Analysis Method and Device for Insulation State of Converter Transformer Valve Side Bushing

Abstract

The present application discloses a method and device for analyzing the insulation state of the valve side bushing of a converter transformer. First, according to finite element analysis software, a geometric model corresponding to the valve side bushing is established, and then based on boundary conditions, the geometric model is preprocessed to obtain the mesh division for electric field and temperature field calculations. Further, the current and voltage data at the current moment are input into the corresponding electric field and temperature fields for coupled analysis of Joule heat calculation and dielectric loss heat generation calculation, to obtain the temperature distribution at the current moment, and to determine whether the temperature distribution is within the error bound. If it is within the error bound, the insulation damage distribution and cumulative value are calculated, and then it is determined whether the insulation damage cumulative value exceeds the limit. If it exceeds the limit, the temperature distribution result is output. By comprehensively analyzing the insulation state from two scenarios of the electric field and temperature field, the result of analyzing the insulation state of the valve side bushing of the converter transformer is more accurate, thereby increasing the safety and reliability of the application of the valve side bushing of the converter transformer in the power system.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation state detection of electrical components, and more specifically, to a method and device for analyzing the insulation state of the valve side bushing of a converter transformer. Background Art

[0002] In a high-voltage direct current transmission project, the electrical connection and related insulation functions between the converter transformer and the converter valve hall are all realized through the valve side bushing of the converter transformer. Therefore, the valve side bushing of the converter transformer plays a key role, and its operating safety and reliability directly determine the overall operating effect of the converter transformer and even the converter transformer system. The flow chart of the existing method for analyzing the insulation state of the valve side bushing of a converter transformer is as Figure 1 shown. Step S101: Extract the current data of the converter station at present; Step S102: Perform Fourier decomposition on the current data to obtain the fundamental wave current data and harmonic current data at this time; Step S103: Perform Joule heating analysis and calculation based on the obtained current harmonic data at present; Step S104: Use the Joule heat generation as the excitation heat source and complete the calculation of the temperature field distribution according to the heat transfer formula; Step S105: Compare whether the calculation results of the temperature field at different times meet the preset accuracy in the same period; Step S106: If it meets the standard, the distribution result of the temperature field can be directly obtained; Step S107: If it does not meet the standard, update the resistivity and re-perform the Joule heating analysis and calculation until the accuracy meets the standard.

[0003] Currently, in the process of analyzing the insulation state, first extract the current data of the converter station, and then analyze and calculate the temperature field distribution based on the harmonic current data, and determine the insulation state according to the analysis results. However, the accuracy of the analysis results obtained in this way is relatively low, which will further affect the production design and operation of other electrical equipment. Summary of the Invention

[0004] In view of this, the present invention provides a method and device for analyzing the insulation state of the valve side bushing of a converter transformer. By calculating the distribution of the electric field and temperature field of the main insulation part of the converter transformer with frequency and temperature dependence under the joint action of multiple harmonic currents and voltages, and based on this, accurately analyze the insulation state of the main insulation structure.

[0005] To achieve the above object, the embodiments of the present invention provide the following technical solutions:

[0006] The first aspect of the embodiments of the present invention provides a method for analyzing the insulation state of the valve side bushing of a converter transformer, including:

[0007] Based on the finite element analysis software, a geometric model corresponding to the characteristic parameter information of the valve-side bushing is established; wherein, the characteristic parameter information includes: dimensions and material information;

[0008] Corresponding boundary conditions are set for the geometric model; wherein, the boundary conditions include: electric field and temperature field boundary conditions;

[0009] According to the boundary conditions, the geometric model is preprocessed to obtain the mesh division for electric field and temperature field calculations;

[0010] The current data at the current moment is input into the temperature field for joule heat calculation to obtain the temperature field distribution at the current moment;

[0011] The voltage data at the current moment is input into the electric field for dielectric loss heating calculation to obtain the electric field distribution at the current moment;

[0012] Based on the coupled analysis of the joule heat calculation and the dielectric loss heating calculation, the temperature distribution at the current moment is calculated;

[0013] According to the temperature distribution, it is judged whether the temperature distribution is within the error bound. If it is within the error bound, the insulation damage distribution and cumulative value in the electric field and temperature field are calculated;

[0014] After calculating the insulation damage distribution and cumulative value in the electric field and temperature field, it is judged whether the insulation damage cumulative value exceeds the limit. If it exceeds the limit, the temperature distribution result at the current moment is output.

