CN107482600B - Yyn0 type three-phase group formula transformer drops excitation surge current suppressing method - Google Patents
Yyn0 type three-phase group formula transformer drops excitation surge current suppressing method Download PDFInfo
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- CN107482600B CN107482600B CN201710585514.1A CN201710585514A CN107482600B CN 107482600 B CN107482600 B CN 107482600B CN 201710585514 A CN201710585514 A CN 201710585514A CN 107482600 B CN107482600 B CN 107482600B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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Abstract
The invention discloses a kind of Yyn0 type three-phase group formula transformers to drop excitation surge current suppressing method, and this method comprises the following steps: firstly, protective device is sampled and recorded to the voltage and current of mutual inductor during transformer separating brake；Then, electric current blow-out sequence and voltage blow-out phase angle are determined according to the three-phase voltage current waveform that sampling obtains；Finally, determining Transformer Close sequence and closing phase angle according to information above；Three-phase voltage current waveform is when this method need to only sample Yyn0 type three-phase group formula transformer station high-voltage side bus to obtain three-phase current blow-out sequence and voltage blow-out phase angle information, determine therefrom that switching order and switching voltage phase angle, it can inhibit idle-loaded switching-on excitation surge current, relevant parameter easily obtains, it may be convenient in Practical Project.
Description
Technical field
The invention belongs to transformer excitation flow suppression technology fields, are related to a kind of Yyn0 type three based on option principle
Phase group formula transformer excitation flow suppressing method.
Background technique
Power transformer is one of core equipment of electric system, is directly related to electric system energy whether normal work
No continuously and stably to run, its maintenance difficulty is big, the time between overhauls(TBO) is long since failure damages afterwards for transformer, not only will affect electricity
The normal operation of Force system, or even will cause immeasurable economic loss and social influence.Transformer zero load investment when or
When voltage restores after Removal of external faults, since iron core magnetic flux cannot be mutated, the transient state magnetic flux generated due to voltage jump can
Iron core can be caused to be saturated, it will to generate the very big electric current of numerical value in the side of transformer voltage mutation, which is referred to as
Excitation surge current.
Exciting current very little when transformer works normally, and the amplitude of excitation surge current is likely to be breached the 6~8 of rated current
Times, on the one hand may cause protective relaying maloperation work makes transformer put into operation unsuccessfully, and winding deformation on the other hand may be made to influence to become
Depressor service life；The a large amount of harmonic components contained in excitation surge current simultaneously will pollute power grid, deteriorate power quality；For simultaneously
Column operation or higher level's transformer, excitation surge current may induce and echo surge current, interferes neighbouring operating transformer, cause transformer and
Breaker induces the consequences such as switching overvoltage, damage electrical equipment because electric power is excessive impaired.Therefore it must take measures to inhibit
The excitation surge current of transformer, to reduce the various destructive consequences of excitation surge current bring.
Inhibit the method for transformer excitation flow to be broadly divided into following two categories at present: 1) being controlled from inside.I.e. from change
The excitation principle of depressor iron core sets out, by changing the internal structure of transformer to achieve the purpose that cut down excitation surge current, such as
Change transformer primary, distribution of vice-side winding etc..But such method but the structure due to needing to change transformer, this will band
Carry out other problem, such as whether the insulation of transformer can be made to degenerate or the steady-state operation for influencing transformer etc., develops its and have
There is certain limitation.2) it is controlled from outside.Take some remedial measures to cut down excitation surge current outside transformer,
Such as series connected resistance, low-pressure side install capacitor method, soft start method and phase selection switch technology etc. additional.Wherein first two method needs
Optional equipment is put into, operation expense is increased, there are parameter tuning and control problem, excitation surge currents to inhibit for the third method
Less effective.
Phase selection switch technology is the development with switching technique and a kind of novel electric power apparatus for proposing closes means,
It is effective to inhibit power system operation overvoltage and shove and improve the key technology of power quality comprehensively.Phase selection switch technology
Inhibit excitation surge current principle be control breaker dynamic/static contact the designated phase angle moment of system voltage or current waveform into
Row closes, and keeps the iron core remanent magnetism of closing moment identical as the pre- inducting flux determined by system voltage, to weaken excitation
It shoves.The basic reason that the method is generated from excitation surge current one by one lead to oversaturated angle and start with by iron core magnetic, theoretically can be complete
Eliminate excitation surge current.As novel mainstream research direction, this method is to raising Operation of Electric Systems stability and economy meaning
It is far-reaching, and have a extensive future.
