change rate data, j [i]
For the target sinusoidal data, θ is used for the k as i=mmaxIt is equal with sinusoidal data j [m], wherein m is the sequential value.
Optionally, the first determination unit 30 includes: the 4th computing module, for passing through formula
The sinusoidal coefficients of the difference current are calculated, wherein S is the sinusoidal coefficients, kiFor the change rate data, jiFor institute
State target sinusoidal data, wherein i=1,2 ..., N-1, Δ T are the sampling interval of the sampled data, and N is the hits
Data amount check in.
Optionally, the second determination unit 40 is used for: if sinusoidal coefficients are less than preset threshold, it is determined that difference current is not
Excitation surge current；If sinusoidal coefficients are greater than or equal to preset threshold, it is determined that difference current is excitation surge current.
Unless specifically stated otherwise, the opposite step of the component and step that otherwise illustrate in these embodiments, digital table
It is not limit the scope of the invention up to formula and numerical value.
The technical effect and preceding method embodiment phase of device provided by the embodiment of the present invention, realization principle and generation
Together, to briefly describe, Installation practice part does not refer to place, can refer to corresponding contents in preceding method embodiment.
The recognition methods of excitation surge current provided in an embodiment of the present invention, the identification with excitation surge current provided by the above embodiment
Device technical characteristic having the same reaches identical technical effect so also can solve identical technical problem.
Embodiment three:
Referring to fig. 23, the embodiment of the present invention also provides a kind of electronic equipment 120, comprising: processor 1201, memory
1202, bus 1203 and communication interface 1204, the processor 1201, communication interface 1204 and memory 1202 pass through bus
1203 connections；Processor 1201 is for executing the executable module stored in memory 1202, such as computer program.
Wherein, memory 1202 may include high-speed random access memory (RAM, Random Access Memory),
It may also further include nonvolatile memory (non-volatile memory), for example, at least a magnetic disk storage.By extremely
A few communication interface 1204 (can be wired or wireless) is realized between the system network element and at least one other network element
Communication connection, can be used internet, wide area network, local network, Metropolitan Area Network (MAN) etc..
Bus 1203 can be isa bus, pci bus or eisa bus etc..The bus can be divided into address bus, number
According to bus, control bus etc..Only to be indicated with a four-headed arrow in Figure 23 convenient for indicating, it is not intended that only one total
Line or a type of bus.
Wherein, memory 1202 is for storing program, and the processor 1201 is after receiving and executing instruction, described in execution
Program, method performed by the device that the stream process that aforementioned any embodiment of the embodiment of the present invention discloses defines can be applied to locate
It manages in device 1201, or realized by processor 1201.
Processor 1201 may be a kind of IC chip, the processing capacity with signal.It is above-mentioned during realization
Each step of method can be completed by the integrated logic circuit of the hardware in processor 1201 or the instruction of software form.On
The processor 1201 stated can be general processor, including central processing unit (Central Processing Unit, abbreviation
CPU), network processing unit (Network Processor, abbreviation NP) etc.；It can also be digital signal processor (Digital
Signal Processing, abbreviation DSP), specific integrated circuit (Application Specific Integrated
Circuit, abbreviation ASIC), ready-made programmable gate array (Field-Programmable Gate Array, abbreviation FPGA) or
Person other programmable logic device, discrete gate or transistor logic, discrete hardware components.It may be implemented or execute sheet
Disclosed each method, step and logic diagram in inventive embodiments.General processor can be microprocessor or the processing
Device is also possible to any conventional processor etc..The step of method in conjunction with disclosed in the embodiment of the present invention, can be embodied directly in
Hardware decoding processor executes completion, or in decoding processor hardware and software module combination execute completion.Software mould
Block can be located at random access memory, flash memory, read-only memory, programmable read only memory or electrically erasable programmable storage
In the storage medium of this fields such as device, register maturation.The storage medium is located at memory 1202, and the reading of processor 1201 is deposited
Information in reservoir 1202, in conjunction with the step of its hardware completion above method.
In another embodiment, the embodiment of the invention provides a kind of non-volatile programs that can be performed with processor
The computer-readable medium of code, said program code make the processor execute method described in above method embodiment.
In addition, in the description of the embodiment of the present invention unless specifically defined or limited otherwise, term " installation ", " phase
Even ", " connection " shall be understood in a broad sense, for example, it may be being fixedly connected, may be a detachable connection, or be integrally connected；It can
To be mechanical connection, it is also possible to be electrically connected；It can be directly connected, can also can be indirectly connected through an intermediary
Connection inside two elements.For the ordinary skill in the art, above-mentioned term can be understood at this with concrete condition
Concrete meaning in invention.
