A method, device and medium for improving transformer simulation accuracy

Abstract

The present invention relates to the technical field of transformer simulation, and discloses a method, device and medium for improving transformer simulation accuracy, comprising: calculating the magnetic induction intensity of the leakage magnetic field of the transformer's live winding according to the harmonic current, and calculating the electromagnetic force acting on the winding according to the magnetic induction intensity of the leakage magnetic field; obtaining a winding motion differential equation according to the dynamics of the mechanical system and the electromagnetic force acting on the winding; calculating the coil displacement of the winding under forced vibration by calculating the equation, and obtaining a winding vibration acceleration formula by taking the second-order derivative of the coil displacement; considering the different winding methods of the transformer grid-side winding and the valve-side winding, establishing an equivalent model of winding currents of different winding methods, and setting the flow direction of the excitation current in different coils of the windings with different winding methods according to the model; establishing a finite element simulation model identical to the equivalent current flow diagram in the coil, and using the excitation current composed of harmonics and fundamental waves as input for simulation.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer simulation, and more particularly to a method, device and medium for improving transformer simulation accuracy. Background Art

[0002] Traditional transformer R&D relies on a large number of physical tests, such as no-load tests, load tests, and temperature-rise tests, which are costly and time-consuming. High-precision simulation can replace some of these tests, especially for ultra-high voltage and large-capacity transformers. Simulation can save hundreds of thousands of dollars in testing costs. The accuracy of transformer simulation is the key to determining whether the simulation can meet energy efficiency indicators. Therefore, how to improve the simulation accuracy of transformers is an urgent problem to be solved.

[0003] The finite element method discretizes the complex structure of a transformer into a finite number of elements and nodes, transforming continuous field problems into a system of algebraic equations to be solved. By solving partial differential equations to calculate the electromagnetic field distribution, the method can accurately handle complex geometries and boundary conditions. However, to reduce computational complexity and cost, some complex transformer structures are often simplified during modeling. Simulation models are typically built under ideal conditions. However, actual transformers operate in complex power grid environments and are affected by various factors, including grid harmonics. These discrepancies between actual operating conditions and simulation assumptions make model verification and calibration difficult, making it difficult to ensure the reliability of simulation results in actual operation.

[0004] Therefore, how to provide a method for improving transformer simulation accuracy is an urgent problem that those skilled in the art need to solve. Summary of the Invention

[0005] In view of this, the present invention provides a method, device and medium for improving the simulation accuracy of a transformer, taking the valve-side winding and grid-side winding currents of the transformer measured under working conditions as excitation sources, and considering that the winding methods of the grid-side and valve-side windings are usually different, and the flow directions of the winding currents with different winding methods in different coils are different, so that the electric field distribution in the transformer box and the electric field force acting on the windings are completely different, which has a great influence on the simulation accuracy of the transformer. Therefore, based on the actual model of the transformer, an equivalent model of the valve-side spiral winding and the grid-side tangled continuous winding current is established, and the current flow directions of the winding coils with different winding methods in the transformer simulation model are set according to the model, thereby improving the simulation accuracy of the transformer.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for improving transformer simulation accuracy, comprising:

[0008] Calculate the leakage magnetic field intensity of the transformer live winding based on the harmonic current, and calculate the electromagnetic force formula on the winding based on the leakage magnetic field intensity;

[0009] According to the coil structure of the winding, it is equivalent to a mass-spring-damper model. According to the dynamics of the mechanical system and the electromagnetic force formula of the winding, the winding motion differential equation is obtained;

[0010] Calculate the winding motion differential equation to obtain the coil displacement formula for the forced vibration of the winding caused by electromagnetic force. Based on the coil displacement formula, calculate the winding vibration acceleration formula.

[0011] Considering the different winding methods of transformer grid-side winding and valve-side winding, the current equivalent model of windings with different winding methods is established;

[0012] The monitored grid-side current is used as the excitation current to be fed into the grid-side winding, and the monitored valve-side current is used as the excitation current to be fed into the valve-side winding. Based on the current equivalent models of windings with different winding methods, the equivalent current flow diagram in the coil is obtained.

[0013] A finite element simulation model is established based on the equivalent model of winding current in different winding methods and the equivalent current flow diagram in the coil. The excitation current composed of harmonics and fundamental waves is used as input, and the electromagnetic force formula of the winding, the winding motion differential equation and the winding vibration acceleration formula are set as simulation conditions for simulation.