[0015] Optionally, the step of inputting the current data at the current moment into the temperature field for joule heat calculation to obtain the temperature field distribution at the current moment includes:

[0016] The current data at the current moment is subjected to discrete Fourier decomposition to obtain the harmonic current components in the current data at the current moment;

[0017] According to the harmonic current components, the multi-harmonic current density distribution data set on the cross-section of the current-carrying conductor rod is obtained by using the frequency-domain magnetic field analysis method;

[0018] Based on the multi-harmonic current density distribution data set, the joule heat calculation is performed to obtain the temperature field distribution at the current moment.

[0019] Optionally, the step of performing the joule heat calculation based on the multi-harmonic current density distribution data set to obtain the temperature field distribution at the current moment includes:

[0020] According to the electrical conductivity γ of the conduit copper CuPerform the Joule heat calculation with the target current density ρn(r) in the multiple harmonic current density distribution data set to obtain the Joule heat generation Q at the radius r of the current-carrying conductor rod. r (r); where,

[0021] The target current density ρ n (r) is the nth harmonic current density in the multiple harmonic current density distribution data set at a distance r from the center point of the current-carrying conductor rod.

[0022] Optionally, inputting the voltage data at the current moment into the electric field to perform dielectric loss heat generation calculation to obtain the electric field distribution at the current moment includes: the electric field is an alternating electric field;

[0023] Using the method of multi-physics field coupling analysis to obtain the effective value distribution data set of the alternating electric field under the action of alternating voltages of various frequencies;

[0024] Performing the dielectric loss heat generation calculation based on the effective value distribution data set of the alternating electric field to obtain the electric field distribution at the current moment.

[0025] Optionally, performing the dielectric loss heat generation calculation based on the effective value distribution data set of the alternating electric field to obtain the electric field distribution at the current moment includes:

[0026] According to the fundamental wave frequency f, the vacuum permittivity ε0, the relative permittivity ε of the insulating medium r , the loss tangent value tanδ of the insulating medium, and the effective value E of the target electric field strength in the effective value distribution data set of the alternating electric field n,rms (r,z) to perform dielectric loss heat generation calculation to obtain the dielectric loss heat generation Q at a radius r of the current-carrying conductor rod when the temperature at the corresponding point r is T; e (r,z); where,

[0027] The effective value E of the target electric field strength n,rms (r,z) is the effective value of the nth electric field strength in the effective value distribution data set of the alternating electric field at a distance r from the center point of the current-carrying conductor rod when the temperature at the corresponding point r is T.

[0028] Optionally, calculating the temperature distribution at the current moment according to the coupling analysis of the Joule heat calculation and the dielectric loss heat generation calculation includes:

[0029] Based on the Joule heat generation Q r and the dielectric loss heat generation Q e , combined with the density ρ of the analysis object at the current moment and the heat capacity C of the analysis object P, the temperature distribution at the current moment is obtained from the external field dependent variable u and the conduction heat coefficient k.

[0030] Optionally, the determining whether the temperature distribution is within the error bound according to the temperature distribution further includes:

[0031] If the temperature distribution is not within the error bound, the method described above is continued to be executed.

[0032] Optionally, the determining whether the cumulative value of the insulation damage exceeds the limit further includes:

[0033] If it does not exceed the limit, an alarm message is sent.

[0034] Optionally, the electric field boundary condition is set based on the potentials of the boundaries of the electric field;

[0035] The temperature field boundary condition is set based on the temperature at the current moment and the operating temperature of the transformer.

[0036] In the second aspect of the embodiments of the present invention, an insulation state analysis device for the valve side bushing of a converter transformer is provided. The insulation state analysis device includes:

[0037] A model establishment module, configured to establish a geometric model corresponding to the characteristic parameter information of the valve side bushing according to finite element analysis software, where the characteristic parameter information includes: dimensions and material information;

[0038] A condition design module, configured to set corresponding boundary conditions for the geometric model, where the boundary conditions include: electric field and temperature field boundary conditions;

[0039] A mesh generation module, configured to preprocess the geometric model according to the boundary conditions to obtain the mesh generation for the calculation of the electric field and the temperature field;

[0040] A joule heat calculation module, configured to input the current data at the current moment into the temperature field to perform joule heat calculation to obtain the temperature field distribution at the current moment;

[0041] A dielectric loss heating calculation module, configured to input the voltage data at the current moment into the electric field to perform dielectric loss heating calculation to obtain the electric field distribution at the current moment;