In the description of the present invention, it should be noted that term " center ", "upper", "lower", "left", "right", "vertical",
The orientation or positional relationship of the instructions such as "horizontal", "inner", "outside" be based on the orientation or positional relationship shown in the drawings, merely to
Convenient for description the present invention and simplify description, rather than the device or element of indication or suggestion meaning must have a particular orientation,
It is constructed and operated in a specific orientation, therefore is not considered as limiting the invention.In addition, term " first ", " second ",
" third " is used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance.
It is apparent to those skilled in the art that for convenience and simplicity of description, the system of foregoing description,
The specific work process of device and unit, can refer to corresponding processes in the foregoing method embodiment, and details are not described herein.
In several embodiments provided herein, it should be understood that disclosed systems, devices and methods, it can be with
It realizes by another way.The apparatus embodiments described above are merely exemplary, for example, the division of the unit,
Only a kind of logical function partition, there may be another division manner in actual implementation, in another example, multiple units or components can
To combine or be desirably integrated into another system, or some features can be ignored or not executed.Another point, it is shown or beg for
The mutual coupling, direct-coupling or communication connection of opinion can be through some communication interfaces, device or unit it is indirect
Coupling or communication connection can be electrical property, mechanical or other forms.
The unit as illustrated by the separation member may or may not be physically separated, aobvious as unit
The component shown may or may not be physical unit, it can and it is in one place, or may be distributed over multiple
In network unit.It can select some or all of unit therein according to the actual needs to realize the mesh of this embodiment scheme
's.
It, can also be in addition, the functional units in various embodiments of the present invention may be integrated into one processing unit
It is that each unit physically exists alone, can also be integrated in one unit with two or more units.
It, can be with if the function is realized in the form of SFU software functional unit and when sold or used as an independent product
It is stored in the executable non-volatile computer-readable storage medium of a processor.Based on this understanding, of the invention
Technical solution substantially the part of the part that contributes to existing technology or the technical solution can be with software in other words
The form of product embodies, which is stored in a storage medium, including some instructions use so that
One computer equipment (can be personal computer, server or the network equipment etc.) executes each embodiment institute of the present invention
State all or part of the steps of method.And storage medium above-mentioned includes: USB flash disk, mobile hard disk, read-only memory (ROM, Read-
Only Memory), random access memory (RAM, Random Access Memory), magnetic or disk etc. are various can be with
Store the medium of program code.
Finally, it should be noted that embodiment described above, only a specific embodiment of the invention, to illustrate the present invention
Technical solution, rather than its limitations, scope of protection of the present invention is not limited thereto, although with reference to the foregoing embodiments to this hair
It is bright to be described in detail, those skilled in the art should understand that: anyone skilled in the art
In the technical scope disclosed by the present invention, it can still modify to technical solution documented by previous embodiment or can be light
It is readily conceivable that variation or equivalent replacement of some of the technical features；And these modifications, variation or replacement, do not make
The essence of corresponding technical solution is detached from the spirit and scope of technical solution of the embodiment of the present invention, should all cover in protection of the invention
Within the scope of.Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (6)
1. a kind of recognition methods of excitation surge current, which is characterized in that the described method includes:
The sampled data of the difference current a cycle of transformer is obtained, and the sampled data is normalized, is obtained
To target data, wherein the value of data is in default value range in the target data；
The change rate for calculating the target data obtains change rate data, and sinusoidal based on change rate data prediction target
Data, wherein target sinusoidal data is for the reference data as the change rate data, so that the change rate data and institute
Target sinusoidal data is stated to compare；
The sinusoidal coefficients of the difference current are determined in conjunction with the change rate data and the target sinusoidal data；
The difference current that the transformer is determined based on the sinusoidal coefficients is the excitation surge current or fault current；
The sinusoidal coefficients for determining the difference current in conjunction with the change rate data and the target sinusoidal data include:
Pass through formulaThe sinusoidal coefficients of the difference current are calculated, wherein S
For the sinusoidal coefficients, k [i] is the change rate data, and j [i] is the target sinusoidal data, wherein i=1,2 ..., N-
1, Δ T are the sampling interval of the sampled data, and N is the data amount check in the sampled data.