The method is applied to the key of transformer during no-load closing excitation surge current is inhibited to be to select optimal switching-on phase angle,
It include the cooperation of the grasp and alternate switching order to transformer core remanent magnetism information.For Yyn0 type three-phase group formula transformer
For, basic structure is three single-phase transformer compositions, and iron core is mainly by silicon steel sheet stack at former vice-side winding is star-like
Knot and vice-side winding neutral ground.Since each phase magnetic flux is closed along respective magnetic circuit, therefore its magnetic circuit system is independently of each other, in electricity
One timing of source frequency and umber of turn, each phase iron core magnetic flux are determined by winding applied voltage and (are ignored coil resistance and leakage magnetic flux).
Therefore each phase iron core remanent magnetism information can be grasped by three-phase voltage during monitoring separating brake, determines therefrom that best closing phase angle.This
Invention fully considers the influence of the factors such as blow-out characteristic, transformer iron-core structure and the winding connection way of breaker, gives
One kind being directed to Yyn0 type three-phase group formula transformer phase selection method, and this method can be very good that transformer during no-load closing is inhibited to produce
Raw excitation surge current.
Summary of the invention
In order to solve the above-mentioned problems of the prior art, the present invention provides a kind of Yyn0 type three-phase group formula transformer air-drop
Excitation surge current suppressing method, this method need to only sample three-phase voltage current waveform during Yyn0 type three-phase group formula transformer separating brake,
Each phase current blow-out sequence and voltage blow-out phase angle are recorded, that is, may determine therefrom that phase selection closes sequence and switching voltage phase angle, phase
It closes parameter easily to obtain, it may be convenient in Practical Project.
In order to achieve the above object, the present invention adopts the following technical scheme:
Yyn0 type three-phase group formula transformer drops excitation surge current suppressing method, includes the following steps:
During step 1:Yyn0 type three-phase group formula transformer separating brake, signal pickup assembly is by mutual inductor to Yyn0 type three-phase
The three-phase voltage current waveform of group formula transformer is sampled and is recorded；
Step 2: the three-phase current waveform obtained according to step 1 sampling determines three-phase blow-out sequence and blow-out time；Its
Middle blow-out sequence includes the last two-phase of first disconnected phase and blow-out simultaneously, and the head is disconnected mutually to refer to the phase disconnected first, i.e., when certain phase
Electric current be reduced to zero first and remain unchanged, then phase of breaking headed by the phase, the end two-phase refers to be simultaneously switched off after prime minister disconnects
Two-phase；
Step 3: according to the resulting blow-out sequence of step 2, in conjunction with the three-phase voltage waveform that step 1 sampling obtains, record is first
Disconnected phase blowout voltage phase angleAnd last two-phase blow-out phase angleIt is describedIt is with the disconnected phase voltage positive zero crossing of head
Reference point is broken mutually when voltage positive zero crossing blow-out when first,
Step 4: Yyn0 type three-phase group formula Transformer Close sequence being determined according to the resulting blow-out sequence of step 2, i.e., first
It closes a floodgate simultaneously to last two-phase, switching voltage phase angle isIt is delayed after 2~3 cycles to the disconnected phase combined floodgate of head, switching voltage phase
Angle is
Determination blow-out sequence and blow-out time in the step 2, comprising the following steps:
Step 1: determining first disconnected phase and prime minister blow-out moment td1；
The disconnected phase mutually as disconnected first of head, according to breaker zero crossing blow-out sequence, when the electric current of certain phase drops first
It is zero and phase of breaking headed by remaining unchanged i.e., which is prime minister blow-out moment td1；
Step 2: determining end two-phase blow-out moment td2；
Yyn0 type three-phase group formula transformer primary side is the wye connection of isolated neutral, remaining two-phase after the disconnected phase blow-out of head
Circuit each other, size of current equal direction is on the contrary, its electric current of event while zero passage, and the blow-out moment is identical, according to current recording waveform
Obtain last two-phase blow-out moment td2。
First disconnected phase blowout voltage phase angle is determined in the step 3And last two-phase blow-out phase angleIncluding following step
It is rapid:
Step 1: first disconnected phase voltage positive going zeror crossing point moment t is determined according to voltage recording waveform0；
Step 2: with t0Moment is reference point, calculates first disconnected phase blowout voltage phase angle and is
Step 3: calculating last two-phase blowout voltage phase angle is
Compared to the prior art compared with the present invention has following advantage:
1, relevant parameter easily obtains.I.e. all parameters of excitation surge current suppressing method can be by directly measuring acquisition.
Inhibit Yyn0 type three-phase group formula transformer air-drop excitation surge current method 2. closing compared to traditional phase selection, fully considers
The influence of iron core remanent magnetism, excitation surge current inhibitory effect are more preferable.
Detailed description of the invention
Fig. 1 is Yyn0 type three-phase group formula transformer connection group schematic diagram.
