CN110119557A - A kind of lower three-phase three-limb Y/ Δ transformer winding electric current discrimination method of direct current disturbance - Google Patents
A kind of lower three-phase three-limb Y/ Δ transformer winding electric current discrimination method of direct current disturbance Download PDFInfo
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- CN110119557A CN110119557A CN201910361419.2A CN201910361419A CN110119557A CN 110119557 A CN110119557 A CN 110119557A CN 201910361419 A CN201910361419 A CN 201910361419A CN 110119557 A CN110119557 A CN 110119557A
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- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
Abstract
The present invention is a kind of lower three-phase three-limb Y/ Δ transformer winding electric current discrimination method of direct current disturbance, its main feature is that, including the following steps: inside transformer magnetic field model is established, energy balance Finite element arithmetic time domain inductance is utilized；Counted inductance parameters will be counted and substitute into circuit model, the identification to transformer winding electric current is realized by the time domain circuit differential equation and electromagnetic coupling iteration.Lower transformer winding no-load current is disturbed to different direct currents and carries out simulation calculation and Rule Summary.Constructing modular dynamic model experiment platform verifies simulation result, to judge that alternating current-direct current mixes inside transformer excitation degree of saturation under environment, ensures that transformer safety stable operation provides foundation, has scientific and reasonable, authentic and valid, the advantages that practical value is high.
Description
Technical field
The present invention relates to transformer technology fields, are a kind of lower three-phase three-limb Y/ Δ transformer winding electric currents of direct current disturbance
Discrimination method is applied to direct current and disturbs lower Power Transformer Faults operation and security evaluation.
Background technique
In the prior art, direct current disturbance can have an impact the power transformer equipment in AC network, and operation can
The safety and stability of electric system is directly related to by property.(standard) direct current inflow transformer will lead to transformer half-wave saturation, make iron
The heart generates bias effect, also results in Point Drifting, exciting current distortion, harmonic wave increase, leakage field increase, transformer is caused to damage
A series of adverse consequences such as consumption increases, vibration aggravates, or even partial burnt-out, iron core looseness, winding deformation occurs.Meanwhile it is unloaded
Winding current and exciting current are essentially identical when operation, therefore, the identification of no-load transformer electric current under environment are mixed to alternating current-direct current
It can reflect the situation of change of its internal exciting current, to characterize static exciter degree of saturation, to research transformer fault fortune
Capable and security evaluation is of great significance.
Summary of the invention
The object of the present invention is to overcome the deficiencies of the prior art and provide a kind of scientific and reasonable, highly effective, it is accurate to calculate
Direct current disturb lower three-phase three-limb transformer winding electric current discrimination method, the method can be according to actual parameter, respectively
Transformer magnetic field and circuit model are established, using energy balance finite element model for solving magnetic field model, when calculating using High Order Differential-Iterative
Domain circuit.It obtained coupling parameter will be solved substitutes into magnetic field, circuit model loop iteration respectively and winding current will be distinguished with realizing
Know.
The purpose of the present invention is what is realized by following technical scheme: a kind of lower three-phase three-limb Y/ Δ transformation of direct current disturbance
Device winding current discrimination method, characterized in that it the following steps are included:
1. establishing magnetic field model
Assuming that the winding current at certain moment is it is known that can be using based on vector magnetic potentialAEnergy balance FInite Element (EBFEM) meter
Calculate the time domain inductance matrix at the moment.Magnetic field model is as follows:
(1)
In formula,νFor magnetic reluctance；JFor current density vectors, the distribution situation of winding energization electric current is indicated.
Magnetic field model passes through Galerkin surplus equations:
(2)
In formula,G eFor Galerkin surplus；{M m It is sequence of weighting function, weight function is identical as basic function,mIt is logical for sequence of weighting function
Item number,e nFor boundary face unit normal component,
Above formula is derived, is obtained:
(3)
Wherein:
(4)
Weighted Residual equation is discretely formed Algebraic Equation set, solution can obtainA, and then calculated magnetic induction intensityB, magnetic field strengthH
Deng.
Energy budget method refers to that in transformer current-carrying coil composition field system, magnetic field energy is numerically equal to this and is
The energy that external power supply is provided and converted during construction in a systematic way is vertical, a certain moment any two winding currents variation is di η 、di θ (η,θ=
A, B, C, a, b, c), the inductance between two windings isL ηθ (di η 、di θ WithL ηθ Physical circuit parameter meaning be shown in Table 1), can be by winding
Electric current increases diWhen power supply provide energy increment dW 1With the magnetic field energy increment d of inside transformer systemW 2Association, obtains:
(5)
By the conservation of energy can equation calculation time domain inductance in simultaneous (5), and substitute into circuit model and carry out next step calculating.
