CN109670258A - One kind is based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field - Google Patents
One kind is based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field Download PDFInfo
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Abstract
The present invention relates to one kind based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field, method is as follows: obtaining target transformer parameter, construct its structural model, calculate short circuit current excitation, each vector in the entire transformer of FEM calculation, compare each winding maximum displacement vector sum single-turn winding diameter of target transformer, determines transformer short-circuit steadiness.Calculated result of the invention is more accurate, more can directly reflect transformer short-circuit steadiness.
Description
Technical field
This application involves technical field of electric power, more particularly to steady based on three-phase transformer short circuit is calculated under the influence of phased magnetic field
Qualitative method.
Background technique
Transformer is one of power grid energy source necessary equipment, and transformer stability is the important pivot for being related to the stabilization of power grids
Knob.As power utilization network increasingly increases, transformer short circuit fault frequently occurs, right to ensure power system stability safe operation
Transformer short-circuit stability requirement is higher and higher.
At this stage, transformer short-circuit determination of stability is mostly used and transformer short-circuit stability is sentenced when factory
It is fixed.If meeting the requirements, can put into operation.But with the increase of transformer transporting or runing time, often make transformation
The decline of device short-circuit stability, needs again to evaluate transformer short-circuit stability.However, in the present state-of-the technology,
When judging transformer stability, under the influence of not accounting for transformer phased magnetic field, the actual shape of calculating transformer winding
Become, and is calculated only with summary of experience or indirect parameter.Since summary of experience and indirect parameter (such as power, electric current) calculating cannot
Directly reflect deformation of transformer winding, these calculating be all with a wherein phase of three-phase three-limb (three-phase five-limb) transformer into
Row analysis, there is no the influences for considering phased magnetic field, and so as to cause calculating transformer stability, there are inexactnesies.Therefore it needs
The method more accurately to analyze transformer short-circuit stability.
Summary of the invention
Goal of the invention
This application provides one kind based on three-phase transformer short-circuit stability method is calculated under the influence of phased magnetic field, to solve
The problem that deformation of transformer winding can not be accurately reflected in the prior art and cause calculating transformer winding stability inaccurate.
Technical solution
One kind is based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field, it is characterised in that: method is such as
Under:
Target transformer parameter is obtained, its structural model is constructed and Computing Principle is as follows:
Think when short-circuit transformer core unsaturation, due to three-phase shortcircuit be three-phase symmetrical short circuit, thus each phase with
Single-phase transformer short circuit calculation；
When calculating single-phase transformer short circuit, it is composed in series using resistance, inductance, switch and any initial phase angle power supply equivalent
Circuit counting indicates the phase voltage vector form of equivalent i-th phase with any initial phase angle power supply Usi ∠ θ, and wherein θ indicates initial phase angle,
Ii is expressed as the i-th phase current, indicates the i-th equivalent resistance with Ri, indicates that the i-th equivalent inductance, S1 indicate switch, i table with Li
It is shown as A phase or B phase or C phase；To the model after solution three-phase shortcircuit curent change situation conversion in order to single order
The solution procedure of the differential equation；
It is as follows to calculate short circuit current excitation:
Assuming that being full-load run before transformer short-circuit, i.e. S1 is closed after short circuit；The expression formula Usi at any time of Usi ∠ θ
(t) it indicates, wherein t is indicated time interval 0 second to 0.04 second, it is as follows to solve short circuit current process:
Usi (t)=Us × sin (100 π × t+ θ) (1)
S1 closing moment is enabled to use t1It indicates, t1For any time in time interval 0 second to 0.02 second, secondary side suddenly-applied short circuit
When circuit in inductance element there are energy storage, the energy storage is related to the S1 closing moment phase current values, and Us is expressed as power supply amplitude, by
It is to be synthesized by the operation after circuit construction variations of transformer primary side power supply in Usi (t), it is believed that Usi (t) and Ui (t)
Middle timing synchronization, Ui (t) indicate the i-th phase voltage expression formula at any time；
Size of current before short circuit are as follows:
Ii (t in formula1) function that changes over time of phase current when indicating the full-load run of i phase is in t1Moment current value, Ui
(t1) function that changes over time of phase voltage when indicating the i-th phase full-load run is in t1Moment voltage value, Z are load impedance, Z value
It is related according to the actual operation, when full-load run, enable Z aobvious purely；
It is obtained after short circuit by Kirchhoff's second law:
Ii (t) indicates that the phase current after the short circuit of the i-th phase changes over time value in formula；
Equation general solution are as follows:
Ii (t)=I1 (t)+I2 (t) (4)
I1 (t) indicates the homogeneous equation general solution of equation (3) in formula, and I2 (t) indicates the spy of the nonhomogeneous equation of equation (3)
Solution；
Homogeneous equation general solution are as follows:
The particular solution of nonhomogeneous equation solves as follows:
I2 (t)=Nsin (100 π t+ θ)+Qcos (100 π t+ θ) (6)
Roman N, Q, P are constant to be asked in formula (5) and (6), can bring formula (1) and (6) into formula when solving constant N, Q
(3) it acquires, utilizes short circuit front and back electric current original state as follows when solving constant P, the final moment is denoted as t before short circuit1-, Ii (t1-)
Finally the i-th phase current values of moment are expressed as before short circuit, and initially the moment is denoted as t after short circuit1+, Ii (t1+) be expressed as after short circuit initially
The i-th phase current values of moment；
Ii(t1+)=Ii (t1)=Ii (t1) (7)
It brings formula (2), (5) and (6) into formula (7) and finds out constant P, and then find out different t1Corresponding to moment short circuit
Short circuit current；So as to find the short-circuit moment that maximum short circuit current is occurred, since three-phase current differs 120 degree each other, institute
The short circuit current of other two-phases can be found out by same method；
After finding out transformer short-circuit electric current, it is limited that transformer winding is found out using 3 d structure model summation finite element method
The flux density and power of first unit are distributed；Simplified model method is as follows:
(1) then think that each face of fuel tank be at vertical connecting corner is right angle if oil-immersed transformer；If non-oil immersion
Formula transformer does not have to then consider mailbox problem；
(2) ignore iron core vortex, winding circulation and the hardwares hysteresis characteristic such as kelvin effect and folder to transformer
Electrodynamic influence；
(3) three-phase current is sinusoidal variations, ignores higher hamonic wave；
(4) for winding subregion using unified line cake spacing；
(5) ignore the influence in magnetic field produced by winding overhang and section of winding line；
(6) line cake is refine to the middle pressure winding analyzed, other windings are all made of cylindrical structure；
Required short circuit current is loaded into three-dimensional transformer winding cross section with exiting form, and takes every phase short circuit current equal
It is even to be distributed in single-turn winding cross section；
Each vector method is as follows in the entire transformer of FEM calculation:
In vortex:
In non-vortex area:
In above-mentioned (8) and (9) two groups of equations, ν is magnetic resistance, and A1 is vector magnetic potential, and φ is scalar potential, and σ is conductivity, B1
It is magnetic induction vector, E is electric field vector, and j is current density；
It short-circuit electromotive force can be distributed into winding based on Lorentz force formula, unit electric power distribution formula is as follows:
In formula, fx、fy、fzThe respectively average electric power in three directions of unit x, y, z, Bx、By、BzRespectively unit x, y,
The average magnetic induction intensity in tri- directions z；Jx、Jy、JzRespectively the current density in three directions of unit x, y, z, current density are
Short-circuit ampere-turn electric current is acquired divided by the sum of every circle sectional area of winding；
Each unit vectorial force load of winding, which is added, to be had in cushion block and the three-phase windings of stay support, and finite element is used
Software finds out each winding maximum displacement vector；
Compare each winding maximum displacement vector sum single-turn winding diameter of target transformer, determines transformer short-circuit stability
Situation.
The transformer parameter include high-voltage winding parameter, low pressure winding parameter, transformer core parameter, cushion block, stay,
Fuel tank, folder, pretightning force, ampere-turn unbalance factor, transformer connection type, transformer load side on-link mode (OLM), short-circuit impedance, volume
Constant volume, high-low pressure voltage rating, high-low pressure rated current.
According to each winding maximum displacement vector sum single-turn winding diameter of the transformer, it is steady to calculate target transformer short-circuit
Qualitative situation, specifically includes:
The difference of each winding maximum displacement vector sum single-turn winding diameter of calculating transformer, if in the difference at least
One is greater than zero, then judges that transformer short-circuit stability is unqualified, if the difference is respectively less than zero, judge that transformer short-circuit is steady
Qualitative qualification.
