CN110119557B - Method for identifying three-phase three-limb Y/delta transformer winding current under direct-current disturbance - Google Patents
Method for identifying three-phase three-limb Y/delta transformer winding current under direct-current disturbance Download PDFInfo
- Publication number
- CN110119557B CN110119557B CN201910361419.2A CN201910361419A CN110119557B CN 110119557 B CN110119557 B CN 110119557B CN 201910361419 A CN201910361419 A CN 201910361419A CN 110119557 B CN110119557 B CN 110119557B
- Authority
- CN
- China
- Prior art keywords
- current
- transformer
- magnetic field
- winding
- inductance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- Evolutionary Computation (AREA)
- Geometry (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
- Protection Of Transformers (AREA)
Abstract
The invention relates to a method for identifying the winding current of a three-phase three-column Y/delta transformer under direct current disturbance, which is characterized by comprising the following steps: establishing a magnetic field model inside the transformer, and calculating time domain inductance by using an energy balance finite element method; and substituting the calculated inductance parameters into the circuit model, and identifying the current of the transformer winding through a time domain circuit differential equation and electromagnetic coupling iteration. And (4) carrying out simulation calculation on the no-load current of the transformer winding under different direct current disturbances and summarizing the rule. The modularized movable mould experiment platform is built to verify a simulation result, and a basis is provided for judging the internal excitation saturation degree of the transformer in the alternating current-direct current hybrid environment and ensuring the safe and stable operation of the transformer.
Description
Technical Field
The invention relates to the technical field of transformers, in particular to a method for identifying winding current of a three-phase three-column Y/delta transformer under direct-current disturbance, which is applied to fault operation and safety evaluation of a power transformer under direct-current disturbance.
Background
In the prior art, direct current disturbance can affect power transformer equipment in an alternating current power grid, and the operation reliability of the direct current disturbance is directly related to the safety and stability of a power system. The (quasi) direct current flowing into the transformer can cause the half-wave saturation of the transformer, so that the iron core generates a magnetic biasing effect, and simultaneously causes the deviation of a working point, the distortion of exciting current, the increase of harmonic wave and the increase of magnetic leakage, thereby causing the loss increase and the vibration aggravation of the transformer, and even a series of adverse consequences such as local burning, iron core loosening, winding deformation and the like occur. Meanwhile, the winding current and the exciting current are basically the same in no-load operation, so that the identification of the transformer no-load current in the alternating current and direct current hybrid environment can reflect the change condition of the exciting current inside the transformer, so as to represent the excitation saturation degree of the transformer, and the method has important significance for researching transformer fault operation and safety evaluation.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for identifying the winding current of a three-phase three-column transformer under direct current disturbance, which is scientific, reasonable, efficient, practical and accurate in calculation. And respectively substituting the solved coupling parameters into the magnetic field and the circuit model for cyclic iteration to realize the identification of the winding current.
The purpose of the invention is realized by the following technical scheme: a method for identifying three-phase three-column Y/delta transformer winding current under direct current disturbance is characterized by comprising the following steps:
1. establishing a magnetic field model
Vector-based magnetic potential can be used, assuming that the winding current at a certain moment is knownAThe Energy Balance Finite Element Method (EBFEM) of (a) calculates the time domain inductance matrix at that moment. The magnetic field model is as follows:
in the formula (I), the compound is shown in the specification,νis the reluctance ratio;Jrepresenting the distribution of the excitation current of the winding as a current density vectorThe method is described.
The magnetic field model is solved by a Galerkin margin formula:
in the formula (I), the compound is shown in the specification,G e is the balance of Galerkin; {M m Is a sequence of weight functions, which are identical to the basis functions,mis the general item number of the weight function sequence,e n is the unit normal component of the boundary surface,
deriving the above equation yields:
wherein:
the weighted residual equation is dispersed to form an algebraic equation set, and the algebraic equation set is obtained by solvingAFurther calculating the magnetic induction intensityBIntensity of magnetic fieldHAnd the like.
