CN104483639B - Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer - Google Patents
Residual magnetism estimation method for non-fault tripping of YNd11 type three-phase combined transformer Download PDFInfo
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Abstract
The invention discloses a residual magnetism estimation method for non-fault tripping of a YNd11 type three-phase combined transformer. The method comprises the following steps: firstly sampling voltage and current waveforms of the YNd11 type three-phase combined transformer through a mutual inductor by a signal acqusition device to obtain voltage and current instantaneous values, and solving the plural form of each electrical quantity through a fourier algorithm to further obtain a power factor angle and a core steady-state flux peak; then determining a first open phase and a first open phase drop-out voltage phase angle according to the sampled three-phase current waveform; finally estimating three-phase core residual magnetism according to the change situation of winding voltage in the tripping process and the relation of the voltage with core flux. According to the method, only the three-phase voltage and current waveforms during operation of the YNd11 type three-phase combined transformer are required to be sampled, and the power factor angle and the core steady-state flux peak in the steady-state operation are obtained through data processing, so the residual magnetism of a core can be estimated thereby; related parameters are easy to acquire; the method can be conveniently used for actual engineering estimation.
Description
Technical field
The invention belongs to transformator remanent magnetism method of estimation technical field is and in particular to a kind of YNd11 type three-phase group formula transformation
The remanent magnetism method of estimation of device non-faulting tripping operation.
Background technology
YNd11 type three-phase group formula transformator is made up of three single-phase transformers, and iron core is mainly built up by stalloy, former limit around
The star-like connection of group and neutral ground, vice-side winding triangle junction.Because each phase magnetic flux closes along respective magnetic circuit, therefore its magnetic
Road system is independently of each other, and in supply frequency and umber of turn one timing, each phase iron core magnetic flux is determined (to ignore by winding applied voltage
Coil resistance and leakage magnetic flux).
Because stalloy belongs to ferromagnetic material, there are hysteresis, after transformator separating brake, external magnetic field cancels, ferromagnetics
Remain to keep original part magnetic, make transformer fe in-core leave part magnetic flux, this magnetic flux is referred to as iron core remanent magnetism.Therefore can be approximate
After thinking transformator separating brake, remanent magnetism is over time and inconspicuous, and remanent magnetism is approximately equal to separating brake moment iron core magnetic flux.YNd11 type
When three-phase group formula transformator normally runs in three-phase symmetrical system, former limit three-phase current is equal in magnitude, 120 ° of phase place mutual deviation, by
Natural disjunction when each phase chopper is in current over-zero, therefore three-phase separating brake moment non-synchronous, this process will result in and powers up outside winding
The change of pressure, and then affect iron core remanent magnetism.And in transformer during no-load closing, due to core material excitation property have non-linear
Characteristic, is affected by iron core remanent magnetism and breaker closing phase angle, is likely to result in the saturation of iron core, led to transformator in voltage jump
Side produces very big exciting current, and up to 6～8 times of rated current, this electric current is known as transformator to its numerical value maximum
Excitation surge current.Because excitation surge current amplitude is very big and flows only through transformator side, Differential Protection of Transformer will be caused to produce very
Big difference stream, leads to differential protection misoperation to trip, so that putting into operation of transformator is repeatedly failed；The very big excitation surge current of numerical value also can
Lead to transformator and chopper excessive and impaired because of electric power；Excitation surge current is also possible to induce to be transported adjacent to other transformer station etc.
The transformator of row produces " and echo surge current " and mistrip, causes large-area power-cuts；A large amount of harmonic wave therein is to the electrical network quality of power supply
Will also result in serious pollution.
Phase selection technology be as the development of switching technique and a kind of novel electric power apparatus of proposing close means, its
The principle of suppression excitation surge current is to select suitable switching-on phase according to the remanent magnetism in separating brake back core, controls chopper sound to touch
Head carries out switch in the designated phase angle moment of system voltage or current waveform and closes, and makes that during combined floodgate, remanent magnetism and magnetic bias can be approximate
Cancel out each other, thus avoiding the supersaturation of transformer core magnetic flux, fundamentally reach weaken excitation surge current purpose.
Existing multiple traditional counting model with regard to remanent magnetism or magnetic field include Product model, Preisach model,
Stoner-Wohlfarth model, but model above computational methods are directed to the parameter that part not directly measures, and utilize
Software emulation transformator remanent magnetism requires system work behavior is compared with accurate simulation, and model buildings are complex, therefore
In the concrete estimation of transformer core remanent magnetism, practicality is all little.