[0042] A coupling analysis module, configured to calculate and obtain the temperature distribution at the current moment according to the coupling analysis of the joule heat calculation and the dielectric loss heating calculation;

[0043] A temperature distribution analysis module, configured to determine whether the temperature distribution is within the error bound according to the temperature distribution, and if it is within the error bound, calculate the insulation damage distribution and the cumulative value in the electric field and the temperature field;

[0044] A result output module, which is used to judge whether the cumulative value of insulation damage exceeds the limit after calculating the insulation damage distribution and the cumulative value in the electric field and temperature fields, and if it exceeds the limit, output the temperature distribution result at the current moment.

[0045] The present invention provides a method for analyzing the insulation state of the valve side bushing of a converter transformer. First, according to finite element analysis software, a geometric model corresponding to the characteristic parameter information of the valve side bushing is established, where the characteristic parameter information includes: size and material information. Then, corresponding boundary conditions are set for the geometric model; among them, the boundary conditions include: electric field and temperature field boundary conditions. Further, according to the boundary conditions, the geometric model is preprocessed to obtain the mesh division for electric field and temperature field calculations. Further, the current data at the current moment is input into the temperature field for joule heat calculation to obtain the temperature field distribution at the current moment, and the voltage data at the current moment is input into the electric field for dielectric loss heat generation calculation to obtain the electric field distribution at the current moment. Then, according to the coupled analysis of joule heat calculation and dielectric loss heat generation calculation, the temperature distribution at the current moment is calculated. According to the temperature distribution, it is judged whether the temperature distribution is within the error range. If it is within the error range, the insulation damage distribution and the cumulative value in the electric field and temperature fields are calculated. After calculating the insulation damage distribution and the cumulative value in the electric field and temperature fields, it is judged whether the cumulative value of insulation damage exceeds the limit. If it exceeds the limit, the temperature distribution result at the current moment is output. By considering the influence of the dielectric insulation state generated by the electric field of the valve side bushing of the converter transformer on the temperature field, the insulation state can be comprehensively analyzed from two scenarios of the electric field and the temperature field. Using this method, the result of analyzing the insulation state of the valve side bushing of the converter transformer is more accurate, thereby increasing the safety and reliability of the application of the valve side bushing of the converter transformer in the power system. Description of the Drawings

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0047] Figure 1 It is a flowchart of a method for analyzing the insulation state of the valve side bushing of a converter transformer provided by the prior art;

[0048] Figure 2 It is a flowchart of a method for analyzing the insulation state of the valve side bushing of a converter transformer provided by an optional embodiment of the present invention;

[0049] Figures 3 to 4Flowcharts of two other insulation state analysis methods for the valve side bushing of the converter transformer provided by the embodiments of the present invention;

[0050] Figure 5 Block diagram schematic of an insulation state analysis device for the valve side bushing of a converter transformer provided by the embodiments of the present invention. Detailed implementation manners

[0051] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0052] The embodiments of the present invention provide an insulation state analysis method for the valve side bushing of a converter transformer, as Figure 2 shown, the method includes:

[0053] S201. According to the finite element analysis software, establish a geometric model corresponding to the characteristic parameter information of the valve side bushing, where the characteristic parameter information includes: dimensions and material information.

[0054] Optionally, in an optional embodiment of the present invention, a function related to the characteristic parameter information is defined on the corresponding geometric model by using the finite element analysis software. The fundamental difference between the finite element analysis method and other approximate methods for solving boundary value problems lies in that its approximation is limited to a relatively small area. It not only has high calculation accuracy but also can adapt to various complex shapes. Therefore, this solution uses this method to construct the geometric model, enhancing the accuracy of the construction.

[0055] Specifically, the characteristic parameter information may further include: element type, real constant, cross-sectional type, and element coordinate system, etc., which can be determined according to its specific application environment and are all within the protection scope of this application.

[0056] S202. Set corresponding boundary conditions for the geometric model. Among them, the boundary conditions include: electric field and temperature field boundary conditions.

[0057] Optionally, the electric field boundary condition is set based on the potential of each boundary of the electric field. Generally, the boundary of the electric field is a zero potential boundary. Optionally, the temperature field boundary condition is set based on the current temperature and the operating temperature of the transformer.

[0058] Specifically, by using the surrounding temperature sensors to measure the temperature of the surrounding environment and the operating temperature of the converter transformer at the current moment, if the temperature of a certain area of the geometric model is known, it can be fixed at that value.

