CN110165635A - A kind of transformer circulation determines method, shove circulation compensation method and its application - Google Patents
A kind of transformer circulation determines method, shove circulation compensation method and its application Download PDFInfo
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- CN110165635A CN110165635A CN201910529255.XA CN201910529255A CN110165635A CN 110165635 A CN110165635 A CN 110165635A CN 201910529255 A CN201910529255 A CN 201910529255A CN 110165635 A CN110165635 A CN 110165635A
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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
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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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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Abstract
The invention discloses a kind of transformer circulation to determine method, shove circulation compensation method and its application, comprising: the three-phase current of windings when obtaining transformer air-drop in real time；Based on three-phase current, the unsaturated phase current values of each moment transformer are determined；The opposite number of each unsaturated phase current values is determined as a circulation value, constitutes circulation value set.The three-phase current that windings are repaid using circulation value set value complement obtains the practical excitation surge current of three-phase；Based on practical excitation surge current, differential protection is carried out.Since windings unsaturation phase current is windings " counteracting " electric current under the influence of circulation, the opposite number of the current unsaturated phase current values of transformer is determined as secondary winding circulation value by the present invention, it does not need to measure any voltage, transformer neutral point ground connection and earth-free equal specified conditions are not needed, system voltage balanced, symmetrical is not required yet, it is simple and convenient, strong applicability, strong antijamming capability.And it is verified, present invention determine that circulation accuracy it is higher.
Description
Technical field
The present invention relates to Relay Protection Technology in Power System field, more particularly to a kind of transformer circulation determine method,
It shoves circulation compensation method and its application.
Background technique
Windings electric current is compensated using transformer triangle secondary winding circulation, transformer differential protection can be improved
Sensitivity.And the transformer of 500kV or more at present, secondary winding circulation are can to measure to obtain, but 220kV and following
Circulation can not be measured directly inside the triangle winding of voltage class transformer.
Currently, many scholars propose the acquiring method of circulation.One type assumes that the three-phase electricity of electric system flattens
Weighing apparatus, and zero mould electric current of circulation and the side Y has been obtained come the secondary winding circulation of calculating transformer according to the transformer circuit differential equation
Proportionate relationship (iD=ki0), when according to unsaturation, windings electric current and secondary winding circulation are approximately the relationship of opposite number
Proportionality coefficient is acquired, and then circulation is sought according to zero mould electric current.But such methods are only applicable to transformer neutral point ground connection
Situation is invalid when isolated neutral.In addition, because when such methods have ignored Operation of Electric Systems caused by voltage disturbance
Imbalance, such methods may fail in external disturbance, therefore, in the above method Three-phase Power Systems balance of voltage this
Assuming that not close with being actually bonded, adaptability is not strong enough.The case where wherein another kind of method is applicable to isolated neutral, but
Such methods need to obtain (measurement) transformer neutral point voltage, and scene is generally not easy to obtain this voltage, the original substantially of method
Reason and implementation are required to further improve.
Therefore, still lack a kind of strong applicability, simple and reliable practical circulation acquiring method at present.
Summary of the invention
The present invention provide a kind of transformer circulation determine method, shove circulation compensation method and its application, it is existing to solve
There is transformer circulation to determine in method because 220kV and following voltage class transformer can not be calculated by measuring to directly obtain
The method technical problem that the practicability is poor causes circulation determination difficult.
The technical scheme to solve the above technical problems is that a kind of transformer secondary winding circulation determines method,
Include:
Step 1, the three-phase current for obtaining windings when transformer drops in real time；
Step 2 is based on the three-phase current, determines the unsaturated phase and its unsaturation phase electricity of transformer described in each moment
Flow valuve；
The opposite number of each unsaturated phase current values is determined as a circulation value by step 3, constitutes circulation value collection
It closes, completes the determination of transformer secondary winding circulation.