According to each winding maximum displacement vector sum single-turn winding diameter of the transformer, it is steady to calculate target transformer short-circuit
Qualitative situation, specifically includes:
The maximum ratio of each winding maximum displacement vector sum single-turn winding diameter of calculating transformer
If ratio is greater than 1, then it is assumed that target transformer short-circuit stability is unqualified；
If ratio is greater than 0.5 less than 1, then it is assumed that target transformer short-circuit qualified stability；
If ratio is greater than 0.1 less than 0.5, then it is assumed that target transformer short-circuit has good stability；
If ratio is less than 0.1, then it is assumed that target transformer short-circuit stability is outstanding.
Advantage and effect
The invention discloses one kind based on three-phase transformer short-circuit stability method is calculated under the influence of phased magnetic field, passes through conjunction
Reason simplifies and builds target transformer threedimensional model, after the excitation of three-phase shortcircuit maximum transient current is added to three-phase windings, by A-
The finite element method calculating transformer magnetic field Ф-A and distribution of force, by the addition of each unit vectorial force load of winding have cushion block and
In the three-phase windings of stay support, each winding maximum displacement vector is found out with finite element software, and based on the analysis results, sentence
Disconnected transformer short-circuit stability.The present invention is based on three-phase transformer short-circuit stability is calculated under the influence of phased magnetic field, it is built upon
Calculating about short-circuit stability is carried out to each vector of object module, provides data supporting for transformer short-circuit stability；
And calculating process considers under the actual operating state of transformer, the influence in magnetic field produced by transformer neighbour's phase winding, respectively
Each winding maximum displacement vector X1i and single-turn winding diameter X2i are compared, determines transformer short-circuit steadiness.It solves
At this stage when judging transformer stability, can not accurately reflect transformer phased magnetic field effect under winding deformation and cause to count
Calculate the inaccurate situation of transformer winding stability.Calculated result of the invention is more accurate, more can directly reflect transformer
Short-circuit stability situation.
Detailed description of the invention
Fig. 1 phase short circuit current solves equivalent model figure.
Specific embodiment
One kind is based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field, it is characterised in that: method is such as
Under:
Obtain target include high-voltage winding parameter, low pressure winding parameter, transformer core parameter, cushion block, stay, fuel tank,
Folder, pretightning force, ampere-turn unbalance factor, transformer connection type, transformer load side on-link mode (OLM), short-circuit impedance, specified appearance
Amount, high-low pressure voltage rating, high-low pressure rated current transformer parameter, construct its structural model and Computing Principle are as follows:
Think when short-circuit transformer core unsaturation, due to three-phase shortcircuit be three-phase symmetrical short circuit, thus each phase with
Single-phase transformer short circuit calculation；
When calculating single-phase transformer short circuit, it is composed in series using resistance, inductance, switch and any initial phase angle power supply equivalent
Circuit counting indicates the phase voltage vector form of equivalent i-th phase with any initial phase angle power supply Usi ∠ θ, and wherein θ indicates initial phase angle,
Ii is expressed as the i-th phase current, indicates the i-th equivalent resistance with Ri, indicates that the i-th equivalent inductance, S1 indicate switch, i table with Li
It is shown as A phase or B phase or C phase；To the model after solution three-phase shortcircuit curent change situation conversion in order to single order
The solution procedure of the differential equation；
It is as follows to calculate short circuit current excitation:
Assuming that being full-load run before transformer short-circuit, i.e. S1 is closed after short circuit；The expression formula Usi at any time of Usi ∠ θ
(t) it indicates, wherein t is indicated time interval 0 second to 0.04 second, it is as follows to solve short circuit current process:
Usi (t)=Us × sin (100 π × t+ θ) (1)
S1 closing moment is enabled to use t1It indicates, t1For any time in time interval 0 second to 0.02 second, secondary side suddenly-applied short circuit
When circuit in inductance element there are energy storage, the energy storage is related to the S1 closing moment phase current values, and Us is expressed as power supply amplitude, by
It is to be synthesized by the operation after circuit construction variations of transformer primary side power supply in Usi (t), it is believed that Usi (t) and Ui (t)
Middle timing synchronization, Ui (t) indicate the i-th phase voltage expression formula at any time；
Size of current before short circuit are as follows:
The function that phase current in formula when Ii (t1) expression i phase full-load run changes over time is in t1Moment current value, Ui
(t1) function that changes over time of phase voltage when indicating the i-th phase full-load run is in t1Moment voltage value, Z are load impedance, Z value
It is related according to the actual operation, when full-load run, enable Z aobvious purely；
It is obtained after short circuit by Kirchhoff's second law:
Ii (t) indicates that the phase current after the short circuit of the i-th phase changes over time value in formula；
Equation general solution are as follows:
Ii (t)=I1 (t)+I2 (t) (4)
I1 (t) indicates the homogeneous equation general solution of equation (3) in formula, and I2 (t) indicates the spy of the nonhomogeneous equation of equation (3)
Solution；
Homogeneous equation general solution are as follows:
The particular solution of nonhomogeneous equation solves as follows:
I2 (t)=Nsin (100 π t+ θ)+Qcos (100 π t+ θ) (6)
Roman N, Q, P are constant to be asked in formula (5) and (6), can bring formula (1) and (6) into formula when solving constant N, Q
(3) it acquires, utilizes short circuit front and back electric current original state as follows when solving constant P, the final moment is denoted as t before short circuit1-, Ii (t1-)
Finally the i-th phase current values of moment are expressed as before short circuit, and initially the moment is denoted as t after short circuit1+, Ii (t1+) be expressed as after short circuit initially
The i-th phase current values of moment；
Ii(t1+)=Ii (t1)=Ii (t1) (7)
It brings formula (2), (5) and (6) into formula (7) and finds out constant P, and then find out different t1Corresponding to moment short circuit
Short circuit current；So as to find the short-circuit moment that maximum short circuit current is occurred, maximum short circuit current method is solved using exhaustion
Method, i.e., in view of phased magnetic field there are the case where, by all short-circuit moment that may occur in an ac cycle from 0 second to
1000 each moment points at equal intervals are resolved within 0.02 second, 1000 short circuit currents are calculated, to find out maximum short circuit in 1000 times
The short-circuit moment corresponding to electric current and maximum short circuit current.
Since three-phase current differs 120 degree each other, so the short circuit current of other two-phases can be found out by same method；
After finding out transformer short-circuit electric current, it is limited that transformer winding is found out using 3 d structure model summation finite element method
The flux density and power of first unit are distributed；Simplified model method is as follows:
(1) then think that each face of fuel tank be at vertical connecting corner is right angle if oil-immersed transformer；If non-oil immersion
Formula transformer does not have to then consider mailbox problem；
(2) ignore iron core vortex, winding circulation and the hardwares hysteresis characteristic such as kelvin effect and folder to transformer
Electrodynamic influence；
(3) three-phase current is sinusoidal variations, ignores higher hamonic wave；
(4) for winding subregion using unified line cake spacing；
(5) ignore the influence in magnetic field produced by winding overhang and section of winding line；
(6) line cake is refine to the middle pressure winding analyzed, other windings are all made of cylindrical structure；
Required short circuit current is loaded into three-dimensional transformer winding cross section with exiting form, and takes every phase short circuit current equal
It is even to be distributed in single-turn winding cross section；
When addition excitation, if the three-phase Non-completety symmetry of three-phase transformer spatial distribution, should solve finite element mould twice
Type is once loaded into A phase or C phase for maximum current excitation, and another time is that maximum current excitation is loaded into interphase B phase.
Each vector method is as follows in the entire transformer of FEM calculation:
In vortex:
In non-vortex area:
In above-mentioned (8) and (9) two groups of equations, ν is magnetic resistance, and A1 is vector magnetic potential, and φ is scalar potential, and σ is conductivity, B1
It is magnetic induction vector, E is electric field vector, and j is current density；
It short-circuit electromotive force can be distributed into winding based on Lorentz force formula, unit electric power distribution formula is as follows:
In formula, fx、fy、fzRespectively unitx, tri- directions y, z average electric power, Bx、By、BzRespectively unit x, y,
The average magnetic induction intensity in tri- directions z；Jx、Jy、JzRespectively the current density in three directions of unit x, y, z, current density are
Short-circuit ampere-turn electric current is acquired divided by the sum of every circle sectional area of winding；
Each unit vectorial force load of winding, which is added, to be had in cushion block and the three-phase windings of stay support, and finite element is used
Software finds out each winding maximum displacement vector；
Compare each winding maximum displacement vector sum single-turn winding diameter of target transformer, determines transformer short-circuit stability
Situation.