[0059] Specifically, the formula for the temperature field boundary conditions can be shown as follows:

[0060]

[0061] Where λ is the thermal conductivity of the material used at the current moment; n' is the normal vector of the calculation boundary.

[0062] By solving through the boundary conditions of the temperature field, T = C1 can be obtained; where C1 is the specific value of the temperature at the current moment.

[0063] Specifically, solving a problem of a geometric model can usually be represented by a set of differential equations with variable boundary conditions containing the problem state. To be suitable for finite element solution, the differential equation is usually transformed into an equivalent functional form.

[0064] S203. According to the boundary conditions, preprocess the geometric model to obtain the mesh division for calculating the electric field and temperature field.

[0065] Specifically, the preprocessing is to divide the finite element mesh of the geometric model, and then obtain the mesh division for calculating the electric field and temperature field. The result of the mesh division corresponds to the regions of the electric field and temperature field.

[0066] It should be noted that in the actual application scenario, the above preprocessing is implemented by a finite element analysis software that can perform coupled analysis of the electric field and temperature field. Among them, there can be various types of the above finite element analysis software, such as: engineering simulation finite element software (ABAQUS) and computer-aided engineering software (ANSYS), etc. The present invention does not make excessive limitations and elaborations on the specific types and application methods of the above software.

[0067] S204. Input the current data at the current moment into the temperature field to perform joule heat calculation and obtain the temperature field distribution at the current moment.

[0068] Optionally, inputting the current data at the current moment into the temperature field to perform joule heat calculation and obtain the temperature field distribution at the current moment includes the following steps:

[0069] (1) Perform discrete Fourier decomposition on the current data at the current moment to obtain the harmonic current components in the current data at the current moment.

[0070] Specifically, when performing discrete Fourier decomposition on the current data, the fundamental wave current component i sf and the harmonic current component i sh are as shown in the following formula:

[0071]

[0072] Where and are the amplitudes of the fundamental wave and harmonic components of the current, respectively, a i1 and b i1 are the Fourier coefficients of the fundamental wave of the current, a in and b in are the Fourier coefficients of the current harmonics.

[0073] Specifically, in this embodiment, the harmonic current component in the current data at the current moment is obtained. Since the harmonic current component will affect the normal operation of various electrical equipment and cause serious local overheating of the transformer, it is one of the factors affecting the insulation state of the valve-side bushing of the converter transformer.

[0074] (2) According to the harmonic current component, use the frequency-domain magnetic field analysis method to obtain a data set of the distribution of multiple harmonic current densities on the cross-section of the current-carrying conductor rod.

[0075] (3) Based on the data set of the distribution of multiple harmonic current densities, perform Joule heat calculation to obtain the temperature field distribution at the current moment.

[0076] Optionally, based on the data set of the distribution of multiple harmonic current densities, perform Joule heat calculation to obtain the temperature field distribution at the current moment, including:

[0077] According to the conductivity γ of the conduit copper Cu and the target current density ρ n in the data set of the distribution of multiple harmonic current densities, perform Joule heat calculation to obtain the Joule heat generation Q r (r) at the radius r of the current-carrying conductor rod.

[0078] Specifically, the target current density ρ n (r) is the nth harmonic current density in the data set of the distribution of multiple harmonic current densities at a distance r from the center point of the current-carrying conductor rod.

[0079] Specifically, the formula for performing Joule heat calculation can be as follows:

[0080]

[0081] Among them, the specific meanings of different symbols in this formula have been elaborated in the above content and will not be repeated here.

[0082] The present invention exemplarily provides a way to perform Joule heat calculation. In practical applications, there can also be various representation methods, all within the protection scope of this application.

[0083] S205. Input the voltage data at the current moment into the electric field to perform dielectric loss heat generation calculation, and obtain the electric field distribution at the current moment.

[0084] Optionally, the electric field is an alternating electric field.

[0085] Optionally, input the voltage data at the current moment into the electric field to calculate the dielectric loss heating and obtain the electric field distribution at the current moment, including the following steps:

[0086] (1) Obtain the effective value distribution data set of the alternating electric field under the action of alternating voltages of various frequencies by using the method of multi-physical field coupling analysis.