[0014] Preferably, calculating the magnetic induction intensity of the leakage magnetic field of the live winding of the transformer according to the harmonic current, and calculating the electromagnetic force on the winding according to the magnetic induction intensity of the leakage magnetic field, includes:

[0015] Assume that the current flowing through the winding of the converter transformer in the working state is , calculate the leakage magnetic field intensity of the transformer live winding according to the harmonic current: ;

[0016] in, is the winding current amplitude, is the initial phase, is the proportional coefficient of leakage flux density and winding current, is the harmonic order, , is the angular frequency;

[0017] Decompose the leakage magnetic field into axial and radial induction intensity and calculate the axial electromagnetic force and radial electromagnetic force respectively:

[0018]

[0019] in, is the axial electromagnetic force, is the radial electromagnetic force, is the magnetic induction intensity of the axial leakage magnetic field, is the radial leakage magnetic field intensity, is the radius of the winding coil;

[0020] The formula for calculating the electromagnetic force on the winding by combining the axial electromagnetic force and the radial electromagnetic force is:

[0021]

[0022] in, is the electromagnetic force on the winding, is the current amplitude.

[0023] Preferably, the coil displacement formula of the forced vibration of the winding caused by electromagnetic force is:

[0024]

[0025] in, is the winding coil mass matrix, is the damping matrix, is the elastic coefficient matrix, is the displacement of the coil, G is the displacement coefficient, is the phase angle;

[0026] The second-order derivative of the coil displacement formula is used to obtain the winding vibration acceleration formula:

[0027] .

[0028] Preferably, according to the winding vibration acceleration formula, the winding vibration acceleration frequency is twice the excitation current frequency, the winding vibration acceleration amplitude is proportional to the excitation current amplitude, and is proportional to the square of the harmonic order of the excitation current.

[0029] Preferably, the transformer winding includes a spiral winding and a tangled continuous winding, wherein the grid-side winding of the transformer is a tangled continuous winding and the valve-side winding is a spiral winding. The current equivalent model of windings with different winding modes is established, including:

[0030] The spiral winding wire is wound in a spiral shape, and each turn of the wire rises along the axial direction to form a multi-layer spiral structure;

[0031] The tangled continuous winding adopts a continuous winding method. The wire transitions continuously from one coil to the next to form an overall structure. On the basis of continuous winding, the wire is cross-tangled at specific positions to form a complex inter-turn connection.

[0032] The current flows in the same direction between adjacent coils of the spiral winding, while the current flows in the opposite direction between adjacent coils of the tangled continuous winding. Based on this, the current equivalent models of the spiral winding and the tangled continuous winding are established.

[0033] Preferably, the monitored grid-side current is brought into the grid-side winding as the excitation current, and the monitored valve-side current is brought into the valve-side winding as the excitation current. The equivalent current flow diagram in the coil is obtained according to the current equivalent model of the windings with different winding methods, including:

[0034] For the monitored grid-side current and valve-side current, Fourier transform is performed on the grid-side current and the valve-side current to extract the fundamental and harmonic components of the current signal, as well as the amplitudes corresponding to the fundamental and each harmonic. The cosine signal is set according to the frequency and corresponding amplitude of the current signal, and the current signal is equivalent to a plurality of cosine signals. The equivalent current signal is input as the excitation current into the current equivalent model of the spiral winding and the tangled continuous winding. The current flow direction of each coil of the spiral winding is set to clockwise, the current flow direction in the odd-order coil of the tangled continuous winding is clockwise, and the current flow direction in the even-order coil is counterclockwise, so as to obtain the equivalent current flow diagram in the corresponding coil.