The energy balance method is that in the magnetic field system formed by current-carrying coils of transformer, its magnetic field energy is numerically equal to the energy supplied and converted by external power supply in the course of building said system, and at a certain moment any two windings are converted into di η 、di θ (η,θ= a, B, C, a, B, C), the inductance between the two windings beingL ηθ (di η 、di θ AndL ηθ see table 1) can increase the winding current by diIncrement of energy supplied by time-varying power supplyW 1 Increment d of magnetic field energy with internal system of transformerW 2 Correlating to obtain:
the time domain inductance is calculated by the equation in the energy conservation simultaneous method (5), and is substituted into the circuit model for the next calculation.
2. Establishing a circuit model
The differential equation of the time domain circuit of the three-phase three-column Y/delta transformer is as follows:
in the formula:i A 、i B 、i C is the current of the high-voltage side winding,i a 、i b 、i c is the current of the port at the low-voltage side,i a1 、i b1 、i c1 connecting a winding current for a low-voltage side delta;Lin order to be self-inductive,Mis mutual inductance;r 1 、r 2 is a resistance of the winding, and is,u A 、u B 、u C is the voltage of the high-voltage side,u a 、u b 、u c is a voltage of a low-voltage side,i cn is a low pressure side circulating current.
3. Current identification based on electromagnetic coupling iteration
If it ist k The inductance parameter at a given moment can be substituted into a circuit differential equation by using an improved Euler methodi k The current at the next moment is calculated:
in the formula:hin order to be the step size,sa slope column vector is calculated for the segment within the step size. The time domain current is taken as the state variable of the magnetic field model.
The solving principle of the winding current based on electromagnetic coupling is as follows:
1) And calculating inductance parameters of the magnetic field model by using an energy balance finite element method, and calculating current at the next moment by using the feedback circuit model.
2) And taking the time domain current obtained by the circuit model calculation as an input variable of the next magnetic field solution of the magnetic field model.
The method for identifying the winding current of the three-phase three-column Y/delta transformer under the direct current disturbance comprises the steps of obtaining dynamic inductance through solving based on an energy balance finite element method on the basis of establishing a three-dimensional electromagnetic coupling model of the transformer with the model size and the actual proportion of 1:1, correcting inductance parameters of a circuit equation, feeding the obtained time domain current into a magnetic field model to be used as excitation at the next moment, and identifying the winding current of the transformer through a loop iteration method. The method provides a basis for judging the internal excitation saturation degree of the transformer under the direct-current disturbance, and has the advantages of being scientific, reasonable, real, effective, accurate in calculation, high in practical value and the like.
Drawings
Fig. 1 is a schematic diagram of a three-phase three-limb transformer model in a three-dimensional structure.
Fig. 2 is a transformer dc disturbance model.
FIG. 3 is a drawing showingαAnd (4) carrying out no-load operation on the primary side simulation current waveform diagram of the transformer when the voltage is not equal to 0.
FIG. 4 is a drawing showingαAnd (4) carrying out no-load operation on the primary side simulation current waveform diagram of the transformer when the voltage is 1.0.
FIG. 5 is a drawing showingαAnd (4) carrying out no-load operation on the primary side simulation current waveform diagram of the transformer when the voltage is not less than 2.0.
FIG. 6 is a schematic view ofαAnd (4) operating the primary side simulation current waveform diagram without load of the transformer at the time of = 3.0.
Fig. 7 is a wiring diagram of the transformer experiment platform.
FIG. 8 is a drawing showingαAnd (4) carrying out primary side experiment current waveform diagram during no-load operation of the transformer when the current is not equal to 0.
FIG. 9 is a schematic view ofαAnd (4) operating the primary side experiment current waveform diagram without load when the voltage is 1.0.
FIG. 10 is a drawing showingαAnd (4) carrying out primary side experiment current waveform diagram during no-load operation of the transformer when the current is not less than 2.0.
FIG. 11 is a schematic view ofαAnd (4) operating the primary side experiment current waveform diagram without load when the voltage is 3.0.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments:
referring to fig. 1, the method for identifying the winding current of the three-phase three-limb Y/delta transformer under the direct-current disturbance comprises the following steps:
1. establishing a magnetic field model
Vector-based magnetic potential can be used, assuming that the winding current at a certain moment is knownAThe time domain inductance matrix at the moment is calculated by an Energy Balance Finite Element Method (EBFEM), and the magnetic field model is as follows:
in the formula (I), the compound is shown in the specification,νis the reluctance ratio;Jis a current density vector, represents the distribution of the excitation current of the winding,
the magnetic field model is solved by a Galerkin margin formula:
in the formula (I), the compound is shown in the specification,G e is the balance of Galerkin; {M m Is a sequence of weight functions, which are identical to the basis functions,mis the general item number of the weight function sequence,e n is the unit normal component of the boundary surface,
derivation of the above equation yields:
wherein:
the weighted residual equation is dispersed to form an algebraic equation set, and the algebraic equation set is obtained by solvingAFurther calculating the magnetic induction intensityBIntensity of magnetic fieldHAnd the like.