[0087] Specifically, to simplify the analysis, the charge accumulation between the plates is ignored in this model, that is, it is considered that the volume charge amount in the corresponding area of the alternating electric field is zero. When the frequency of the applied voltage excitation is below kHz and does not cause the loss of the capacitance effect, it is an alternating electric field, which is within the protection scope of this embodiment. Therefore, the electric field distribution in the electric field and temperature field can be described by the Laplace equation in the following formula:

[0088]

[0089] Specifically, considering that the capacitor plate composed of the conductor aluminum foil also presents as an equipotential body under the action of the electric field, but since its two sides are insulating plates respectively, its specific potential cannot be determined in advance. In the specific calculation, it is set as the floating potential, and the specific value needs to be determined specifically during the calculation process:

[0090]

[0091] Where is the potential of the mth capacitor plate, is the mth undetermined floating potential, where ud is the abbreviation of (Undefined).

[0092] By setting a capacitor plate with a floating potential in the valve side bushing of a higher voltage class, it can be used to improve the electric field distribution on the surface of the valve side bushing.

[0093] (2) Based on the effective value distribution data set of the alternating electric field, perform dielectric loss heating calculation to obtain the electric field distribution at the current moment.

[0094] Optionally, based on the effective value distribution data set of the alternating electric field, perform dielectric loss heating calculation to obtain the electric field distribution at the current moment, including:

[0095] According to the fundamental wave frequency f, the vacuum permittivity ε0, the relative permittivity ε r of the insulating medium, the tangent of the loss angle tanδ of the insulating medium, and the effective value E of the target electric field strength in the effective value distribution data set of the alternating electric field n,rmsPerform dielectric loss heating calculation for (r, z), and obtain the dielectric loss heat generation Q at the temperature T at the corresponding point r where the radius of the current-carrying conductor rod is r. e (r, z).

[0096] Specifically, the effective value E of the target electric field strength n,rms (r, z) is the effective value of the nth electric field strength in the data set of the effective value distribution of the alternating electric field at the temperature T at the corresponding point r, which is at a distance r from the center point of the current-carrying conductor rod.

[0097] Specifically, the formula for performing dielectric loss heating calculation can be as follows:

[0098]

[0099] ε r = ε r (nf, T)

[0100] tanδ = tanδ(nf, T)

[0101] Among them, the specific meanings of different symbols in this formula have been elaborated in the above content and will not be repeated here one by one.

[0102] The present invention exemplarily provides a method for performing dielectric loss heating calculation. In practical applications, there can also be multiple representation methods, all of which are within the protection scope of this application.

[0103] The running order of the above step S204 and step S205 can be determined according to the on-site situation, or they can be performed simultaneously, and no further limitation is made here.

[0104] S206. Calculate and obtain the temperature distribution at the current moment according to the coupled analysis of Joule heat calculation and dielectric loss heating calculation.

[0105] Optionally, calculating and obtaining the temperature distribution at the current moment according to the coupled analysis of Joule heat calculation and dielectric loss heating calculation includes:

[0106] Based on the Joule heat generation Q r and the dielectric loss heat generation Q e , combined with the density ρ of the analysis object, the heat capacity C P of the analysis object, the external field dependent variable u, and the heat conduction coefficient k at the current moment, obtain the temperature distribution at the current moment.

[0107] Specifically, the temperature distribution here is consistent with the structural region involved in the coupled analysis of the electric field and the temperature field.

[0108] Specifically, the formula for calculating the temperature distribution can be as follows:

[0109]

[0110] Specifically, the coupling analysis includes: indirect coupling analysis and direct coupling analysis. The method of indirect coupling analysis is to use the result of the previous analysis as the boundary condition for the subsequent analysis, which corresponds to defining the order of joule heat calculation and dielectric loss heat generation calculation; the direct coupling analysis is to obtain the temperature distribution without restricting the order of joule heat calculation or dielectric loss heat generation calculation. In this application, both of the above two coupling analysis methods are acceptable and are within the protection scope of this application.

[0111] Specifically, during the analysis process, we assume that the ambient temperature does not change significantly. In unit time, harmonic voltage and current act together on the bushing. However, during the analysis, this application can only process the current or voltage component at a single harmonic frequency after decomposition. Further, in order to fully consider the temperature dependence of the insulating material, the temperature and related heat source conditions in the temperature field result obtained from the previous calculation need to be considered as the background field in the current calculation process. Considering the superposition effect of the heat generation of the medium under the action of alternating electric fields at different frequencies, the reasonable superposition of the calculation results of more previous iteration times also needs to be considered.

[0112] S207. According to the temperature distribution, determine whether the temperature distribution is within the error bound.

[0113] Specifically, corresponding iteration conditions must be available during the iterative calculation process to ensure that reasonable results meeting the actual engineering requirements can be obtained within a reasonable time length. Considering the convergence and rationality of the iteration criterion, the temperature distribution convergence at key nodes is selected as the criterion here. Specifically, when the difference in temperature at the key nodes between the previous and current iteration cycles enters an error bound, it is considered that the calculation of the temperature field has converged, and thus the entire iterative process ends.

[0114] S208. If it is within the error bound, calculate the insulation damage distribution and cumulative value in the electric field and temperature fields.

[0115] After the iterative process ends, calculate the insulation damage distribution and cumulative value in the electric field and temperature fields of the valve side bushing of the converter transformer, and evaluate the insulation state of the valve side bushing of the converter transformer.

[0116] Specifically, according to the temperature and electric field distribution obtained above, the insulation damage degree D ID (t) of the medium at time t can be obtained through the following formula:

[0117]

[0118] Among them, b is a constant obtained according to the relevant properties of the material, and there is a close relationship between it and the activation energy required during the chemical degradation process of the corresponding insulating medium and the temperature at which the material is located; n is a constant obtained by fitting relevant data measured by an accelerated life test. At the same time, the cumulative insulation damage degree can be obtained by summing up the insulation damage degrees under different time spans. When this cumulative value is greater than a certain threshold, the main insulation will undergo insulation failure including electrical breakdown; the threshold here is also determined according to relevant accelerated life experiments and the installation environment of the equipment.

[0119] S209. After calculating the insulation damage distribution and cumulative value in the electric field and temperature fields, it is determined whether the cumulative value of insulation damage exceeds the limit.

[0120] S210. If it exceeds the limit, the temperature distribution result at the current moment is output.

[0121] Specifically, a threshold for the insulation damage distribution and cumulative value is preset in advance, and the insulation damage distribution and cumulative value obtained in the electric field and temperature fields are compared with the threshold to determine whether it exceeds the limit. If it exceeds the limit, the process ends, and the temperature distribution result at the current moment is immediately output.

[0122] Based on the previous embodiment, the method further includes: if the temperature distribution is not within the error range, the method in step S206 as described above is continued to be executed, and the corresponding flowchart is as Figure 3 shown.

[0123] Specifically, the Joule heat and dielectric loss heat generation conditions obtained at the current moment are returned to step S206 for another iterative solution calculation until the temperature distribution obtained by the solution calculation is within the error range, and then the iteration stops, and the next step S208 is continued.

[0124] Furthermore, determining whether the cumulative value of insulation damage exceeds the limit further includes: if it does not exceed the limit, an alarm message is issued, and the corresponding flowchart is as Figure 4 shown.

[0125] Specifically, if the cumulative value of insulation loss does not exceed the limit, step S301 is executed to issue an alarm message, and the alarm message can be issued in the form of sound or an indicator light. After issuing the alarm message, this process ends directly, aiming to ensure the accuracy of the output temperature distribution result.

[0126] Figure 5 A valve side bushing insulation state analysis device for a converter transformer provided by the present invention, as Figure 5 shown, the insulation state analysis device provided by the present invention includes:

[0127] The model establishment module 401 is used to establish a geometric model corresponding to the characteristic parameter information of the valve side bushing according to finite element analysis software, where the characteristic parameter information includes: dimensions and material information.

[0128] The condition design module 402 is used to set corresponding boundary conditions for the geometric model, where the boundary conditions include: electric field and temperature field boundary conditions.

[0129] The mesh generation module 403 is used to preprocess the geometric model according to the boundary conditions to obtain the mesh generation for electric field and temperature field calculations.

[0130] The joule heat calculation module 404 is used to input the current data at the current moment into the temperature field to perform joule heat calculation and obtain the temperature field distribution at the current moment.

[0131] The dielectric loss heating calculation module 405 is used to input the voltage data at the current moment into the electric field to perform dielectric loss heating calculation and obtain the electric field distribution at the current moment.

[0132] The coupling analysis module 406 is used to calculate the temperature distribution at the current moment according to the coupling analysis of joule heat calculation and dielectric loss heating calculation.

[0133] The temperature distribution analysis module 407 is used to determine whether the temperature distribution is within the error bound according to the temperature distribution. If it is within the error bound, it calculates the insulation damage distribution and cumulative value in the electric field and temperature field.