[0035] Through the above technical solutions, it can be seen that compared with the prior art, the present invention discloses a method, device and medium for improving the simulation accuracy of transformers. In view of the influence of small-amplitude high-order harmonic currents and windings with different winding methods on transformers, by deducing the winding vibration mechanism under the action of harmonic currents, it can be seen that high-order harmonic electromagnetic forces are generated by high-order harmonic currents with small amplitudes, small-amplitude high-order harmonic electromagnetic forces can produce large vibrations, and small-amplitude high-order harmonic currents can cause large winding vibrations. Therefore, when simulating a transformer, attention should be paid to the influence of high-order harmonics on the transformer; at the same time, the winding of the transformer windings should be considered. There are many ways, and the winding methods of the grid-side and valve-side windings are usually different. The flow direction of the winding current in different coils with different winding methods is different, which makes the electric field distribution in the transformer box and the electric field force acting on the winding completely different. Therefore, by comparing the winding structures of spiral and tangled continuous windings, a current schematic diagram and an equivalent current flow diagram in the coils are established. The current flow direction of adjacent coils of the spiral winding is the same, and the current flow direction of adjacent coils of the tangled continuous winding is opposite. By establishing a finite element simulation model with the same winding method as the actual winding and using the measured current containing high-order harmonics as the excitation source, the simulation accuracy can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0037] Figure 1 This is a flow chart of a method for improving transformer simulation accuracy provided by the present invention.

[0038] Figure 2 The mass-spring-damper model provided by the present invention.

[0039] Figure 3 This is the grid-side current provided by the present invention.

[0040] Figure 4 This is the valve side current provided by the present invention.

[0041] Figure 5 This is a schematic diagram of the results of Fourier transformation of the grid-side current provided by the present invention.

[0042] Figure 6 This is a schematic diagram of the results of Fourier transformation of the valve-side current provided by the present invention.

[0043] Figure 7 The present invention provides a schematic diagram of the spiral winding current and a diagram of the equivalent current flow in the coil, wherein (a) is a schematic diagram of the spiral winding current, and (b) is a diagram of the equivalent current flow in the spiral winding coil.

[0044] Figure 8 The current schematic diagram of the tangled continuous winding and the equivalent current flow diagram in the coil provided by the present invention, wherein (a) is the current schematic diagram of the tangled continuous winding, and (b) is the equivalent current flow diagram in the coil of the tangled continuous winding.

[0045] Figure 9 This is a three-dimensional geometric model diagram of the converter transformer provided by the present invention.

[0046] Figure 10 This is a simulation flow chart provided by the present invention.

[0047] Figure 11 This is a time domain comparison diagram of the measurement signal and simulation signal provided by the present invention.

[0048] Figure 12 This is a frequency domain comparison diagram of the measured signal and the simulated signal provided by the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The embodiment of the present invention discloses a method for improving transformer simulation accuracy, such as Figure 1 Shown, including:

[0051] Derive the vibration mechanism of the winding under the action of harmonic current, calculate the leakage magnetic field intensity of the energized winding based on the harmonic current, and calculate the formula for the electromagnetic force acting on the winding based on the leakage magnetic field intensity;

[0052] According to the coil structure of the winding, it is equivalent to a mass-spring-damper model. According to the dynamics of the mechanical system and the electromagnetic force formula of the winding, the winding motion differential equation is obtained;

[0053] Calculate the winding motion differential equation to obtain the coil displacement formula for the forced vibration of the winding caused by electromagnetic force. Based on the coil displacement formula, calculate the winding vibration acceleration formula.

[0054] Considering the different winding methods of transformer grid-side winding and valve-side winding, the current equivalent model of windings with different winding methods is established;

[0055] The monitored grid-side current is used as the excitation current to be fed into the grid-side winding, and the monitored valve-side current is used as the excitation current to be fed into the valve-side winding. Based on the current equivalent models of windings with different winding methods, the equivalent current flow diagram in the coil is obtained.

[0056] A finite element simulation model is established based on the equivalent model of winding current in different winding methods and the equivalent current flow diagram in the coil. The excitation current composed of harmonics and fundamental waves is used as input, and the electromagnetic force formula, motion differential equation, and winding vibration acceleration formula of the winding are set as simulation conditions for simulation.

[0057] In this embodiment, the leakage magnetic field intensity of the transformer live winding is calculated based on the harmonic current, and the electromagnetic force on the winding is calculated based on the leakage magnetic field intensity. The formula includes:

[0058] Assume that the current flowing through the winding of the converter transformer in the working state is , calculate the leakage magnetic field intensity of the transformer live winding according to the harmonic current: ;

[0059] in, is the winding current amplitude, is the initial phase, is the proportional coefficient of leakage flux density and winding current, is the harmonic order, , is the angular frequency;

[0060] Decompose the leakage magnetic field into axial and radial directions and calculate the axial electromagnetic force (axial Lorentz force) and radial electromagnetic force (radial Lorentz force) respectively:

[0061]

[0062] in, is the axial electromagnetic force, is the radial electromagnetic force, is the magnetic induction intensity of the axial leakage magnetic field, is the radial leakage magnetic field intensity, is the radius of the winding coil;

[0063] The formula for calculating the electromagnetic force acting on the winding by combining the axial electromagnetic force and the radial electromagnetic force (the total Lorentz force acting on the winding) is:

[0064]

[0065] in, is the electromagnetic force on the winding, is the current amplitude.

