CN117408204A - Temperature rise characteristic calculation method and device for converter transformer winding - Google Patents

Abstract

The invention discloses a method and device for calculating the temperature rise characteristics of a converter transformer winding, which are used to solve the problems existing in the existing winding temperature rise characteristics calculation methods such as low solution accuracy, difficulty in mapping grid data between different physical fields, and computational complexity. time and other technical issues. The method includes: calculating the line cake loss density distribution of the converter transformer winding; constructing a loss distribution grid array of multiple line cake areas according to the line cake loss density distribution, each line cake area corresponding to a grid array point; according to the loss Distribute the grid array, perform grid division on multiple line cake areas, and then calculate the array point loss density of each grid array point based on the grid division results; based on the loss density of each array point, calculate the different converter transformer windings Temperature distribution characteristics of the line cake area; if the temperature distribution characteristics and loss density distribution meet the preset conditions, the temperature rise characteristics results of the converter transformer windings will be output.

Description

Calculation method and device for temperature rise characteristics of converter transformer windings

Technical field

The present invention relates to the technical field of calculating temperature rise characteristics of electric equipment windings containing iron core windings, and in particular to a method for calculating temperature rise characteristics of converter transformer windings, a device for calculating temperature rise characteristics of converter transformer windings, an electronic device and A storage medium.

Background technique

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

In practical applications, once the transformer is connected to current, a corresponding electromagnetic field will be generated within the transformer body, which will then produce corresponding losses, leading to heating problems in the internal components and structural parts of the transformer. At the same time, during normal operation of the converter transformer, the grid-side winding and valve-side winding currents contain a large number of high-order harmonic components, which in turn generates a large amount of harmonic leakage magnetic field, resulting in unevenly distributed harmonic losses in the transformer windings. This loss characteristic of a converter transformer makes it more susceptible to local overheating than an ordinary power transformer. Once local overheating occurs in the converter transformer, the performance deterioration of the insulation material will be accelerated, resulting in a reduction in 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 crucial to study the winding temperature rise.

For the study of electromagnetic-thermal-flow multi-field coupling characteristics of converter transformers, the calculation method of single coupling of fluid field and temperature field is mostly used at this stage. However, in the calculation process, if only the temperature change of the loss accumulation effect is considered, the solution accuracy will be reduced. is low, which affects the accurate solution of the temperature rise characteristics. In addition, when constructing a two-way coupling model of electromagnetic-heat-flow multi-physics fields of a converter transformer based on existing simulation software, there is a large number of mesh subdivisions and the network between different physical fields. Problems such as difficulty in grid data mapping and time-consuming calculations have restricted the development of electromagnetic-heat-flow multi-physics numerical simulation technology for large-scale converter transformers.

Contents of the invention

The 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 existing related technologies. When calculating the winding temperature rise characteristics of power equipment containing core windings, technical problems such as low solution accuracy, difficulty in mapping grid data between different physical fields, and time-consuming calculations are addressed.

The invention provides a method for calculating the temperature rise characteristics of a converter transformer winding, which method includes:

Calculate the line cake loss density distribution of the converter transformer winding, and the line cake loss density distribution corresponds to multiple line cake areas;

Construct a loss distribution grid array of the multiple line cake areas according to the line cake loss density distribution, and each line cake area corresponds to a grid array point;

According to the loss distribution grid array, perform grid division on the plurality of line cake areas, and then calculate the array point loss density of each grid array point based on the grid division results;

Calculate the temperature distribution characteristics of different line cake areas of the converter transformer winding according to the loss density of each array point;

If the temperature distribution characteristic and the loss density distribution meet the preset conditions, the temperature rise characteristic result of the converter transformer winding is output.

Optionally, the calculation of the line cake loss density distribution of the converter transformer winding includes:

Establish a numerical model of the electromagnetic field corresponding to the converter transformer winding, and divide the converter transformer winding into multiple line cake areas;

Based on the electromagnetic field numerical model, load the excitation current, perform high-order harmonic analysis on the excitation current, and obtain the high-order harmonic current;

Obtain the winding conductor temperature of the converter transformer winding, and calculate the winding conductivity value based on the winding conductor temperature;

According to the high-order harmonic current and the winding conductivity value, the line cake loss density distribution of the converter transformer winding is calculated.

Optionally, constructing a loss distribution grid array of the multiple line cake areas according to the line cake loss density distribution includes:

Based on the plurality of line cake areas, construct an original distribution grid array, and set a grid array point for each of the line cake areas;

Continuously increase the number of width and axial points of the original distribution grid array, while continuously reducing the grid array point spacing corresponding to each of the line cake areas, and combined with the line cake loss density distribution, calculate the replacement The overall loss equivalent error of the current transformer winding;

When the overall loss equivalent error is less than or equal to the preset loss error, the loss distribution grid array of the multiple line cake areas is determined.

Optionally, the plurality of line cake areas are meshed according to the loss distribution grid array, and then the array point loss density of each grid array point is calculated based on the meshing results. ,include:

Establish a thermal-flow coupling numerical model corresponding to the converter transformer winding;

According to the loss distribution grid array, perform line cake meshing on the converter transformer winding in the thermal-flow coupling numerical model;

According to the line cake meshing results, the bilinear interpolation method is used to perform loss density interpolation calculation on each of the grid array points through the electromagnetic field numerical model, and the corresponding interpolation points of each of the grid array points are obtained. loss density, and use the interpolation point loss density as the array point loss density of the grid array points.

Optionally, the thermal-flow coupling numerical model includes a plurality of winding grid nodes, each of the winding grid nodes corresponds to a line cake area, and the exchanger is calculated according to the loss density of each array point. The temperature distribution characteristics of different line cake areas of the current transformer winding include:

For each line cake area, load the array point loss density to the winding grid node;

Obtain the line cake area of the converter transformer winding, and use the thermal-flow coupling numerical model to calculate the different line cake areas in the converter transformer winding according to the winding conductor temperature and the line cake area. The temperature is integrated and homogenized to obtain the average temperature of the line cake. The average temperature of the line cake is used to characterize the temperature distribution characteristics of different line cake areas in the converter transformer winding.

Optionally, if the temperature distribution characteristics and the loss density distribution meet preset conditions, then output the temperature rise characteristic results of the converter transformer winding, including:

If the temperature distribution characteristics represent that the error between the average temperature of the wire cake in different wire cake areas and the reference temperature is less than the preset temperature difference value, and the wire cake loss density distribution represents the winding loss is less than the preset accuracy error value, then output the Temperature rise characteristic results of converter transformer windings.

Optionally, the method also includes:

If the temperature distribution characteristics represent that the error between the average temperature of the wire cake in different wire cake areas and the reference temperature is greater than or equal to the preset temperature difference value, and/or, the wire cake loss density distribution represents that the winding loss is greater than or equal to the preset accuracy error value , then based on the current average temperature of the wire cake in different wire cake areas, the winding conductivity value is recalculated, and the processing flow from the wire cake loss density distribution calculation step to the temperature distribution characteristic calculation step is repeated.

The invention also provides a device for calculating the temperature rise characteristics of the converter transformer winding, which includes:

The line cake loss density distribution calculation module is used to calculate the line cake loss density distribution of the converter transformer winding, and the line cake loss density distribution corresponds to multiple line cake areas;

A loss distribution grid array building module, configured to construct a loss distribution grid array of the plurality of line cake areas according to the line cake loss density distribution, each of the line cake areas corresponding to a grid array point;

Array point loss density calculation module, used to perform grid division on the plurality of line cake areas according to the loss distribution grid array, and then calculate the array of each grid array point based on the grid division results. Point loss density;

A temperature distribution characteristic calculation module, used to calculate the temperature distribution characteristics of different line cake areas of the converter transformer winding according to the loss density of each array point;

A temperature rise characteristic result output module is 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 invention also provides an electronic device, which includes a processor and a memory:

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

The processor is configured to execute the method for calculating the temperature rise characteristics of the converter transformer winding as described in any one of the above according to the instructions in the program code.

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

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

A method for calculating the temperature rise characteristics of converter transformer windings is provided. First, by calculating the line cake loss density distribution and constructing a loss distribution grid array, it is possible to achieve a targeted construction based on the distribution of the converter transformer winding loss density. Rectangular grid array; then mesh the multiple line cake areas according to the loss distribution grid array, and then calculate the array point loss density of each grid array point based on the meshing results, so that the array point loss density can be calculated through the rectangular mesh The thermal load transfer process of the converter transformer winding loss density is carried out in the form of a grid array to avoid the node coupling process in the heterogeneous grid between the electromagnetic field and the temperature field of the converter transformer; and then according to the loss density of each array point, different lines of the converter transformer winding are calculated Temperature distribution characteristics of the cake area, and when the temperature distribution characteristics and loss density distribution meet the preset conditions, the temperature rise characteristics results of the converter transformer windings are output, thereby realizing the electromagnetic control of the converter transformer by considering the temperature change characteristics of the winding conductivity. -Heat-flow bidirectional coupling further improves the accuracy of winding temperature calculation.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a step flow chart of a method for calculating the temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention;

Figure 2 is a schematic diagram of a rectangular grid array and rectangular grid division of the loss density distribution of a converter transformer winding cake provided by an embodiment of the present invention;

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

Figure 4 is 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.

Detailed ways

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 existing problems. In related technologies, there are technical problems such as low solution accuracy, difficulty in mapping grid data between different physical fields, and time-consuming calculations when calculating the winding temperature rise characteristics of electric power equipment containing iron core windings.

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 accompanying drawings in the embodiments of the present invention. Obviously, what is mentioned below The described embodiments are only some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

As an example, for the study of electromagnetic-thermal-flow multi-field coupling characteristics of converter transformers, the calculation method of single coupling of fluid field and temperature field is mostly used at this stage. During the calculation process, if only the temperature change of the loss accumulation effect is considered, It will lead to lower solution accuracy, which will affect the accurate solution of temperature rise characteristics. When building a converter transformer electromagnetic-heat-flow multi-physics two-way coupling model based on existing simulation software, there are also problems with a large number of grids and different physics. Problems such as difficulty in mapping grid data between fields and time-consuming calculations have restricted the development of electromagnetic-thermal-flow multi-physics numerical simulation technology for large-scale converter transformers.