Judge the mode one of target transformer short-circuit steadiness:
According to each winding maximum displacement vector sum single-turn winding diameter of the transformer, it is steady to calculate target transformer short-circuit
Qualitative situation, specifically includes:
The difference of each winding maximum displacement vector sum single-turn winding diameter of calculating transformer, if in the difference at least
One is greater than zero, then judges that transformer short-circuit stability is unqualified, if the difference is respectively less than zero, judge that transformer short-circuit is steady
Qualitative qualification.
Judge the mode two of target transformer short-circuit steadiness:
According to each winding maximum displacement vector sum single-turn winding diameter of the transformer, it is steady to calculate target transformer short-circuit
Qualitative situation, specifically includes:
The maximum ratio of each winding maximum displacement vector sum single-turn winding diameter of calculating transformer
If ratio is greater than 1, then it is assumed that target transformer short-circuit stability is unqualified；
If ratio is greater than 0.5 less than 1, then it is assumed that target transformer short-circuit qualified stability；
If ratio is greater than 0.1 less than 0.5, then it is assumed that target transformer short-circuit has good stability；
If ratio is less than 0.1, then it is assumed that target transformer short-circuit stability is outstanding.
Claims (4)
1. one kind is based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field, it is characterised in that: method is as follows:
Target transformer parameter is obtained, its structural model is constructed and Computing Principle is as follows:
Transformer core unsaturation is thought when short-circuit, since three-phase shortcircuit is three-phase symmetrical short circuit, thus each phase with single-phase
Transformer short-circuit calculates；
When calculating single-phase transformer short circuit, using resistance, inductance, switch and any equivalent circuit that is composed in series of initial phase angle power supply
It calculates, the phase voltage vector form of equivalent i-th phase is indicated with any initial phase angle power supply Usi ∠ θ, wherein θ indicates initial phase angle, Ii table
It is shown as the i-th phase current, indicates the i-th equivalent resistance with Ri, indicates that the i-th equivalent inductance, S1 indicate that switch, i are expressed as with Li
A phase or B phase or C phase；To the model after solution three-phase shortcircuit curent change situation conversion in order to first differential
The solution procedure of equation；
It is as follows to calculate short circuit current excitation:
Assuming that being full-load run before transformer short-circuit, i.e. S1 is closed after short circuit；Usi (t) table of expression formula at any time of Usi ∠ θ
Show, wherein t is indicated time interval 0 second to 0.04 second, it is as follows to solve short circuit current process:
Usi (t)=Us × sin (100 π × t+ θ) (1)
S1 closing moment is enabled to use t1It indicates, t1For any time in time interval 0 second to 0.02 second, electricity when secondary side suddenly-applied short circuit
There are energy storage for inductance element in road, and the energy storage is related to the S1 closing moment phase current values, UsIt is expressed as power supply amplitude, due to
Usi (t) is synthesized by the operation after circuit construction variations of transformer primary side power supply, it is believed that in Usi (t) and Ui (t)
Timing synchronization, Ui (t) indicate the i-th phase voltage expression formula at any time；
Size of current before short circuit are as follows:
Ii (t in formula1) function that changes over time of phase current when indicating the full-load run of i phase is in t1Moment current value, Ui (t1) table
Show function that phase voltage when the i-th phase full-load run changes over time in t1Moment voltage value, Z are load impedances, and Z value is according to reality
Border operating condition is related, when full-load run, enables Z aobvious purely；
It is obtained after short circuit by Kirchhoff's second law:
Ii (t) indicates that the phase current after the short circuit of the i-th phase changes over time value in formula；
Equation general solution are as follows:
Ii (t)=I1 (t)+I2 (t) (4)
I1 (t) indicates the homogeneous equation general solution of equation (3) in formula, and I2 (t) indicates the particular solution of the nonhomogeneous equation of equation (3)；
Homogeneous equation general solution are as follows:
The particular solution of nonhomogeneous equation solves as follows:
I2 (t)=Nsin (100 π t+ θ)+Qcos (100 π t+ θ) (6)
Roman N, Q, P are constant to be asked in formula (5) and (6), can bring formula (1) and (6) into formula (3) when solving constant N, Q
It acquires, utilizes short circuit front and back electric current original state as follows when solving constant P, the final moment is denoted as t before short circuit1, Ii (t1) indicate
For the i-th phase current values of final moment before short circuit, initially the moment is denoted as t after short circuit1+, Ii (t1+) it is expressed as the initial moment after short circuit
I-th phase current values；
Ii(t1+)=Ii (t1)=Ii (t1) (7)
It brings formula (2), (5) and (6) into formula (7) and finds out constant P, and then find out different t1Short circuit corresponding to moment short circuit
Electric current；So as to find the short-circuit moment that maximum short circuit current is occurred, since three-phase current differs 120 degree each other, so can
The short circuit current of other two-phases is found out by same method；
After finding out transformer short-circuit electric current, transformer winding finite element list is found out using 3 d structure model summation finite element method
Flux density and the power distribution of member；Simplified model method is as follows:
(1) then think that each face of fuel tank be at vertical connecting corner is right angle if oil-immersed transformer；Become if non-oil immersed type
Depressor does not have to then consider mailbox problem；
(2) it is electronic to transformer to ignore iron core vortex, winding circulation and the hardwares hysteresis characteristic such as kelvin effect and folder
The influence of power；
(3) three-phase current is sinusoidal variations, ignores higher hamonic wave；
(4) for winding subregion using unified line cake spacing；
(5) ignore the influence in magnetic field produced by winding overhang and section of winding line；
(6) line cake is refine to the middle pressure winding analyzed, other windings are all made of cylindrical structure；
Required short circuit current is loaded into three-dimensional transformer winding cross section with exiting form, and every phase short circuit current is taken uniformly to divide
Cloth is in single-turn winding cross section；
Each vector method is as follows in the entire transformer of FEM calculation:
In vortex:
In non-vortex area:
In above-mentioned (8) and (9) two groups of equations, ν is magnetic resistance, and A1 is vector magnetic potential, and φ is scalar potential, and σ is conductivity, and B1 is magnetic
Induction vector, E are electric field vectors, and j is current density；
It short-circuit electromotive force can be distributed into winding based on Lorentz force formula, unit electric power distribution formula is as follows:
In formula, fx、fy、fzThe respectively average electric power in three directions of unit x, y, z, Bx、By、BzRespectively unit x, y, z three
The average magnetic induction intensity in a direction；Jx、Jy、JzThe respectively current density in three directions of unit x, y, z, current density are short
Road ampere-turn electric current is acquired divided by the sum of every circle sectional area of winding；
Each unit vectorial force load of winding, which is added, to be had in cushion block and the three-phase windings of stay support, and finite element software is used
Find out each winding maximum displacement vector；
Compare each winding maximum displacement vector sum single-turn winding diameter of target transformer, determines that transformer short-circuit stablizes disposition
Condition.
2. it is according to claim 1 based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field, it is special
Sign is: the transformer parameter include high-voltage winding parameter, low pressure winding parameter, transformer core parameter, cushion block, stay,
Fuel tank, folder, pretightning force, ampere-turn unbalance factor, transformer connection type, transformer load side on-link mode (OLM), short-circuit impedance, volume
Constant volume, high-low pressure voltage rating, high-low pressure rated current.
3. it is according to claim 1 based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field, it is special
Sign is: according to each winding maximum displacement vector sum single-turn winding diameter of the transformer, it is steady to calculate target transformer short-circuit
Qualitative situation, specifically includes:
The difference of each winding maximum displacement vector sum single-turn winding diameter of calculating transformer, if at least one in the difference
Greater than zero, then judge that transformer short-circuit stability is unqualified, if the difference is respectively less than zero, judges transformer short-circuit stability
It is qualified.
4. it is according to claim 1 based on calculating three-phase transformer short-circuit stability method under the influence of phased magnetic field, it is special
Sign is: according to each winding maximum displacement vector sum single-turn winding diameter of the transformer, it is steady to calculate target transformer short-circuit
Qualitative situation, specifically includes:
The maximum ratio of each winding maximum displacement vector sum single-turn winding diameter of calculating transformer
If ratio is greater than 1, then it is assumed that target transformer short-circuit stability is unqualified；
If ratio is greater than 0.5 less than 1, then it is assumed that target transformer short-circuit qualified stability；
If ratio is greater than 0.1 less than 0.5, then it is assumed that target transformer short-circuit has good stability；
If ratio is less than 0.1, then it is assumed that target transformer short-circuit stability is outstanding.
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