2. obtaining change rate the method according to claim 1, wherein calculating the change rate of the target data
Data, and include: based on change rate data prediction target sinusoidal data
Pass through formulaDerivation is carried out to the target data, obtains the change rate data, wherein i=1,
2 ..., N-1, k [i] are the change rate data,For the target data, the π of ω=2 f, f are fundamental frequency, and Δ T is described
The sampling interval of sampled data, N are the data amount check in the sampled data；
Calculate sequential value corresponding to the maximum value of the change rate data and the maximum value of the change rate data；
Pass through formula j [i]=kmax* the target sinusoidal data is calculated in sin (2* π * (i-1)/(N-1)+θ), wherein i=
1,2 ..., N-1, kmaxFor the maximum value of the change rate data, j [i] is the target sinusoidal data, and θ is used for as i=m,
kmaxIt is equal with sinusoidal data j [m], wherein m is the sequential value.
3. the method according to claim 1, wherein determining the differential of the transformer based on the sinusoidal coefficients
Electric current is the excitation surge current or fault current includes:
If the sinusoidal coefficients are less than preset threshold, it is determined that the difference current is the fault current；
If the sinusoidal coefficients are greater than or equal to the preset threshold, it is determined that the difference current is the excitation surge current.
4. a kind of identification device of excitation surge current, which is characterized in that described device includes:
Data processing unit, the sampled data of the difference current a cycle for obtaining transformer, and to the sampled data
It is normalized, obtains target data, wherein the value of data is in default value range in the target data；
Computing unit obtains change rate data, and be based on the change rate data for calculating the change rate of the target data
Predict target sinusoidal data, wherein target sinusoidal data is for the reference data as the change rate data, so that the change
Rate data and the target sinusoidal data compare change rate data；
First determination unit, for determining the difference current just in conjunction with the change rate data and the target sinusoidal data
String coefficient；
Second determination unit, for determined based on the sinusoidal coefficients difference current of the transformer be the excitation surge current also
It is fault current；
First determination unit includes:
4th computing module, for passing through formulaThe difference current is calculated
Sinusoidal coefficients, wherein S be the sinusoidal coefficients, k [i] be the change rate data, j [i] be the target sinusoidal data,
Wherein, i=1,2 ..., N-1, Δ T are the sampling interval of the sampled data, and N is the data amount check in the sampled data.
5. device according to claim 4, which is characterized in that the computing unit includes:
Derivation module, for passing through formulaDerivation is carried out to the target data, obtains the change rate number
According to, wherein i=1,2 ..., N-1, k [i] are the change rate data,For the target data, the π of ω=2 f, f are fundamental wave
Frequency, Δ T are the sampling interval of the sampled data, and N is the data amount check in the sampled data；
Second computing module, for calculate the change rate data maximum value and the change rate data maximum value institute it is right
The sequential value answered；
Third computing module, for passing through formula j [i]=kmax* the target is calculated in sin (2* π * (i-1)/(N-1)+θ)
Sinusoidal data, wherein i=1,2 ..., N-1, kmaxFor the maximum value of the change rate data, j [i] is the positive chord number of the target
According to θ is used for the k as i=mmaxIt is equal with sinusoidal data j [m], wherein m is the sequential value.
6. a kind of computer-readable medium for the non-volatile program code that can be performed with processor, which is characterized in that described
Program code makes the processor execute any the method in the claims 1 to 3.
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| CN109494684B (en) * | 2018-12-04 | 2020-05-26 | 三峡大学 | Transformer excitation inrush current and fault differential current identification method based on babbitt distance algorithm |
| CN109871832A (en) * | 2019-03-18 | 2019-06-11 | 国家电网有限公司 | Excitation flow recognition method and system based on the amplitude degree of correlation |
| CN111049104B (en) * | 2019-12-04 | 2021-02-19 | 华南理工大学 | Converter transformer sympathetic inrush current identification method based on positive sequence second harmonic |
| CN111969556B (en) * | 2020-08-13 | 2022-07-26 | 广东电网有限责任公司 | Excitation inrush current judgment method and judgment device |
| CN113807592B (en) * | 2021-09-22 | 2023-07-07 | 长春工程学院 | Method, system and equipment for predicting direct-current magnetic bias current of neutral point grounding transformer |
| CN114167117A (en) * | 2021-12-02 | 2022-03-11 | 合肥工业大学 | Method for identifying differential protection excitation inrush current of double-winding transformer |
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