The energy balance method refers to that in a magnetic field system formed by current-carrying coils of a transformer, the magnetic field energy of the system is equal to the energy provided and converted by an external power supply in the system building process in value. Any two windings current change to d at a certain timei η 、di θ (η,θ= a, B, C, a, B, C), the inductance between the two windings beingL ηθ (di η 、di θ AndL ηθ see table 1) for the meaning of the specific circuit parameters. The winding current can be increased by diIncrement of energy supplied by time-varying power supplyW 1 Increment d of magnetic field energy with internal system of transformerW 2 Correlating to obtain:
the time domain inductance is calculated by the equation in the energy conservation simultaneous method (5) and is substituted into the circuit model for the next calculation,
2. establishing a circuit model
The direct current disturbance model of the three-phase three-limb Y/delta transformer is shown in figure 2, and the circuit differential equation is as follows:
in the formula:i A 、i B 、i C is the current of the high-voltage side winding,i a 、i b 、i c is the current of the port at the low-voltage side,i a1 、i b1 、i c1 is delta connection on the low-voltage sideA winding current;Lin order to be self-inductive,Mis mutual inductance;r 1 、r 2 is a resistance of the winding and is,u A 、u B 、u C is the voltage at the high-voltage side,u a 、u b 、u c is a voltage of a low-voltage side,i cn is a low pressure side circulating current.
3. Current identification based on electromagnetic coupling iteration
If it ist k The inductance parameter at a given moment can be substituted into a circuit differential equation by using an improved Euler methodi k The current at the next moment is calculated:
in the formula:hin order to be the step size,sa slope column vector is calculated for the segment within the step size. The time domain current is taken as the state variable of the magnetic field model,
the principle of identifying the winding current based on electromagnetic coupling is as follows:
1) And calculating inductance parameters of the magnetic field model by using an energy balance finite element method, and calculating current at the next moment by using the feedback circuit model.
2) And taking the time domain current obtained by the circuit model calculation as an input variable of the next magnetic field solution of the magnetic field model.
4. Simulation analysis
Establishing a simulation model (parameters are shown in table 2) according to the actual three-phase three-column Y/delta transformer BSS-1000VA, connecting a direct current source to a primary side to simulate direct current disturbance, calculating the electromagnetic characteristic of the direct current source,
the DC current generated by the DC source connected to the primary side of the transformer isI DC (I DC =αI 0 )，αAnd representing the magnitude of the direct current disturbance for the direct current horizontal coefficient. Are respectively pairedα=0And (3) simulating the transformer operation modes under the four direct current disturbances of 1.0, 2.0 and 3.0, wherein the current waveform of the primary side winding of the transformer under no-load operation is shown in figures 3-6.
When the transformer is in no-load operation, the winding current is basically the same as the exciting current. The peak and trough areas of the primary side current in normal operation indicate that the transformer excitation is in a saturated state, and the area near the zero point indicates that the excitation is in an unsaturated state. Under the alternating current-direct current hybrid mode, no-load current is distorted, the distortion degree is larger and larger along with the rise of the direct current level, and the waveform shows the phenomena of half-wave distortion and half-wave attenuation, which indicates that the internal excitation state of the transformer is gradually saturated under the direct current disturbance; wherein the content of the first and second substances,i B andi A 、i C the phase ratio is small, mainly because the B-phase winding corresponds to the central core column of the iron core, the magnetic circuit is short, the magnetic resistance is small, the inductive reactance is increased, and the current amplitude is reduced.
5. Experimental verification
In order to verify the correctness of a simulation result, a modular three-phase three-column Y/delta transformer moving die experiment platform is built, the wiring of the experiment platform is shown in a figure 7, and the specific experiment steps are as follows:
1) Regulating a three-phase voltage regulator T in a voltage regulation module 1 So that the voltage applied to the primary side of the transformer reaches a rated value.
