CN107332212B - The three-phase group formula transformer excitation flow suppressing method to close a floodgate from delta windings side - Google Patents
The three-phase group formula transformer excitation flow suppressing method to close a floodgate from delta windings side Download PDFInfo
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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
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Abstract
The invention discloses a kind of three-phase group formula transformer excitation flow suppressing methods to close a floodgate from delta windings side, and this method comprises the following steps：First, protective device is sampled and is recorded to the voltage and current of mutual inductor in transformer steady state operation；Then, the three-phase voltage current waveform obtained according to sampling determines electric current blow-out sequence and voltage blow-out phase angle；Finally, Transformer Close sequence and closing phase angle are determined according to information above；Three-phase voltage current waveform is to obtain three-phase current blow-out sequence and voltage blow-out phase angle information when this method need to only sample the three-phase group formula transformer station high-voltage side bus that combined floodgate side winding is delta connection, 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 three-phase to close a floodgate from delta windings side
Group formula transformer excitation flow suppressing method.
Background technology
Power transformer is one of core equipment of electric system, and electric system energy is directly related to 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, can not only influence electricity
The normal operation of Force system, or even immeasurable economic loss and social influence can be caused.Transformer zero load put into 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 prodigious 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, it on the one hand may cause protective relaying maloperation work that transformer is made to put into operation unsuccessfully, 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
Row 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 various destructive consequences that excitation surge current is brought.
The method of transformer excitation flow is inhibited to be broadly divided into following two categories at present：1) it is controlled from inside.I.e. from change
The excitation principle of depressor iron core sets out, and achievees the purpose that cut down excitation surge current by changing the internal structure of transformer, such as
Change the distribution etc. of transformer primary, vice-side winding.But such method but the structure due to needing change transformer, this will band
Carry out other problems, such as whether the steady-state operation etc. that the insulation of transformer can be made to degenerate or influence transformer, makes its development tool
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 that a kind of novel electric power apparatus for being proposed with the development of switching technique 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 improving 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 best switching-on phase angle,
Include the grasp to transformer core remanent magnetism information and the cooperation of alternate switching order.It is delta connection for primary side winding
Three-phase group formula transformer for, three-phase current not same period blow-out after breaker open operation.After first broken phase current zero passage blow-out, by
The effect of delta windings, tri-phase iron core magnetic flux are further change in.Since primary side winding is delta connection, prime minister's blow-out disconnects
Afterwards, remaining biphase current etc. is big reversed, while zero passage blow-out, remanent magnetism are determined (to ignore coil resistance and leakage by winding applied voltage
Magnetic flux) without further changing, therefore by last two-phase blowout voltage during monitoring separating brake its remanent magnetism information can be grasped, according to
This determines best closing phase angle.The present invention fully considers blow-out characteristic, transformer iron-core structure and the winding coupling side of breaker
The influence of the factors such as formula, give it is a kind of for the three-phase group formula transformer phase selection method closed a floodgate from delta windings side,
This method can be very good the excitation surge current for inhibiting transformer during no-load closing to generate.
Invention content
In order to solve the above-mentioned problems of the prior art, the present invention provides a kind of for closing a floodgate from delta windings side
Three-phase group formula transformer drops excitation surge current suppressing method, and this method need to only sample the three-phase that combined floodgate side winding is delta connection
Three-phase voltage current waveform is to obtain three-phase current blow-out sequence and voltage blow-out phase angle information when group formula transformer station high-voltage side bus, accordingly
Determine switching order and switching voltage phase angle, you can idle-loaded switching-on excitation surge current, relevant parameter is inhibited easily to obtain, it may be convenient to
For in Practical Project.