Fig. 2 is the overall plan figure of the method for the present invention.
Fig. 3 is simulation model figure.
Fig. 4 is voltage oscillogram when emulating obtained separating brake.
Fig. 5 is current waveform figure when emulating obtained separating brake.
Voltage oscillogram when Fig. 6 is phase selection.
Current waveform figure when Fig. 7 is phase selection.
Specific embodiment
The present invention is described in detail with reference to the accompanying drawings and detailed description:
It is as shown in Figure 1 Yyn0 type three-phase group formula transformer connection group schematic diagram, if A phase supply voltage is uA(t)=
UmSin (ω t+ α), UmIt is primary side winding voltage peak, ω is voltage angular frequency, and α is supply voltage initial phase angle, can define some time
The voltage phase angle at quarter is
To A phase transformer first winding column loop-voltage equation are as follows:
Wherein: uNFor neutral point voltage, R is transformer primary circuit equivalent resistance, and i is transformer primary circuit electric current, N1
It is primary side winding the number of turns, φAIt is transformer core magnetic flux；Due to transformer primary circuit equivalent resistance R very little, often can be ignored not
Meter, and u when three-phase symmetrical operationN=0, then have
That is:
Both sides integrate:
Fig. 2 is the overall plan figure of the method for the present invention, in figure: XLIndicate line impedance, TV indicates voltage transformer, TA table
Show that current transformer, QK indicate three-phase breaker.Sub-switching operation carried out to three-phase breaker QK, signal pickup assembly by TA and
TV acquires three-phase voltage current waveform.Yyn0 type three-phase group formula transformer is acquired by current transformer TA and voltage transformer TV
Primary side winding voltage and current information during separating brake, primary side three-phase current is big when which operates normally in three-phase symmetrical system
It is small equal, phase mutual deviation 120°, due to the nature disjunction in current over-zero of each phase breaker, therefore the three-phase separating brake moment is non-synchronous.
Assume that A phase disconnects first after breaker open operation, blowout voltage phase angle isConvolution (1) and formula (5) know that its iron core remanent magnetism is
Due to the wye connection that Yyn0 type three-phase group formula transformer primary side is isolated neutral, after A phase blow-out, B, C two
Mutually circuit each other, then primary side loop equation has:
Wherein uB=Umsin(ωt+α-120°),uC=UmSin (+120 ° of ω t+ α), same negligible resistance R, then formula (7)
Abbreviation obtains:
Both sides integrate:
Due to B, C two-phase circuit each other, then its blow-out moment is identical.Assuming that blowout voltage phase angle isBringing formula (9) into can
Obtaining B, C two-phase remanent magnetism has:
Switching order and switching voltage phase angle are determined according to the above remanent magnetism information, due to Yyn0 type three-phase group formula transformer primary
Side isolated neutral, the no current circuit if closing a floodgate to a wherein phase, therefore close a floodgate first to wherein two-phase.It is of the invention first
First last blow-out two-phase (B, C) is carried out while being closed a floodgate, shown in the same formula of closing circuit equation (7), then B, the C determined by supply voltage
The pre- inducting flux of phase iron core are as follows:
In order to make to close a floodgate, moment iron core magnetic flux is directly entered steady-state operation, then requires to control the moment iron core remanent magnetism and premonition
Answer magnetic flux identical, i.e.,
φ'B(t1)-φ'C(t1)=ΦrB-ΦrC (12)
Wherein, t1For the best closing time of B, C；
Convolution (11) has with formula (12)
Have
Therefore selecting last two-phase blowout voltage phase angle is its closing phase angle.
After closing a floodgate to B, C phase, due to the symmetry of tri-phase iron core structure, three equivalent excitation impedance phases when iron core unsaturation
Together, then B, C winding partial pressure are identical when entering steady-state operation, have
I.e.
It brings formula (2) into and knows that the pre- inducting flux of A phase winding is
Enable φ 'A(t2)=φrA, i.e.,
The best closing phase angle of A phase, which can then be obtained, is
Since three-phase system has symmetry, thus break headed by B, C phase phase when, head it is disconnected mutually and another two-phase flux change rule with
Above situation is identical, therefore switching order and the selection of switching voltage phase angle follow mentioned above principle.
Embodiment
Fig. 3 is the simulation model built, and transformer is three-phase two-simulation transformer group in this simulation model, and voltage rating is
345/289kV, rated capacity 1209MVA, rated no-load current are about 2A., by Fig. 3 I, V acquire transformer primary side around
Group electric current and voltage waveform, control switch are cut-off at the not inphase angle of voltage waveform, observe primary side winding current waveform.
The current-voltage waveform difference at separating brake moment is as shown in Figure 4 and Figure 5, and three-phase current blow-out sequence is as shown in Figure 4
A-B (C), first disconnected phase (A phase) blowout voltage phase angle known to comparative diagram 5 areLast two-phase blowout voltage phase angle is
Therefore can determine that the Three-Phase Transformer switching order is B (C)-A, B, C phase can be obtained by bringing formula (14) and (17) into respectively
Best switching voltage phase angle is β1=108 °, the best switching voltage phase angle of A phase is β1=123.5 °.It is closed according to above-mentioned closing phase angle
Voltage current waveform difference when lock is as shown in Figure 6 and Figure 7, it can be seen that period three phase current magnitude of closing a floodgate is close to stable state sky
Electric current is carried, excitation surge current is totally constrained.
Above-described specific embodiment has carried out further the purpose of the present invention, technical scheme and beneficial effects
It is described in detail, it should be understood that being not intended to limit the present invention the foregoing is merely a specific embodiment of the invention
Protection scope, all within the spirits and principles of the present invention, any modification, equivalent substitution, improvement and etc. done should all include
Within protection scope of the present invention.
Claims (2)
1.Yyn0 type three-phase group formula transformer drops excitation surge current suppressing method, which comprises the steps of:
During step 1:Yyn0 type three-phase group formula transformer separating brake, signal pickup assembly is by mutual inductor to Yyn0 type three-phase group formula
The three-phase voltage current waveform of transformer is sampled and is recorded；
Step 2: the three-phase current waveform obtained according to step 1 sampling determines three-phase blow-out sequence and blow-out time；Wherein put out
Arc sequence includes the last two-phase of first disconnected phase and blow-out simultaneously, and the head is disconnected mutually to refer to the phase disconnected first, i.e., when the electricity of certain phase
Stream is reduced to zero first and remains unchanged, then phase of breaking headed by the phase, and the end two-phase refers to the two-phase simultaneously switched off after prime minister's disconnection；
Step 3: first disconnected phase is determined in conjunction with the three-phase voltage waveform that step 1 sampling obtains according to the resulting blow-out sequence of step 2
Blowout voltage phase angleAnd last two-phase blow-out phase angleIt is describedIt is reference with the disconnected phase voltage positive zero crossing of head
Point breaks mutually when voltage positive zero crossing blow-out when first,
Step 4: Yyn0 type three-phase group formula Transformer Close sequence being determined according to the resulting blow-out sequence of step 2, i.e., first to end
Two-phase is closed a floodgate simultaneously, and switching voltage phase angle isIt is delayed after 2~3 cycles to the disconnected phase combined floodgate of head, switching voltage phase angle is
First disconnected phase blowout voltage phase angle is determined in the step 3And last two-phase blow-out phase angleThe following steps are included:
Step 1): first disconnected phase voltage positive going zeror crossing point moment t is determined according to voltage recording waveform0；
Step 2): with t0Moment is reference point, calculates first disconnected phase blowout voltage phase angle and is
Step 3): calculating last two-phase blowout voltage phase angle is
2. Yyn0 type three-phase group formula transformer according to claim 1 drops excitation surge current suppressing method, which is characterized in that
Determination blow-out sequence and blow-out time in the step 2, comprising the following steps:
Step 1: determining first disconnected phase and prime minister blow-out moment td1；
The disconnected phase mutually as disconnected first of head, according to breaker zero crossing blow-out sequence, when the electric current of certain phase is reduced to zero first
And phase of breaking headed by remaining unchanged i.e., which is prime minister blow-out moment td1；
Step 2: determining end two-phase blow-out moment td2；
Yyn0 type three-phase group formula transformer primary side is the wye connection of isolated neutral, and remaining two-phase is each other after the disconnected phase blow-out of head
Circuit, for size of current equal direction on the contrary, its electric current of event while zero passage, the blow-out moment is identical, is obtained according to current recording waveform
Last two-phase blow-out moment td2。
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| CN108767826B (en) * | 2018-06-14 | 2019-07-12 | 西安交通大学 | Do not demagnetize converter power transformer air-drop excitation surge current suppressing method after straight resistance test |
| CN114237075B (en) * | 2021-12-17 | 2024-03-29 | 福州大学 | Electromagnetic switch closing control method for intelligently identifying load |
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| EP3157114B1 (en) * | 2014-06-11 | 2020-01-22 | Indra Sistemas, S.A. | Method for reducing the inrush current of an inductive load |
| CN104459578B (en) * | 2014-12-02 | 2017-04-05 | 西安交通大学 | The remanent magnetism method of estimation of Yyn0 type three-phase group formula transformator non-faulting tripping operations |
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