Transformer internal temperature field deduction method based on multi-point transformation

Abstract

The invention discloses a transformer internal temperature field deduction method based on multi-point transformation, which relates to the field of transformer state monitoring, and realizes temperature deduction of points which cannot be directly measured in a transformer by selecting part of surface temperature measurement points in an external box body of the transformer and carrying out multi-point transformation on the surface temperature measurement points. After modeling of the deduction model is completed, temperature data of a to-be-deduced temperature point in the transformer can be obtained through calculation in combination with the deduction model after data processing of the surface temperature measurement point under any working condition. Compared with an existing method for directly measuring the temperature rise of the transformer, the method has the advantages that the operation is simple, and the temperature of each point in the transformer can be deduced without pre-embedded sensing and intrusion temperature measurement experiments.

Description

Technical Field

[0001] The invention relates to the field of transformer state monitoring, and in particular to a transformer internal temperature field deduction method based on multi-point transformation. Background Art

[0002] Transformer condition monitoring technology is a technology used to monitor and evaluate the operating status of power transformers. It can detect potential faults and abnormal conditions of transformers in a timely manner, thereby preventing accidents and ensuring the safe and stable operation of power systems. It has important application scenarios in the preventive maintenance and intelligent management of smart grids. Transformer condition monitoring technology collects data on indicators required for condition monitoring and evaluation through various sensors, and combines various analysis methods and processing methods to maintain the stable operation of transformers. In transformer condition monitoring technology, temperature field monitoring plays an important role in preventing transformers from overheating and loss. Due to the complex internal structure of the transformer and the complex electromagnetic effects during operation, it is difficult to directly measure the internal temperature of the transformer through sensors, which is the focus and difficulty of current research. Summary of the invention

[0003] The present invention aims at the problem that the specific distribution of the internal temperature field of the transformer is difficult to measure, and proposes a transformer internal temperature field deduction method based on multi-point transformation. The multi-point transformation deduction model is established through the data provided by the transformer temperature field simulation model, so as to achieve the goal of deducing the temperature of the internal point to be deduced by using the surface part point temperature through the deduction model. The technical solution of the present invention is as follows:

[0004] In a first aspect, the present application provides a method for deducing a transformer internal temperature field based on multi-point transformation, comprising the following steps:

[0005] Taking the transformer structure as a reference and combining the physical effects that affect the temperature distribution of the transformer in actual operation, a transformer temperature field simulation model is established.

[0006] Select N surface temperature measurement points at various locations on the transformer box surface, and select m temperature points to be deduced inside the transformer;

[0007] The transformer temperature field simulation model is used to calculate the temperature data corresponding to N surface temperature measurement points and m temperature points to be deduced under different working conditions;

[0008] The multi-point transformation deduction model is solved based on the calculated temperature data. The multi-point transformation deduction model is used to combine the temperature data of multiple surface temperature measurement points obtained to calculate the temperature data of the temperature points to be deduced inside the transformer under any working conditions.

[0009] A further technical solution is to solve a multi-point transformation deduction model based on the calculated temperature data, including:

[0010] Perform sensitivity analysis on the temperature data corresponding to the N calculated surface temperature measurement points under different working conditions, and select n points with higher sensitivity as surface characteristic temperature measurement points;

[0011] According to the temperature data of the selected m temperature points to be deduced and the temperature data of the n surface characteristic temperature measurement points, a corresponding multi-point transformation deduction model is established, and a solution is performed based on the temperature data.

[0012] A further technical solution is to perform sensitivity analysis on the temperature data corresponding to the N calculated surface temperature measurement points under different working conditions, including:

[0013] Sensitivity is defined as the ratio of the relative temperature change of the surface temperature measurement point to the relative temperature change of the temperature point to be deduced, expressed as:

[0014]

[0015] Where Y i is the temperature data of a certain temperature point to be deduced inside the transformer, ΔY i is the temperature change of the point under different working conditions, i = 1, 2, ..., m; X j is the temperature data of a certain temperature measuring point on the selected transformer surface, ΔX j is the temperature change of this point under different working conditions, j=1,2,…,N.

[0016] Its further technical solution is to calculate ΔX to meet the accuracy of sensitivity analysis. j , ΔY i The operating conditions selected should be similar.

[0017] A further technical solution is to establish a corresponding multi-point transformation deduction model based on the temperature data of the selected m temperature points to be deduced and the temperature data of the n surface characteristic temperature measurement points, as shown below:

[0018]

[0019] Where, Y matrix is ​​the temperature matrix of the temperature point to be deduced, Y i represents the temperature data of the selected i-th temperature point to be deduced, i = 1, 2, ..., m; X matrix is ​​the temperature matrix of the selected surface characteristic temperature measurement point, X j represents the temperature data of the jth surface characteristic temperature measurement point, j = 1, 2, ..., n; the K matrix is ​​the parameter matrix of the established multi-point transformation deduction model, K ij represents the jth surface characteristic temperature measurement point X j For the i-th temperature point Y to be deduced i Corresponding contribution in the multi-point transformation deduction model.

[0020] A further technical solution is to solve a multi-point transformation deduction model based on temperature data, including:

[0021]

[0022] Where, Y matrix is ​​the temperature matrix of the temperature point to be deduced, (Y i ) w represents the specific temperature data of the i-th temperature point to be deduced under the w-th group of working conditions calculated by the simulation model, i = 1, 2, ..., m; the X matrix is ​​the temperature matrix of the selected surface characteristic temperature measurement points, (X j ) w represents the specific temperature data of the jth surface characteristic temperature measurement point under the wth group of working conditions calculated by the simulation model, j = 1, 2, ..., n; the K matrix is ​​the parameter matrix of the multi-point transformation deduction model to be solved, (K ij ) w represents the jth surface characteristic temperature measurement point X under the wth group of working conditions j For the i-th temperature point Y to be deduced i Corresponding contribution in the multi-point transformation deduction model.

[0023] The further technical solution is to establish a transformer temperature field simulation model based on the transformer structure and the physical effects that affect the transformer temperature distribution in actual operation, including:

[0024] In COMSOL simulation software, simplify each part of the transformer and select appropriate materials to fill it so as to establish the transformer geometry model;

[0025] The relevant parameters of the in-domain effect and the heat transfer effect of the boundary part that affect the temperature field of the transformer are reasonably set to simulate the temperature field changes in the actual operation of the transformer; the in-domain effect includes the internal heat source of the transformer and the loss during operation, and the heat transfer effect includes heat conduction, heat convection and heat radiation between the transformer and the external environment;

[0026] The transformer geometric model is meshed, and the temperature field frequency domain steady-state calculation is performed to obtain the stable temperature field results of each coordinate point of the transformer geometric model.

[0027] Its further technical solution is that the internal heat source of the transformer and the loss during operation include:

[0028] Electromagnetic losses in nonlinear material cores, including hysteresis losses and eddy current losses;

[0029] The Joule heat of the coil winding is related to the current and the resistance of the coil.

[0030] Its further technical solution is that the method further comprises:

[0031] Select the temperature data of the surface characteristic temperature measurement points under different verification conditions, substitute them into the multi-point transformation deduction model to calculate the temperature data of the temperature point to be deduced;

[0032] The transformer temperature field simulation model is used to calculate the temperature data corresponding to the temperature point to be deduced under the corresponding verification conditions;

[0033] The two types of temperature data are compared to verify the reliability of the prediction performance of the multi-point transformation deduction model;

[0034] Among them, the verification conditions are the working conditions that are not used to establish the multi-point transformation deduction model.

[0035] In a second aspect, the present application further provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method described in the first aspect are implemented.

[0036] The beneficial technical effects of the present invention are:

[0037] (1) Easy to operate. The internal structure of the transformer is complex, and there are many factors that affect the temperature field. Directly measuring the temperature points to be measured inside the transformer not only requires high tolerance of the measurement equipment in harsh environments, but also requires intrusion into the transformer when the location of the temperature measurement point needs to be changed, which is cumbersome. In the transformer internal temperature field deduction method based on multi-point transformation, it is only necessary to establish a deduction model based on the temperature data provided by a reliable simulation model as a reference, and then use the temperature of some surface temperature measurement points that are easy to measure combined with the deduction model for calculation, so as to quickly obtain the temperature of the internal points to be deduced during the operation of the transformer.

[0038] (2) The algorithm is simple. Compared with the modeling process of other algorithms, the multi-point transformation deduction model is easy to implement and has a fast calculation speed. When there are many selected points, it can achieve better prediction performance for the specific temperature of the internal points to be deduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of a method for deducing the internal temperature field of a transformer based on multi-point transformation provided in this application.

[0040] Figure 2 It is a schematic diagram of the geometric structure composition of the simplified transformer temperature field simulation model provided in this application.

[0041] Figure 3 It is a schematic diagram of the distribution of the temperature points to be deduced inside the transformer and some surface temperature measurement points selected in this application on the transformer simulation model.

[0042] Figure 4 It is a transformer temperature field calculation flow chart provided in this application.

[0043] Figure 5 It is a schematic diagram of the grid division results of the transformer geometric model provided in this application.

[0044] Figure 6 It is a schematic diagram of the distribution of the surface characteristic temperature measurement points selected in this application on the transformer simulation model.

[0045] Figure 7 This is a diagram of the error sizes under different verification conditions obtained during the reliability verification of the deduction model provided in this application.

[0046] Figure 8 It is an internal structure diagram of the computer device provided by this application. DETAILED DESCRIPTION

[0047] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0048] Please refer to Figure 1 As shown, the present application provides a method for deducing the internal temperature field of a transformer based on multi-point transformation, which specifically includes the following steps:

[0049] Step 1: Taking the transformer structure as a reference and combining the physical effects that affect the temperature distribution of the transformer in actual operation, establish a transformer temperature field simulation model. Figure 2 As shown, the geometric structure of the transformer temperature field simulation model includes a transformer box 1, a plurality of heat sinks 2 distributed on the outside of the box 1, an iron core 3 located inside the box 1, and a primary winding 4 and a secondary winding 5 wound on the iron core 3. This step can be implemented in COMSOL simulation software.

[0050] Step 2: Select N surface temperature measurement points at various locations on the transformer box surface, denoted as X1, X2, X3, ..., X N , and select m temperature points to be deduced inside the transformer, denoted as Y1, Y2, ..., Y m The position distribution of each point on the transformer simulation model is as follows: Figure 3 shown.

[0051] Step 3: Use the transformer temperature field simulation model to calculate the temperature data corresponding to N surface temperature measurement points and m temperature points to be deduced under different working conditions.

[0052] Step 4: Solve the multi-point transformation deduction model based on the calculated temperature data. The multi-point transformation deduction model is used to combine the temperature data of multiple surface temperature measurement points obtained to calculate the temperature data of the temperature point to be deduced inside the transformer under any working condition.

[0053] In this embodiment, the above method steps select some surface temperature measurement points on the external box of the transformer and perform multi-point transformation on the surface temperature measurement points, thereby realizing the temperature deduction of the points inside the transformer that cannot be directly measured. Compared with the existing transformer temperature rise direct measurement method, this method has the advantages of simple operation and can deduce the temperature of each point inside the transformer without pre-embedded sensors and invasive temperature measurement experiments.

[0054] In step 1, the specific process of establishing the transformer temperature field simulation model is as follows: Figure 4 First, simplify the various parts of the transformer and select appropriate materials to fill them so as to establish Figure 2 The transformer geometric model is shown in the figure. The specific simplification method is as follows: the insulation layer, pad, fan and other structures that have little effect on the temperature field are ignored, and the external box of the transformer is equivalent to a rectangular box 1 with a heat sink 2; the iron core originally stacked by silicon steel sheets is equivalent to two pieces of low-loss soft magnetic materials of the same size and the gap between the iron core gaskets is ignored; it is assumed that the space density inside and outside the box is stable, the external environment is stable, there is no forced convection phenomenon, and the internal fluid flow rate is not considered; the materials shown in Table 1 are selected to fill the corresponding geometric model.

[0055] Table 1 Electromagnetic parameters and heat transfer parameters of oil-immersed transformer

[0056]

[0057] Then, the relevant parameters of the in-domain effect and the heat transfer effect of the boundary part that affect the temperature field of the transformer are reasonably set to accurately simulate the temperature field changes in the actual operation of the transformer. Among them, the in-domain effect includes the internal heat source of the transformer and the loss during operation. This part mainly includes the electromagnetic loss of the nonlinear material core and the Joule heat of the coil winding. The calculation formula of the electromagnetic loss is expressed as follows:

[0058] P Fe =P h +P c +P e =K h ·B m 2 ·f+K c ·(f·B m ) 2 +K e ·(f·B m ) 2 (1)

[0059] In formula (1), B m is the maximum magnetic flux peak value, f is the frequency, K h It is a constant that reflects the effect of hysteresis loss on power, K c It is a constant that reflects the effect of eddy current loss on electromagnetic loss, Ke It is a constant that represents the effect of stray loss on electromagnetic loss. Hysteresis loss (P h ) refers to the energy lost when the magnetic domain of the core material overcomes the friction of the outer wall of the magnetic domain. This part of the loss is converted into heat energy generated by the core. c ) is due to the fact that the resistivity of the core material is a finite value, and at high frequencies, eddy currents will be generated due to excitation, resulting in losses. Stray losses (P e ) is the loss due to magnetic hysteresis effect. In this model, the stray loss is relatively small and is therefore ignored.

[0060] The Joule heat of the coil winding is mainly related to the current and the resistance of the coil. Considering it as a heat source and taking into account its geometric structure, the Joule heat formula of the coil is derived as follows:

[0061]

[0062] In formula (2), Q is the total Joule heat of the coil, q0 is the unit Joule heat generated by the coil, r1 is the outer diameter of the annular coil, r2 is the inner diameter of the coil, I is the current flowing through the coil, ρ is the conductivity, N is the number of coil turns, and h is the convection heat transfer coefficient.

[0063] The heat transfer effect includes heat conduction, heat convection and heat radiation between the transformer and the external environment. The heat conduction equation is expressed as:

[0064]

[0065] In formula (3), ΔT is the temperature difference between the transformer and the external environment, λ is the thermal conductivity, S is the heat transfer contact area of ​​the transformer, and L is the core thickness.

[0066] The heat convection equation can be expressed as follows:

[0067] q=h·ΔT=Q / S (4)

[0068] In formula (4), q is the heat flux per unit area.

[0069] Thermal radiation is obtained by solving the Stefan-Boltzmann equation, which can be expressed as:

[0070]

[0071] In formula (5), ε is the emissivity (0-1), δ is the Stefan-Boltz constant, and T1 and T2 are the temperatures of the radiation surfaces 1 and 2, respectively.

[0072] Finally, mesh the geometric model of the transformer and perform a steady-state frequency-domain calculation of the temperature field to obtain the steady temperature field results of each coordinate point of the transformer geometric model. In this embodiment, free tetrahedral meshes are selected during meshing, with the maximum cell size being 0.366 m, the minimum cell size being 0.0457 m, the maximum cell growth rate being 1.45, the curvature factor being 0.5, and the narrow region resolution being 0.6. The result of the meshing is as shown in Figure 5 shown. It should be noted that the temperature field calculation in the COMSOL simulation model is based on the above heat sources and three heat transfer equations. Although the presentation forms may be different, the principles and description contents are the same.

[0073] In step 4, solving the multi-point transformation deduction model based on the calculated temperature data specifically includes: First, perform a sensitivity analysis on the temperature data corresponding to N surface temperature measurement points obtained under different working conditions, select n points (n < N) with higher sensitivity, and re-number them as X1, X2, …, X n as the surface characteristic temperature measurement points used for building the deduction model, and their position distributions on the transformer simulation model are as shown in Figure 6 shown. In this embodiment, the sensitivity is defined as: the ratio of the relative change in temperature of the surface temperature measurement point to the relative change in temperature of the temperature point to be deduced, that is, the sensitivity of temperature point X to Y should be expressed as:

[0074]

[0075] In formula (6), Y i is the temperature data of a certain temperature point to be deduced inside the transformer, ΔY i is the temperature change of this point under different working conditions, i = 1, 2, …, m. X j is the temperature data of a certain surface temperature measurement point selected on the transformer surface, ΔX j is the temperature change of this point under different working conditions, j = 1, 2, …, N. To ensure the accuracy of the sensitivity analysis, the working conditions selected when calculating ΔX j and ΔY i should be similar, so that ΔX j and ΔY i are as small as possible, and the final point selection result will be determined by comprehensively considering the sensitivity values of each surface temperature measurement point X to each Y.

[0076] Secondly, according to the temperature data of the selected m temperature points to be deduced and the temperature data of the n surface characteristic temperature measurement points, establish the corresponding multi-point transformation deduction model, which is expressed as follows:

[0077]

[0078] In formula (7), Y matrix is ​​the temperature matrix of the temperature point to be deduced, Y i represents the temperature data of the selected i-th temperature point to be deduced, i = 1, 2, ..., m. The X matrix is ​​the temperature matrix of the selected surface characteristic temperature measurement point, X j represents the temperature data of the jth surface characteristic temperature measurement point, j = 1, 2, ..., n. The K matrix is ​​the parameter matrix of the established multi-point transformation deduction model, K ij represents the jth surface characteristic temperature measurement point X j For the i-th temperature point Y to be deduced i Corresponding contribution in the multi-point transformation deduction model.

[0079] Finally, the process of solving the multi-point transformation deduction model based on temperature data includes:

[0080]

[0081] In formula (8), the specific temperature data in the X and Y matrices are calculated based on the transformer temperature field simulation model in step 1 in this solution process. It is required to select reasonable working conditions to avoid the occurrence of singular matrices in the data that affect the calculation results. The Y matrix is ​​the temperature matrix of the temperature point to be deduced, (Y i ) w represents the specific temperature data of the i-th temperature point to be deduced under the w-th group of working conditions calculated by the simulation model, i = 1, 2, ..., m; the X matrix is ​​the temperature matrix of the selected surface characteristic temperature measurement points, (X j ) w represents the specific temperature data of the jth surface characteristic temperature measurement point under the wth group of working conditions calculated by the simulation model, j = 1, 2, ..., n; the K matrix is ​​the parameter matrix of the multi-point transformation deduction model to be solved, (K ij ) w represents the jth surface characteristic temperature measurement point X under the wth group of working conditions j For the i-th temperature point Y to be deduced i Corresponding contribution in the multi-point transformation deduction model.

[0082] Optionally, a method for deducing the internal temperature field of a transformer based on multi-point transformation also includes step 5: selecting the temperature data of the surface characteristic temperature measurement points under different verification conditions, substituting them into the solved multi-point transformation deduction model to calculate the temperature data of the temperature point to be deduced, and using the transformer temperature field simulation model to calculate the temperature data corresponding to the temperature point to be deduced under the corresponding verification conditions, and comparing the two types of temperature data to verify the reliability of the prediction performance of the multi-point transformation deduction model. Among them, the verification conditions are working conditions that are not used to establish the multi-point transformation deduction model. It should be noted that when the multi-point transformation deduction model is actually applied, after selecting N measurable surface temperature measurement points at various parts of the transformer box surface, it is also necessary to select several surface characteristic temperature measurement points with higher sensitivity according to the sensitivity analysis method in step 4, and then substitute them into the multi-point transformation deduction model to calculate the temperature data of the temperature point to be deduced inside the transformer under any working condition, so that the deduced internal temperature data of the transformer is more accurate.

[0083] The following takes the transformer model SF11-M-8000 / 110 as an example, and combines the specific contents of each step of the above method to introduce the multi-point transformation deduction process of the temperature points to be deduced on each three-phase winding inside the transformer. First, according to step 1, simplify the structure of the transformer part that has little effect on the temperature field and is difficult to model, and establish a transformer temperature field simulation model with the actual transformer model SF11-M-8000 / 110 as a reference. According to the point selection principle in step 2, select Figure 3 There are N=14 transformer surface temperature measurement points and m=3 transformer internal temperature points to be deduced, and the specific coordinates of each point are shown in Table 2.

[0084] Table 2 Coordinates of transformer surface temperature measurement points and internal temperature points to be deduced

[0085]

[0086] After completing the selection of measurable points, Figure 3 The sensitivity analysis is performed on the 14 transformer surface temperature measurement points shown in the figure. The specific analysis process is as follows:

[0087] (1) Five working conditions with similar conditions are selected, and the working conditions are set as follows: ①h=10, T=20℃, I=60A; ②h=10, T=20.5℃, I=60A; ③h=9, T=20℃, I=60A; ④h=10, T=20℃, I=61A; ⑤h=15, T=20℃, I=62A. Taking working condition ① as the benchmark, the sensitivity corresponding to working conditions ⑤-①, ④-①, ③-①, and ②-① is calculated according to formula (6), and the 14 points on the surface are matched with the 3 points inside to form a 3×14 matrix, thereby obtaining the sensitivity matrices S1, S2, S3, and S4. The corresponding elements in the four sensitivity matrices are added and averaged to obtain the matrix Sa , S a The element S in aij It means S(X j ,Y i ) is X j Y i The sensitivity of S a The values ​​of each element are shown in Table 3 (keep two decimal places). It is worth noting that although the operating conditions of ⑤ and ① seem to be quite different, the increase in current is actually equivalent to increasing the heat generated by the heat source, and the increase in the convection heat transfer coefficient h is the increase in the heat exchanged between the convection heat transfer and the external environment, which is equivalent to more heat dissipation. Therefore, after neutralizing and calculating, ΔX and ΔY can also be guaranteed to be small.

[0088] Table 3 Sensitivity matrix S a Each element value

[0089]

[0090] (2) Because the matrix S a Each column of data is the value of the surface temperature measurement point for each internal point to be deduced. Therefore, in order to comprehensively consider the sensitivity of each point, it should be selected according to the average value of the sum of the elements in each column, and the sensitivity should be arranged from large to small as shown in Table 4 (the sensitivity size retains 2 decimal places).

[0091] Table 4 Sensitivity matrix S a The mean of each column element is sorted from large to small

[0092]

[0093] (3) In summary, take n = 7, select Figure 3 The 7 points with the highest sensitivity, X2, X3, X5, X6, X7, X8, and X9, are renumbered as X1, X2, ..., X7, and the following is obtained: Figure 6 Schematic diagram of the distribution of surface feature temperature measurement points shown.

[0094] After completing the selected points for sensitivity analysis, the temperature field sizes under several groups of different working conditions are calculated to obtain the specific temperature data of each selected point under the corresponding working conditions. Seven groups are selected to solve the multi-point transformation deduction model, and the specific values ​​of the K matrix are finally obtained as shown in Table 5 (keep two decimal places).

[0095] Table 5K matrix element values

[0096]

[0097] After the model is obtained, in order to verify the reliability of the model and its prediction performance of internal temperature under different working conditions, 15 working conditions as shown in Table 6 are selected to compare the internal deduced temperatures calculated based on the deduction model at their surface characteristic temperature measurement points with the actual temperature data of the corresponding points calculated in the simulation model, and the specific data shown in the following table are obtained:

[0098] Table 6 Comparison data between simulation calculation and model calculation of internal deduction temperature

[0099]

[0100]

[0101] The error size of each internal point to be deduced under each working condition in Table 6 is fitted into a curve, and the following is obtained: Figure 7 The corresponding error size under each working condition is shown. It can be seen that after selecting the 7 most sensitive surface characteristic temperature measurement points, the multi-point transformation deduction model formed has a temperature error of less than 1% in most of the deduced conditions. A few forced convection conditions (i.e., h is very large) have relatively large errors within 3% due to the small number of similar conditions selected during the solution. The above analysis shows that the multi-point transformation deduction model has good predictive performance. For any other temperature point to be deduced inside the transformer, it can also be obtained in a similar way according to the multi-point transformation deduction model establishment method of Y1, Y2, and Y3 mentioned above, and finally the deduction function relationship of each point is obtained, and the temperature field distribution at any position inside the transformer can be deduced.

[0102] Based on the same inventive concept, the present application also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 8 As shown. The computer device includes a processor, a memory, a communication interface, a display unit and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, the above-mentioned transformer internal temperature field deduction method based on multi-point transformation is implemented. The display unit of the computer device can be a liquid crystal display or an electronic ink display, and the input device of the computer device can be a touch layer covered on the display, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse.

[0103] Those skilled in the art will understand that Figure 8 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0104] The above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the protection scope of the present invention.

Claims

1. A method for deducing the internal temperature field of a transformer based on multi-point transformation, characterized in that: The method comprises: Taking the transformer structure as a reference and combining the physical effects that affect the temperature distribution of the transformer in actual operation, a transformer temperature field simulation model is established. Select N surface temperature measurement points at various locations on the transformer box surface, and select m temperature points to be deduced inside the transformer; The transformer temperature field simulation model is used to calculate the temperature data corresponding to N surface temperature measurement points and m temperature points to be deduced under different working conditions; A multi-point transformation deduction model is solved based on the calculated temperature data. The multi-point transformation deduction model is used to combine the temperature data of multiple surface temperature measurement points obtained to calculate the temperature data of the temperature point to be deduced inside the transformer under any working condition.

2. The transformer internal temperature field deduction method based on multi-point transformation according to claim 1 is characterized in that: The method of solving the multi-point transformation deduction model based on the calculated temperature data includes: Perform sensitivity analysis on the temperature data corresponding to the N calculated surface temperature measurement points under different working conditions, and select n points with higher sensitivity as surface characteristic temperature measurement points; According to the temperature data of the selected m temperature points to be deduced and the temperature data of the n surface characteristic temperature measurement points, a corresponding multi-point transformation deduction model is established, and a solution is performed based on the temperature data.

3. The transformer internal temperature field deduction method based on multi-point transformation according to claim 2 is characterized in that: The sensitivity analysis of the temperature data corresponding to the calculated N surface temperature measurement points under different working conditions includes: Sensitivity is defined as the ratio of the relative temperature change of the surface temperature measurement point to the relative temperature change of the temperature point to be deduced, expressed as: Where Y i is the temperature data of a certain temperature point to be deduced inside the transformer, ΔY i is the temperature change of the point under different working conditions, i = 1, 2, ..., m; X j is the temperature data of a certain temperature measuring point on the selected transformer surface, ΔX j is the temperature change of this point under different working conditions, j=1,2,…,N.

4. The transformer internal temperature field deduction method based on multi-point transformation according to claim 3 is characterized in that: To ensure the accuracy of sensitivity analysis, calculate ΔX j , ΔY i The operating conditions selected should be similar.

5. The transformer internal temperature field deduction method based on multi-point transformation according to claim 2 is characterized in that: The corresponding multi-point transformation deduction model is established based on the temperature data of the selected m temperature points to be deduced and the temperature data of the n surface characteristic temperature measurement points, and is expressed as follows: Where, Y matrix is ​​the temperature matrix of the temperature point to be deduced, Y i represents the temperature data of the selected i-th temperature point to be deduced, i = 1, 2, ..., m; X matrix is ​​the temperature matrix of the selected surface characteristic temperature measurement point, X j represents the temperature data of the jth surface characteristic temperature measurement point, j = 1, 2, ..., n; the K matrix is ​​the parameter matrix of the established multi-point transformation deduction model, K ij represents the jth surface characteristic temperature measurement point X j For the i-th temperature point Y to be deduced i Corresponding contribution in the multi-point transformation deduction model.

6. The transformer internal temperature field deduction method based on multi-point transformation according to claim 2 is characterized in that: Solving a multi-point transformation deduction model based on the temperature data includes: Where, Y matrix is ​​the temperature matrix of the temperature point to be deduced, (Y i ) w represents the specific temperature data of the i-th temperature point to be deduced under the w-th group of working conditions calculated by the simulation model, i = 1, 2, ..., m; the X matrix is ​​the temperature matrix of the selected surface characteristic temperature measurement points, (X j ) w represents the specific temperature data of the jth surface characteristic temperature measurement point under the wth group of working conditions calculated by the simulation model, j = 1, 2, ..., n; the K matrix is ​​the parameter matrix of the multi-point transformation deduction model to be solved, (K ij ) w represents the jth surface characteristic temperature measurement point X under the wth group of working conditions j For the i-th temperature point Y to be deduced i Corresponding contribution in the multi-point transformation deduction model.

7. The transformer internal temperature field deduction method based on multi-point transformation according to claim 1 is characterized in that: The transformer temperature field simulation model is established based on the transformer structure as a reference and combined with the physical effects that affect the temperature distribution law of the transformer in actual operation, including: In COMSOL simulation software, simplify each part of the transformer and select appropriate materials to fill it so as to establish the transformer geometry model; The relevant parameters of the in-domain effect and the heat transfer effect of the boundary part that affect the temperature field of the transformer are reasonably set to simulate the temperature field changes in the actual operation of the transformer; wherein the in-domain effect includes the internal heat source of the transformer and the loss during operation, and the heat transfer effect includes heat conduction, heat convection and heat radiation between the transformer and the external environment; The transformer geometric model is meshed, and a temperature field frequency domain steady-state calculation is performed to obtain a stable temperature field result of each coordinate point of the transformer geometric model.

8. The transformer internal temperature field deduction method based on multi-point transformation according to claim 7 is characterized in that: The internal heat source of the transformer and the losses during operation include: Electromagnetic losses in nonlinear material cores, including hysteresis losses and eddy current losses; The Joule heat of the coil winding is related to the current and the resistance of the coil.

9. The transformer internal temperature field deduction method based on multi-point transformation according to claim 2 is characterized in that: The method further comprises: Select the temperature data of the surface characteristic temperature measurement points under different verification conditions, substitute them into the multi-point transformation deduction model to calculate the temperature data of the temperature point to be deduced; Utilizing the transformer temperature field simulation model to calculate the temperature data corresponding to the temperature point to be deduced under the corresponding verification working condition; The two types of temperature data are compared to verify the reliability of the prediction performance of the multi-point transformation deduction model; The verification conditions are operating conditions that are not used to establish a multi-point transformation deduction model.

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

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