In order to achieve the above object, the present invention adopts the following technical scheme that：
A kind of three-phase group formula transformer excitation flow suppressing method to close a floodgate from delta windings side, includes the following steps：
Step 1：During primary side winding is the three-phase group formula transformer separating brake of delta connection, signal pickup assembly passes through mutual
Sensor is sampled and is recorded to three-phase voltage current waveform；
Step 2：According to the three-phase current waveform that step 1 sampling obtains, three-phase blow-out sequence and blow-out time are determined；Its
Include first disconnected phase and the last two-phase of blow-out simultaneously, first break refers to mutually the phase disconnected first, i.e., as the electric current of certain phase head
It is first reduced to zero and remains unchanged, then phase of breaking headed by the phase, the end two-phase refers to the two-phase simultaneously switched off after prime minister disconnects；
Step 3：According to the last biphase current blow-out moment t obtained by step 2d, in conjunction with the three-phase voltage of step 1 sampling acquisition
Waveform records last two-phase blowout voltage phase angleIt is describedUsing the disconnected phase phase voltage positive zero crossings of head as reference point, that is, work as head
Break mutually when voltage positive zero crossing blow-out,
Step 4：It closes a floodgate simultaneously to last two-phase first after receiving switching signal, switching voltage phase angle isDelay 2
Disconnected to head after~3 cycles mutually to close a floodgate, switching voltage phase angle is βh2=90 ° or βh2=270 °, the switching voltage phase angle is with head
Disconnected phase voltage positive zero crossing is reference point.
Determination three-phase blow-out sequence and blow-out time in the step 2 include the following steps：
Step 1：Determine first disconnected phase；
The disconnected phases 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.；
Step 2：Determine end two-phase blow-out moment td；
Three-phase group formula transformer primary side is delta connection, remaining two-phase circuit each other, size of current after the disconnected phase blow-outs of head
For equal direction on the contrary, its electric current of event while zero passage, the blow-out moment is identical, and the last two-phase blow-out moment is obtained according to current recording waveform
td。
Last two-phase blowout voltage phase angle is determined in the step 3Include the following steps：
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 last two-phase blowout voltage phase angle and 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.
2. being closed compared to traditional phase selection inhibits Yd11 type three-phase group formula transformers to drop excitation surge current method, fully consider
The influence of iron core remanent magnetism, excitation surge current inhibition are more preferable.
Description of the drawings
Fig. 1 is the three-phase group formula transformer connection group schematic diagram that primary side is delta connection.
Fig. 2 is the overall plan figure of the method for the present invention.
Break tri-phase iron core dynamic flux plot after mutually closing a floodgate headed by Fig. 3.
Fig. 4 is simulation model figure.
Fig. 5 is the separating brake current waveform figure that emulation obtains.
Fig. 6 is the separating brake voltage oscillogram that emulation obtains.
Fig. 7 is the switching voltage oscillogram that emulation obtains.
Fig. 8 is the switching current oscillogram that emulation obtains.
Specific implementation mode
The present invention is described in detail with reference to the accompanying drawings and detailed description：
Be three-phase group formula transformer connection group schematic diagram that primary side is delta connection as shown in Figure 1, original when normal operation
Side is symmetrical and 120 ° of phase mutual deviation.Due to current zero-crossing point blow-out characteristic after breaker open operation, three-phase current not same period blow-out.By
It is delta connection in primary side, after prime minister's electric current blow-out (the disconnected phases of head), remaining biphase current etc. is big reversed, while zero passage blow-out,
Referred to as last two-phase.For convenience of explanation it is assumed that phase of breaking headed by B phases.
After B phase current blow-outs, A, C phase original edge voltage are still system voltage UAAnd UC(ignoring system impedance and primary leakage reactance),
Winding C-Z and winding B-Y series operations at this time, while being run with winding A-X inverse parallels, it is line voltage U to bear pressure dropA-C=UA-
UC, then tri-phase iron core magnetic flux is all dynamic magnetic flux at this time, until the blow-out simultaneously of A, C phase current, tri-phase iron core magnetic flux remain unchanged
As remanent magnetism.