The beneficial effects of the present invention are: since the generation of windings unsaturation phase current is original side under the influence of circulation
Therefore the opposite number of the current unsaturated phase current values of transformer is determined as the circulation of secondary winding by winding " counteracting " electric current
Value, theoretical and experiment demonstrate the accuracy and reliability of the conclusion.Therefore, method of the invention does not need to measure any electricity
Pressure amount does not need transformer neutral point ground connection and earth-free equal specified conditions yet, need to only be extracted according to three-phase current, simple side
Just, strong applicability.In addition, even if this method remains to be applicable in when the voltage of electric system imbalance occurs because of various factors,
Strong antijamming capability.It is applicable to high-tension transformer and low-tension transformer, is had a wide range of application.
On the basis of above-mentioned technical proposal, the present invention can also be improved as follows.
Further, the step 1 includes:
The windings are obtained in real time in transformer air-drop by the current transformer of the leading-out terminal of windings
Three-phase current.
Further, the step 2 includes:
By in the three-phase current, non-maximum and non-minimum current value in each moment corresponding three-phase electricity flow valuve, really
It is set to the unsaturated phase current values of transformer described in the moment, wherein the corresponding phase of the current value is transformation described in the moment
The unsaturated phase of device.
Further beneficial effect of the invention is: by maximum and non-minimum current value pair non-in each moment three-phase current
The phase answered is determined as the electric current unsaturation phase of the moment transformer, with the opposite number of the windings current value of unsaturated phase
Instead of circulation value.Since during transformer drops, institute's making alive is alternating voltage, the size and Orientation of voltage constantly occurs
Variation, therefore, a certain phase of transformer primary side and not always unsaturated phase, the interior saturation of a cycle replace rotation with unsaturation,
Each moment, unsaturated phase current values are three-phase electricity flow valuve mediant, and determination process is simple and efficient, and high reliablity, application
By force.Correlation theory proves and verifying is detailed in specific embodiment part.
The present invention also provides a kind of circulation compensation methodes of transformer excitation flow, comprising:
The three-phase current and determination that method obtains are determined based on any transformer secondary winding circulation as described above
Circulation value set, which is compensated using the circulation value set, obtains the practical excitation surge current of transformer, completes transformer
The circulation of excitation surge current compensates.
The beneficial effects of the present invention are: the electric current of transformer two sides is equal, without current difference when transformer operates normally.
And when transformer air-drop, there are electric current, other side outlet no current in side, and three-phase windings electric current shoves, thus generates
Difference stream, this needs to use waveform recognition criterion to identify the malfunction shoved and braked to prevent differential protection.Again due to pair
The counteracting of square winding circulation, shoving for primary current are distorted, and waveform recognition criterion is affected.At this time, it may be necessary to three-phase
Windings, which are shoved, to be compensated, and the present invention is compensated using the circulation value set that above-mentioned circulation determines that method determines, is not easy
It is influenced by Voltage unbalance and neutral point needs the measurement method when limitation being grounded and isolated neutral to need to obtain
It is difficult to the neutral point voltage measured, therefore, this method is simple and efficient, and high reliablity is practical, has biggish Practical Project
Application value.
Further, the three-phase current obtained in real time with when m- electric current curve form indicate, then the circulation value collection
Close with when m- circulation value curve form indicate.
Further beneficial effect of the invention is: three-phase current and circulation value set is indicated in the form of curve, intuitively
And convenience of calculation.
Further, non-maximum and non-minimum in each moment corresponding three-phase electricity flow valuve when by the three-phase current
Current value when being determined as the unsaturated phase current values of transformer described in the moment, and constituting circulation value set, then uses the circulation
Value set compensates the three-phase current, obtains the practical excitation surge current of transformer, specifically:
By the circulation values all in the circulation value set, new circulation value set is constituted sequentially in time；
By in the three-phase current, each moment, the corresponding three-phase electricity flow valuve was added respectively in the circulation value set
The moment corresponding circulation value, obtains compensated three-phase current；
Based on the compensated three-phase current, the practical excitation surge current of transformer is obtained.
Further beneficial effect of the invention is: circulation value being arranged sequentially in time, may make up m- circulation at one
Curvilinear function facilitates compensating for calculating, and whole process is simple and efficient, the circulation value high reliablity sought using this method.
The present invention also provides a kind of transformer differential protection methods, comprising:
The practical excitation of transformer that circulation compensation method based on any transformer excitation flow as described above obtains
It shoves, carries out differential protection.
The beneficial effects of the present invention are: the electric current of transformer two sides is equal, without current difference when transformer operates normally.
And when transformer air-drop, there are electric current, other side outlet no current in side, and three-phase windings electric current shoves, difference stream is generated,
It needs to shove and braked using the identification of waveform recognition criterion.Again due to the counteracting of secondary winding circulation, primary current is gushed
Stream is distorted, and waveform recognition criterion is affected.At this point, differential protection is during the work time, acquisition transformer air-drop
When three-phase current, " shoving " is determined based on three-phase current, " shoving " at this time is influencing waveform recognition criterion just due to distortion
Really judgement, it is possible to cause differential protection to think the phenomenon that " shoving " at this time is fault current, thus malfunction.Therefore,
Differential protection malfunction in order to prevent, needing to shove to three-phase windings compensates, and the present invention uses above-mentioned static exciter
The excitation surge current for the circulation compensation method compensation shoved, power grid can be correctly identified as by differential protection and is in normal condition,
Malfunction will not occur, which is simple and efficient, and high reliablity is practical.
The present invention also provides a kind of storage medium, instruction is stored in the storage medium, when computer reads the finger
When enabling, so that the computer is executed above-mentioned any transformer secondary winding circulation as described above and determine method, as described above
Any transformer excitation flow circulation compensation method and/or a kind of transformer differential protection method as described above.
Detailed description of the invention
Fig. 1 is the flow diagram that a kind of transformer secondary winding circulation provided by one embodiment of the present invention determines method；
Compensation effect figure when Fig. 2 is consideration remanent magnetism provided by one embodiment of the present invention；
Fig. 3 is compensation effect figure when transformer neutral point provided by one embodiment of the present invention is grounded；
Fig. 4 is compensation effect figure when transformer neutral point provided by one embodiment of the present invention is earth-free；
Compensation effect figure when Fig. 5 is voltage disturbance provided by one embodiment of the present invention and neutral ground；
Compensation effect figure when Fig. 6 is voltage disturbance provided by one embodiment of the present invention and isolated neutral；
Fig. 7 is the compensation effect of recording electric current provided by one embodiment of the present invention.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
Not constituting a conflict with each other can be combined with each other.
Embodiment one
A kind of transformer secondary winding circulation determines method 100, as shown in Figure 1, comprising:
Step 110, the three-phase current for obtaining windings when transformer drops in real time；
Step 120 is based on three-phase current, determines the unsaturated phase and its unsaturated phase current values of each moment transformer；
The opposite number of each unsaturated phase current values is determined as a circulation value by step 130, constitutes circulation value set,
Complete the determination of transformer secondary winding circulation.
It should be noted that referring to continuous electric current in one whole time when describing " circulation ", " electric current ", " shoving ".
And the value that current time is expressed as when " circulation value ", " current value ", " value of shoving " is described.Then wherein " circulation value set " is equivalent to
Whole section of circulation.
Since the generation of windings unsaturation phase current is windings " counteracting " electric current under the influence of circulation, because
The opposite number of the current unsaturated phase current values of transformer, is determined as the circulation value of secondary winding by this.The method of the present embodiment
It does not need to measure any voltage, does not need transformer neutral point ground connection and earth-free equal specified conditions yet, it only need to be according to three-phase
Electric current extracts, simple and convenient, strong applicability.Even if in addition, there is imbalance because of various factors in the voltage in electric system
When, this method remains to be applicable in, strong antijamming capability.It is applicable to high-tension transformer and low-tension transformer, is had a wide range of application.It is theoretical
The accuracy and reliability of the conclusion is demonstrated with experiment, Correlation Theory and experimental verification are see subsequent descriptions.
Preferably, step 110 includes:
The three of windings are obtained in real time in transformer air-drop by the current transformer of the leading-out terminal of windings
Phase current.
Preferably, step 120 includes:
By in three-phase current, non-maximum and non-minimum current value in each moment corresponding three-phase electricity flow valuve is determined as
The unsaturated phase current values of the moment transformer, wherein the corresponding phase of the current value is the unsaturated phase of the moment transformer.
By the maximum and non-minimum corresponding phase of current value non-in each moment three-phase current, it is determined as the moment transformation
The electric current unsaturation phase of device replaces circulation value with the opposite number of the windings current value of unsaturated phase.Due in transformer sky
During throwing, institute's making alive is alternating voltage, and the size and Orientation of voltage constantly changes, therefore, transformer primary side certain
One phase and not always unsaturated phase, the interior saturation of a cycle replace rotation, each moment with unsaturation, and unsaturated phase current values are
Three-phase electricity flow valuve mediant, determination process is simple and efficient, and high reliablity, and application is strong.
The opposite number of unsaturated phase current values, i.e. circulation value can be indicated with following formula:
Wherein, iDIndicate circulation value, A, B and C respectively represent windings three-phase, iARepresent a moment original side A phase winding
Electric current, iBRepresent the electric current of a moment original side B phase winding, iCRepresent the electric current of a moment original side C phase winding.
Now above scheme is proved, process is as follows:
Assuming that A phase supply voltage is UsAsin (ω t+ α), switching angle α, A phase magnetic linkage are ψA, do not consider resistive component
It influences, according toIt obtains:
It enablesψmFor specified magnetic linkage amplitude, then obtain:
ψA=-ψmcos(ωt+α)+ψmcosα+ψrA (2)
Formula (2) is divided by ψm, the degree of saturation coefficient T of A phase and B, C two-phase is obtained after mark changeA、TBAnd TC:
TA=-cos (ω t+ α)+cos α+KrA
TB=- cos (α -120 ° of ω t+)+cos (α -120 °)+KrB
TC=-cos (+120 ° of ω t+ α)+cos (+120 ° of α)+KrC (3)
KrA=-Krcosθ
KrB=-Krcos(θ+120°)
KrC=-Krcos(θ+240°) (4)
Wherein KrFor remanence coefficient, separating brake angle when θ is last separating brake, KrA、KrBAnd KrCSaturation magnetic is accounted for for three-phase remanent magnetism
The percentage of chain.Obviously, as | TX| when≤1, X phase magnetic linkage is less than saturation magnetic linkage, unsaturated (certain in X A, B, C of X phase iron core
Phase)；When | TX| when > 1, X phase core sataration.When unsaturated, there is following relationship establishment:
iX+iD=iXm≈0 (5)
According to formula (3), analyzed by mathematical relationship it is found that if not considering remanent magnetism (Kr=0), TA、TBAnd TCIn at least exist
One satisfaction | TX| in≤1, that is, entire time cycle at least there is phase unsaturation in each moment, at this time according to formula (5),
In whole cycle, secondary winding circulation can be replaced with the opposite number of the windings unsaturation phase current, it may be assumed that
iD=-iX (6)
Because in the entire time cycle at least there is phase unsaturation in each moment, can be with windings not in a cycle
It is 100% that the opposite number for being saturated phase current, which replaces the effective time accounting of circulation,.
(1) certain moment only exists phase unsaturation, it is thus necessary to determine that unsaturated phase.It can be according to the numerical analysis of formula (3) (i.e.
Each variable is adjusted, traverses all possible numerical result, variable is exactly time inside formula, separating brake angle, switching angle.Time
It is carried out by a cycle 0.02s, step-length 0.0001s；Separating brake angle and switching angle press 360 degree, 1 degree of step-length progress；) obtain, when
When an only phase unsaturation (be assumed to be A phase, i.e., | TA|≤1), both the two-phase of remaining saturation must meet degree of saturation coefficient
Opposite (the i.e. T of symbolB·TC< 0), that is, two saturation phases windings current values plus (subtracting not after circulation value
It is saturated the windings current value of phase) symbol is opposite.Obviously, only one electricity bigger than the windings current value of unsaturated phase
The windings electric current of unsaturated phase is individually subtracted in flow valuve and a current value smaller than the windings current value of unsaturated phase
Value can just obtain two opposite numerical value of symbol.Therefore, what three-phase windings current value was in mediant is mutually unsaturated phase.