Content of the invention
In order to solve the problems, such as above-mentioned prior art, the present invention provides a kind of YNd11 type three-phase group formula transformator non-
The remanent magnetism method of estimation of fault trip, the method only need to sample YNd11 type three-phase group formula transformer station high-voltage side bus when three-phase voltage current
Waveform, obtains power-factor angle and the iron core stable state magnetic flux peak value under steady-state operation by data processing, you can estimate ferrum accordingly
Core remanent magnetism, during relevant parameter easily obtains in that context it may be convenient to estimate for Practical Project.
In order to achieve the above object, the present invention adopts the following technical scheme that：
The remanent magnetism method of estimation of YNd11 type three-phase group formula transformator non-faulting tripping operation, comprises the steps：
Step 1：During YNd11 type three-phase group formula transformer station high-voltage side bus, signal pickup assembly passes through transformer to YNd11 type three-phase
The voltage current waveform of group formula transformator is sampled, and obtains voltage x current instantaneous value；
Step 2：YNd11 type three-phase group formula transformator stable state three-phase voltage, electric current plural form are obtained by fourier algorithm,
Obtain power-factor angleAnd iron core stable state magnetic flux peak value φm, described iron core stable state magnetic flux peak valueWherein：UmTable
Show phase voltage amplitude, N represents umber of turn, ω is system angular frequency；
Step 3：The three-phase current waveform being obtained according to step 1 sampling, determine first disconnected mutually and first disconnected phase drop-out voltage phase angleOrThe described first disconnected phase mutually referring to disconnection first, that is, when the electric current of certain phase is reduced to zero first and keeps
Constant, then phase of breaking headed by this phase；
Step 4：Estimation tri-phase iron core remanent magnetism
Assume that first breaking is mutually A phase, and first disconnected phase voltage phase angle is δ, A phase cut-offs rear three-phase windings voltage still approximately as formula
(5), shown in, mutually to cut-off rear three-phase windings voltage approximately constant due to first disconnected, therefore magnetic flux is still pressed formula (7) and changed, three-phase current such as formula
(8) shown in；
From formula (8), during+30 ° of ω t=δ, C phase current is reduced to zero, and this phase chopper cut-offs.After C phase is cut-off, three-phase around
Group voltage is approximately
Three-phase current is approximately
According to formula (7), C phase cut-offs+30 ° of moment ω t=δ, shown in tri-phase iron core magnetic flux such as formula (11)；
According to the law of electromagnetic induction, magnetic flux φ is sensed in advance by the three-phase that C phase cut-offs rear three-phase windings voltage generationay、
φby、φcyFor formula (12)；
According to continuity of magnetic flux theorem, this moment magnetic flux cannot be mutated, by produce magnetic bias as shown in formula (13) pass to
Disappear the pre- sensing magnetic flux in this moment；
Therefore after C phase disconnects, tri-phase iron core magnetic flux is formula (11), (12), (13) formula sum are formula (14)；
From formula (10), B phase will the current over-zero blow-out in+120 ° of ω t=δ；ω t=δ is brought into formula for+120 °
(14), can obtain tri-phase iron core remanent magnetism is formula (15)；
Because three-phase system has symmetry, therefore B, headed by C phase during disconnected phase, first disconnected mutually and separately biphase flux change rule with
Above-mentioned situation is identical, can obtain first disconnected phase remanent magnetism expression formula accordingly, as shown in formula (16)；
Normal when running voltage-phase in advance first disconnected 120 ° of phase be mutually time disconnected phase, this phase remanent magnetism is shown in formula (17)
When normally running, delayed first disconnected 120 ° of the phase of voltage-phase is mutually last disconnected phase, and this phase remanent magnetism is shown in formula (18)
φmd=φmsin(δ-90°) (18).
Compared to the prior art relatively, the present invention possesses following advantage：
1st, relevant parameter easily obtains.I.e. this all parameter of remanent magnetism method of estimation all can be obtained by direct measurement or indirect calculating
?.
2. the system model of complexity compared to software emulation YNd11 type three-phase group formula transformator remanent magnetism, need not be built, convenient
Estimate for engineering.
Brief description
Fig. 1 is voltage-current relationship figure.
Fig. 2 is YNd11 type three-phase group formula transformator connection group schematic diagram.
Fig. 3 is phantom equivalent circuit diagram.
Fig. 4 is to estimate magnetic flux and emulation flux waveformses comparison diagram.