If B phase supply voltages are
uB(t)=Umsin(ωt+α) (1)
Wherein, 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
Three-phase voltage is symmetrical, 120 ° of phase mutual deviation, then A, C phase voltage are respectively
After B phase current blow-outs, it is to primary side winding row loop-voltage equation：
Wherein：R is transformer primary circuit equivalent resistance, and i is transformer primary circuit electric current, N1It is primary side winding circle
Number, φA-X、φA-X、φC-ZIt is winding A-X, B-Y, C-Z institutes linkage iron core magnetic flux respectively；Due to the equivalent electricity in transformer primary circuit
R very littles are hindered, it is often negligible, then have
Convolution (3) abbreviation obtains：
Both sides integrate：
Fig. 2 is the overall plan figure of the method for the present invention, in figure：XLIndicate that line impedance, TV indicate voltage transformer, TA tables
Show that current transformer, QF indicate three-phase breaker.Sub-switching operation carried out to three-phase breaker QF, signal pickup assembly by TA and
TV acquires three-phase voltage current waveform.Primary side is acquired as the three of delta connection by current transformer TA and voltage transformer TV
Primary side winding voltage and current information during phase group formula transformer separating brake, the transformer are former when normal operation in three-phase symmetrical system
Side three-phase current is equal in magnitude, 120 ° of phase mutual deviation, due to the nature disjunction in current over-zero of each phase breaker, therefore three-phase separating brake
Moment is non-synchronous.Assuming that blow-out sequence is B-A (C), A, C phase voltage blowout voltage phase angle areConvolution (2) and formula (7) can
Know that its tri-phase iron core remanent magnetism is
It can determine the switching order of the three-phase group formula transformer to close a floodgate from delta windings side and phase of most preferably closing a floodgate accordingly
Angle.
Since primary side winding is delta connection, the no current circuit if to wherein phase combined floodgate, therefore first to wherein two
Mutually close a floodgate.The present invention is carried out while being closed a floodgate to last blow-out two-phase (A, C) first, shown in the same formula of closing circuit equation (4), then
The pre- inducting flux of A, C phase iron core determined by supply voltage is：
In order to make combined floodgate moment iron core magnetic flux be directly entered steady-state operation, then require to control the moment iron core remanent magnetism and premonition
Answer magnetic flux identical, i.e.,
Wherein, t1For the best closing time of A, C；
Convolution (9) has with formula (10)
Have
Therefore select A, C phase blowout voltage phase angle for its closing phase angle.
As shown in figure 3, before entering steady-state operation after A, C phase are closed a floodgate, due to iron core B-Y, C-Z remanent magnetism is different, equivalent
Magnetizing inductance has differences, therefore winding partial pressure is different, and dynamic magnetic flux has differences.A, C phases close a floodgate 2~3 cycles into surely
After state operation, due to a group symmetry for formula Three-Phase Transformer magnetic circuit, B-Y, C-Z windings partial pressure is identical, has
Wherein, uB-YAnd uC-ZRespectively B-Y, C-Z winding pressure drop；
Since iron core magnetic flux integrates for winding voltage, then iron core B-Y, C-Z dynamic magnetics are connected with
Primary side winding row loop-voltage equation (ignoring loop resistance R) after closing a floodgate to B phases has
Equally, convolution (15) integrates equation both sides, then understands that B-Y, the pre- inducting flux of C-Z windings are
Enable φ 'B-Y(t2)=φB-Y(t),φ'C-Z(t2)=φC-Z(t), convolution (1) and formula (3) can obtain
The best closing phase angle of B phases, which can then be obtained, is
βB=90 ° or βB=270 ° (18)
Since three-phase system has symmetry, thus break headed by A, C phase phase when, head it is disconnected mutually and another two-phase flux change rule with
The above situation is identical, therefore switching order and the selection of switching voltage phase angle follow mentioned above principle.