2) Closing the DC branch switch K at the DC injection module by adjusting the sliding rheostatR d Varying DC voltage sourceU DC The magnitude of the injected direct current.
3) And recording the current waveform in a winding current monitoring module.
The primary side winding current when the transformer operates in no-load operation under different direct current disturbances is as shown in fig. 8-11:
when no direct current exists, the positive half cycle and the negative half cycle of the current are asymmetric waveforms due to the hysteresis effect. With the rise of the direct current level, the excitation saturation degree is deepened, and the current waveform distortion is intensified; comparing fig. 3-6, it can be seen that the simulation result of the winding current is substantially consistent with the experimental waveform, and the correctness of the adopted winding current identification method is verified; meanwhile, the inventor finds that the medicine composition has the advantages of good curative effect and no toxic or side effect by further experimentsαIncreasing to 2.5 the transformer had experienced significant vibration, continuing to increaseαThe violent vibration occurred up to 3.0, and the insulation burnout phenomenon was accompanied.
Experimental research shows that the transformer can not be on the direct current levelαThe transformer can be operated for a long time under the working condition of more than 2.5, and whether the transformer is in a safe working condition can be judged through the distortion condition of the winding current waveform when the transformer is in no-load operation.
According to the method for identifying the winding current of the three-phase three-column Y/delta transformer under the direct-current disturbance, the simulation and experimental analysis result shows that the internal magnetic field and the circuit of the transformer can be effectively simulated so as to identify the winding current. The excitation saturation degree is judged according to the distortion degree of the winding current under no-load operation, and whether the transformer operates under the safe working condition or not is analyzed, so that the purpose of the invention is achieved and the effect is achieved.
The terms of calculation, illustration and the like in the embodiments of the present invention are used for further description, are not exhaustive, and do not limit the scope of the claims, and those skilled in the art can conceive other substantially equivalent alternatives without inventive step in light of the teaching of the embodiments of the present invention, which fall within the scope of the present invention.
Claims (1)
1. A method for identifying the winding current of a three-phase three-limb Y/delta transformer under direct current disturbance is characterized by comprising the following steps:
(1) Establishing a magnetic field model
Assuming that the winding current at a certain moment is known, a vector-based magnetic potential is usedAThe time domain inductance matrix at the moment is calculated by an Energy Balance Finite Element Method (EBFEM), and a magnetic field model is as follows:
in the formula (I), the compound is shown in the specification,νto be the magnetic resistance rate, is,Jis a current density vector, represents the distribution of the excitation current of the winding,
the magnetic field model is solved by a Galerkin margin formula:
in the formula (I), the compound is shown in the specification,G e is a surplus of GalerkinM m Is a sequence of weight functions, which are identical to the basis functions,mis the general item number of the weight function sequence,e n deriving the above equation for the boundary surface unit normal component to obtain:
wherein:
the weighted residual equation is dispersed to form an algebraic equation set, and the algebraic equation set is obtained by solvingAFurther calculating the magnetic induction intensityBIntensity of magnetic fieldH，
The energy balance method is that in a magnetic field system formed by current-carrying coils of a transformer, the magnetic field energy is numerically equal to the energy provided and converted by an external power supply in the system establishing process; at a certain time, the current of any two windings changes to di η 、di θ The inductance between the two windings isL ηθ (ii) a Increasing the winding current by diIncrement of energy supplied by time-varying power supplyW 1 Increment d of magnetic field energy with internal system of transformerW 2 Correlating to obtain:
the time domain inductance is calculated by the equation in the formula which can be simultaneously established by energy conservation, and is substituted into a circuit model for the next calculation,
(2) Establishing a circuit model
The differential equation of the time domain circuit of the three-phase three-column Y/delta transformer is as follows:
in the formula:i A 、i B 、i C is the current of the high-voltage side winding,i a 、i b 、i c is the current of the port at the low-voltage side,i a1 、i b1 、i c1 connecting a low-voltage side delta with a winding current;Lin order to be self-inductive,Mis mutual inductance;r 1 、r 2 is a resistance of the winding, and is,u A 、u B 、u C is the voltage of the high-voltage side,u a 、u b 、u c is a voltage of a low-voltage side,i cn is a low-pressure side circulating current,
