Method and system for drawing main flow line of oil flow in transformer

Abstract

The invention discloses a method and a system for drawing a main flow line of oil flow in a transformer. The method comprises the following steps of: establishing a finite element analysis model aiming at a target transformer, and performing grid division on the finite element analysis model; calculating a fluid velocity field and a temperature field according to the finite element analysis model after grid division; drawing a first streamline according to the fluid velocity field and the temperature field in combination with a preset streamline drawing logic; and according to the first streamline drawing result, selecting a main oil flow line in the transformer in combination with a main flow line extraction rule. The drawing process of the oil flow lines in the transformer is specifically displayed, and the complex oil flow lines in the transformer are divided into three types of main flow lines, so that the heat flow diffusion rule in the transformer is analyzed based on flow line distribution. By selecting the external temperature measuring points near the streamline points on the optimal main streamline, the characteristic temperature measuring points having a strong association relationship with the winding hot-spot temperature can be selected, and support is provided for selection of the shell characteristic temperature measuring points in the transformer hot-spot temperature monitoring process.

Description

Technical Field

[0001] The invention relates to the technical field of drawing the main flow line of oil flow inside a transformer, and in particular to a method and system for drawing the main flow line of oil flow inside a transformer. Background Art

[0002] As one of the most important equipment in the power system, transformers are numerous and complex in structure. Their health is directly related to the reliability and safety of power supply. In order to ensure the safety and efficiency of transformer equipment in operation and avoid failures during operation, online detection of transformer hot spots is essential. In order to implement real-time monitoring of operating transformers, predict online operating hot spot temperatures based on historical transformer operating data, and adjust dynamic loads in time according to working conditions, the use of artificial intelligence algorithms to invert hot spot temperatures has become a hot topic in today's research.

[0003] However, when using artificial intelligence algorithms to invert hot spot temperatures, the temperature of the transformer's characteristic temperature measurement points needs to be known. By drawing the internal streamlines of the transformer and using the theoretical methods of graphics to express the information implied in the huge data set in the vector field with graphic symbols and colors, we can gain a deeper understanding of the flow trajectory of the transformer oil and thus grasp the law of heat flow diffusion inside the transformer. Based on the law of heat flow diffusion, streamline points that can characterize the trend of the streamline temperature change curve are selected, and then 1 to 3 points closest to the streamline points are selected on the transformer casing and heat sink as characteristic temperature measurement points.

[0004] Therefore, it is necessary to study an efficient and accurate streamline drawing method to ensure accurate selection of characteristic temperature measurement points. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a method and system for drawing the main flow lines of oil flow inside a transformer, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a method for drawing the main flow line of oil flow inside a transformer, comprising:

[0010] Establishing a finite element analysis model for a target transformer, and performing meshing on the finite element analysis model;

[0011] Calculate the fluid velocity field and temperature field based on the meshed finite element analysis model;

[0012] According to the fluid velocity field and temperature field, combined with a preset streamline drawing logic, a first streamline drawing is performed;

[0013] According to the first streamline drawing result and the main stream line extraction rule, the main stream line of the oil flow inside the transformer is selected.

[0014] As a preferred solution of the method for drawing the main flow lines of the oil flow inside the transformer according to the present invention, wherein: the first streamline drawing is performed according to the fluid velocity field and temperature field in combination with the preset streamline drawing logic, including:

[0015] The streamline drawing logic includes streamline drawing constraints, streamline control equations and streamline drawing termination conditions;

[0016] The first streamline drawing is performed according to the streamline drawing constraint conditions, the streamline control equations and the streamline drawing termination conditions.

[0017] As a preferred solution of the method for drawing the main flow lines of oil flow inside a transformer described in the present invention, the streamline drawing constraint conditions include at least a number of constraints for fluid particles.

[0018] As a preferred solution of the method for drawing the main flow lines of oil flow inside the transformer according to the present invention, the termination conditions of the flow line drawing include:

[0019] The number of integration steps during streamline drawing reaches the maximum number of integration steps preset by the user;

[0020] During the streamline drawing process, the streamline integral reaches the flow field boundary;

[0021] The velocity vector of the integration point during streamline drawing is 0;

[0022] During the streamline drawing process, the distance between the newly generated streamline point and the generated streamline is less than the first distance threshold.

[0023] As a preferred solution of the method for drawing the main flow lines of oil flow inside the transformer described in the present invention, the main flow line extraction rules include: selecting the main flow line at least from the streamlines flowing through the oil temperature measuring points on the top layer of the transformer, or the streamlines flowing through the middle winding of the transformer, or the streamlines flowing through the side phase windings of the transformer.

[0024] As a preferred solution of the method for drawing the main flow lines of the oil flow inside the transformer described in the present invention, the flow line drawing constraints include:

[0025] The velocity direction of each fluid particle on the drawn streamline is tangent to the streamline;

[0026] The drawn streamlines cannot intersect or be broken lines, they can only be straight lines or smooth curves;

[0027] When the flow state reaches stability, the streamlines and traces coincide;

[0028] The density of the drawn streamlines reflects the flow velocity.

[0029] As a preferred solution of the method for drawing the main flow lines of oil flow inside the transformer described in the present invention, the calculation of the fluid velocity field and the temperature field according to the finite element analysis model after meshing includes:

[0030] Solve the temperature fluid field control equations based on the finite volume method;

[0031] The calculation results of fluid velocity field and temperature field are obtained according to the solved temperature fluid field control equation;

[0032] The temperature data and velocity data of each grid node or unit center of the transformer under the rated load ambient temperature of 25°C and no wind conditions are obtained for subsequent streamline drawing.

[0033] In a second aspect, the present invention provides a system for drawing the main flow lines of oil flow inside a transformer, comprising:

[0034] A model building module, used to build a finite element analysis model for a target transformer and perform meshing on the finite element analysis model;

[0035] A data calculation module is used to calculate the fluid velocity field and temperature field according to the finite element analysis model after meshing;

[0036] A first streamline drawing module, used for performing first streamline drawing according to the fluid velocity field and temperature field in combination with a preset streamline drawing logic;

[0037] The second streamline drawing module is used to select the main stream line of the oil flow inside the transformer according to the first streamline drawing result and the main stream line extraction rule.

[0038] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0039] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0040] Compared with the prior art, the present invention has the following beneficial effects: the present invention proposes a method and system for drawing the main flow lines of oil flow inside a transformer, establishes a finite element analysis model for a target transformer, and meshes the finite element analysis model; calculates the fluid velocity field and temperature field according to the meshed finite element analysis model; performs first streamline drawing according to the fluid velocity field and temperature field in combination with a preset streamline drawing logic; selects the main flow lines of oil flow inside the transformer according to the first streamline drawing result in combination with the main flow line extraction rule. The drawing process of the oil flow streamline inside the transformer is specifically demonstrated, and the complex oil flow streamlines inside the transformer are divided into three types of main flow lines, which is convenient for analyzing the heat flow diffusion law inside the transformer based on the streamline distribution. By selecting external temperature measurement points near the streamline points on the best main flow line, characteristic temperature measurement points with a strong correlation with the hot spot temperature of the winding can be selected, providing support for the selection of characteristic temperature measurement points of the outer shell during the hot spot temperature monitoring of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0042] Figure 1 A method flow chart of a method and system for drawing the main flow line of oil flow inside a transformer provided by an embodiment of the present invention;

[0043] Figure 2 A transformer internal grid segmentation diagram of a transformer internal oil flow main flow line drawing method and system provided by an embodiment of the present invention;

[0044] Figure 3 A transformer housing mesh subdivision diagram of a transformer internal oil flow main flow line drawing method and system provided by an embodiment of the present invention;

[0045] Figure 4 A schematic diagram of a method and system for drawing the main flow lines of oil flow inside a transformer provided by an embodiment of the present invention;

[0046] Figure 5 A three-dimensional flow field streamline distribution diagram of a transformer internal oil flow main flow line drawing method and system provided by an embodiment of the present invention;

[0047] Figure 6 A trilinear interpolation diagram of a method and system for drawing the main oil flow lines inside a transformer provided by an embodiment of the present invention;

[0048] Figure 7A method for drawing the main flow lines of oil flow inside a transformer and a flow line generation process diagram of the system provided by an embodiment of the present invention;

[0049] Figure 8 A transformer internal oil flow main flow line drawing method and system provided by an embodiment of the present invention is a transformer internal oil flow main flow line drawing method and system;

[0050] Fig. 9 A typical streamline diagram of a transformer internal oil flow main flow line drawing method and system passing through the top oil temperature measurement point position provided by an embodiment of the present invention;

[0051] Fig.10 A distribution diagram of oil flow streamlines near a transformer middle winding provided by a transformer internal oil flow mainstream line drawing method and system according to an embodiment of the present invention;

[0052] Fig.11 A distribution diagram of oil flow streamlines near a transformer side phase winding, provided by a method and system for drawing the main flow streamlines of oil flow inside a transformer according to an embodiment of the present invention;

[0053] Fig.12 A transformer winding middle streamline temperature distribution diagram of a transformer internal oil flow main flow line drawing method and system provided by an embodiment of the present invention;

[0054] Fig.13 An internal structural diagram of a computer device of a method and system for drawing the main flow lines of oil flow inside a transformer provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0056] Example 1

[0057] Reference Figure 1-Figure 13 , which is the first embodiment of the present invention, and provides a method and system for drawing the main flow lines of oil flow inside a transformer.

[0058] There are some problems in the existing related technologies. For example, the complexity of the oil flow streamlines inside the transformer makes it difficult to accurately draw them, and it is difficult to select characteristic temperature measurement points that have a strong correlation with the hot spot temperature of the winding when monitoring the hot spot temperature of the transformer.

[0059] The present application provides a method that can effectively solve the above-mentioned problems. Next, a method for drawing the main flow line of the oil flow inside the transformer will be described in detail in combination with multiple embodiments.

[0060] Figure 1 A method flow chart of a method and system for drawing the main flow line of oil flow inside a transformer is shown, including:

[0061] S101, establishing a finite element analysis model for a target transformer, and performing meshing on the finite element analysis model;

[0062] In an optional embodiment, the establishment of a finite element analysis model for the target transformer can be achieved by using different means in combination with different requirements. For example, finite element analysis software can be used to construct a three-dimensional model of the transformer and perform meshing. The density and quality of the meshing directly affect the accuracy and efficiency of subsequent calculations, so it is necessary to reasonably select the mesh size and type according to the specific structure and analysis requirements of the transformer.

[0063] In an optional embodiment, in addition to using finite element analysis software, other methods can be used to establish the model. For example, the physical size and material properties of the transformer can be used to establish the model through manual calculation or using other auxiliary tools. After meshing, the model needs to be appropriately simplified to ensure the feasibility and efficiency of the calculation.

[0064] In the embodiment of the present application, in order to ensure the accuracy of drawing the main oil flow line inside the transformer, a finite element analysis model for the target transformer is established using finite element analysis software. The present application establishes a three-dimensional transformer model coupled with multiple physical fields, and the three-dimensional transformer model includes an iron core, windings, structural parts, oil channels and a radiator. When the transformer grid is segmented, in order to obtain a good-quality segmented grid, the present application uses scanning mapping segmentation for regular structures such as transformer windings, insulation, and oil channels, and free segmentation for irregular structures such as transformer housing, transformer oil, and internal structural parts of the transformer.

[0065] In an optional embodiment, the mesh division can be performed according to actual needs. For example, in the mesh division of the three-dimensional model of the transformer, tetrahedron units can be used for division to adapt to the complex geometric shapes and structures inside the transformer. Tetrahedron units have good adaptability and flexibility and can effectively capture the streamline features inside the transformer. During the division process, special attention should be paid to the mesh refinement of key parts such as windings and oil channels to ensure the accuracy of streamline analysis.

[0066] In an optional embodiment, the meshing can also be performed using hexahedral units, especially in the oil passages and winding areas of the transformer, to improve the accuracy of the streamline analysis. Hexahedral units have a high meshing efficiency in regular areas and can provide more accurate simulation results when dealing with fluid dynamics problems. When performing meshing, the temperature distribution and heat conduction characteristics inside the transformer must also be considered to ensure that the model can truly reflect the thermal state of the transformer during operation.

[0067] In an optional embodiment, the meshing can also be performed using a custom meshing standard to meet specific analysis requirements. For example, local mesh refinement can be performed for the hot spot area of ​​the transformer to improve the accuracy of the streamline analysis in the area. In addition, the meshing strategy can be adjusted according to the operating conditions and environmental factors of the transformer to simulate the oil flow under actual working conditions.

[0068] It should be noted that the schematic diagram after meshing can be shown as follows: Figure 2 , 3 As shown, Figure 2 is the internal grid division structure of the transformer, Figure 2 (a) is a schematic diagram of the overall mesh division of the internal structure. Figure 2 (b) is the mapping decomposition of the winding part, Figure 3 The grid division structure of the transformer housing can be divided into three parts by the same or different grid division methods, which is not limited here.

[0069] In the embodiment of the present application, the solution of the convective heat transfer process of transformer oil follows three basic laws of physics, including the law of conservation of mass, the law of conservation of momentum, and the law of conservation of energy. The specific description of the three in the Cartesian coordinate system is as follows:

[0070] (1) Mass conservation equation. The mass conservation equation of the fluid flow in the transformer in differential form is expressed as:

[0071]

[0072] Among them, u x ,u y ,u z -X, Y, Z direction velocity components, m / s; t-time, s; ρ-density, kg / m 3 .

[0073] (2) Momentum conservation equation. The momentum equations in the X, Y, and Z directions inside the transformer are:

[0074]

[0075] Where: p-fluid pressure, Pa; τ xx , τyy , τ zz - represents the normal stress in the X, Y, and Z directions, τ xy , τ xz , τ yx , τ yz , τ zx , τ zy Indicates the shear stress in each direction, Pa; f x , f y , f z -Force per unit mass.

[0076] (3) Energy conservation equation. The energy conservation law inside the transformer can be expressed as:

[0077]

[0078] Where: c-transformer oil specific heat capacity; T-temperature, K; k-thermal conductivity, W / (m 2 ·K); Q-heat increment, J; -Harmony operator.

[0079] It should be noted that establishing a finite element analysis model for the target transformer can provide a basis for calculating the fluid velocity field and temperature field. In this embodiment, the flow of the oil flow inside the transformer can be simulated by the finite element analysis model, so as to obtain the distribution of the oil flow velocity field and temperature field. Specifically, it is first necessary to solve the fluid dynamics equations inside the transformer, which include the continuity equation, the momentum equation and the energy equation. The continuity equation ensures the conservation of fluid mass, the momentum equation describes the motion state of the fluid, and the energy equation reflects the transfer and conversion of energy inside the fluid. By solving these equations, the velocity distribution and temperature distribution of the oil flow inside the transformer can be obtained.

[0080] S102, calculating the fluid velocity field and temperature field according to the finite element analysis model after meshing;

[0081] In the embodiment of the present application, calculating the fluid velocity field and temperature field according to the finite element analysis model after meshing includes:

[0082] Solve the temperature fluid field control equations based on the finite volume method;

[0083] The calculation results of fluid velocity field and temperature field are obtained according to the solved temperature fluid field control equation;

[0084] The temperature data and velocity data of each grid node or unit center of the transformer under the rated load ambient temperature of 25°C and no wind conditions are obtained for subsequent streamline drawing.

[0085] In an optional embodiment, computational fluid dynamics (CFD) software can be used to perform numerical simulation during the solution process. These software can handle complex fluid flow and heat transfer problems and provide detailed flow field and temperature field information. During the simulation, it is necessary to set appropriate boundary conditions and initial conditions, such as the physical properties of the oil, the operating conditions of the transformer, etc., to ensure the accuracy of the simulation results.

[0086] In an embodiment of the present application, the finite volume method discretizes the field to be solved into a finite number of non-overlapping control volumes, and integrates and discretizes the differential control equation for each control volume, thereby deriving a set of linear equations based on the field node variables and calculating and solving them.

[0087] In an embodiment of the present application, the finite volume method is used to discretely solve the above control equations, and the temperature data and velocity data of each grid node or unit center of the transformer under the rated load ambient temperature of 25°C and no wind conditions are obtained for subsequent streamline drawing.

[0088] It should be noted that calculating the fluid velocity field and temperature field based on the meshed finite element analysis model can more accurately simulate the thermodynamic behavior inside the transformer. In this way, the flow pattern of the oil flow inside the transformer and how the temperature distribution changes with time and the operating state of the transformer can be analyzed in detail. In addition, through the accurate calculation of the fluid velocity field and temperature field, the performance of the transformer under different working conditions can be predicted and evaluated, thus providing a scientific basis for the design and optimization of the transformer. In practical applications, this analysis method helps to improve the operating efficiency and reliability of the transformer, reduce the failure rate, and extend the service life of the equipment.

[0089] S103, performing first streamline drawing according to the fluid velocity field and temperature field in combination with a preset streamline drawing logic;

[0090] In the embodiment of the present application, according to the fluid velocity field and the temperature field, combined with the preset streamline drawing logic, performing the first streamline drawing includes:

[0091] Streamline drawing logic includes streamline drawing constraints, streamline control equations, and streamline drawing termination conditions;

[0092] The first streamline drawing is performed according to the streamline drawing constraint conditions, the streamline control equations and the streamline drawing termination conditions.

[0093] In an optional embodiment, the streamline drawing constraints may include parameters such as the magnitude, direction, and temperature gradient of the fluid velocity, which will determine the generation and distribution of the streamlines. The streamline control equations are used to guide the generation path of the streamlines to ensure that the streamlines can accurately reflect the motion state of the fluid. The streamline drawing termination conditions are used to determine the end point of the streamline drawing, which may be when the fluid velocity drops below a certain threshold, or when the streamline reaches a specific structural boundary inside the transformer. Through the comprehensive application of these constraints and control equations, the precise drawing of the main oil flow lines inside the transformer can be achieved, thereby providing a powerful tool for transformer design and fault diagnosis.

[0094] In the embodiment of the present application, since the drawing of streamlines needs to be considered, the constraints on the fluid particles in the streamlines are the most important. Therefore, the streamline drawing constraint conditions include at least several constraints on the fluid particles.

[0095] In the embodiment of the present application, the streamline drawing constraints include:

[0096] The velocity direction of each fluid particle on the drawn streamline is tangent to the streamline;

[0097] The drawn streamlines cannot intersect or be broken lines, they can only be straight lines or smooth curves;

[0098] When the flow state reaches stability, the streamlines and traces coincide;

[0099] The density of the drawn streamlines reflects the flow velocity.

[0100] It should be noted that the velocity direction of each fluid particle on the drawn streamline is tangent to the streamline and cannot intersect the drawn streamline, nor can it be a broken line. It can only be a straight line or a smooth curve. These are all constraints on the fluid particles, because the fluid particles can only have one velocity direction at the same moment, so the streamline can only be a straight line or a smooth curve.

[0101] In an optional embodiment, the streamline drawing constraint condition may also include that the length of the streamline is proportional to the fluid velocity to ensure that the distribution of the streamline can reflect the characteristics of the velocity field; the density of the streamline is inversely proportional to the magnitude of the fluid velocity, so that the streamline is sparse in the area with higher velocity and dense in the area with lower velocity, thereby intuitively showing the change of the velocity field; the drawing of the streamline should be avoided in the area where the fluid velocity is extremely low or zero to avoid misleading the analysis results. Through these detailed constraints, it can be ensured that the streamline drawing results are both scientific and practical, providing strong support for the analysis and optimization of the oil flow inside the transformer. In practical applications, the setting and application of these streamline drawing constraints will directly affect the accuracy of streamline drawing and the effectiveness of transformer performance analysis. This application only considers the specific constraints mentioned above, and considering more will not have any other beneficial effects, but relevant technical personnel can add corresponding constraints according to actual needs, but the constraints for the purpose of realizing the main flow line of the oil flow inside the transformer should be within the scope of protection of this application.

[0102] In an optional embodiment, the streamline control equation can be designed in different ways. For example, based on the principle of fluid dynamics, the streamline control equation can adopt the Euler equation or the Lagrange equation to adapt to different fluid characteristics and research purposes. For example, the Euler equation is suitable for describing the movement of fluid in a fixed space, while the Lagrange equation focuses on the movement trajectory of fluid particles over time. In practical applications, choosing the right equation is crucial to ensure the accuracy and practicality of streamline drawing.

[0103] In the embodiments of the present application, there are two main ways to describe the trajectory of particle motion in the fluid field: trace and streamline. Trajectory refers to the trajectory of motion formed by the same fluid particle at different times in the fluid field. Streamline is a curve formed by different fluid particles at the same time, which indicates the velocity direction of the particle in the flow field at that time, such as Figure 4 shown.

[0104] In the embodiment of the present application, a three-dimensional flow field is given, and at any time t, any spatial coordinate point (x, y, z), u x ,u y ,u z are the projections of the velocity vector v on the x, y, and z coordinate axes respectively. The velocity vector v at any point on the streamline is tangent to the streamline, and the streamline equation satisfies the condition v×dl=O. In the rectangular coordinate system, Figure 5 As shown, the streamlines satisfy the differential equation:

[0105]

[0106] In the formula, except for the stagnation point where the velocity is v = 0 (the end point of the fluid velocity) and the singular point where v = ∞ (such as the source flow and the confluence), there can only be one streamline at any point, that is, there is only one flow velocity direction.

[0107] In an optional embodiment, the streamline can be expressed as the intersection of two flow surfaces f(x, y, z, t) and g(x, y, z, t), and the velocity of the streamline point on the streamline can be expressed as:

[0108]

[0109] That is:

[0110]

[0111] In an optional embodiment, the streamline is a path line in the velocity vector field along the tangent direction of the velocity field, and the streamline can be described by a first-order differential equation, as shown in the following formula:

[0112]

[0113] In the formula, X(t) is the motion position of the streamline particle at time t, v(X(t)) is the tangent direction of point X(t) on the streamline, and t is time. The solution formula for the flow field is as follows:

[0114]

[0115] In an optional embodiment, before solving the streamline calculation, the velocity vector of each point needs to be obtained. During the streamline generation process, the points on the streamline are generally not on the grid, and the velocity vector value on the grid point cannot be used directly. Therefore, it is necessary to interpolate the velocity vector of the discrete grid points to obtain the velocity of the current integral point. This article adopts the trilinear interpolation algorithm. Trilinear interpolation is an interpolation method used in three-dimensional space to estimate the unknown point value in three-dimensional grid data. Trilinear interpolation obtains the approximate value of any point in space by performing step-by-step linear interpolation in three dimensions. Figure 6 As shown. The trilinear interpolation method is as follows:

[0116] a=c000*(1-tx)+c100*tx

[0117] b=c010*(1-tx)+c110*tx

[0118] c=c001*(1-tx)+c101*tx

[0119] d=c011*(1-tx)+c111*tx

[0120] P=(1-ty)(a*(1-tz)+c*tz)+ty*(b*(1-tz)+d*tz)

[0121] Among them, c, x, y, z: represent the value of a specific point in the three-dimensional grid, where x, y, z represent the coordinates of the point in three dimensions respectively. tx, ty, tz: These are normalized coordinates, indicating the relative position of the target point relative to the cell in each dimension. Their value range is usually between [0, 1]. a, b, c, d: These are intermediate values ​​calculated by linear interpolation, corresponding to the results of interpolation in the x direction respectively. P: The final interpolation result, representing the value at the target point P. It is obtained by interpolating a and c in the y direction, combined with the results of interpolating b and d in the z direction.

[0122] In the embodiment of the present application, the data in the flow field data set is discrete and the streamlines cannot be calculated directly by integration, so the numerical integration method is used to generate the streamlines.

[0123] In the embodiment of the present application, the fourth-order Runge-Kutta method is used to calculate the movement of particles from one position to the next position. The calculation formula of the fourth-order Runge-Kutta method is:

[0124]

[0125] F1=V(X n )

[0126]

[0127]

[0128] F4=V(X n +Δt×F3)

[0129] Where V(Xn) represents the n The velocity function at the position, F1, F2, F3, F4 represent the intermediate values, which are obtained by the above formula, X n+1 represents the position of the n+1th time step, X n represents the position of the nth time step, and Δt represents the time step.

[0130] In the embodiment of the present application, the streamline generation process: First, streamline generation needs to read the velocity field data in step 1 and pre-process the input velocity field data to ensure the continuity and stability of the data. Arrange the seed points for streamline generation, and solve the integration step and select the integration method at the same time. Finally, check whether the termination condition of streamline generation is met. If the condition is not met, return to recalculate the next step of streamlines; if the condition is met, end the streamline generation process. The specific process is as follows Figure 7 shown.

[0131] In an optional embodiment, during the streamline generation process, each time the next position of the streamline is solved by numerical integration, it is necessary to determine whether the streamline continues to be generated.

[0132] In an optional embodiment, the setting of the streamline drawing termination condition also needs to consider the actual engineering requirements and physical meaning. For example, the streamline drawing termination condition can be that the fluid velocity drops below a certain threshold, or the streamline reaches a specific structural boundary inside the transformer. Such termination conditions help ensure that the streamline drawing results can truly reflect the main flow line of the oil flow inside the transformer, providing an intuitive reference for transformer maintenance and fault analysis.

[0133] In the embodiment of the present application, the streamline drawing termination conditions include:

[0134] The number of integration steps during streamline drawing reaches the maximum number of integration steps preset by the user;

[0135] During the streamline drawing process, the streamline integral reaches the flow field boundary;

[0136] The velocity vector of the integration point during streamline drawing is 0;

[0137] During the process of drawing streamlines, the distance between the newly generated streamline point and the generated streamline is less than the first distance threshold. Thus, the overall oil flow streamline distribution inside the transformer can be drawn. Figure 8 .

[0138] In an optional embodiment, the first distance threshold can be set to the minimum distance between streamline points to ensure the continuity and clarity of the streamlines. For example, when the distance between the newly generated streamline point and the existing streamline point is less than 0.1 mm, it can be considered that the streamline is dense enough and there is no need to continue to generate new streamline points. Such a setting helps to improve the efficiency of streamline drawing while ensuring the accuracy and readability of the streamline diagram. Finally, through the above method and steps, a detailed streamline distribution diagram of the oil flow inside the transformer can be obtained, providing a scientific basis for the design optimization and fault diagnosis of the transformer.