[0066] In this embodiment, the winding can be equivalent to a mass-spring-damper model based on its coil structure. The motion differential equation of the winding is obtained based on the dynamics of the mechanical system, and the electromagnetic force acting on the winding is incorporated into the equation. The displacement formula of the forced vibration of the winding caused by the electromagnetic force is solved, and the second-order derivative of this formula is taken to obtain the winding vibration acceleration formula.

[0067] The formula for coil displacement due to forced vibration of the winding caused by electromagnetic force is:

[0068]

[0069] in, is the winding coil mass matrix, is the damping matrix, is the elastic coefficient matrix, is the displacement of the wire cake, is the phase angle;

[0070] The second-order derivative of the coil displacement formula is used to obtain the winding vibration acceleration formula:

[0071] .

[0072] From the formula of winding vibration acceleration caused by harmonic current, it can be seen that the vibration acceleration of the winding is related to both the amplitude of the current and the harmonic order of the current; more specifically, the frequency of the winding vibration acceleration is twice the frequency of the excitation current, the amplitude of the winding vibration acceleration is proportional to the amplitude of the excitation current, and is proportional to the square of the harmonic order of the excitation current.

[0073] In this embodiment, the transformer grid-side and valve-side windings have different winding methods. The transformer windings include spiral windings and tangled continuous windings. The transformer grid-side winding is a tangled continuous winding, and the valve-side winding is a spiral winding. Current equivalent models of windings with different winding methods are established to simulate the actual situation of current in different coils of windings with different winding methods, including:

[0074] The spiral winding wire is wound in a spiral shape, and each turn of the wire rises along the axial direction to form a multi-layer spiral structure;

[0075] The tangled continuous winding adopts a continuous winding method. The wire transitions continuously from one coil to the next to form an overall structure. On the basis of continuous winding, the wire is cross-tangled at specific positions to form a complex inter-turn connection.

[0076] The current flows in the same direction between adjacent coils of the spiral winding, while the current flows in the opposite direction between adjacent coils of the tangled continuous winding. Based on this, the current equivalent models of the spiral winding and the tangled continuous winding are established.

[0077] In this embodiment, the monitored grid-side current is brought into the grid-side winding as the excitation current, and the monitored valve-side current is brought into the valve-side winding as the excitation current. Based on the current equivalent models of windings with different winding methods, the equivalent current flow diagram in the coil is obtained, including:

[0078] For the monitored grid-side and valve-side current signals, the current signals are subjected to Fourier transform to extract the fundamental and harmonic components of the current signals, as well as the amplitudes corresponding to the fundamental and harmonics. The cosine signal is set according to the frequency and corresponding amplitude of the current signal, and the current signal is equivalent to a plurality of cosine signals. The equivalent current signal is input as the excitation current into the current equivalent model of the spiral winding and the tangled continuous winding. The current flow direction of each coil of the spiral winding is set to clockwise, the current flow direction in the odd-order coil of the tangled continuous winding is clockwise, and the current flow direction in the even-order coil is counterclockwise, so as to obtain the equivalent current flow diagram in the corresponding coil.

[0079] In this embodiment, a current composed of fundamental frequency and harmonics is used as the excitation source. At the same time, the influence of different winding methods is considered. A finite element simulation model with the same equivalent current flow diagram as the coil is established. This makes the transformer simulation process consistent with the actual model, thereby improving the transformer simulation accuracy.

[0080] The current composed of the fundamental frequency and harmonics is used as the excitation source. The mechanism of winding vibration acceleration under the action of current containing harmonics shows that the winding vibration acceleration is related to the order of the harmonics. Therefore, a small-amplitude high-order harmonic current can cause a large winding vibration. Therefore, the current composed of the fundamental frequency and harmonics as the excitation source can make the winding deformation more accurate.

[0081] Taking into account the influence of different winding methods, which will affect the electric field distribution inside the transformer and the electromagnetic force acting on the winding, a winding model that conforms to the actual winding method is established, so that the electric field distribution inside the transformer box and the electric field force acting on the winding are close to reality, thereby improving the transformer simulation accuracy.

[0082] The specific implementation process of the present invention is as follows:

[0083] Derive the winding vibration mechanism under the action of current containing harmonics. Assume that the current flowing through the winding in the working state of the converter transformer is , the power frequency is 50Hz, ,The magnetic induction intensity of the leakage magnetic field of the current is shown in formula (1).

[0084] (1)

[0085] In the formula is the winding current amplitude; is the initial phase; is the proportional coefficient of leakage flux density and winding current;

[0086] Will Axial and radial decomposition and , we can get the formula by calculating the Lorentz force:

[0087] (2)

[0088] Axial electromotive force and radial electromotive force The square sum of the two is the electromagnetic force on the converter transformer winding:

[0089] (3)

[0090] Since the pancake coil structure of the winding can be equivalent to a mass-spring-damper model, such as Figure 2 As shown, Figure 2 Represents a multi-layer cascade mass-spring-damper model, where m i , i=1,2,…,n: represents the i-th mass block, which is equivalent to the concentrated mass of a layer of coils in the pancake coil. k is the stiffness coefficient of each spring, which is equivalent to simulating the elastic support characteristics between the coil layers. The damper in the figure is equivalent to simulating the damping force applied to the coil during movement.

[0091] Substitute equation (2) into equation (3) and split the nonhomogeneous equation into equation (4) and equation (5):

[0092] (4)

[0093] (5)

[0094] Solving the differential equation (5) yields the displacement of the winding forced vibration caused by the electromagnetic force as shown in (6):

[0095] (6)

[0096] in, is the winding coil mass matrix, is the damping matrix, is the elastic coefficient matrix, is the displacement of the coil, G is the displacement coefficient, is the phase angle, g is the acceleration due to gravity;

[0097] The acceleration can be obtained by taking the second-order derivative of equation (6) as shown in equation (7):

[0098] (7)

[0099] It can be seen from formula (7) that the fundamental frequency of the converter transformer winding vibration acceleration is 100 Hz, accompanied by higher harmonics with a frequency multiple of 100 Hz, and the amplitude of the acceleration is proportional to the square of the winding current. At the same time, the amplitude of each harmonic component is related to the harmonic coefficient.

[0100] By installing Rogowski coils on the busbars between the grid-side conductor and the valve-side winding and the converter valve, the grid-side and valve-side operating currents of the converter transformer are measured. Figure 3 and Figure 4 shown.

[0101] Perform Fourier transform on the current signal and visualize the result as follows Figure 5 and Figure 6 The harmonic components in the grid-side and valve-side currents are basically the same, and the main components include fundamental wave, 5th harmonic, 7th harmonic, 11th harmonic, 13th harmonic, 23rd harmonic, 25th harmonic and other harmonics.

[0102] The 5th, 7th, 23rd and 25th harmonic currents of the converter transformer and the fundamental frequency component are combined into a current signal, and the current signal is normalized as shown in formula (8).

[0103] (8)

[0104] Substituting equation (8) into equation (1), the magnetic induction intensity of the leakage magnetic field caused by the current can be obtained as shown in equation (9):

[0105] (9)

[0106] Substituting Equation (9) into Equation (2), the Lorentz force on the winding is obtained as shown in Equation (10). .

[0107] (10)

[0108] From formula (7), we can see , from the calculation results of formula (10), it can be seen that the distribution of the electromagnetic force and vibration component of the winding under the action of harmonics is shown in Table 1.

[0109] Table 1 Distribution of electromagnetic force and vibration components of windings under harmonic action

[0110]

[0111] Combining Equation (10) and Table 1, it can be seen that high-order harmonic electromagnetic forces are generated by high-order harmonic currents with smaller amplitudes. High-order harmonic electromagnetic forces with smaller amplitudes can produce larger vibrations, while high-order harmonic currents with smaller amplitudes can cause larger winding vibrations. Therefore, when simulating a transformer, attention should be paid to the impact of high-order harmonics on the transformer.

[0112] The grid-side winding of the converter transformer under test is a tangled continuous type, and the valve-side winding is a spiral type. The spiral winding conductor is wound in a spiral shape, and each turn of the conductor rises along the axial direction to form a multi-layer spiral structure. The tangled continuous winding adopts a continuous winding method, and the conductor continuously transitions from one coil to the next coil to form an overall structure. On the basis of continuous winding, the conductor is cross-tangled at specific positions to form a complex inter-turn connection. Based on the structural differences, the current schematic diagram of the spiral winding and the tangled continuous winding and the equivalent current flow diagram in the coil are established, as shown in the figure. Figure 7 and Figure 8 , the currents of adjacent coils of spiral winding flow in the same direction, while the currents of adjacent coils of tangled continuous winding flow in opposite directions. is the radius of the winding coil, L is the total height of the coil winding, B -7 , B0, B5, etc. are winding numbers.

[0113] When establishing the finite element simulation model of the converter transformer, the winding method should be consistent with the actual winding method. In the simulation model, the current flow direction in the coil is set according to the equivalent current model of the winding with different winding methods. The three-dimensional geometric model of the converter transformer is as follows: Figure 9 shown.

[0114] Set the properties of materials including windings, cores, boxes, and insulation parts, including density, elastic modulus, Poisson's ratio, magnetic permeability, and loss characteristics. Then, add magnetic field physics to calculate the electromagnetic field distribution in the windings and cores, set the excitation conditions to the measured current signal, and set boundary conditions such as magnetic insulation and initial values. Add solid mechanics physics to calculate the force deformation of the windings and cores, and set boundary conditions such as fixed support and roller support. Add magnetostrictive effect and Lorentz force coupling to transfer the electromagnetic field calculation results to the structural mechanics field as an excitation source for deformation. Finally, mesh the model and divide the continuous geometric model into a finite number of discrete units such as triangles, quadrilaterals, tetrahedrons, etc. for numerical calculations. The simulation process is as follows: Figure 10 shown.

[0115] Depend on Figure 10 The vibration conditions of the converter transformer winding and core can be obtained, and the simulated vibration signal of the converter transformer and the measured vibration signal can be compared. Figure 11 and Figure 12 As shown in Figure 3, the frequency component change trends of the measured vibration signal and the simulated vibration signal are basically consistent, with only the difference in amplitude.

[0116] This embodiment provides a computer device including a memory and a processor. The memory stores a computer program that can be run on the processor. When the processor executes the computer program, a method for improving transformer simulation accuracy is implemented.

[0117] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, a method for improving transformer simulation accuracy is implemented.

[0118] Those skilled in the art will appreciate that all or part of the steps of the above-mentioned method embodiments may be implemented by hardware associated with program instructions, and the aforementioned program may be stored in a computer-readable storage medium. When the program is executed, the program executes the steps of the above-mentioned method embodiments. The aforementioned storage medium includes various media that can store program codes, such as mobile storage devices, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0119] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0120] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for improving transformer simulation accuracy, characterized in that: include: Calculate the leakage magnetic field intensity of the transformer live winding based on the harmonic current, and calculate the electromagnetic force formula on the winding based on the leakage magnetic field intensity; According to the coil structure of the winding, it is equivalent to a mass-spring-damper model. According to the dynamics of the mechanical system and the electromagnetic force formula of the winding, the winding motion differential equation is obtained; Calculate the winding motion differential equation to obtain the coil displacement formula for the forced vibration of the winding caused by electromagnetic force. Based on the coil displacement formula, calculate the winding vibration acceleration formula. Considering the different winding methods of transformer grid-side winding and valve-side winding, the current equivalent model corresponding to the windings with different winding methods is established; The monitored grid-side current is used as the excitation current to be fed into the grid-side winding, and the monitored valve-side current is used as the excitation current to be fed into the valve-side winding. Based on the current equivalent models of the windings with different winding methods, the corresponding equivalent current flow diagram in the coil is obtained; A finite element simulation model is established based on the equivalent model of winding current in different winding methods and the equivalent current flow diagram in the coil. The excitation current composed of harmonics and fundamental waves is used as input, and the electromagnetic force formula of the winding, the winding motion differential equation and the winding vibration acceleration formula are set as simulation conditions for simulation.

2. A method for improving transformer simulation accuracy according to claim 1, characterized in that: The formula for calculating the leakage magnetic field intensity of the transformer live winding based on the harmonic current and the electromagnetic force on the winding based on the leakage magnetic field intensity includes: Assume that the current flowing through the winding of the converter transformer in the working state is i=I k′ cos(k′ωt+θ0), calculate the leakage magnetic field intensity of the transformer live winding based on the harmonic current: B l =λI k′ cos(k′ωt+θ0),k′=6n±1; Among them, I k′ is the winding current amplitude, θ0 is the initial phase, λ is the proportional coefficient of leakage flux density to winding current, k′ is the harmonic order, n=0, 1, 2..., ω is the angular frequency; Decompose the leakage magnetic field into axial and radial induction intensity and calculate the axial electromagnetic force and radial electromagnetic force respectively: F x =2πRiB z ,F z =2πRiB x Among them, F x is the axial electromagnetic force, F z is the radial electromagnetic force, B x is the magnetic induction intensity of the axial leakage magnetic field, B z is the radial leakage magnetic field intensity, R is the radius of the winding coil; The formula for calculating the electromagnetic force on the winding by combining the axial electromagnetic force and the radial electromagnetic force is: Among them, F is the electromagnetic force on the winding, and I is the current amplitude.

3. A method for improving transformer simulation accuracy according to claim 2, characterized in that: The formula for coil displacement due to forced vibration of the winding caused by electromagnetic force is: x=Gcos(2k′ωt+2θ0+β) Where M is the winding coil mass matrix, C is the damping matrix, K is the elastic coefficient matrix, x is the coil displacement, G is the displacement coefficient, and β is the phase angle; The second-order derivative of the coil displacement formula is used to obtain the winding vibration acceleration formula: a=-4(k′) 2 oh 2 G cos(2k′ωt+2θ0+β).

4. A method for improving transformer simulation accuracy according to claim 3, characterized in that: According to the winding vibration acceleration formula, the winding vibration acceleration frequency is twice the excitation current frequency, the winding vibration acceleration amplitude is proportional to the excitation current amplitude, and is proportional to the square of the harmonic order of the excitation current.

5. The method for improving transformer simulation accuracy according to claim 1, characterized in that: The transformer winding includes spiral winding and tangled continuous winding. The grid-side winding of the transformer is tangled continuous winding, and the valve-side winding is spiral winding. The current equivalent models of windings with different winding methods are established, including: The spiral winding wire is wound in a spiral shape, and each turn of the wire rises along the axial direction to form a multi-layer spiral structure; The tangled continuous winding adopts a continuous winding method. The wire transitions continuously from one coil to the next to form an overall structure. On the basis of continuous winding, the wire is cross-tangled at specific positions to form a complex inter-turn connection. The current flows in the same direction between adjacent coils of the spiral winding, while the current flows in the opposite direction between adjacent coils of the tangled continuous winding. Based on this, the current equivalent models of the spiral winding and the tangled continuous winding are established.

6. The method for improving transformer simulation accuracy according to claim 5, characterized in that: The monitored grid-side current is used as the excitation current to be fed into the grid-side winding, and the monitored valve-side current is used as the excitation current to be fed into the valve-side winding. Based on the current equivalent models of windings with different winding methods, the equivalent current flow diagram in the coil is obtained, including: For the monitored grid-side current and valve-side current, Fourier transform is performed on the grid-side current and the valve-side current to extract the fundamental and harmonic components of the current signal, as well as the amplitudes corresponding to the fundamental and each harmonic. The cosine signal is set according to the frequency and corresponding amplitude of the current signal, and the current signal is equivalent to a plurality of cosine signals. The equivalent current signal is input as the excitation current into the current equivalent model of the spiral winding and the tangled continuous winding. The current flow direction of each coil of the spiral winding is set to clockwise, the current flow direction in the odd-order coil of the tangled continuous winding is clockwise, and the current flow direction in the even-order coil is counterclockwise, so as to obtain the equivalent current flow diagram in the corresponding coil.

7. A computer device, characterized in that: include: A memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor executes the computer program, the method according to any one of claims 1 to 6 is implemented.

8. A computer-readable storage medium, characterized in that The storage medium stores a computer program, which, when executed by a processor, implements the method according to any one of claims 1 to 6.

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