Specific embodiment
The present invention is described in detail with reference to the accompanying drawings and detailed description：
During transformer station high-voltage side bus, signal pickup assembly passes through the voltage x current to YNd11 type three-phase group formula transformator for the transformer
Waveform carries out sampling and obtains voltage x current instantaneous value, obtains stable state three-phase voltage plural form by fourier algorithmAnd electric current plural formAs formula (1), (2).Wherein UmRepresent phase voltage amplitude, α
Represent A phase voltage phase angle, ImRepresent line current amplitude, β represents A phase current phase angle, power-factor angle is each phase voltage and electricity
Stream phase angle difference, therefore
If A phase voltage phase angle α=0 °, stable state three-phase voltage time-domain expression u can be obtained by (1), (2)A(t)、uB(t)、uC
(t), and electric current time-domain expression iA(t)、iB(t)、iCT (), as formula (3), (4).
Wherein ω is system angular frequency.
Because transformer primary side winding connects for YN, each phase winding voltage u during normal operationAX、uBY、uCZIt is each mutually electricity
Pressure, as shown in formula (5).
According to Faraday law of electromagnetic induction,
Wherein u represents winding voltage, and φ represents iron core magnetic flux, and N represents umber of turn.
Then tri-phase iron core magnetic flux φa、φb、φcIt is represented by
Wherein iron core stable state magnetic flux peak value is
In Fig. 1, u represents former limit phase voltage, and i represents phase current, because during separating brake, chopper will divide naturally in current over-zero
Disconnected, therefore first disconnected phase voltage phase angle isOr
Assume that first breaking is mutually A phase, cut-off rear electric parameters and can be analyzed with symmetrical component method.For YNd11 type group formula three phase transformation
Depressor, as shown in Fig. 2 when residual voltage is added on transformator YN side, zero-sequence current clicks and enters landform by this side winding neutrality
Become loop, therefore be believed that in sequence net, zero sequence impedance is approximately equal to transformator leakage reactance, and because transformator sequence impedance is much smaller than load
Impedance, can obtain A phase accordingly and cut-off rear three-phase windings voltage, and still as shown in formula (5), tri-phase iron core magnetic flux is still pressed formula (7) and changed, and three
Shown in phase current such as formula (8).
From formula (8), C phase current zero passage during+30 ° of ω t=δ, chopper blow-out, be equivalent to three-phase transformer group former limit
The biphase broken string of A, C, is equally analyzed with symmetrical component method.
Can obtain after C phase cut-offs, former limit three-phase windings voltage is approximately
Former limit three-phase current is approximately
According to formula (7), C phase is cut-off the moment shown in (+30 ° of ω t=δ) tri-phase iron core magnetic flux such as formula (11).
According to the law of electromagnetic induction, magnetic flux φ is sensed in advance by the three-phase that C phase cut-offs rear three-phase windings voltage generationay、φby、
φcyFor formula (12)
According to continuity of magnetic flux theorem, this moment magnetic flux cannot be mutated, by produce magnetic bias as shown in formula (13) pass to
Disappear the pre- sensing magnetic flux in this moment.
Therefore after C phase disconnects, tri-phase iron core magnetic flux is formula (11), (12), (13) formula sum.
From formula (10), B phase chopper will cut-off in+120 ° of ω t=δ in current over-zero blow-out.By+120 ° of ω t=δ
Bring formula (14) into, can obtain tri-phase iron core remanent magnetism is
Because three-phase system has symmetry, therefore B, headed by C phase during disconnected phase, first disconnected mutually and separately biphase flux change rule with
Above-mentioned situation is identical, can obtain first disconnected phase remanent magnetism expression formula accordingly, as shown in formula (16).
Normal when running voltage-phase in advance first disconnected 120 ° of phase be mutually time disconnected phase, this phase remanent magnetism is
When normally running, delayed first disconnected 120 ° of the phase of voltage-phase is mutually last disconnected phase, and this phase remanent magnetism is
φmd=φmsin(δ-90°) (18).
Embodiment
Build phantom as shown in Figure 3, in figure：XLRepresent line impedance, TV represents voltage transformer, TA represents electricity
Current transformer, QK represents three-phase breaker.Sub-switching operation is carried out to three-phase breaker QK, signal pickup assembly is adopted by TA and TV
Collection three-phase voltage current waveform.In this emulation, power-factor angleIron core stable state magnetic flux peak value φm=47.83wb*
N, first breaking is mutually A phase, first disconnected phase angleThe first disconnected phase separating brake moment is as shown in Figure 4.Using formula (16), (17) and (18) matching
Tri-phase iron core magnetic flux during separating brake, is compared with emulation magnetic flux, as can be seen from the figure：Estimate during separating brake that magnetic flux can
With preferable Curve fitting simulation magnetic flux, after three-phase equal separating brake, estimate that between magnetic flux and emulation magnetic flux, error very little is it is seen that this method is permissible
Effectively estimate tri-phase iron core remanent magnetism.
Above in association with accompanying drawing, the specific embodiment of the present invention is described, but these explanations can not be understood to limit
The scope of the present invention, protection scope of the present invention is limited by appended claims, any in the claims in the present invention base
Change on plinth is all protection scope of the present invention.
Claims (1)
- The remanent magnetism method of estimation of 1.YNd11 type three-phase group formula transformator non-faulting tripping operation it is characterised in that：Comprise the steps：Step 1：During YNd11 type three-phase group formula transformer station high-voltage side bus, signal pickup assembly passes through transformer to YNd11 type three-phase group formula The voltage current waveform of transformator is sampled, and obtains voltage x current instantaneous value；Step 2：YNd11 type three-phase group formula transformator stable state three-phase voltage, electric current plural form are obtained by fourier algorithm, obtains Power-factor angleAnd iron core stable state magnetic flux peak value φm, described iron core stable state magnetic flux peak valueWherein：UmRepresent mutually electricity Pressure amplitude value, N represents umber of turn, and ω is system angular frequency；Step 3：The three-phase current waveform being obtained according to step 1 sampling, determine first disconnected mutually and first disconnected phase voltage phase angleOrThe described first disconnected phase mutually referring to disconnection first, that is, when the electric current of certain phase is reduced to zero first and keeps constant, then should Disconnected phase headed by phase；Step 4：Estimation tri-phase iron core remanent magnetismAssume that first breaking is mutually A phase, and first disconnected phase voltage phase angle is δ, A phase cut-offs rear three-phase windings voltage still approximately as formula (5) institute Show, mutually to cut-off rear three-phase windings voltage approximately constant due to first disconnected, therefore magnetic flux is still pressed formula (7) and changed, three-phase current such as formula (8) institute Show；From formula (8), during+30 ° of ω t=δ, C phase current is reduced to zero, and this phase chopper cut-offs.After C phase is cut-off, three-phase windings electricity Pressure is approximatelyThree-phase current is approximatelyAccording to formula (7), C phase cut-offs+30 ° of moment ω t=δ, shown in tri-phase iron core magnetic flux such as formula (11)；According to the law of electromagnetic induction, magnetic flux φ is sensed in advance by the three-phase that C phase cut-offs rear three-phase windings voltage generationay、φby、φcy For formula (12)；According to continuity of magnetic flux theorem, this moment magnetic flux cannot be mutated, and the magnetic bias producing as shown in formula (13) is passed to counteracting should The pre- sensing magnetic flux in moment；Therefore after C phase disconnects, tri-phase iron core magnetic flux is formula (11), (12), (13) formula sum are formula (14)；From formula (10), B phase will the current over-zero blow-out in+120 ° of ω t=δ；ω t=δ is brought into formula (14) for+120 °, can Obtaining tri-phase iron core remanent magnetism is formula (15)；Because three-phase system has symmetry, therefore B, headed by C phase during disconnected phase, first disconnected mutually and separately biphase flux change rule with above-mentioned Situation is identical, can obtain first disconnected phase remanent magnetism expression formula accordingly, as shown in formula (16)；Normal when running voltage-phase in advance first disconnected 120 ° of phase be mutually time disconnected phase, this phase remanent magnetism is shown in formula (17)When normally running, delayed first disconnected 120 ° of the phase of voltage-phase is mutually last disconnected phase, and this phase remanent magnetism is shown in formula (18)φmd=φmsin(δ-90°) (18).
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| CN104833928B (en) * | 2015-04-30 | 2017-09-29 | 国网四川省电力公司电力科学研究院 | A kind of large-scale power transformer remanent magnetism detection method |
| CN106019186B (en) * | 2016-06-03 | 2019-11-05 | 国网河北省电力公司电力科学研究院 | A kind of transformer core remanent magnetism detection method based on no-load current method |
| CN107302216B (en) * | 2017-07-18 | 2018-10-19 | 西安交通大学 | YNd11 type three-phase transformers drop excitation surge current suppressing method |
| CN107947115A (en) * | 2017-12-14 | 2018-04-20 | 中南大学 | Monitoring is with suppressing transformer DC magnetic bias system in a kind of AT tractive power supply systems |
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