(3) Current identification based on electromagnetic coupling iteration
If it ist k The inductance parameter at a given moment can be substituted into a circuit differential equation by using an improved Euler methodi k The current at the next moment is calculated:
in the formula: k =0,.., n-1;hin order to be the step size,scalculating a slope column vector for the segments within the step size; taking the time domain current as a state variable of a magnetic field model, and solving the principle of the winding current based on electromagnetic coupling as follows:
1) Calculating inductance parameters of the magnetic field model by using an energy balance finite element method, and calculating current at the next moment by using a feedback circuit model;
2) And (4) taking the time domain current obtained by the calculation of the circuit model as an input variable of the next magnetic field solution of the magnetic field model.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| 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 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| 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 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110119557A CN110119557A (en) | 2019-08-13 |
| CN110119557B true CN110119557B (en) | 2023-01-20 |
Family
ID=67520297
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910361419.2A Active CN110119557B (en) | 2019-04-30 | 2019-04-30 | Method for identifying three-phase three-limb Y/delta transformer winding current under direct-current disturbance |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110119557B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| CN108629080B (en) * | 2018-03-27 | 2022-01-28 | 东北电力大学 | Transformer core vibration calculation method under alternating current-direct current hybrid mode |
| CN108694270B (en) * | 2018-03-27 | 2022-03-18 | 东北电力大学 | Transformer AC/DC hybrid operation excitation state-component loss mapping method |
-
2019
- 2019-04-30 CN CN201910361419.2A patent/CN110119557B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN110119557A (en) | 2019-08-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101794321B (en) | Single-phase three-winding autotransformer model taking account of nonlinear influences of excitation impedance | |
| CN104331544B (en) | A kind of three-phase full-bridge converter modeling method based on EIC principles | |
| CN107317331A (en) | A kind of extra-high voltage transformer axial symmetry D.C. magnetic biasing simulation model | |
| Guerra et al. | Current transformer model | |
| CN103577633B (en) | A kind of transformer DC magnetic bias raised based on earth potential is simulated and suppressing method | |
| CN109446681B (en) | J-A model-based optimization implementation method for hysteresis of analog transformer | |
| Chandrasena et al. | An improved low-frequency transformer model for use in GIC studies | |
| Mitra et al. | Reduction of three-phase transformer inrush currents using controlled switching | |
| Zhang et al. | Calculation of DC bias reactive power loss of converter transformer via finite element analysis | |
| CN110399677A (en) | Based on the transformer DC magnetic bias simulation method for improving J-A formula under bias state | |
| CN110119557B (en) | Method for identifying three-phase three-limb Y/delta transformer winding current under direct-current disturbance | |
| CN109460609B (en) | Method for calculating turn-to-turn short circuit reverse circulation of transformer winding | |
| CN108694270B (en) | Transformer AC/DC hybrid operation excitation state-component loss mapping method | |
| CN205120903U (en) | Electromagnetic type voltage transformer response withstand voltage test system | |
| CN109446707A (en) | A kind of Y/ Δ transformer winding turn-to-turn short circuit vibration acceleration calculation method | |
| CN110069883B (en) | Method for judging saturation instability of transformer core under direct-current disturbance | |
| Li et al. | Harmonic distortion feature of AC transformers caused by DC bias | |
| Yao et al. | Modeling and characteristics research on EHV magnetically controlled reactor | |
| Zhang et al. | Investigation of harmonic and global loss of three-phase transformer based on a permeance capacitance analogy model | |
| Young et al. | Modeling and simulation of continuously variable series reactor for power system transient analysis | |
| Wan et al. | An Improved Method for Calculating Power Transmission Equipment Loss and Hot Spot Temperature in Distribution Network under Harmonic Disturbance | |
| Zhang et al. | The compensation mothed for temperature rise test of 750kV magnetic controllable reactor | |
| Xing et al. | Study on the effect of different pre-excitation factors on the output characteristics of MCSR | |
| CN104362914B (en) | A kind of real-time computing technique of Excitation Damping controller and STATCOM equivalent capacity | |
| Li et al. | Modeling and simulation of transformer under dc bias based on jiles-atherton model |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |