Method and device for calculating temperature rise characteristics of converter transformer windings

Abstract

The present invention discloses a method and device for calculating the temperature rise characteristics of a converter transformer winding, which is used to solve the technical problems existing in the existing method for calculating the temperature rise characteristics of the winding, such as low solution accuracy, difficulty in mapping grid data between different physical fields, and time-consuming calculation. The method comprises: calculating the loss density distribution of the coils of the converter transformer winding; constructing a loss distribution grid array of multiple coil areas according to the loss density distribution of the coils, each coil area corresponding to a grid array point; meshing the multiple coil areas according to the loss distribution grid array, and then calculating the array point loss density of each grid array point based on the meshing result; calculating the temperature distribution characteristics of different coil areas of the converter transformer winding according to the loss density of each array point; if the temperature distribution characteristics and the loss density distribution meet the preset conditions, then outputting the temperature rise characteristic results of the converter transformer winding.

Description

Technical Field

[0001] The present invention relates to the technical field of calculating the temperature rise characteristics of the windings of power equipment containing iron core windings, and in particular to a method for calculating the temperature rise characteristics of a converter transformer winding, a device for calculating the temperature rise characteristics of a converter transformer winding, an electronic device and a storage medium. Background Art

[0002] The converter transformer is mainly used to connect the converter bridge and the AC system to achieve the connection between the converter bridge and the AC bus, and provide a three-phase commutation voltage with an ungrounded neutral point for the converter bridge. The converter transformer and the converter bridge are the main components of the converter unit. Therefore, the converter transformer is a key node equipment of the high-voltage direct current transmission system.

[0003] In practical applications, once the transformer is connected to the current, a corresponding electromagnetic field will be generated in the transformer body, and then corresponding losses will be generated, resulting in heating problems in the internal components and structural parts of the transformer. At the same time, during the normal operation of the converter transformer, the currents of the grid-side winding and the valve-side winding contain a large number of high-order harmonic components, which will then generate a large amount of harmonic leakage magnetic fields, resulting in unevenly distributed harmonic losses in the transformer winding. This loss characteristic of the converter transformer makes it more prone to local overheating than ordinary power transformers. Once the converter transformer is locally overheated, the performance degradation of its insulation material will be accelerated, resulting in reduced insulation performance and further shortening the service life of the converter transformer. Therefore, in order to ensure the reliable operation of the converter transformer, it is very important to study the temperature rise of its windings.

[0004] For the study of electromagnetic-thermal-fluid multi-field coupling characteristics of converter transformers, the current stage mostly adopts the calculation method of single coupling of fluid field and temperature field. In the calculation process, if only the temperature change of loss accumulation effect is considered, it will lead to low solution accuracy, which will affect the accurate solution of temperature rise characteristics. In addition, based on the existing simulation software to build a bidirectional coupling model of electromagnetic-thermal-fluid multi-physics field of converter transformer, there are problems such as large number of grid divisions, difficulty in mapping grid data between different physical fields, and time-consuming calculation, which restricts the development of electromagnetic-thermal-fluid multi-physics field numerical simulation technology for large converter transformers. Summary of the invention

[0005] The present invention provides a method for calculating the temperature rise characteristics of a converter transformer winding, a device for calculating the temperature rise characteristics of a converter transformer winding, an electronic device and a storage medium, which are used to solve or partially solve the technical problems in the existing related technology such as low solution accuracy, difficulty in mapping grid data between different physical fields, and time-consuming calculation when calculating the temperature rise characteristics of the windings of power equipment containing iron core windings.

[0006] The present invention provides a method for calculating the temperature rise characteristics of a converter transformer winding, the method comprising:

[0007] Calculating a coil loss density distribution of a converter transformer winding, wherein the coil loss density distribution corresponds to a plurality of coil regions;

[0008] According to the wire cake loss density distribution, construct a loss distribution grid array of the plurality of wire cake areas, each of the wire cake areas corresponding to a grid array point;

[0009] According to the loss distribution grid array, the plurality of wire pancake regions are meshed, and then based on the meshing result, the array point loss density of each of the grid array points is calculated;

[0010] Calculating the temperature distribution characteristics of different coil regions of the converter transformer winding according to the loss density of each array point;

[0011] If the temperature distribution characteristics and the loss density distribution meet the preset conditions, the temperature rise characteristic results of the converter transformer winding are output.

[0012] Optionally, the calculating of the coil loss density distribution of the converter transformer winding includes:

[0013] Establishing an electromagnetic field numerical model corresponding to a converter transformer winding, and dividing the converter transformer winding into a plurality of coil regions;

[0014] Based on the electromagnetic field numerical model, an excitation current is loaded, and a high-order harmonic analysis is performed on the excitation current to obtain a high-order harmonic current;

[0015] Acquiring the winding conductor temperature of the converter transformer winding, and calculating the winding conductivity value according to the winding conductor temperature;

[0016] The coil loss density distribution of the converter transformer winding is calculated according to the high-order harmonic current and the winding conductivity value.

[0017] Optionally, constructing a loss distribution grid array of the plurality of wire bobbins regions according to the wire bobbins loss density distribution includes:

[0018] Based on the plurality of wire cake regions, construct an original distribution grid array, and set a grid array point for each of the wire cake regions;

[0019] Continuously increase the radial and axial points of the original distribution grid array, while continuously reducing the grid array point spacing corresponding to each of the coil regions, and calculate the overall loss equivalent error of the converter transformer winding in combination with the coil loss density distribution;

[0020] When the overall loss equivalent error is less than or equal to a preset loss error, a loss distribution grid array of the plurality of wire pancake regions is determined.

[0021] Optionally, the gridding of the plurality of coil regions according to the loss distribution grid array, and then calculating the array point loss density of each grid array point based on the gridding result, comprises:

[0022] Establishing a thermal-fluid coupling numerical model corresponding to the converter transformer winding;

[0023] According to the loss distribution grid array, the converter transformer winding in the thermal-fluid coupling numerical model is divided into a wire cake grid;

[0024] According to the results of the wire-pie grid division, a bilinear interpolation method is adopted to perform loss density interpolation calculation on each of the grid array points through the electromagnetic field numerical model to obtain the interpolation point loss density corresponding to each of the grid array points, and the interpolation point loss density is used as the array point loss density of the grid array point.

[0025] Optionally, the thermal-fluid coupling numerical model includes a plurality of winding grid nodes, each of which corresponds to a coil region, and the temperature distribution characteristics of different coil regions of the converter transformer winding are calculated according to the loss density of each array point, including:

[0026] For each coil area, the array point loss density is loaded to the winding grid node;

[0027] The coil area of ​​the converter transformer winding is obtained, and the thermal-fluid coupling numerical model is used to integrate and homogenize the regional temperatures of different coil areas in the converter transformer winding according to the winding conductor temperature and the coil area to obtain the coil average temperature. The coil average temperature is used to characterize the temperature distribution characteristics of different coil areas in the converter transformer winding.

[0028] Optionally, if the temperature distribution characteristics and the loss density distribution meet preset conditions, outputting the temperature rise characteristic result of the converter transformer winding includes:

[0029] If the temperature distribution characteristic characterizes that the error between the average temperature of the coils in different coil areas and the reference temperature is less than the preset temperature difference value, and the coil loss density distribution characterizes that the winding loss is less than the preset accuracy error value, then the temperature rise characteristic result of the converter transformer winding is output.

[0030] Optionally, the method further comprises:

[0031] If the temperature distribution characteristic characterizes that the error between the average coil temperature of different coil areas and the reference temperature is greater than or equal to a preset temperature difference value, and / or the coil loss density distribution characterizes that the winding loss is greater than or equal to a preset accuracy error value, then based on the current average coil temperature of different coil areas, the winding conductivity value is recalculated, and the processing flow from the coil loss density distribution calculation step to the temperature distribution characteristic calculation step is repeated.

[0032] The present invention also provides a device for calculating the temperature rise characteristics of a converter transformer winding, comprising:

[0033] A coil loss density distribution calculation module is used to calculate the coil loss density distribution of the converter transformer winding, wherein the coil loss density distribution corresponds to a plurality of coil areas;

[0034] A loss distribution grid array construction module is used to construct a loss distribution grid array of the plurality of wire cake areas according to the wire cake loss density distribution, each of the wire cake areas corresponds to a grid array point;

[0035] An array point loss density calculation module, used to perform grid division on the plurality of wire pancake regions according to the loss distribution grid array, and then calculate the array point loss density of each of the grid array points based on the grid division result;

[0036] A temperature distribution characteristic calculation module, used for calculating the temperature distribution characteristics of different coil regions of the converter transformer winding according to the loss density of each array point;

[0037] The temperature rise characteristic result output module is used to output the temperature rise characteristic result of the converter transformer winding if the temperature distribution characteristic and the loss density distribution meet preset conditions.

[0038] The present invention also provides an electronic device, the device comprising a processor and a memory:

[0039] The memory is used to store program code and transmit the program code to the processor;

[0040] The processor is used to execute the temperature rise characteristic calculation method of the converter transformer winding as described in any one of the above items according to the instructions in the program code.

[0041] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program codes, and the program codes are used to execute the method for calculating the temperature rise characteristics of the converter transformer winding as described in any one of the above items.

[0042] It can be seen from the above technical solutions that the present invention has the following advantages:

[0043] A method for calculating the temperature rise characteristics of a converter transformer winding is provided. First, by calculating the loss density distribution of coils and constructing a loss distribution grid array, a rectangular grid array can be specifically constructed according to the distribution of the loss density of the converter transformer winding; then, according to the loss distribution grid array, multiple coil areas are gridded, and then based on the grid division result, the array point loss density of each grid array point is calculated, so that the heat load transfer process of the loss density of the converter transformer winding can be carried out in the form of a rectangular grid array, avoiding the node coupling process in the heterogeneous grid between the electromagnetic field and the temperature field of the converter transformer; then, according to the loss density of each array point, the temperature distribution characteristics of different coil areas of the converter transformer winding are calculated, and when the temperature distribution characteristics and the loss density distribution meet the preset conditions, the temperature rise characteristic results of the converter transformer winding are output, so that by considering the temperature change characteristics of the winding conductivity, the electromagnetic-thermal-fluid bidirectional coupling of the converter transformer is realized, and the accuracy of the winding temperature calculation is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative labor.

[0045] Figure 1 A flowchart of the steps of a method for calculating the temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention;

[0046] Figure 2 A rectangular grid array and a schematic diagram of rectangular grid division of a converter transformer winding wire loss density distribution provided by an embodiment of the present invention;

[0047] Figure 3 A schematic diagram of the overall flow of a method for calculating the temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention;

[0048] Figure 4 A structural block diagram of a device for calculating temperature rise characteristics of a converter transformer winding provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The embodiments of the present invention provide a method for calculating the temperature rise characteristics of a converter transformer winding, a device for calculating the temperature rise characteristics of a converter transformer winding, an electronic device and a storage medium, which are used to solve or partially solve the technical problems in the existing related technology such as low solution accuracy, difficulty in mapping grid data between different physical fields, and time-consuming calculation when calculating the temperature rise characteristics of the windings of power equipment containing iron core windings.

[0050] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below 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 creative work are within the scope of protection of the present invention.

[0051] As an example, for the study of the electromagnetic-thermal-fluid multi-field coupling characteristics of converter transformers, the current stage mostly adopts the calculation method of single coupling of fluid field and temperature field. In the calculation process, if only the temperature change of loss accumulation effect is considered, it will lead to low solution accuracy, which in turn affects the accurate solution of temperature rise characteristics. The construction of electromagnetic-thermal-fluid multi-physics field bidirectional coupling model of converter transformer based on existing simulation software also has problems such as large number of grid divisions, difficulty in mapping grid data between different physical fields, and time-consuming calculation, which restricts the development of electromagnetic-thermal-fluid multi-physics field numerical simulation technology for large converter transformers.

[0052] Therefore, one of the core invention points of the embodiment of the present invention is: starting from the perspective of heat load transfer and grid division in the electromagnetic-thermal-fluid coupling model of the converter transformer, a method for calculating the temperature rise characteristics of the converter transformer winding is provided. First, a numerical model of the electromagnetic field of the converter transformer is established to solve the loss density distribution of the converter transformer winding; then, according to the winding loss density distribution, a rectangular grid array of loss distribution in different coil areas of the converter transformer winding is constructed, so that a rectangular grid array can be constructed in a targeted manner according to the distribution of the loss density of the converter transformer winding; then, a thermal-fluid coupling numerical model of the converter transformer is established, and according to the rectangular grid array, the converter transformer winding coil is divided into rectangular grids; then, the converter transformer is constructed based on the rectangular grid array. The thermal load transfer process of the winding loss density can avoid the node coupling process in the heterogeneous grid between the electromagnetic field and the temperature field of the converter transformer, and can also flexibly adjust the rectangular grid array of the winding coil according to the calculation requirements to improve the accuracy of the winding temperature calculation; then the simulation calculation of the transformer winding thermal-fluid coupling numerical model is performed, and the winding coil temperature distribution under the thermal-fluid coupling of the converter transformer winding is used as the reference temperature of the winding conductivity temperature variation characteristic, which is used for the update calculation of the winding conductivity of the electromagnetic field numerical model. Therefore, in the embodiment of the present invention, by considering the temperature variation characteristics of the winding conductivity, the electromagnetic-thermal-fluid bidirectional coupling of the converter transformer is realized, and the node coupling process in the heterogeneous grid between different physical fields can be avoided. It has strong versatility and broad application prospects.

[0053] Reference Figure 1, shows a flowchart of a method for calculating the temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention, which may specifically include the following steps:

[0054] Step 101, calculating the coil loss density distribution of the converter transformer winding, wherein the coil loss density distribution corresponds to a plurality of coil regions;

[0055] Calculating the coil loss density distribution is the first step in calculating the temperature rise characteristics of the converter transformer winding. Among them, the winding mentioned in the embodiment of the present invention can be specifically a pancake winding, which is composed of a number of coils wound with flat wires, and pads are added between the coils to form radial oil channels as insulation between the coils. The coil loss can be understood as the heat loss generated by the winding coils when the converter transformer winding is in operation, and the coil loss density distribution can be understood as the distribution of the heat loss (density) of the converter transformer winding in different coil areas. The greater the loss density of a coil area, the greater the heat loss of the area. Conversely, the smaller the loss density, the smaller the heat loss of the area.

[0056] In practical applications, the loss density distribution on the converter transformer winding can be calculated by establishing a numerical model of the electromagnetic field of the converter transformer. This process can be mainly summarized as the construction of the electromagnetic field numerical model (including the addition of model materials), the loading of the excitation current, the high-order harmonics of the excitation current, and the temperature variation characteristics of the winding conductivity.

[0057] Specifically, the step of calculating the coil loss density distribution of the converter transformer winding may include: firstly, establishing an electromagnetic field numerical model corresponding to the converter transformer winding, and dividing the converter transformer winding into a plurality of coil regions; then, based on the electromagnetic field numerical model, loading the excitation current, and performing high-order harmonic analysis on the excitation current to obtain the high-order harmonic current; then, obtaining the winding conductor temperature of the converter transformer winding, and calculating the winding conductivity value according to the winding conductor temperature; finally, calculating the coil loss density distribution of the converter transformer winding according to the high-order harmonic current and the winding conductivity value.

[0058] Furthermore, the electromagnetic field numerical model corresponding to the converter transformer winding established in the embodiment of the present invention may mainly include structures such as the converter transformer core, windings, clips, pull plates, magnetic shielding, and the external air area, wherein the size of the external air area may be determined according to the specific model to be solved and the requirements.

[0059] Among them, the excitation current can be understood as the input current that plays a role in promoting the operation of the circuit. It is input into the circuit by the power supply or signal source. The excitation current distribution can be calculated based on the field-circuit coupling model. At the same time, since the converter transformer winding is a high-power device, when it is working, it belongs to the situation of large resistance and small current. Therefore, the heat loss of the winding (winding loss) can be calculated by Joule's law.

[0060] The field-circuit coupling model of synchronous generator is one of the important models in the power system, which describes the interaction between the generator and the power grid. During the operation of the power system, the parameterization of the field-circuit coupling model of synchronous generator directly affects the stability and safety of the power system.

[0061] Among them, the analytical formula for high-order harmonic current is as follows:

[0062] i(t)=∑I mh sin(hωt)(h=6n±1)

[0063] Where i(t) represents the excitation current including high-order harmonics, t represents time, and I mh It represents the amplitude of each harmonic current, ω represents the frequency, n represents the harmonic order, n=1, 2, 3…

[0064] The calculation method based on Joule's law can be regarded as a calculation process of heat loss based on current loss. During the operation of the converter transformer winding, current loss will cause the temperature of the conductor to rise. If the temperature rise is too high, it will cause equipment failure or even cause serious accidents such as fire. Therefore, the calculation of current loss is an important influencing factor in the analysis of temperature rise characteristics.

[0065] In the embodiment of the present invention, the current loss of the converter transformer winding during operation is used as the heat loss of the winding coil, and the energy loss inside the conductor per unit time is calculated, with watt (W) as the unit. According to Joule's law, it can be obtained that: P w =I Rt, where P w Represents heat loss, I represents current, R represents resistance, and t represents time in seconds. After calculating the heat loss of the winding coil, combined with the coil volume or coil area of ​​the winding, the loss density of different coil areas of the winding can be obtained.

[0066] Among them, since the density distribution has spatial properties, when calculating the loss density of the winding, resistivity can be used instead of resistance for calculation. Resistivity refers to the resistance of the conductor per unit length and unit cross-sectional area.

[0067] Furthermore, the reciprocal of resistivity is conductivity, and the two are in a reciprocal relationship. In power-related calculations, the temperature change characteristics have a great correlation with conductivity. Generally speaking, the conductivity of metals decreases with increasing temperature, while the conductivity of semiconductors increases with increasing temperature. Within a temperature range, conductivity can be approximated to be proportional to temperature. In practical applications, a reference temperature needs to be pre-set according to actual conditions to compare the conductivity of the converter transformer winding under different temperature conditions.

[0068] Among them, the linear characteristic of the temperature change of the conductivity of the converter transformer winding is shown as follows:

[0069]

[0070] Wherein, σ(T) represents the conductivity of the winding conductor, σ0 represents the conductivity at the reference temperature, T represents the winding conductor temperature of the converter transformer winding, T0 is the reference temperature, and α is the coefficient of conductivity changing with temperature.

[0071] Step 102, constructing a loss distribution grid array of the plurality of wire-pie regions according to the wire-pie loss density distribution, wherein each wire-pie region corresponds to a grid array point;

[0072] In a specific implementation, the process of constructing a loss distribution grid array of multiple wire bobbin regions according to the wire bobbin loss density distribution may include the following steps:

[0073] Firstly, an original distribution grid array is constructed based on multiple wire pie regions, and a grid array point is set for each wire pie region;

[0074] Then, the radial and axial points of the original distribution grid array are continuously increased, while the grid array point spacing corresponding to each coil area is continuously reduced, and the overall loss equivalent error of the converter transformer winding is calculated in combination with the coil loss density distribution;

[0075] When the overall loss equivalent error is less than or equal to the preset loss error, the loss distribution grid arrays of multiple coil regions are determined, so that a rectangular grid array can be specifically constructed according to the distribution of the loss density of the converter transformer winding.

[0076] Further, in the rectangular grid division method, the loss density distribution of the converter transformer winding can be continuously increased by increasing the radial and axial points of the rectangular grid array, and continuously reducing the point spacing of the rectangular grid array in each coil area until the overall loss equivalent error satisfies the following formula:

[0077]

[0078] Where P irepresents the loss density at the rectangular grid array point, a represents the radial spacing of the rectangular grid array points, b represents the axial spacing of the rectangular grid array points, P represents the loss density distribution of the wire pancake, and S represents the area of ​​the wire pancake.

[0079] In this step, the actual winding loss density distribution is equivalent to the winding loss density grid array form to ensure that the equivalent error of the overall winding loss does not exceed 1%, so that the appropriate winding loss density distribution rectangular grid array amplitude and axial point number can be automatically selected.

[0080] In the steps of the aforementioned embodiment, when constructing the loss distribution grid array, the converter transformer winding is divided into coil areas as a whole, that is, several coils in a converter transformer winding are regarded as a whole for area division, and are divided into multiple coil areas. For example, there are 3 coils in the converter transformer winding. When performing area division, the 3 coils are regarded as a whole and divided into 15 coil areas. At this time, a loss distribution grid array can be constructed. The loss distribution grid array corresponds to 15 coil areas. There are 15 grid array points in the loss distribution grid array, and one grid array point corresponds to one coil area.

[0081] In another processing method (processing method 2), in addition to the above-mentioned area division method, local division can also be used for area division, that is, taking the wire cake as the basis for area division, the converter transformer winding is first divided into multiple wire cake areas, and then the wire cake area corresponding to each wire cake is divided into multiple sub-areas. Then, for the step of constructing the loss distribution grid array, according to the loss distribution on the converter transformer winding, the loss distribution rectangular grid arrays of different wire cake areas of the converter transformer winding can be constructed respectively. For example, there are 3 wire cakes in the converter transformer winding. When performing area division, it can be divided into 3 wire cake areas, and each wire cake area corresponds to a There are wire cakes, and then each wire cake can be further divided into regions. For example, according to the actual situation, the first wire cake area is divided into 10 sub-regions, the second wire cake area is divided into 15 sub-regions, and the third wire cake area is divided into 20 sub-regions. Then, the corresponding loss distribution grid arrays can be constructed for the three wire cakes respectively. At this time, the loss distribution grid array corresponding to the first wire cake has 15 grid array points, the loss distribution grid array corresponding to the second wire cake has 20 grid array points, and the loss distribution grid array corresponding to the third wire cake has 20 grid array points, and each grid array point corresponds to a sub-region of the wire cake.

[0082] Step 103, meshing the plurality of coil regions according to the loss distribution grid array, and then calculating the array point loss density of each grid array point based on the meshing result;

[0083] In a specific implementation, according to the loss distribution grid array, multiple coil regions are meshed, and then based on the meshing result, the array point loss density of each grid array point is calculated. The implementation process may include the following steps:

[0084] Step S1031: establishing a thermal-fluid coupling numerical model corresponding to the converter transformer winding;

[0085] Specifically, the established thermal-fluid coupling numerical model of the converter transformer may include structures such as the converter transformer core, windings, baffles, and oil tanks. The process of establishing the thermal-fluid coupling numerical model may mainly include: first adding model materials, then setting heat transfer and inlet and outlet boundary conditions, and then determining the heat transfer coefficient, thermal conductivity, and environmental parameters.

[0086] Among them, the boundary condition of the converter transformer oil flow inlet is set to the velocity inlet, the direction is perpendicular to the inlet boundary, the boundary condition of the oil flow outlet is set to the pressure outlet, the contact surface between the converter transformer oil and the solid wall is set to the coupling wall, and the convection heat transfer coefficient and surface radiation emissivity of the converter transformer surface are set.

[0087] Step S1032: performing coil mesh division on the converter transformer winding in the thermal-fluid coupling numerical model according to the loss distribution grid array;

[0088] Then, according to the loss distribution grid array, the converter transformer winding in the thermal-fluid coupling numerical model can be divided into a wire-pie rectangular grid with the loss distribution grid array point as the center, so that the winding loss density distribution rectangular grid array point is located at the center of the winding wire-pie rectangular grid.

[0089] Specifically, five boundary layers are set at the fluid-solid coupling interface between the winding coil and the transformer oil, and the boundary layer height growth rate is set. The height of the first layer of grid can be adjusted according to the appropriate wall function y + The height of the first layer of grid is determined as follows:

[0090]

[0091] In the formula, represents the height of the first grid layer, μ is the dynamic viscosity of transformer oil, ρ represents the density of transformer oil, and u τ represents the boundary layer height growth rate.

[0092] In addition to meshing the winding coil area, in order to improve the calculation accuracy, the area around the winding can also be meshed according to the solution requirements. For example, for meshes in other oil flow areas, a suitable meshing method can be selected based on a comprehensive consideration of calculation accuracy and efficiency.

[0093] Similarly, for the processing method 2 mentioned in the aforementioned embodiment, for the step of meshing the coils of the converter transformer winding, according to the loss distribution rectangular grid array of different coil areas of the converter transformer winding, with reference to the above-mentioned grid division method, the different coils of the converter transformer winding can be divided into rectangular grids with the loss distribution grid array point as the center, so that the winding loss density distribution rectangular grid array point is located at the center of the winding coil rectangular grid.

[0094] For better explanation, refer to Figure 2 , showing the rectangular grid array of converter transformer winding loss density distribution and the schematic diagram of rectangular grid division.

[0095] exist Figure 2 In the figure, the first schematic diagram is a schematic diagram of the segmentation of the winding coil of the converter transformer magnetic field numerical model, indicating that the converter transformer winding is segmented into multiple coil areas through the electromagnetic field numerical model; the second schematic diagram is a schematic diagram of the construction of the winding coil loss density distribution array, indicating that according to the coil loss density distribution, a loss distribution grid array of multiple coil areas is constructed; the third schematic diagram is a schematic diagram of the rectangular grid segmentation of the converter transformer winding coil, indicating that according to the loss distribution grid array, the converter transformer winding in the thermal-fluid coupling numerical model is segmented into a coil rectangular grid with the loss distribution grid array point as the center, and at this time, the winding loss density distribution rectangular grid array point is located at the center of the winding coil rectangular grid.

[0096] Step S1033: According to the wire-pie grid division result, a bilinear interpolation method is used to perform loss density interpolation calculations on each grid array point through an electromagnetic field numerical model to obtain the interpolation point loss density corresponding to each grid array point, and the interpolation point loss density is used as the array point loss density of the grid array point.

[0097] After the winding coil area is meshed, the converter transformer winding thermal load transfer step can be performed. Specifically, according to the winding meshing situation in the converter transformer thermal-fluid coupling numerical model, the loss density of the rectangular grid array of different coil areas of the converter transformer winding can be interpolated and calculated based on the bilinear interpolation method. The calculation formula is as follows:

[0098]

[0099] Where Q represents the loss density at the interpolation point, Q 11 , Q 21 , Q 12 , Q 22 They respectively represent the loss density of the four corners of the loss density rectangular grid array, (x, y) is the interpolation point coordinate, (x1, y1) and (x2, y2) are the loss density grid array point coordinates.

[0100] Step 104, calculating the temperature distribution characteristics of different coil regions of the converter transformer winding according to the loss density of each array point;

[0101] After the array point loss density is calculated, the interpolation point coordinates and the array point loss density can be combined to set the corresponding winding grid nodes for each coil area. Then, the thermal-fluid coupling numerical model can include multiple winding grid nodes, and each winding grid node can correspond to a coil area. Further, according to each array point loss density, the implementation process of calculating the temperature distribution characteristics of different coil areas of the converter transformer winding can include the following steps:

[0102] Step S1041: for each coil region, the array point loss density is loaded into the winding grid node;

[0103] The calculated array point loss density is loaded into the winding grid unit or node of the thermal-fluid coupling numerical model of the converter transformer in the form of grid array points, wherein the loss density loading method includes but is not limited to manual matching input, configuration file loading, and parameterized design language execution, etc.

[0104] Step S1042: Obtain the coil area of ​​the converter transformer winding, and use a thermal-fluid coupling numerical model to integrate and homogenize the regional temperatures of different coil areas in the converter transformer winding according to the winding conductor temperature and the coil area to obtain the coil average temperature, wherein the coil average temperature is used to characterize the temperature distribution characteristics of different coil areas in the converter transformer winding.

[0105] Then, the winding temperature rise can be calculated based on the thermal-fluid coupling numerical model of the converter transformer, and the temperature of different coil areas of the converter transformer winding can be integrated and homogenized. Specifically, the average coil temperature of different coil areas can be expressed as follows:

[0106]

[0107] Where, T av Indicates the average temperature of the coils of the converter transformer winding.

[0108] In this step, the thermal load transfer process of the converter transformer winding loss density is carried out based on the rectangular grid array form, which can avoid the node coupling process in the heterogeneous grid between the electromagnetic field and the temperature field of the converter transformer, and can also flexibly adjust the winding coil rectangular grid array according to the calculation requirements, thereby improving the accuracy of the winding temperature calculation.

[0109] Step 105: If the temperature distribution characteristics and the loss density distribution meet preset conditions, output the temperature rise characteristic result of the converter transformer winding.

[0110] Specifically, determine whether the error between the average temperature of the coil of the converter transformer winding and the initial temperature meets the temperature difference accuracy requirement (for example, whether it is less than ±0.1°C), and at the same time determine whether the coil loss meets the loss accuracy requirement. If so, that is, the temperature distribution characteristic characterizes that the error between the average temperature of the coil in different coil areas and the reference temperature is less than the preset temperature difference value, and the coil loss density distribution characterizes that the winding loss is less than the preset accuracy error value, then output the temperature rise characteristic result of the converter transformer winding.

[0111] Furthermore, when determining the accuracy of coil losses, coil losses of different windings may be calibrated based on the following formula to verify whether the calculation accuracy requirements are met.

[0112]

[0113] In the formula, Q ohm represents the winding loss calculated by the electromagnetic field numerical model, that is, the heat loss, It represents the winding loss at the reference temperature T0, T k is the temperature factor of the resistance change with temperature.

[0114] As an optional embodiment, if the temperature distribution characteristic characterizes that the error between the average coil temperature of different coil areas and the reference temperature is greater than or equal to a preset temperature difference value, and / or the coil loss density distribution characterizes that the winding loss is greater than or equal to a preset accuracy error value, then the current average coil temperature of different coil areas can be based on the current average coil temperature of different coil areas, that is, the current average coil temperature of different coil areas can be used as the new winding conductor temperature, substituted into the conductivity-temperature variation linear characteristic calculation formula in the aforementioned embodiment, the winding conductivity value is recalculated, and the processing flow from the coil loss density distribution calculation step to the temperature distribution characteristic calculation step is repeated. Since this process has been described in detail in the aforementioned embodiment, it will not be repeated here.

[0115] In an embodiment of the present invention, a method for calculating the temperature rise characteristics of a converter transformer winding is provided. First, a numerical model of the electromagnetic field of the converter transformer is established to solve the loss density distribution of the converter transformer winding. Then, according to the loss density distribution of the winding, a rectangular grid array of loss distribution in different coil areas of the converter transformer winding is constructed, so that according to the distribution of the loss density of the converter transformer winding, a rectangular grid array is specifically constructed. Then, a thermal-fluid coupling numerical model of the converter transformer is established, and according to the rectangular grid array, the converter transformer winding coil is divided into rectangular grids. Then, a thermal load transfer process of the loss density of the converter transformer winding is carried out in the form of a rectangular grid array, thereby avoiding the node coupling process in the heterogeneous grid between the electromagnetic field and the temperature field of the converter transformer, and the winding coil rectangular grid array can be flexibly adjusted according to the calculation requirements, thereby improving the accuracy of the winding temperature calculation. Then, a simulation calculation of the thermal-fluid coupling numerical model of the transformer winding is carried out, and the temperature distribution of the winding coil under the thermal-fluid coupling of the converter transformer winding is used as the reference temperature of the temperature change characteristic of the winding conductivity, which is used for the update calculation of the winding conductivity of the electromagnetic field numerical model. In the embodiment of the present invention, by considering the temperature variation characteristics of the winding conductivity, not only the electromagnetic-thermal-fluid bidirectional coupling of the converter transformer is achieved, the calculation accuracy of the winding temperature rise characteristics is improved, but also the node coupling process in heterogeneous grids between different physical fields is avoided.

[0116] For better explanation, refer to Figure 3 , showing an overall flow chart of a method for calculating the temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention. It should be pointed out that in this embodiment, only the general flow chart of the method for calculating the temperature rise characteristics of a converter transformer winding is used as an example. The detailed introduction of each step can be understood by referring to the relevant content in the aforementioned embodiment. It will not be elaborated here. It can be understood that the present invention is not limited to this.

[0117] Step S1 (converter transformer winding loss calculation step): establish an electromagnetic field numerical model of the converter transformer winding, and calculate the wire loss density distribution on the converter transformer winding.

[0118] Step S2 (construction step of a rectangular grid array of converter transformer winding loss density distribution): construct a loss distribution rectangular grid array of different coil areas of the converter transformer winding according to the coil loss density distribution.

[0119] Step S3 (thermal-fluid coupling numerical model establishment step): establish a thermal-fluid coupling numerical model of the converter transformer winding.

[0120] Step S4 (converter transformer winding grid division step): according to the loss distribution rectangular grid array, the converter transformer winding coils are divided into rectangular grids.

[0121] Step S5 (converter transformer winding thermal load transfer step): According to the winding grid division, based on the bilinear interpolation method, the loss density of the rectangular grid array of different coil areas of the converter transformer winding is interpolated and calculated, and the converter transformer winding loss density is loaded into the thermal-fluid coupling numerical model winding grid unit or node in the form of grid array points.

[0122] Step S6 (converter transformer winding temperature rise calculation step): Calculate the temperature distribution characteristics of different coils (regions) of the converter transformer winding according to the thermal-fluid coupling numerical model.

[0123] Step S7 (calculation accuracy judgment step): judge whether the temperature distribution and loss density verification meet the error requirements, that is, judge whether the average temperature of the coil of the converter transformer winding and the initial temperature error meet the temperature difference accuracy requirements, and at the same time judge whether the coil loss meets the loss accuracy requirements. If so, output the temperature rise characteristic result of the converter transformer winding; if not, based on the current converter transformer winding temperature, according to the linear characteristic of conductivity-temperature change, update the winding conductivity value, and then repeat steps S1 to S6.

[0124] Reference Figure 4 , shows a structural block diagram of a device for calculating temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention, which may specifically include:

[0125] A coil loss density distribution calculation module 401 is used to calculate the coil loss density distribution of the converter transformer winding, wherein the coil loss density distribution corresponds to a plurality of coil regions;

[0126] A loss distribution grid array construction module 402 is used to construct a loss distribution grid array of the plurality of wire cake regions according to the wire cake loss density distribution, each of the wire cake regions corresponding to a grid array point;

[0127] An array point loss density calculation module 403 is used to perform grid division on the plurality of wire pancake regions according to the loss distribution grid array, and then calculate the array point loss density of each of the grid array points based on the grid division result;

[0128] A temperature distribution characteristic calculation module 404 is used to calculate the temperature distribution characteristics of different coil regions of the converter transformer winding according to the loss density of each array point;

[0129] The temperature rise characteristic result output module 405 is used to output the temperature rise characteristic result of the converter transformer winding if the temperature distribution characteristic and the loss density distribution meet preset conditions.

[0130] In an optional embodiment, the coil loss density distribution calculation module 401 includes:

[0131] An electromagnetic field numerical model building module is used to build an electromagnetic field numerical model corresponding to a converter transformer winding and divide the converter transformer winding into a plurality of coil regions;

[0132] A high-order harmonic analysis module is used to load an excitation current based on the electromagnetic field numerical model, and perform high-order harmonic analysis on the excitation current to obtain a high-order harmonic current;

[0133] A winding conductivity value calculation module, used to obtain the winding conductor temperature of the converter transformer winding, and calculate the winding conductivity value according to the winding conductor temperature;

[0134] The coil loss density distribution calculation submodule is used to calculate the coil loss density distribution of the converter transformer winding according to the high-order harmonic current and the winding conductivity value.

[0135] In an optional embodiment, the loss distribution grid array construction module 402 includes:

[0136] An original distribution grid array construction module is used to construct an original distribution grid array based on the plurality of wire pie regions, and to set a grid array point for each of the wire pie regions;

[0137] A grid array adjustment module, used to continuously increase the radial and axial points of the original distributed grid array, while continuously reducing the grid array point spacing corresponding to each of the coil regions, and calculate the overall loss equivalent error of the converter transformer winding in combination with the coil loss density distribution;

[0138] The loss distribution grid array determination module is used to determine the loss distribution grid array of the plurality of coil regions when the overall loss equivalent error is less than or equal to a preset loss error.

[0139] In an optional embodiment, the array point loss density calculation module 403 includes:

[0140] A thermal-fluid coupling numerical model establishment model is used to establish a thermal-fluid coupling numerical model corresponding to the converter transformer winding;

[0141] A wire-pie grid division module, used for performing wire-pie grid division on the converter transformer winding in the thermal-fluid coupling numerical model according to the loss distribution grid array;

[0142] The loss density interpolation calculation module is used to perform loss density interpolation calculation on each grid array point according to the wire pancake grid division result and the bilinear interpolation method through the electromagnetic field numerical model, so as to obtain the interpolation point loss density corresponding to each grid array point, and use the interpolation point loss density as the array point loss density of the grid array point.

[0143] In an optional embodiment, the thermal-fluid coupling numerical model includes a plurality of winding grid nodes, each of which corresponds to a coil region, and the temperature distribution characteristic calculation module 404 includes:

[0144] An array point loss density loading module, used for loading the array point loss density to the winding grid node for each coil area;

[0145] The integral homogenization processing module is used to obtain the coil area of ​​the converter transformer winding, and adopt the thermal-fluid coupling numerical model to perform integral homogenization processing on the regional temperature of different coil areas in the converter transformer winding according to the winding conductor temperature and the coil area, so as to obtain the coil average temperature, and the coil average temperature is used to characterize the temperature distribution characteristics of different coil areas in the converter transformer winding.

[0146] In an optional embodiment, the temperature rise characteristic result output module 405 is specifically used for:

[0147] If the temperature distribution characteristic characterizes that the error between the average temperature of the coils in different coil areas and the reference temperature is less than the preset temperature difference value, and the coil loss density distribution characterizes that the winding loss is less than the preset accuracy error value, then the temperature rise characteristic result of the converter transformer winding is output.

[0148] In an optional embodiment, the device further includes:

[0149] If the temperature distribution characteristic characterizes that the error between the average coil temperature of different coil areas and the reference temperature is greater than or equal to a preset temperature difference value, and / or the coil loss density distribution characterizes that the winding loss is greater than or equal to a preset accuracy error value, then based on the current average coil temperature of different coil areas, the winding conductivity value is recalculated, and the processing flow from the coil loss density distribution calculation step to the temperature distribution characteristic calculation step is repeated.

[0150] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the aforementioned method embodiment.

[0151] An embodiment of the present invention further provides an electronic device, the device comprising a processor and a memory:

[0152] The memory is used to store the program code and transmit the program code to the processor;

[0153] The processor is used to execute the temperature rise characteristic calculation method of the converter transformer winding according to any embodiment of the present invention according to the instructions in the program code.

[0154] An embodiment of the present invention further provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the method for calculating the temperature rise characteristics of the converter transformer winding according to any embodiment of the present invention.

[0155] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0156] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0157] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0158] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0159] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0160] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the temperature rise characteristics of a converter transformer winding, characterized in that: include: Calculating a coil loss density distribution of a converter transformer winding, wherein the coil loss density distribution corresponds to a plurality of coil regions; According to the wire cake loss density distribution, construct a loss distribution grid array of the plurality of wire cake regions, each of the wire cake regions corresponding to a grid array point; According to the loss distribution grid array, the plurality of wire pancake regions are meshed, and then based on the meshing result, the array point loss density of each of the grid array points is calculated; Calculating the temperature distribution characteristics of different coil regions of the converter transformer winding according to the loss density of each array point; If the temperature distribution characteristics and the loss density distribution meet the preset conditions, then output the temperature rise characteristic result of the converter transformer winding; The calculation of the coil loss density distribution of the converter transformer winding includes: Establishing an electromagnetic field numerical model corresponding to a converter transformer winding, and dividing the converter transformer winding into a plurality of coil regions; Based on the electromagnetic field numerical model, an excitation current is loaded, and a high-order harmonic analysis is performed on the excitation current to obtain a high-order harmonic current; Acquiring the winding conductor temperature of the converter transformer winding, and calculating the winding conductivity value according to the winding conductor temperature; Calculating the wire loss density distribution of the converter transformer winding according to the high-order harmonic current and the winding conductivity value; The step of constructing a loss distribution grid array of the plurality of wire cake regions according to the wire cake loss density distribution comprises: Based on the plurality of wire cake regions, construct an original distribution grid array, and set a grid array point for each of the wire cake regions; Continuously increase the radial and axial points of the original distribution grid array, while continuously reducing the grid array point spacing corresponding to each of the coil regions, and calculate the overall loss equivalent error of the converter transformer winding in combination with the coil loss density distribution; When the overall loss equivalent error is less than or equal to a preset loss error, determining a loss distribution grid array of the plurality of wire pancake regions; The method of meshing the plurality of coil regions according to the loss distribution grid array, and then calculating the array point loss density of each grid array point based on the meshing result, comprises: Establishing a thermal-fluid coupling numerical model corresponding to the converter transformer winding; According to the loss distribution grid array, the converter transformer winding in the thermal-fluid coupling numerical model is divided into a wire cake grid; According to the results of the wire-pie grid division, a bilinear interpolation method is adopted to perform loss density interpolation calculation on each of the grid array points through the electromagnetic field numerical model to obtain the interpolation point loss density corresponding to each of the grid array points, and the interpolation point loss density is used as the array point loss density of the grid array point.

2. The method for calculating the temperature rise characteristics of the converter transformer winding according to claim 1, characterized in that: The thermal-fluid coupling numerical model includes a plurality of winding grid nodes, each of which corresponds to a coil region. The temperature distribution characteristics of different coil regions of the converter transformer winding are calculated according to the loss density of each array point, including: For each coil area, the array point loss density is loaded to the winding grid node; The coil area of ​​the converter transformer winding is obtained, and the thermal-fluid coupling numerical model is used to integrate and homogenize the regional temperatures of different coil areas in the converter transformer winding according to the winding conductor temperature and the coil area to obtain the coil average temperature. The coil average temperature is used to characterize the temperature distribution characteristics of different coil areas in the converter transformer winding.

3. The method for calculating the temperature rise characteristics of converter transformer windings according to claim 1, characterized in that: If the temperature distribution characteristics and the loss density distribution meet the preset conditions, then outputting the temperature rise characteristic result of the converter transformer winding includes: If the temperature distribution characteristic characterizes that the error between the average temperature of the coils in different coil areas and the reference temperature is less than the preset temperature difference value, and the coil loss density distribution characterizes that the winding loss is less than the preset accuracy error value, then the temperature rise characteristic result of the converter transformer winding is output.

4. The method for calculating the temperature rise characteristics of converter transformer windings according to claim 3, characterized in that: Also includes: If the temperature distribution characteristic characterizes that the error between the average coil temperature of different coil areas and the reference temperature is greater than or equal to a preset temperature difference value, and / or the coil loss density distribution characterizes that the winding loss is greater than or equal to a preset accuracy error value, then based on the current average coil temperature of different coil areas, the winding conductivity value is recalculated, and the processing flow from the coil loss density distribution calculation step to the temperature distribution characteristic calculation step is repeated.

5. A device for calculating the temperature rise characteristics of a converter transformer winding, characterized in that: include: A coil loss density distribution calculation module is used to calculate the coil loss density distribution of the converter transformer winding, wherein the coil loss density distribution corresponds to a plurality of coil areas; A loss distribution grid array construction module is used to construct a loss distribution grid array of the plurality of wire cake areas according to the wire cake loss density distribution, each of the wire cake areas corresponds to a grid array point; An array point loss density calculation module, used to perform grid division on the plurality of wire pancake regions according to the loss distribution grid array, and then calculate the array point loss density of each of the grid array points based on the grid division result; A temperature distribution characteristic calculation module, used for calculating the temperature distribution characteristics of different coil regions of the converter transformer winding according to the loss density of each array point; A temperature rise characteristic result output module, configured to output the temperature rise characteristic result of the converter transformer winding if the temperature distribution characteristic and the loss density distribution meet preset conditions; The wire cake loss density distribution calculation module includes: An electromagnetic field numerical model building module is used to build an electromagnetic field numerical model corresponding to a converter transformer winding and divide the converter transformer winding into a plurality of coil regions; A high-order harmonic analysis module is used to load an excitation current based on the electromagnetic field numerical model, and perform high-order harmonic analysis on the excitation current to obtain a high-order harmonic current; A winding conductivity value calculation module, used to obtain the winding conductor temperature of the converter transformer winding, and calculate the winding conductivity value according to the winding conductor temperature; A coil loss density distribution calculation submodule, used to calculate the coil loss density distribution of the converter transformer winding according to the high-order harmonic current and the winding conductivity value; The loss distribution grid array building module includes: An original distribution grid array construction module is used to construct an original distribution grid array based on the plurality of wire pie regions, and to set a grid array point for each of the wire pie regions; A grid array adjustment module, used to continuously increase the radial and axial points of the original distributed grid array, while continuously reducing the grid array point spacing corresponding to each of the coil regions, and calculate the overall loss equivalent error of the converter transformer winding in combination with the coil loss density distribution; A loss distribution grid array determination module, used for determining the loss distribution grid array of the plurality of coil regions when the overall loss equivalent error is less than or equal to a preset loss error; The array point loss density calculation module includes: A thermal-fluid coupling numerical model establishment model is used to establish a thermal-fluid coupling numerical model corresponding to the converter transformer winding; A wire-pie grid division module, used for performing wire-pie grid division on the converter transformer winding in the thermal-fluid coupling numerical model according to the loss distribution grid array; The loss density interpolation calculation module is used to perform loss density interpolation calculation on each grid array point according to the wire pancake grid division result and the bilinear interpolation method through the electromagnetic field numerical model, so as to obtain the interpolation point loss density corresponding to each grid array point, and use the interpolation point loss density as the array point loss density of the grid array point.

6. An electronic device, characterized in that: The device comprises a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the method for calculating the temperature rise characteristics of the converter transformer winding according to any one of claims 1 to 4 according to the instructions in the program code.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the method for calculating the temperature rise characteristics of the converter transformer winding according to any one of claims 1 to 4.

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