[0134] The result output module 408 is used to determine whether the cumulative value of insulation damage exceeds the limit after calculating the insulation damage distribution and cumulative value in the electric field and temperature field. If it exceeds the limit, it outputs the temperature distribution result at the current moment.

[0135] According to an insulation state analysis device for the valve side bushing of a converter transformer provided by the present invention, by analyzing the joule heat calculation in the electric field and the dielectric loss heating calculation in the temperature field, the temperature distribution is obtained, and the insulation state is determined according to the analysis result. The result of the analysis in this way is more accurate, improving the safety and reliability of various electrical equipment during operation.

[0136] Optionally, in the model establishment module 401, a geometric model is established in the finite element analysis software, and the characteristic parameter information of the valve side bushing needs to be referred to during the establishment process to improve the accuracy of the geometric model establishment.

[0137] Optionally, in the condition design module 402, boundary conditions are set for the established geometric model, and the purpose is to determine the types of state variables including the electric field and temperature field.

[0138] Optionally, in the meshing module 403, using the boundary conditions, the geometric model is divided into a finite element network to obtain a number of regions, and the corresponding electric field or temperature field distribution exists on each region.

[0139] Optionally, in the joule heat calculation module 404, by inputting the harmonic current component data into the temperature field for joule heat calculation, the temperature field distribution can be obtained.

[0140] Optionally, in the dielectric loss heating calculation module 405, by inputting the voltage data into the alternating electric field for dielectric loss heating calculation, the electric field distribution can be obtained.

[0141] Optionally, in the coupling analysis module 406, through the coupling analysis of the joule heat calculation and the dielectric loss heating calculation in the temperature field and the electric field, the temperature distribution is obtained, taking into account the factors affecting the temperature distribution and making the result of the insulation state analysis more accurate.

[0142] Optionally, in the temperature distribution analysis module 407, the obtained temperature distribution is compared with the pre-set error bound. If it is within the error bound, the insulation damage distribution and the cumulative value in the electric field and the temperature field can be calculated to determine whether they exceed the limit, so as to perform the next operation.

[0143] Optionally, in the result output module 408, if the insulation damage distribution and the cumulative value mentioned above exceed the limit, the temperature distribution at the current moment is output. Through the judgment of the over-limit situation, the accuracy of the output temperature distribution can be increased.

[0144] Regarding the insulation state analysis device for the valve side bushing of the converter transformer in the above embodiments, the specific ways for each module to perform operations have been described in detail in the embodiments of the related methods above, and will not be elaborated here.

[0145] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0146] In each embodiment described in this specification, the key points are the differences from other embodiments. The embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0147] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Analysis method for the insulation state of the valve side bushing of a converter transformer, characterized in that, Including: Establish a geometric model corresponding to the characteristic parameter information of the valve side bushing according to finite element analysis software; wherein, the characteristic parameter information includes: size and material information; Set corresponding boundary conditions for the geometric model; wherein, the boundary conditions include: electric field and temperature field boundary conditions; Preprocess the geometric model according to the boundary conditions to obtain mesh division for electric field and temperature field calculations; Input the current data at the current moment into the temperature field to perform joule heat calculation to obtain the temperature field distribution at the current moment; Input the voltage data at the current moment into the electric field to perform dielectric loss heating calculation to obtain the electric field distribution at the current moment; Calculate and obtain the temperature distribution at the current moment according to the coupled analysis of the joule heat calculation and the dielectric loss heating calculation; Judge whether the temperature distribution is within the error bound according to the temperature distribution. If it is within the error bound, calculate the insulation damage distribution and cumulative value in the electric field and temperature field; After calculating the insulation damage distribution and cumulative value in the electric field and temperature field, judge whether the insulation damage cumulative value exceeds the limit. If it exceeds the limit, output the temperature distribution result at the current moment.

2. The method according to claim 1, wherein The step of inputting the current data at the current moment into the temperature field to perform joule heat calculation to obtain the temperature field distribution at the current moment includes: Perform discrete Fourier decomposition on the obtained current data at the current moment to obtain the harmonic current components in the current data at the current moment; According to the harmonic current components, use the frequency domain magnetic field analysis method to obtain a set of data on the distribution of multiple harmonic current densities on the cross-section of the current-carrying conductor rod; Perform the joule heat calculation based on the set of data on the distribution of multiple harmonic current densities to obtain the temperature field distribution at the current moment.