Therefore, one of the core inventions of the embodiments of the present invention is to provide a method for calculating the temperature rise characteristics of the converter transformer windings from the perspective of heat load transfer and meshing in the electromagnetic-thermal-flow coupling model of the converter transformer. , first establish a numerical model of the electromagnetic field of the converter transformer to solve the loss density distribution of the converter transformer windings; then, according to the winding loss density distribution, construct a rectangular grid array of loss distribution in different line cake areas of the converter transformer windings, so that the converter transformer winding losses can be Density distribution, a rectangular grid array is constructed in a targeted manner; then a thermal-flow coupling numerical model of the converter transformer is established, and the converter transformer winding line cake is divided into rectangular grids based on the rectangular grid array; then based on the rectangular The heat load transfer process of the converter transformer winding loss density is carried out in the form of a grid array, 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 rectangular grid of the winding line cake according to the calculation requirements. array to improve the accuracy of the winding temperature calculation; then conduct simulation calculations of the thermal-flow coupling numerical model of the transformer winding, and use the winding wire cake temperature distribution under the thermal-flow coupling of the converter transformer winding as the reference temperature for the winding conductivity temperature change characteristics, using Based on the updated calculation of the winding conductivity of the electromagnetic field numerical model, in the embodiment of the present invention, by considering the temperature change characteristics of the winding conductivity, the electromagnetic-heat-flow two-way coupling of the converter transformer is realized, and heterogeneity between different physical fields can be avoided. The node coupling process in the grid has strong versatility and broad application prospects.

Referring to Figure 1, a flow chart of a method for calculating the temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention is shown. Specifically, it may include the following steps:

Step 101: Calculate the line cake loss density distribution of the converter transformer winding, and the line cake loss density distribution corresponds to multiple line cake areas;

Calculating the wire cake 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 a pie-type winding. The pie-type winding is composed of several wire cakes wound with flat conductors, and spacers are added between the wire cakes to form radial insulation between the cakes. oil passage, the line cake loss can be understood as the heat loss generated by the winding line cake when the converter transformer winding is operating, and the line cake loss density distribution can be understood as the heat loss (density) of the converter transformer winding in different lines. Distribution of the pie area. The greater the loss density in a certain line cake area, the greater the heat loss in this area. On the contrary, the smaller the loss density, the smaller the heat loss in this area.

In practical applications, the electromagnetic field numerical model of the converter transformer can be established to calculate the loss density distribution on the converter transformer winding. This process can be summarized as the construction of the electromagnetic field numerical model (including the addition of model materials), the excitation current Loading, high-order harmonics of excitation current, and temperature change characteristics of winding conductivity.

Specifically, the steps for calculating the line cake loss density distribution of the converter transformer winding may include: first establishing an electromagnetic field numerical model corresponding to the converter transformer winding, and dividing the converter transformer winding into multiple line cake areas; and then based on the electromagnetic field numerical value Model, load the excitation current, perform high-order harmonic analysis on the excitation current, and obtain the high-order harmonic current; then obtain the winding conductor temperature of the converter transformer winding, and calculate the winding conductivity value based on the winding conductor temperature; finally, based on the high-order harmonic current Wave current and winding conductivity values are used to calculate the wire cake loss density distribution of the converter transformer windings.

Furthermore, the electromagnetic field numerical model corresponding to the converter transformer winding established in the embodiment of the present invention can mainly include structures such as the converter transformer core, windings, clamps, pull plates, magnetic shielding and external air areas, where the external The size of the air region can be determined based on the specific model to be solved and the requirements.

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 to the circuit from 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 working, the resistance is large and the current is small. Therefore, the heat loss of the winding (winding loss) can be calculated according to Joule's law.

The field-circuit coupling model of synchronous generator is one of the important models in the power system. It describes the interaction between the generator and the power grid. In the operation of the power system, the parameterization of the field-circuit coupling model of synchronous generator The establishment directly affects the stability and security of the power system.

Among them, the analytical formula of high-order harmonic current is as follows:

i(t)＝∑I _mh sin(hωt)(h＝6n±1)

In the formula, i(t) represents the excitation current containing higher harmonics, t represents time, I _mh represents the amplitude of each harmonic current, ω represents frequency, n represents the order of harmonics, n=1, 2, 3... .

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 Fire and other serious accidents, therefore, the calculation of current loss is an important factor in the analysis of temperature rise characteristics.

In the embodiment of the present invention, the current loss when the converter transformer winding is working is used as the heat loss of the winding wire cake, and the energy loss inside the conductor per unit time is used for calculation. Taking Watt (W) as the unit, according to Joule's law, it can be obtained: P _w =I Rt, where P _w represents heat loss, I represents current, R represents resistance, t represents time, the unit is seconds. After calculating the heat loss of the winding wire cake, combined with the winding wire cake volume or wire cake area , the loss density in different line cake areas of the winding can be obtained.

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

Furthermore, the reciprocal of resistivity is conductivity, and there is a reciprocal relationship between the two. In power-related calculations, temperature change characteristics have a great correlation with conductivity. Generally speaking, the conductivity of metal changes with temperature. It decreases with increasing temperature, while the conductivity of semiconductors increases with increasing temperature. Within a temperature range, the conductivity can be approximated as being proportional to temperature. In practical applications, a reference temperature needs to be preset according to the actual situation to compare the conductivity of the converter transformer winding under different temperature conditions.

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

In the formula, σ(T) represents the conductivity of the winding conductor, σ ₀ represents the conductivity at the reference temperature, T represents the winding conductor temperature of the converter transformer winding, T ₀ is the reference temperature, and α is the coefficient of conductivity change with temperature.

Step 102: Construct a loss distribution grid array of the multiple line cake areas according to the line cake loss density distribution, and each line cake area corresponds to a grid array point;

In a specific implementation, the process of constructing a loss distribution grid array for multiple line cake areas based on the line cake loss density distribution may include the following steps:

First, build an original distribution grid array based on multiple line cake areas, and set a grid array point for each line cake area;

Then, the number of amplitude and axial points of the original distribution grid array is continuously increased, and the spacing of the grid array points corresponding to each line cake area is continuously reduced. Combined with the line cake loss density distribution, the overall loss of the converter transformer winding is calculated, etc. Effective error;

When the overall loss equivalent error is less than or equal to the preset loss error, the loss distribution grid array of multiple line cake areas is determined, so that a rectangular grid array can be constructed specifically based on the distribution of the converter transformer winding loss density.

Further, by using the rectangular grid division method, the rectangular grid array point spacing in each line cake area can be continuously reduced by continuously increasing the loss density distribution of the converter transformer winding in the rectangular grid array width and axial points, until The overall loss equivalent error satisfies the following formula:

In the formula, P _i represents the loss density at the rectangular grid array points, 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 line cake loss density distribution, and S represents the line cake area. area.

In this step, the actual winding loss density distribution is equivalent in the form of a winding loss density grid array 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 width and direction can be automatically selected. Number of axial points.

In the steps of the foregoing embodiments, when constructing the loss distribution grid array, the converter transformer winding is treated as a whole to divide the line cake area, that is, several line cakes in a converter transformer winding are regarded as a whole. Area division is divided into multiple line cake areas. For example, there are 3 line cakes in the converter transformer winding. When dividing the area, the 3 line cakes are divided as a whole and divided into 15 line cake areas. At this time A loss distribution grid array can be constructed, which corresponds to 15 line cake areas. There are 15 grid array points in the loss distribution grid array, and one grid array point corresponds to one line cake area. .

In another processing method (processing method 2), in addition to the above-mentioned regional division method, the regional division method can also be used for regional division. That is, the line cake is used as the basis for regional division, and the converter transformer windings are first divided into There are multiple line cake areas, and then the line cake area corresponding to each line cake is divided into multiple sub-areas. For the construction steps of the loss distribution grid array, the converter transformer can be constructed separately according to the loss distribution on the converter transformer windings. Rectangular grid array of loss distribution in different line cake areas of the converter transformer winding. For example, there are 3 line cakes in the converter transformer winding. When dividing the area, it can be divided into 3 line cake areas, and each line cake area corresponds to one line cake, and then you can continue to divide each line cake into areas. For example, according to the actual situation, divide the first line cake area into 10 sub-areas, divide the second line cake area into 15 sub-areas, and divide the third line cake area into 15 sub-areas. The line cake area is divided into 20 sub-areas, and then corresponding loss distribution grid arrays can be constructed for the three line cakes. At this time, there are 15 grid array points in the loss distribution grid array corresponding to the first line cake. , there are 20 grid array points in the loss distribution grid array corresponding to the second line cake, and there are 20 grid array points in the loss distribution grid array corresponding to the third line cake, and each grid array point is Each corresponds to a sub-area of the current line pie.

Step 103, perform meshing on the plurality of line cake areas according to the loss distribution grid array, and then calculate the array point loss density of each grid array point based on the meshing results;

In a specific implementation, the implementation process of meshing multiple line cake 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 results can include Follow these steps:

Step S1031: Establish a thermal-flow coupling numerical model corresponding to the converter transformer winding;

Specifically, the established thermal-flow coupling numerical model of the converter transformer can include structures such as the converter transformer core, windings, baffles, and oil tanks. The establishment process of the thermal-flow coupling numerical model can mainly include: first adding model materials, and then Set the heat transfer and inlet and outlet boundary conditions, and then determine the heat transfer coefficient, thermal conductivity and environmental parameters.

Among them, the boundary condition of the oil flow inlet of the converter transformer is set to the velocity inlet, the direction is the vertical 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 commutation The convective heat transfer coefficient of the transformer surface and the surface radiation emissivity.

Step S1032: Carry out line cake meshing for the converter transformer windings in the thermal-flow coupling numerical model according to the loss distribution grid array;

Then, according to the loss distribution grid array, with the loss distribution grid array point as the center, the converter transformer winding in the thermal-flow coupling numerical model can be divided into line cake rectangular grids, so that the winding loss density distribution rectangular grid array The point is located at the center of the rectangular grid of the winding wire pie.

Specifically, five boundary layers are set at the fluid-solid coupling interface between the winding wire cake and the transformer oil, and the boundary layer height growth rate is set. The grid height of the first layer can be determined according to the appropriate wall function y ⁺ . The grid height of the first layer is Determine the following formula:

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

In addition to meshing the winding line cake area, in order to improve the calculation accuracy, the area around the winding can also be selected for meshing according to the solution requirements. For example, for other oil flow area meshes, the calculation accuracy and Choose an appropriate meshing method based on efficiency.

In the same way, for the processing method 2 mentioned in the previous embodiment, for the line cake grid segmentation step of the converter transformer winding, a rectangular grid array can be based on the loss distribution in different line cake areas of the converter transformer winding, with reference to the above grid section. In this way, the different line cakes of the converter transformer winding are 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 line cake rectangular grid.

For better explanation, refer to Figure 2, which shows a rectangular grid array and rectangular grid division diagram of the loss density distribution of the converter transformer winding cake.

In Figure 2, the first schematic diagram is a schematic diagram of the winding line cake of the converter transformer magnetic field numerical model, which shows that the converter transformer winding is divided into multiple line cake areas through the electromagnetic field numerical model; the second schematic diagram is the winding line Schematic diagram of the construction of the cake loss density distribution array, which shows that the loss distribution grid array of multiple line cake areas is constructed based on the line cake loss density distribution; the third schematic diagram is a schematic diagram of the rectangular grid division of the converter transformer winding line cake, which shows that according to Loss distribution grid array, with the loss distribution grid array point as the center, the converter transformer winding in the thermal-flow coupling numerical model is divided into line cake rectangular grids. At this time, the winding loss density is distributed at the rectangular grid array points. Located in the center of the rectangular grid of the winding wire cake.

Step S1033: According to the line cake meshing results, the bilinear interpolation method is used to calculate the loss density of each grid array point through the electromagnetic field numerical model, and the corresponding interpolation point loss density of each grid array point is obtained. And the interpolated point loss density is used as the array point loss density of the grid array points.

After meshing the winding line cake area, the heat load transfer step of the converter transformer winding can be performed. Specifically, according to the winding meshing situation in the thermal-flow coupling numerical model of the converter transformer, based on the double-line The linear interpolation method is used to interpolate the loss density of the rectangular grid array in different line cake areas of the converter transformer winding. The calculation formula is as follows:

In the formula, Q represents the loss density of the interpolation point, Q ₁₁ , Q ₂₁ , Q ₁₂ , and Q ₂₂ respectively represent the loss density at the four corners of the loss density rectangular grid array, (x, y) is the coordinate of the interpolation point, (x ₁ , y ₁ ) and (x ₂ , y ₂ ) are both loss density grid array point coordinates.

Step 104: Calculate the temperature distribution characteristics of different line cake areas of the converter transformer winding according to the loss density of each array point;

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

Step S1041: For each line cake area, load the array point loss density to the winding grid node;

In the form of grid array points, load the calculated array point loss density to the winding grid unit or node of the thermal-flow coupling numerical model of the converter transformer. The loading method of the loss density includes but is not limited to manual matching input, Configuration file loading and parametric design language execution, etc.

Step S1042: Obtain the line cake area of the converter transformer winding, and use a thermal-flow coupling numerical model to perform integral homogenization processing on the regional temperatures of different line cake areas in the converter transformer winding according to the winding conductor temperature and line cake area. , obtain the average temperature of the wire cake, where the average temperature of the wire cake is used to characterize the temperature distribution characteristics of different wire cake areas in the converter transformer winding.

Then the winding temperature rise can be calculated based on the thermal-flow coupling numerical model of the converter transformer, and the temperatures in different line cake areas of the converter transformer winding can be integrated and homogenized. Specifically, the average line cake temperature in different line cake areas can be expressed as The following formula:

In the formula, T _av represents the average temperature of the wire cake of the converter transformer winding.

In this step, the heat load transfer process of the converter transformer winding loss density is 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 be flexibly based on calculation needs Adjust the winding pie rectangular grid array to improve the accuracy of winding temperature calculations.

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

Specifically, it is judged whether the average temperature of the line cake of the converter transformer winding and the initial temperature error meet the temperature difference accuracy requirements (for example, whether it is less than ±0.1°C), and at the same time, it is judged whether the line cake loss meets the loss accuracy requirements. If so, the temperature The distribution characteristics represent that the error between the average temperature of the line cake in different line cake areas and the reference temperature is less than the preset temperature difference value, and the line cake loss density distribution represents that the winding loss is less than the preset accuracy error value, then the temperature rise characteristics of the converter transformer windings are output. result.

Furthermore, when judging the accuracy of the wire cake loss, the wire cake losses of different windings can be calibrated based on the following formula to verify whether the calculation accuracy requirements are met.

In the formula, Q _ohm represents the winding loss calculated through the electromagnetic field numerical model, that is, the heat loss, Represents the winding loss when the winding is at the reference temperature T ₀ , and T _k is the temperature factor of the resistance changing with temperature.

As an optional embodiment, if the temperature distribution characteristics represent that the error between the average temperature of the wire cake in different wire cake areas and the reference temperature is greater than or equal to the preset temperature difference value, and/or, the wire cake loss density distribution represents that the winding loss is greater than or equal to the preset temperature difference, Assuming the accuracy error value, it can be based on the current average temperature of the wire cake in different wire cake areas, that is, the current average temperature of the wire cake in different wire cake areas can be used as the new winding conductor temperature, and substituted into the conductivity temperature change in the previous embodiment Linear characteristic calculation formula, recalculate the winding conductivity value, and repeat the processing flow from the wire cake loss density distribution calculation step to the temperature distribution characteristic calculation step. Since this process is introduced in detail in the previous embodiment, it will not be described in detail here. .

In the embodiment of the present invention, 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 for the loss density distribution of the converter transformer winding. Then, a commutation transformer is constructed based on the winding loss density distribution. The loss distribution in different line cake areas of the transformer winding is a rectangular grid array, so as to construct a rectangular grid array in a targeted manner according to the distribution of the loss density of the converter transformer winding; then a thermal-flow coupling numerical model of the converter transformer is established, and based on the rectangular grid The grid array is used to divide the converter transformer winding line cake into rectangular grids; then the heat load transfer process of the converter transformer winding loss density is carried out based on the rectangular grid array form, which avoids the heterogeneity between the electromagnetic field and the temperature field of the converter transformer. In the node coupling process in the grid, the rectangular grid array of the winding line cake can also be flexibly adjusted according to the calculation requirements, thereby improving the accuracy of the winding temperature calculation. Then, the simulation calculation of the thermal-flow coupling numerical model of the transformer winding is carried out to convert the converter transformer The temperature distribution of the winding wire cake under winding heat-flow coupling is used as the reference temperature for the temperature change characteristics of the winding conductivity, and is used for the updated calculation of the winding conductivity of the electromagnetic field numerical model. In the embodiment of the present invention, by considering the temperature change characteristics of the winding conductivity, it not only realizes the electromagnetic-heat-flow bidirectional coupling of the converter transformer, improves the calculation accuracy of the winding temperature rise characteristics, but also avoids heterogeneity between different physical fields. Node coupling process in the grid.

For better explanation, refer to FIG. 3 , which shows an overall flow chart of a method for calculating the temperature rise characteristics of a commutation transformer winding provided by an embodiment of the present invention. It should be noted that in this embodiment, only commutation The general process of the method for calculating the temperature rise characteristics of the transformer winding is exemplified. The detailed introduction of each step can be understood with reference to the relevant content in the foregoing embodiments. It will not be described in detail here. It can be understood that the present invention does not limit this.

Step S1 (converter transformer winding loss calculation step): Establish the electromagnetic field numerical model of the converter transformer winding, and calculate the line cake loss density distribution on the converter transformer winding.

Step S2 (Construction step of rectangular grid array of loss density distribution of converter transformer winding): According to the loss density distribution of the line cake, construct a rectangular grid array of loss distribution in different line cake areas of the converter transformer winding.

Step S3 (thermal-flow coupling numerical model establishment step): Establish a thermal-flow coupling numerical model of the converter transformer winding.

Step S4 (converter transformer winding meshing step): Carry out rectangular meshing on the converter transformer winding line cake according to the loss distribution rectangular grid array.

Step S5 (converter transformer winding heat load transfer step): According to the winding grid segmentation and based on the bilinear interpolation method, the loss density of the rectangular grid array in different line cake areas of the converter transformer winding is interpolated to calculate The converter transformer winding loss density is loaded into the thermal-flow coupled numerical model winding grid cells or nodes in the form of grid array points.

Step S6 (converter transformer winding temperature rise calculation step): According to the thermal-flow coupling numerical model, calculate the temperature distribution characteristics of different line cakes (regions) of the converter transformer winding.

Step S7 (calculation accuracy judgment step): Determine whether the temperature distribution and loss density verification meet the error requirements, that is, judge whether the average temperature of the wire cake of the converter transformer winding and the initial temperature error meet the temperature difference accuracy requirements, and determine the wire cake loss at the same time Whether the loss accuracy requirements are met, if so, the temperature rise characteristic results of the converter transformer winding are output; if not, based on the current converter transformer winding temperature and the conductivity temperature change linear characteristics, the winding conductivity value is updated, and then repeated Execute step S1 to step S6.

Referring to Figure 4, a structural block diagram of a device for calculating the temperature rise characteristics of a converter transformer winding provided by an embodiment of the present invention is shown. Specifically, it may include:

The line cake loss density distribution calculation module 401 is used to calculate the line cake loss density distribution of the converter transformer winding, and the line cake loss density distribution corresponds to multiple line cake areas;

The loss distribution grid array construction module 402 is used to construct a loss distribution grid array of the plurality of line cake areas according to the line cake loss density distribution, and each of the line cake areas corresponds to a grid array point;

The array point loss density calculation module 403 is used to mesh the multiple line cake areas according to the loss distribution grid array, and then calculate the density of each grid array point based on the meshing results. Array point loss density;

The temperature distribution characteristic calculation module 404 is used to calculate the temperature distribution characteristics of different line cake areas of the converter transformer winding according to the loss density of each array point;

The temperature rise characteristic result output module 405 is 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.

In an optional embodiment, the line cake loss density distribution calculation module 401 includes:

An electromagnetic field numerical model establishment module is used to establish an electromagnetic field numerical model corresponding to the converter transformer winding, and divide the converter transformer winding into multiple line cake areas;

A high-order harmonic analysis module is used to load the excitation current based on the electromagnetic field numerical model, and perform high-order harmonic analysis on the excitation current to obtain 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 based on the winding conductor temperature;

The line cake loss density distribution calculation submodule is used to calculate the line cake loss density distribution of the converter transformer winding based on the high-order harmonic current and the winding conductivity value.

In an optional embodiment, the loss distribution grid array building module 402 includes:

An original distribution grid array building module is used to construct an original distribution grid array based on the plurality of line cake areas, and set a grid array point for each of the line cake areas;

The grid array adjustment module is used to continuously increase the width and axial points of the original distribution grid array, while continuously reducing the grid array point spacing corresponding to each of the line cake areas, and combined with the line cake Loss density distribution, calculating the overall loss equivalent error of the converter transformer winding;

The loss distribution grid array determination module is configured to determine the loss distribution grid array of the plurality of line cake areas when the overall loss equivalent error is less than or equal to the preset loss error.

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

A thermal-flow coupling numerical model is used to establish a thermal-flow coupling numerical model corresponding to the converter transformer winding;

A line cake meshing module, configured to perform line cake meshing on the converter transformer windings in the thermal-flow 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 of the grid array points through the electromagnetic field numerical model using the bilinear interpolation method based on the line cake grid segmentation results to obtain each of the grids. Corresponding interpolation point loss density of each grid array point, and use the interpolation point loss density as the array point loss density of the grid array point.

In an optional embodiment, the thermal-flow coupling numerical model includes multiple winding grid nodes, each of the winding grid nodes corresponds to a line cake area, and the temperature distribution characteristic calculation module 404 includes:

An array point loss density loading module is used to load the array point loss density to the winding grid node for each line cake area;

The integral homogenization processing module is used to obtain the line cake area of the converter transformer winding, and use the thermal-flow coupling numerical model to calculate the commutation transformer according to the winding conductor temperature and the line cake area. The regional temperatures of different line cake areas in the transformer winding are integrated and homogenized to obtain the average line cake temperature. The average line cake temperature is used to characterize the temperature distribution characteristics of different line cake areas in the converter transformer winding.

In an optional embodiment, the temperature rise characteristic result output module 405 is specifically used to:

If the temperature distribution characteristics represent that the error between the average temperature of the wire cake in different wire cake areas and the reference temperature is less than the preset temperature difference value, and the wire cake loss density distribution represents the winding loss is less than the preset accuracy error value, then output the Temperature rise characteristic results of converter transformer windings.

In an optional embodiment, the device further includes:

If the temperature distribution characteristics represent that the error between the average temperature of the wire cake in different wire cake areas and the reference temperature is greater than or equal to the preset temperature difference value, and/or, the wire cake loss density distribution represents that the winding loss is greater than or equal to the preset accuracy error value , then based on the current average temperature of the wire cake in different wire cake areas, the winding conductivity value is recalculated, and the processing flow from the wire cake loss density distribution calculation step to the temperature distribution characteristic calculation step is repeated.

As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For relevant details, please refer to the partial description of the foregoing method embodiment.

An embodiment of the present invention also provides an electronic device, which includes a processor and a memory:

Memory is used to store program code and transmit the program code to the processor;

The processor is configured to execute the method for calculating the temperature rise characteristics of the converter transformer winding according to any embodiment of the present invention according to the instructions in the program code.

Embodiments of the present invention also provide a computer-readable storage medium. The computer-readable storage medium is used to store program codes. The program codes are used to execute the method for calculating the temperature rise characteristics of the converter transformer windings according to any embodiment of the present invention.

Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be described again here.

In the several embodiments provided in this 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 illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or can be integrated into another system, or some features can be ignored, or not implemented. On the other hand, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection of the devices or units may be in electrical, mechanical or other forms.

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 they may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or software functional units.

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

As mentioned above, the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the foregoing. The technical solutions described in each embodiment may be modified, or some of the technical features may be equivalently replaced; however, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims (10)

1. A method for calculating the temperature rise characteristics of a converter transformer winding, which is characterized by including: Calculate the line cake loss density distribution of the converter transformer winding, and the line cake loss density distribution corresponds to multiple line cake areas; Construct a loss distribution grid array of the multiple line cake areas according to the line cake loss density distribution, and each line cake area corresponds to a grid array point; According to the loss distribution grid array, perform grid division on the plurality of line cake areas, and then calculate the array point loss density of each grid array point based on the grid division results; Calculate the temperature distribution characteristics of different line cake areas of the converter transformer winding according to the loss density of each array point; If the temperature distribution characteristic and the loss density distribution meet the preset conditions, the temperature rise characteristic result of the converter transformer winding is output. 2. The method for calculating the temperature rise characteristics of the converter transformer winding according to claim 1, characterized in that the calculation of the line cake loss density distribution of the converter transformer winding includes: Establish a numerical model of the electromagnetic field corresponding to the converter transformer winding, and divide the converter transformer winding into multiple line cake areas; Based on the electromagnetic field numerical model, load the excitation current, perform high-order harmonic analysis on the excitation current, and obtain the high-order harmonic current; Obtain the winding conductor temperature of the converter transformer winding, and calculate the winding conductivity value based on the winding conductor temperature; According to the high-order harmonic current and the winding conductivity value, the line cake loss density distribution of the converter transformer winding is calculated. 3. The method for calculating the temperature rise characteristics of the converter transformer winding according to claim 2, wherein the loss distribution grid array of the plurality of line cake areas is constructed according to the line cake loss density distribution, include: Based on the plurality of line cake areas, construct an original distribution grid array, and set a grid array point for each of the line cake areas; Continuously increase the number of width and axial points of the original distribution grid array, while continuously reducing the grid array point spacing corresponding to each of the line cake areas, and combined with the line cake loss density distribution, calculate the replacement The overall loss equivalent error of the current transformer winding; When the overall loss equivalent error is less than or equal to the preset loss error, the loss distribution grid array of the multiple line cake areas is determined. 4. The method for calculating the temperature rise characteristics of the converter transformer winding according to claim 2 or 3, characterized in that the plurality of line cake areas are meshed according to the loss distribution grid array. , and then based on the meshing results, calculate the array point loss density of each grid array point, including: Establish a thermal-flow coupling numerical model corresponding to the converter transformer winding; According to the loss distribution grid array, perform line cake meshing on the converter transformer winding in the thermal-flow coupling numerical model; According to the line cake meshing results, the bilinear interpolation method is used to perform loss density interpolation calculation on each of the grid array points through the electromagnetic field numerical model, and the corresponding interpolation points of each of the grid array points are obtained. loss density, and use the interpolation point loss density as the array point loss density of the grid array points. 5. The method for calculating the temperature rise characteristics of the converter transformer winding according to claim 4, characterized in that the thermal-flow coupling numerical model contains a plurality of winding grid nodes, and each of the winding grid nodes corresponds to A line cake area, the temperature distribution characteristics of different line cake areas of the converter transformer winding are calculated based on the loss density of each array point, including: For each line cake area, load the array point loss density to the winding grid node; Obtain the line cake area of the converter transformer winding, and use the thermal-flow coupling numerical model to calculate the different line cake areas in the converter transformer winding according to the winding conductor temperature and the line cake area. The temperature is integrated and homogenized to obtain the average temperature of the line cake. The average temperature of the line cake is used to characterize the temperature distribution characteristics of different line cake areas in the converter transformer winding. 6. The method for calculating the temperature rise characteristics of the converter transformer winding according to claim 2, characterized in that if the temperature distribution characteristics and the loss density distribution meet preset conditions, the converter transformer is output The winding temperature rise characteristics results include: If the temperature distribution characteristics represent that the error between the average temperature of the wire cake in different wire cake areas and the reference temperature is less than the preset temperature difference value, and the wire cake loss density distribution represents the winding loss is less than the preset accuracy error value, then output the Temperature rise characteristic results of converter transformer windings. 7. The method for calculating the temperature rise characteristics of the converter transformer winding according to claim 6, further comprising: If the temperature distribution characteristics represent that the error between the average temperature of the wire cake in different wire cake areas and the reference temperature is greater than or equal to the preset temperature difference value, and/or, the wire cake loss density distribution represents that the winding loss is greater than or equal to the preset accuracy error value , then based on the current average temperature of the wire cake in different wire cake areas, the winding conductivity value is recalculated, and the processing flow from the wire cake loss density distribution calculation step to the temperature distribution characteristic calculation step is repeated. 8. A device for calculating temperature rise characteristics of converter transformer windings, which is characterized in that it includes: The line cake loss density distribution calculation module is used to calculate the line cake loss density distribution of the converter transformer winding, and the line cake loss density distribution corresponds to multiple line cake areas; A loss distribution grid array building module, configured to construct a loss distribution grid array of the plurality of line cake areas according to the line cake loss density distribution, each of the line cake areas corresponding to a grid array point; Array point loss density calculation module, used to perform grid division on the plurality of line cake areas according to the loss distribution grid array, and then calculate the array of each grid array point based on the grid division results. Point loss density; A temperature distribution characteristic calculation module, used to calculate the temperature distribution characteristics of different line cake areas of the converter transformer winding according to the loss density of each array point; A temperature rise characteristic result output module is 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. 9. An electronic device, characterized in that the device includes a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the method for calculating the temperature rise characteristics of the converter transformer winding according to any one of claims 1 to 7 according to instructions in the program code. 10. A computer-readable storage medium, characterized in that the computer-readable storage medium is used to store program code, and the program code is used to execute the converter transformer winding according to any one of claims 1-7. Calculation method of temperature rise characteristics.