[0139] It should be noted that, according to the fluid velocity field and temperature field, combined with the preset streamline drawing logic, the first streamline drawing is performed, and a detailed streamline distribution diagram of the oil flow inside the transformer can be obtained, which provides a scientific basis for the design optimization and fault diagnosis of the transformer. It should be noted that, according to the fluid velocity field and temperature field, combined with the preset streamline drawing logic, the first streamline drawing is performed. In the drawing process, the temperature distribution inside the transformer can be considered, because the change of the temperature field will affect the viscosity of the oil, and then affect the speed and direction of the oil flow. By comprehensively considering the velocity field and the temperature field, the actual situation of the oil flow inside the transformer can be more accurately simulated, thereby improving the accuracy and practicality of streamline drawing. In addition, according to the different stages of transformer operation, such as startup, normal operation and fault state, streamline drawing can be performed separately, so as to more comprehensively analyze the dynamic changes of the oil flow inside the transformer. Through these methods, a more accurate and comprehensive streamline distribution diagram can be provided for the maintenance and fault analysis of the transformer, thereby improving the operating efficiency and safety of the transformer.

[0140] S104, selecting the main flow line of the oil flow inside the transformer according to the first streamline drawing result and in combination with the main flow line extraction rule.

[0141] In an embodiment of the present application, the main flow line extraction rule includes: selecting the main flow line at least from the streamlines flowing through the top oil temperature measurement point of the transformer, or the streamlines flowing through the middle winding of the transformer, or the streamlines flowing through the side phase winding of the transformer.

[0142] In an optional embodiment, based on the first streamline drawing result and combined with the mainstream line extraction rules, typical oil flow streamlines flowing through the winding hot spot area and the heat sink area inside the transformer are further extracted, that is, mainstream lines are selected from at least the streamlines flowing through the oil temperature measurement point on the top layer of the transformer, or the streamlines flowing through the middle winding of the transformer, or the streamlines flowing through the side phase winding of the transformer.

[0143] In the embodiment of the present application, a top layer oil temperature measuring hole is reserved during the production of the transformer. The top layer oil temperature measuring position is located at the corner position of the top of the oil tank from the outside, and is located inside the upper end of the transformer side phase winding, and is also the middle part of the heat sink at the wide side end and the heat sink at the narrow side end of the transformer. The top layer oil temperature measuring position is clear, and it is one of the few innermost layers of the transformer that can be directly obtained from the outside. Combined with the extracted streamlines flowing through the top layer oil temperature measuring position, as shown in FIG. Fig. 9 As shown, it can be seen that the oil temperature measurement point on the top layer of the transformer is the location where multiple typical heat dissipation oil flow streamlines flow.

[0144] For the middle winding, the typical streamline clusters extracted are as follows: Fig.10 As shown, the transformer oil flows from the bottom of the middle winding along the outer wall of the winding to the upper end of the winding, diffuses to the sides at the top of the oil tank, and finally flows to the bottom of the oil tank through the wide side heat sink of the transformer to form a reflux.

[0145] For the side phase winding, the transformer oil flows from the bottom end of the winding to the top end of the winding under the heating of the winding, flows to the top of the oil tank, and then flows to the bottom of the oil tank through the heat sink at the end of the oil tank to form a reflux. Fig.11 shown.

[0146] Extract the temperature distribution along the streamline path of the streamline flowing through the edge of the heat sink, such as Fig.12 As shown, it can be seen that the oil flow is heated when flowing through the winding, and then cooled when flowing through the top of the box and the heat sink, forming a reflux at the bottom of the winding and being reheated, thus forming an oil flow heat dissipation cycle inside the transformer.

[0147] In summary, by analyzing the temperature distribution on the streamline path, we can further understand the heat dissipation efficiency and hot spots of the oil flow inside the transformer. For example, by comparing the temperature changes on different streamlines, we can identify which areas have poor oil flow heat dissipation effects, thereby providing a basis for the structural optimization of the transformer. In addition, by monitoring the changes in oil flow temperature during the operation of the transformer, potential overheating problems can be discovered in time to prevent failures. In practical applications, the streamline drawing results can also be verified and calibrated in combination with the transformer's operating data and historical fault records to ensure the accuracy and reliability of the streamline distribution map. Ultimately, through these comprehensive analysis methods, scientific decision-making support can be provided for transformer maintenance and fault prevention, ensuring the long-term stable operation of the transformer.