Therefore, three-phase windings current value mediant is unsaturated phase current values, subject to the opposite number definition of unsaturated phase current values
(firstly, it is necessary to explanation, here in order to rigorous, " standard " word indicates that the circulation value is not stringent to circulation value in " lead ring stream "
Accurate circulation, and actual rings flow valuve have certain deviation, but the circulation value be sufficiently precise to used for excitation surge current compensation and
Differential protection, therefore, here " lead ring stream " namely " circulation " described herein.Secondly, it should be noted that " circulation value
Set " can be described as the circulation of one whole time after arranging sequentially in time the circulation value in it, here by lead ring
Circulation value set namely " circulation value set " above-mentioned subject to the set that flow valuve is constituted), i.e.,.
(2) if certain moment, there are two-phase unsaturations, it is thus necessary to determine that unsaturated phase, two unsaturated phase windings are electric at this time
Flow valuve is almost overlapped, and the phase that three-phase windings current value is in mediant is necessarily unsaturated phase.Therefore, lead ring stream takes three-phase
The opposite number of mediant, formula (7) equally meet.
(3) if certain moment is there are three-phase unsaturation, no-flashy-flow is generated at this time, and then protective device not will start.
By analyzing above, when not considering remanent magnetism, the effective time of circulation can be replaced to account for lead ring stream in a cycle
Than being 100%.
If considering remanent magnetism, the maximum value K being likely to be breached according to remanence coefficientr=0.7, pass through the numerical analysis of formula formula (3)
It obtains, can replace the effective time accounting of circulation in a cycle with lead ring stream is 88%.Moreover, remanence coefficient is smaller, have
It is bigger to imitate time accounting.It is such case because there are some moment three-phases to be all saturated that effective time accounting, which does not reach 100%,
Generation is seriously saturated in a phase, and a phase has just enter into saturation, when a phase will move out saturation.Because lead ring stream is three-phase original side
The opposite number of the mediant of winding current values, at this time mediant be have just enter into saturation or will move out saturation that phase original side around
Group current value, lead ring stream and true circulation difference very little, and the duration is shorter, the probability very little of generation there almost is not method
Have an impact, as shown in Figure 2.
Embodiment two
A kind of circulation compensation method of transformer excitation flow, comprising:
The three-phase current that method obtains is determined based on any transformer secondary winding circulation described in embodiment one as above
And the circulation value set determined, which is compensated using the circulation value set, obtains the practical excitation surge current of transformer, it is complete
It is compensated at the circulation of transformer excitation flow.
Related art scheme is as in the first embodiment, details are not described herein.
When transformer operates normally, the electric current of transformer two sides is equal, without current difference.And when transformer air-drop, side
There are electric current, other side outlet no current, three-phase windings electric current shoves, thus generates difference stream, this is needed using waveform
Identical criterion identifies the malfunction shoved and braked to prevent differential protection.It is former again due to the counteracting of secondary winding circulation
Shoving for square electric current is distorted, and waveform recognition criterion is affected.It is mended at this time, it may be necessary to shove to three-phase windings
It repays, the present invention is compensated using the circulation value set that above-mentioned circulation determines that method determines, not vulnerable to the influence of Voltage unbalance
The measurement method when limitation being grounded and isolated neutral is needed to need to obtain the neutral point electricity for being difficult to measure with neutral point
Pressure, therefore, this method is simple and efficient, and high reliablity is practical, has biggish practical engineering application value.
Preferably, the three-phase current obtained in real time with when m- electric current curve form indicate, then circulation value set with when
The curve form of m- circulation value indicates.
Three-phase current and circulation value set, intuitive and convenience of calculation are indicated in the form of curve.
Preferably, when by three-phase current, non-maximum and non-minimum electric current in each moment corresponding three-phase electricity flow valuve
Value, (related art scheme same embodiment when being determined as the unsaturated phase current values of the moment transformer, and constituting circulation value set
One, details are not described herein), then the three-phase current is compensated using the circulation value set, obtains the practical excitation surge current of transformer, specifically
Are as follows:
By circulation values all in circulation value set, new circulation value set is constituted sequentially in time；
By in three-phase current, it is corresponding that each moment corresponding three-phase electricity flow valuve adds the moment in circulation value set respectively
Circulation value obtains compensated three-phase current；
Based on compensated three-phase current, the practical excitation surge current of transformer is obtained.