2. establishing circuit model
The three-phase three-limb Y/ Δ transformer time domain circuit differential equation are as follows:
(6)
In formula:i A、i B、i CFor high-pressure side winding current,i a、i b、i cFor low-pressure side port current,i a1、i b1、i c1For low-pressure side Δ
Connect winding current；LFor self-induction,MFor mutual inductance；r 1、r 2For winding resistance,u A、u B、u CFor high side voltage,u a、u b、u cFor low-pressure side
Voltage,i cnFor low-pressure side circulation.
3. the electric current based on electromagnetic coupling iteration recognizes
Ift k The inductance parameters at moment are it is known that the circuit differential equation can be substituted into, using improved Euler method, by winding currenti k It calculates
The electric current of subsequent time:
(7)
In formula:hFor step-length,sSlope column vector is calculated for the segmentation in step-length.Become temporal current as the state of magnetic field model
Amount.
Winding current resolution principle based on electromagnetic coupling is as follows:
1) inductance parameters of energy balance Finite element arithmetic magnetic field model are utilized, feedback circuit model calculates subsequent time electricity
Stream.
2) temporal current that circuit model is calculated is as the magnetic field model input variable that magnetic field solves next time.
Direct current of the invention disturbs lower three-phase three-limb Y/ Δ transformer winding electric current discrimination method, is to establish model scale
On the basis of the very little transformer 3 D electromagnetic coupling model for being 1:1 with actual ratio, by being asked based on energy balance FInite Element
Solution obtains dynamic inductance, circuit equation inductance parameters is corrected, using obtained temporal current feed-in magnetic field model as subsequent time
Excitation realizes the identification to transformer winding electric current by loop iteration method.The present invention is that direct current disturbs lower inside transformer
The judgement of excitation degree of saturation provides foundation, has scientific and reasonable, authentic and valid, the advantages that it is accurate to calculate, and practical value is high.
Detailed description of the invention
Fig. 1 is three-phase three-limb transformer model schematic perspective view.
Fig. 2 is transformer dc Disturbance Model.
Fig. 3 isαTransformer idle running primary side simulated current waveform diagram when=0.
Fig. 4 isαTransformer idle running primary side simulated current waveform diagram when=1.0.
Fig. 5 isαTransformer idle running primary side simulated current waveform diagram when=2.0.
Fig. 6 isαTransformer idle running primary side simulated current waveform diagram when=3.0.
Fig. 7 is transformer experiment platform wiring diagram.
Fig. 8 isαTransformer idle running primary side tests current waveform figure when=0.
Fig. 9 isαTransformer idle running primary side tests current waveform figure when=1.0.
Figure 10 isαTransformer idle running primary side tests current waveform figure when=2.0.
Figure 11 isαTransformer idle running primary side tests current waveform figure when=3.0.
Specific embodiment
The invention will be further described in the following with reference to the drawings and specific embodiments:
Referring to Fig.1, three-phase three-limb Y/ Δ transformer winding electric current discrimination method under a kind of direct current of the invention disturbs, including with
Lower step:
1. establishing magnetic field model
Assuming that the winding current at certain moment is it is known that can be using based on vector magnetic potentialAEnergy balance FInite Element (EBFEM) meter
The time domain inductance matrix at the moment is calculated, magnetic field model is as follows:
(1)
In formula,νFor magnetic reluctance；JFor current density vectors, the distribution situation of winding energization electric current is indicated,
Magnetic field model passes through Galerkin surplus equations:
(2)
In formula,G eFor Galerkin surplus；{M m It is sequence of weighting function, weight function is identical as basic function,mIt is logical for sequence of weighting function
Item number,e nFor boundary face unit normal component,
Above formula is derived, is obtained:
(3)
Wherein:
(4)
Weighted Residual equation is discretely formed Algebraic Equation set, solution can obtainA, and then calculated magnetic induction intensityB, magnetic field strengthH
Deng.
Energy budget method refers to that in transformer current-carrying coil composition field system, magnetic field energy is numerically equal to this and is
The energy that external power supply is provided and converted during construction in a systematic way is vertical.A certain moment any two winding currents variation is di η 、di θ (η,θ=
A, B, C, a, b, c), the inductance between two windings isL ηθ (di η 、di θ WithL ηθ Physical circuit parameter meaning be shown in Table 1).It can be by winding
Electric current increases diWhen power supply provide energy increment dW 1With the magnetic field energy increment d of inside transformer systemW 2Association, obtains:
(5)
By the conservation of energy can equation calculation time domain inductance in simultaneous (5), and substitute into circuit model and carry out next step calculating,
2. establishing circuit model
Three-phase three-limb Y/ Δ transformer dc Disturbance Model is as shown in Fig. 2, its circuit differential equation are as follows:
(6)
In formula:i A、i B、i CFor high-pressure side winding current,i a、i b、i cFor low-pressure side port current,i a1、i b1、i c1For low-pressure side Δ
Connect winding current；LFor self-induction,MFor mutual inductance；r 1、r 2For winding resistance,u A、u B、u CFor high side voltage,u a、u b、u cFor low-pressure side
Voltage,i cnFor low-pressure side circulation.
3. the electric current based on electromagnetic coupling iteration recognizes
Ift k The inductance parameters at moment are it is known that the circuit differential equation can be substituted into, using improved Euler method, by winding currenti k It calculates
The electric current of subsequent time:
(7)
In formula:hFor step-length,sSlope column vector is calculated for the segmentation in step-length.Become temporal current as the state of magnetic field model
Amount,
Winding current identification principle based on electromagnetic coupling is as follows:
1) inductance parameters of energy balance Finite element arithmetic magnetic field model are utilized, feedback circuit model calculates subsequent time electricity
Stream.
2) temporal current that circuit model is calculated is as the magnetic field model input variable that magnetic field solves next time.
4. simulation analysis
Simulation model (parameter is shown in Table 2) is established according to practical three-phase three-limb Y/ Δ transformer BSS-1000VA, is once being flanked
Enter the disturbance of DC current source analog DC, calculate its electromagnetic property,
The DC current that the connect DC source of transformer primary side generates isI DC(I DC=αI 0),αFor DC level coefficient, characterization is directly
Flow disturbance size.It is right respectivelyα=0,1.0,2.0, the lower transformer station high-voltage side bus mode of 3.0 4 kind of direct current disturbance emulated, it is unloaded to transport
The lower transformer primary winding current waveform of row is shown in Fig. 3-Fig. 6.
Winding current and exciting current are essentially identical when no-load transformer is run.The wave of primary side current when normal operation
The equal indication transformer excitation of peak, valley regions is in a saturated state, and zero crossings region indicates that excitation is in undersaturated condition.?
Under alternating current-direct current promiscuous mode, no-load current is distorted, and with the raising of DC level, distortion degree is increasing, and waveform is in
The phenomenon that existing " half-wave distortion, half wave attenuation ", illustrates that direct current disturbs lower inside transformer excited state and is gradually saturated；Wherein,i B
Withi A、i CCompared to smaller, mainly since B phase winding corresponds to the central stem of iron core, magnetic circuit is shorter, and magnetic resistance is smaller so that feeling
Anti- increase, current amplitude reduce.
5. experimental verification
The correctness of acquired results is emulated for verifying, constructing modular three-phase three-limb Y/ Δ transformer dynamic model experiment platform is real
It tests platform wiring and sees Fig. 7, steps are as follows for specific experiment:
1) three-phase regulator T is adjusted in voltage regulator module1, so that being applied to transformer primary side voltage reaches rated value.
2) it is closed direct current branch switch K in direct current injection module, by adjusting slide rheostatR dChange DC voltage sourceU DCInject the size of direct current.
3) in winding current monitoring modular record current waveform.
Under different direct current disturbances, first side winding electric current such as Fig. 8-Figure 11 when no-load transformer is run:
When without direct current, since hysteresis effect causes the positive and negative half cycle of electric current to be asymmetric waveform.As DC level increases, excitation
Degree of saturation is deepened, current waveform distortion aggravation；Comparison diagram 3- Fig. 6 it is found that winding current simulation result and experimental waveform base
This is consistent, demonstrates the correctness of used winding current discrimination method；Meanwhile being worked as by further experiment discoveryαIncrease to 2.5
Obviously vibrating has occurred in transformer, and continues growingαOccur high vibration when to 3.0, and has burnt phenomenon with insulation.
Experimental studies have found that transformer can not be in DC levelαLong-play under the operating condition of > 2.5, and pass through transformer
The distortion situation of winding current waveform may determine that whether transformer is in safe operating condition when idle running.
Direct current of the invention disturbs lower three-phase three-limb Y/ Δ transformer winding electric current discrimination method, by emulation and experiment
Analysis the result shows that, can effectively analogue transformer internal magnetic field and circuit to be recognized to winding current.Pass through sky
The distortion degree of winding current judges excitation degree of saturation under carrying row, and whether analysis transformer runs on safe operating condition
Under, it realizes the object of the invention and has achieved the effect that described.