3. The method according to claim 2, wherein The step of performing the joule heat calculation based on the set of data on the distribution of multiple harmonic current densities to obtain the temperature field distribution at the current moment includes: According to the conductivity γ of the copper material of the catheter Cu and the target current density ρn(r) in the multi-harmonic current density distribution data set, perform the Joule heat calculation to obtain the Joule heat generation Qr(r) at the radius r of the current-carrying conductor rod; wherein The target current density ρn(r) is the nth harmonic current density in the set of data on the distribution of multiple harmonic current densities at a distance r from the center point of the current-carrying conductor rod.

4. The method according to claim 1, wherein The step of inputting the voltage data at the current moment into the electric field to perform dielectric loss heating calculation to obtain the electric field distribution at the current moment includes: the electric field is an alternating electric field; Use the method of multi-physics field coupling analysis to obtain a set of data on the effective value distribution of the alternating electric field under the action of alternating voltages of various frequencies; Perform the dielectric loss heating calculation based on the set of data on the effective value distribution of the alternating electric field to obtain the electric field distribution at the current moment.

5. The method according to claim 4, wherein The step of performing the dielectric loss heating calculation based on the set of data on the effective value distribution of the alternating electric field to obtain the electric field distribution at the current moment includes: According to the fundamental wave frequency f, the vacuum permittivity ε0, the relative permittivity ε of the insulating medium r , the tangent value of the loss angle tanδ of the insulating medium, and the effective value E n,rms (r,z) of the target electric field strength in the effective value distribution data set of the alternating electric field, calculate the dielectric loss heating to obtain the dielectric loss heat generation Q at the radius r of the current-carrying conductor rod when the temperature at the corresponding point r is T e (r,z); where The effective value E of the target electric field strength n,rms (r, z) is the effective value of the nth electric field strength in the effective value distribution data set of the alternating electric field when the distance from the center point of the current-carrying conductor rod is r and the temperature at the corresponding point r is T.

6. The method according to any one of claims 2 to 5, characterized in that, The step of calculating and obtaining the temperature distribution at the current moment according to the coupled analysis of the joule heat calculation and the dielectric loss heating calculation includes: Based on the Joule heat generation Qr and the medium loss heat generation Q e , combined with the density ρ of the analysis object and the heat capacity C of the analysis object at the current moment P , the temperature distribution at the current moment is obtained by means of the external field dependent variable u and the heat conduction coefficient k.

7. The method according to claim 1, characterized in that The step of judging whether the temperature distribution is within the error bound according to the temperature distribution further includes: If the temperature distribution is not within the error bound, continue to execute the method described in claim 6.

8. The method according to claim 1, wherein Judging whether the cumulative value of insulation damage exceeds the limit further includes: If it does not exceed the limit, an alarm message is sent.

9. The method according to claim 1, wherein The electric field boundary conditions are set based on the potentials of the boundaries of the electric field; The temperature field boundary conditions are set based on the temperature at the current moment and the operating temperature of the transformer.

10. Analysis device for the insulation state of the valve side bushing of a converter transformer, characterized in that, It includes: A model establishment module, configured to establish a geometric model corresponding to the characteristic parameter information of the valve side bushing according to finite element analysis software, where the characteristic parameter information includes: dimensions and material information; A condition design module, configured to set corresponding boundary conditions for the geometric model, where the boundary conditions include: electric field and temperature field boundary conditions; A mesh generation module, configured to preprocess the geometric model according to the boundary conditions to obtain a mesh generation for electric field and temperature field calculations; A joule heat calculation module, configured to input the current data at the current moment into the temperature field to perform joule heat calculation to obtain the temperature field distribution at the current moment; A dielectric loss heating calculation module, configured to input the voltage data at the current moment into the electric field to perform dielectric loss heating calculation to obtain the electric field distribution at the current moment; A coupling analysis module, configured to calculate the temperature distribution at the current moment through coupling analysis of the joule heat calculation and the dielectric loss heating calculation; A temperature distribution analysis module, configured to judge whether the temperature distribution is within the error bound according to the temperature distribution. If it is within the error bound, the insulation damage distribution and the cumulative value in the electric field and temperature field are calculated; A result output module, configured to judge whether the cumulative value of insulation damage exceeds the limit after calculating the insulation damage distribution and the cumulative value in the electric field and temperature field. If it exceeds the limit, the temperature distribution result at the current moment is output.

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