Embodiment
Fig. 4 is the simulation model built, and transformer is three-phase two-simulation transformer group in this simulation model, and rated voltage is
345/289kV, rated capacity 1209MVA, rated no-load current are about 2A.Transformer primary side winding is acquired by I, V in Fig. 4
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 separating brake current-voltage waveform difference that emulation obtains is as shown in Figure 5 and Figure 6, and three-phase current blow-out is suitable as shown in Figure 5
Sequence is B-A (C), and A (C) phase blowout voltage phase angle known to compares figure 6 is
Therefore can determine that the Three-Phase Transformer switching order is A (C)-B, A, C phase can be obtained by bringing formula (12) and (18) into respectively
Best switching voltage phase angle is βh=291.6 °, the best switching voltage phase angle of B phases is βB=90 ° or βB=270 °.According to above-mentioned conjunction
Voltage current waveform difference when lock phase angle closes a floodgate is as shown in Figure 7 and Figure 8, it can be seen that period three phase current magnitude of closing a floodgate connects
Nearly stable state no-load current, excitation surge current are effectively suppressed.
Above-described specific implementation mode has carried out further the purpose of the present invention, technical solution and advantageous effect
It is described in detail, it should be understood that the foregoing is merely the specific implementation mode of the present invention, is not intended to limit the present invention
Protection domain, 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 (3)
1. a kind of three-phase group formula transformer excitation flow suppressing method to close a floodgate from delta windings side, which is characterized in that including
Following steps：
Step 1：During primary side winding is the three-phase group formula transformer separating brake of delta connection, signal pickup assembly passes through mutual inductor
Three-phase voltage current waveform is sampled and recorded；
Step 2：According to the three-phase current waveform that step 1 sampling obtains, three-phase blow-out sequence and blow-out time are determined；Wherein wrap
First disconnected phase and the last two-phase of blow-out simultaneously are included, first break refers to mutually the phase disconnected first, i.e., when the electric current of certain phase drops first
It is zero and remains unchanged, then phase of breaking headed by the phase, the end two-phase refers to the two-phase simultaneously switched off after prime minister disconnects；
Step 3：According to the last biphase current blow-out moment t obtained by step 2d, the three-phase voltage waveform obtained is sampled in conjunction with step 1,
Determine end two-phase blowout voltage phase angleIt is describedUsing the disconnected phase phase voltage positive zero crossings of head as reference point, i.e., when head it is disconnected mutually in
When voltage positive zero crossing blow-out,
Step 4：It closes a floodgate simultaneously to last two-phase first after receiving switching signal, switching voltage phase angle isDelay 2~3 weeks
Disconnected to head after wave mutually to close a floodgate, switching voltage phase angle is βh2=90 ° or βh2=270 °, the switching voltage phase angle is with the disconnected phases of head
Voltage positive zero crossing is reference point.
2. the three-phase group formula transformer excitation flow suppressing method according to claim 1 to close a floodgate from delta windings side,
It is characterized in that, the determination three-phase blow-out sequence and blow-out time in the step 2 include the following steps：
Step 1：Determine first disconnected phase；
The disconnected phases 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.；
Step 2：Determine end two-phase blow-out moment td；
Three-phase group formula transformer primary side is delta connection, and circuit, size of current are equal each other for remaining two-phase after the disconnected phase blow-outs of head
On the contrary, its electric current of event while zero passage, the blow-out moment is identical in direction, and last two-phase blow-out moment t is obtained according to current recording waveformd。
3. the three-phase group formula transformer excitation flow suppressing method according to claim 1 to close a floodgate from delta windings side,
It is characterized in that, determining last two-phase blowout voltage phase angle in the step 3Include the following steps：
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 last two-phase blowout voltage phase angle and is
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| CN113889972B (en) * | 2021-09-18 | 2022-08-02 | 华中科技大学 | Method and device for inhibiting no-load closing excitation inrush current of three-phase transformer |
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| CN103986385B (en) * | 2014-05-21 | 2017-02-15 | 西安交通大学 | Method for restraining no-load closing magnetizing inrush current of transformer |
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