[0148] This embodiment also provides a system for drawing the main flow line of oil flow inside a transformer, including:

[0149] A model building module is used to build a finite element analysis model for a target transformer and to perform meshing on the finite element analysis model;

[0150] A data calculation module is used to calculate the fluid velocity field and temperature field according to the finite element analysis model after meshing;

[0151] A first streamline drawing module, used for drawing a first streamline according to the fluid velocity field and temperature field in combination with a preset streamline drawing logic;

[0152] The second streamline drawing module is used to select the main stream line of the oil flow inside the transformer according to the first streamline drawing result and the main stream line extraction rule.

[0153] The above-mentioned unit modules may be embedded in or independent of the processor in the computer device in the form of hardware, or may be stored in the memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0154] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Fig.13As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for drawing the main flow line of the oil flow inside the transformer is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device shell, or an external keyboard, touchpad or mouse.

[0155] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0156] Establish a finite element analysis model for the target transformer and perform meshing on the finite element analysis model;

[0157] Calculate the fluid velocity field and temperature field based on the finite element analysis model after meshing;

[0158] According to the fluid velocity field and temperature field, combined with the preset streamline drawing logic, the first streamline drawing is performed;

[0159] According to the first streamline drawing result and the main stream line extraction rule, the main stream line of the oil flow inside the transformer is selected.

[0160] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0161] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0162] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0163] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0164] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0165] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0166] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for drawing the main flow line of oil flow inside a transformer, characterized in that: include: Establishing a finite element analysis model for a target transformer, and performing meshing on the finite element analysis model; Calculate the fluid velocity field and temperature field based on the finite element analysis model after meshing; According to the fluid velocity field and temperature field, combined with a preset streamline drawing logic, a first streamline drawing is performed; According to the first streamline drawing result and the main stream line extraction rule, the main stream line of the oil flow inside the transformer is selected.

2. The method for drawing the main flow line of oil flow inside a transformer according to claim 1, characterized in that: The first streamline drawing according to the fluid velocity field and temperature field and in combination with a preset streamline drawing logic comprises: The streamline drawing logic includes streamline drawing constraints, streamline control equations and streamline drawing termination conditions; The first streamline drawing is performed according to the streamline drawing constraint conditions, the streamline control equations and the streamline drawing termination conditions.

3. The method for drawing the main flow line of oil flow inside a transformer according to claim 2, characterized in that: The streamline drawing constraint conditions include at least several constraints for fluid particles.

4. The method for drawing the main flow line of oil flow inside a transformer according to claim 3, characterized in that: The streamline drawing termination conditions include: The number of integration steps during streamline drawing reaches the maximum number of integration steps preset by the user; During the streamline drawing process, the streamline integral reaches the flow field boundary; The velocity vector of the integration point during streamline drawing is 0; During the streamline drawing process, the distance between the newly generated streamline point and the generated streamline is less than the first distance threshold.

5. The method for drawing the main flow line of oil flow inside a transformer according to claim 4, characterized in that: The main flow line extraction rule includes: selecting the main flow line at least from the streamlines flowing through the oil temperature measurement point on the top layer of the transformer, or the streamlines flowing through the middle winding of the transformer, or the streamlines flowing through the side phase winding of the transformer.

6. The method for drawing the main flow lines of oil flow inside a transformer according to claim 5, characterized in that: The streamline drawing constraints include: The velocity direction of each fluid particle on the drawn streamline is tangent to the streamline; The drawn streamlines cannot intersect or be broken lines, they can only be straight lines or smooth curves; When the flow state reaches stability, the streamlines and traces coincide; The density of the drawn streamlines reflects the flow velocity.

7. The method for drawing the main flow line of oil flow inside a transformer according to claim 6, characterized in that: The calculation of the fluid velocity field and the temperature field according to the finite element analysis model after meshing comprises: Solve the temperature fluid field control equations based on the finite volume method; The calculation results of fluid velocity field and temperature field are obtained according to the solved temperature fluid field control equation; The temperature data and velocity data of each grid node or unit center of the transformer under the rated load ambient temperature of 25°C and no wind conditions are obtained for subsequent streamline drawing.

8. A system for drawing the main oil flow line inside a transformer, characterized in that: include: A model building module, used to build a finite element analysis model for a target transformer and perform meshing on the finite element analysis model; A data calculation module is used to calculate the fluid velocity field and temperature field according to the finite element analysis model after meshing; A first streamline drawing module, used for performing first streamline drawing according to the fluid velocity field and temperature field in combination with a preset streamline drawing logic; The second streamline drawing module is used to select the main stream line of the oil flow inside the transformer according to the first streamline drawing result and the main stream line extraction rule.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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