Design conditions, legend in the embodiment of the present invention etc. are only used for that the present invention is further illustrated, not exhaustive,
Do not constitute the restriction to claims, those skilled in the art's enlightenment that example obtains according to the present invention, without
Crossing creative work would occur to other substantially equivalent substitutions, all fall in the scope of protection of the present invention.
Claims (1)
1. a kind of direct current disturbs lower three-phase three-limb Y/ Δ transformer winding electric current discrimination method, characterized in that it includes following
Step:
(1) magnetic field model is established
Assuming that the winding current at certain moment is it is known that using vector magnetic potential is based onAEnergy balance FInite Element (EBFEM) calculate should
The time domain inductance matrix at moment, magnetic field model are as follows:
In formula,νFor magnetic reluctance,JFor current density vectors, the distribution situation of winding energization electric current is indicated,
Magnetic field model passes through Galerkin surplus equations:
In formula,G eFor Galerkin surplus,M m It is sequence of weighting function, weight function is identical as basic function,mIt is logical for sequence of weighting function
Item number,e nFor boundary face unit normal component, above formula is derived, is obtained:
Wherein:
Weighted Residual equation is discretely formed Algebraic Equation set, solution can obtainA, and then calculated magnetic induction intensityB, magnetic field strengthH,
Energy budget method refers to that in transformer current-carrying coil composition field system, magnetic field energy is numerically equal to the system and builds
The energy that external power supply is provided and converted during vertical；A certain moment any two winding currents variation is di η 、di θ , between two windings
Inductance beL ηθ ；Winding current is increased into diWhen power supply provide energy increment dW 1With the magnetic field energy of inside transformer system
Increment dW 2Association, obtains:
By the conservation of energy can equation calculation time domain inductance in formula on simultaneous, and substitute into circuit model and carry out next step calculating,
(2) circuit model is established
The three-phase three-limb Y/ Δ transformer time domain circuit differential equation are as follows:
In formula:i A、i B、i CFor high-pressure side winding current,i a、i b、i cFor low-pressure side port current,i a1、i b1、i c1For low-pressure side Δ
Connect winding current；LFor self-induction,MFor mutual inductance；r 1、r 2For winding resistance,u A、u B、u CFor high side voltage,u a、u b、u cFor low-pressure side
Voltage,i cnFor low-pressure side circulation,
(3) the electric current identification based on electromagnetic coupling iteration
Ift k The inductance parameters at moment are it is known that the circuit differential equation can be substituted into, using improved Euler method, by winding currenti k It calculates
The electric current of subsequent time:
In formula: k=0 ..., n-1;hFor step-length,sSlope column vector is calculated for the segmentation in step-length；Using temporal current as magnetic
The state variable of field model, the winding current resolution principle based on electromagnetic coupling are as follows:
1) inductance parameters of energy balance Finite element arithmetic magnetic field model are utilized, feedback circuit model calculates subsequent time electricity
Stream；
2) temporal current that circuit model is calculated is as the magnetic field model input variable that magnetic field solves next time.
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| CN201910361419.2A CN110119557B (en) | 2019-04-30 | 2019-04-30 | Method for identifying three-phase three-limb Y/delta transformer winding current under direct-current disturbance |
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Cited By (1)
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| CN111474496A (en) * | 2020-04-09 | 2020-07-31 | 国网山东省电力公司滨州供电公司 | Transformer turn-to-turn short circuit rapid diagnosis method based on vibration signal identification |
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| CN107317331A (en) * | 2017-07-25 | 2017-11-03 | 华北电力大学 | A kind of extra-high voltage transformer axial symmetry D.C. magnetic biasing simulation model |
| CN108629080A (en) * | 2018-03-27 | 2018-10-09 | 东北电力大学 | A kind of transformer core vibration calculating method under alternating current-direct current promiscuous mode |
| CN108694270A (en) * | 2018-03-27 | 2018-10-23 | 东北电力大学 | A kind of transformer alternating current-direct current mixes operation excited state-component loss mapping method |
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| CN107317331A (en) * | 2017-07-25 | 2017-11-03 | 华北电力大学 | A kind of extra-high voltage transformer axial symmetry D.C. magnetic biasing simulation model |
| CN108629080A (en) * | 2018-03-27 | 2018-10-09 | 东北电力大学 | A kind of transformer core vibration calculating method under alternating current-direct current promiscuous mode |
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| CN111474496A (en) * | 2020-04-09 | 2020-07-31 | 国网山东省电力公司滨州供电公司 | Transformer turn-to-turn short circuit rapid diagnosis method based on vibration signal identification |
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