Circulation value is arranged sequentially in time, m- circulation value curvilinear function at one is may make up, facilitates compensating for counting
It calculates, whole process is simple and efficient, the circulation value high reliablity sought using this method.
Specifically, original side's three-phase windings electric current respectively to be added to the lead ring stream acquired, the true excitation surge current i of three-phase is obtainedAm、
iBmAnd iCm, it can be indicated with such as following formula:
Wherein, iDkFor lead ring flow valuve at this time.
The true excitation surge current has the inrush feature of typical discontinuous truncation sinusoidal wave form.
The reliability and accuracy of two method of above-described embodiment one and embodiment are now verified by emulating with live recording,
Specific verifying is as follows:
(1) simulating, verifying
In order to verify the correctness for the circulation acquiring method that embodiment one proposes, transformation is established using PSCAD V4.6 software
Device analogue system simulating actual conditions.It is 240/240/80MVA with capacity, voltage rating no-load voltage ratio is the height of 220/110/10.5kV
Impedance transformer is that prototype is emulated.
Considering to generate the condition that most serious is shoved, the three-phase remanent magnetism of setting transformer simulation model is separating brake angle θ=180 °,
When remanence coefficient is Kr=0.7, the size per unit value (0.70, -0.35, -0.35) of remanent magnetism；A phase switching angle α=0 °.
Fig. 3 and Fig. 4 is respectively that the three-phase that air-drop transformer generates under system voltage balance when being grounded and is earth-free is former
(lead ring stream is that the application method obtains for square winding current (see (a) figure in Fig. 3 and Fig. 4), practical circulation and lead ring stream
Circulation, that the two waveform is reversed in figure in order to compare with three-phase windings electric current) (see (b) in Fig. 3 and Fig. 4
Figure), excitation surge current (see (c) figure in Fig. 3 and Fig. 4).It can be found that circulation and lead ring stream degree of fitting are very good from figure.
Windings electric current is influenced by circulation, produces distortion, and after the compensation for the lead ring stream that the present embodiment method obtains, it obtains
Electric current with typical excitation surge current feature, this is beneficial to improve differential protection action performance.
To sum up, when being grounded and is earth-free, the fitting effect of circulation is relatively good, illustrates that the present embodiment method is versatile.
When Fig. 5 and Fig. 6 is that power system voltage disturbs, the using effect of this method under ground connection and earth-free situation.
It was found that lead ring stream and circulation remain unchanged, compactness is very high, and compensated windings electric current has typical discontinuous truncation sine wave
The excitation surge current feature of form, only overall waveform size is changed, and illustrates the anti-interference of the present embodiment the method
Property is strong.
(2) recording application
Certain transformer (SSZ11-240MVA/220kV) carries out the charging of high-pressure side idle-loaded switching-on, and three-phase current recorder data is such as
Shown in (a) figure of Fig. 7.The lead ring stream obtained by the method that embodiment one proposes, as shown in (b) figure of Fig. 7.Windings electricity
The waveform with typical excitation surge current feature is obtained after flowing through overcompensation, as shown in (c) figure of Fig. 7.It is compensated by lead ring stream
The feature shoved more original than windings of shoving afterwards is more obvious, shows typical discontinuous truncation sinusoidal wave form, this
It is beneficial to improve the sensitivity of differential protection.
Embodiment three
A kind of transformer differential protection method, comprising:
The transformer that circulation compensation method based on any transformer excitation flow described in embodiment two as above obtains
Practical excitation surge current carries out differential protection.
Related art scheme is with embodiment two, and details are not described herein.
Differential protection replaces original windings three-phase using the compensated true excitation surge current of circulation and shoves, in case
Carry out brake criterion operation.
When transformer operates normally, the electric current of transformer two sides is equal, without current difference.And when transformer air-drop, side
There are electric current, other side outlet no current, three-phase windings electric current shoves, and generates difference stream, needs to sentence using waveform recognition
It shoves and is braked according to identification.Again due to the counteracting of secondary winding circulation, shoving for primary current is distorted, waveform recognition
Criterion is affected.At this point, differential protection is during the work time, three-phase current when acquisition transformer drops is based on three
Phase current determines " shoving ", and " shoving " at this time influences the correct judgement of waveform recognition criterion, it is possible to cause difference due to distortion
Dynamic protective device thinks the phenomenon that " shoving " at this time is fault current, thus malfunction.Therefore, differential protection misses in order to prevent
Dynamic, needing to shove to three-phase windings compensates, and the present invention uses the circulation compensation method of above-mentioned transformer excitation flow
The excitation surge current of compensation can be correctly identified as power grid by differential protection and be in normal condition, malfunction will not occur, this is differential
Protection process is simple and efficient, and high reliablity is practical.
Example IV
A kind of storage medium is stored with instruction in storage medium, when computer reads described instruction, makes the computer
It executes above-mentioned any transformer secondary winding circulation as described above and determines method, any static exciter as described above
The circulation compensation method shoved and/or a kind of transformer differential protection method as described above.
Related art scheme is with one~embodiment of embodiment three, and details are not described herein.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (8)
1. a kind of transformer secondary winding circulation determines method characterized by comprising
Step 1, the three-phase current for obtaining windings when transformer drops in real time；
Step 2 is based on the three-phase current, determines the unsaturated phase and its unsaturation phase current of transformer described in each moment
Value；
The opposite number of each unsaturated phase current values is determined as a circulation value by step 3, constitutes circulation value set, complete
At the determination of transformer secondary winding circulation.
2. a kind of transformer secondary winding circulation according to claim 1 determines method, which is characterized in that the step 1
Include:
The three of the windings are obtained in real time in transformer air-drop by the current transformer of the leading-out terminal of windings
Phase current.
3. a kind of transformer secondary winding circulation according to claim 1 or 2 determines method, which is characterized in that the step
Rapid 2 include:
By in the three-phase current, non-maximum and non-minimum current value in each moment corresponding three-phase electricity flow valuve is determined as
The unsaturated phase current values of transformer described in the moment, wherein the corresponding phase of the current value is transformer described in the moment
Unsaturated phase.
4. a kind of circulation compensation method of transformer excitation flow characterized by comprising
The three-phase electricity that method obtains is determined based on a kind of transformer secondary winding circulation as described in any one of claims 1 to 3
Stream and the circulation value set determined, compensate the three-phase current using the circulation value set, obtain the practical excitation surge current of transformer,
Complete the circulation compensation of transformer excitation flow.
5. a kind of circulation compensation method of transformer excitation flow according to claim 4, which is characterized in that obtain in real time
The three-phase current with when m- electric current curve form indicate, then the circulation value set with when m- circulation value curved shape
Formula indicates.
6. a kind of circulation compensation method of transformer excitation flow according to claim 4 or 5, which is characterized in that work as base
The circulation of the three-phase current that method obtains and determination is determined in a kind of transformer secondary winding circulation as claimed in claim 3
It is described that the three-phase current is compensated using the circulation value set when value set, the practical excitation surge current of transformer is obtained, specifically:
By the circulation values all in the circulation value set, new circulation value set is constituted sequentially in time；
By in the three-phase current, when each moment corresponding three-phase electricity flow valuve adds in the circulation value set this respectively
The corresponding circulation value is carved, compensated three-phase current is obtained；
Based on the compensated three-phase current, the practical excitation surge current of transformer is obtained.
7. a kind of transformer differential protection method characterized by comprising
Based on a kind of described in any item transformations that the circulation compensation method of transformer excitation flow obtains of such as claim 4 to 6
The practical excitation surge current of device carries out differential protection.
8. a kind of storage medium, which is characterized in that instruction is stored in the storage medium, when computer reads described instruction
When, so that the computer is executed a kind of above-mentioned transformer secondary winding circulation determination side as described in any one of claims 1 to 3
Method, such as claim 4 to 6 described in any item a kind of the circulation compensation methodes and/or such as claim 7 of transformer excitation flow
A kind of transformer differential protection method.
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| CN110165635B (en) | 2021-01-05 |
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