Method, device and equipment for evaluating insulating property of transformer bushing
By combining a pre-set XY model with the steepest descent method, the problem of neglecting physical and chemical properties in the evaluation of transformer bushing insulation performance is solved, and a more accurate insulation performance evaluation is achieved.
Patent Information
- Application Number
- CN202511809504.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-03-03
AI Technical Summary
Existing methods for evaluating the insulation performance of transformer bushings neglect the physical and chemical properties of the bushings, resulting in low evaluation accuracy.
The frequency domain dielectric spectrum model curve is determined by using a pre-set XY model based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing. The error based on the complex dielectric constant is calculated, and the steepest descent method is used for nonlinear optimization to obtain the water content parameters, thereby evaluating the insulation performance.
This improves the accuracy and efficiency of insulation performance assessment, conforms to the actual situation of bushings, quantifies the difference in dielectric constant, and ensures the accuracy of assessment results.
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Figure CN121601113A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of transformers, and more particularly to a method, apparatus and equipment for evaluating the insulation performance of transformer bushings. Background Technology
[0002] As a core hub device in the power system, the stability of transformer operation is related to the safety and reliability of power grid supply. Transformer bushings, as key connecting components between transformers and external transmission lines, undertake the dual functions of insulation support and current transmission. Their insulation performance is the core prerequisite for ensuring the overall safe operation of transformers.
[0003] Currently, transformer bushings operating on the grid are subjected to a combination of thermal, electrical, and mechanical stresses, causing microcracks to gradually develop within their internal structure. Some latent cracks from the production process, due to operational issues, also develop during this process, providing pathways for moisture intrusion. Furthermore, the insulating paper within the transformer bushings is highly hygroscopic, making it difficult to prevent moisture intrusion during production, transportation, and storage. These factors combined make moisture-induced defects a significant factor affecting the insulation performance of transformer bushings.
[0004] Currently, traditional testing methods are mostly used for assessing the condition of transformer bushing insulation. Before leaving the factory, AC and DC high-voltage tests and operational impact tests are applied to the bushings to determine their health status. For bushings in operation, electrical parameters such as power frequency dielectric loss, capacitance, and insulation resistance are often used to assess the insulation degradation, ignoring their physical and chemical characteristics. As a result, the existing insulation assessment results lack accuracy. Summary of the Invention
[0005] This application provides a method, apparatus, and equipment for evaluating the insulation performance of transformer bushings, which addresses the technical problem that existing transformer bushing insulation degradation evaluation parameters lack specificity and ignore the physical and chemical properties of bushings, resulting in low accuracy of insulation performance evaluation.
[0006] In view of this, the first aspect of this application provides a method for evaluating the insulation performance of transformer bushings, comprising:
[0007] The frequency domain dielectric spectrum model curve is determined by using a preset XY model based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing.
[0008] Based on the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, the error based on the complex dielectric constant is calculated, and an error function is generated;
[0009] The water content parameters of the transformer bushing are obtained by nonlinear optimization solution based on the error function using the steepest descent method.
[0010] The insulation performance of the transformer bushing is evaluated based on the water content parameters, and the insulation evaluation results are obtained.
[0011] Preferably, the step of determining the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a preset XY model includes:
[0012] Obtain the conductivity of the epoxy resin in the transformer bushing;
[0013] The actual dielectric constants of the cardboard, support strips, and epoxy resin in the transformer bushing are determined based on the frequency domain dielectric spectrum characteristic curve and the conductivity.
[0014] Input all the actual dielectric constants into the preset XY model to obtain the complex dielectric constant;
[0015] Based on the complex permittivity, a frequency domain dielectric spectrum model curve at a preset temperature is generated.
[0016] Preferably, the step of determining the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a preset XY model further includes:
[0017] The transformer bushing is subjected to frequency domain dielectric spectrum testing at a preset temperature to obtain the complex dielectric constant, and frequency domain dielectric spectrum test curves are constructed to generate a preset database.
[0018] The test complex permittivity in the preset database is temperature-corrected using the Arrhenius formula to generate a frequency domain dielectric spectrum characteristic curve at the reference temperature.
[0019] Preferably, the step of calculating the error based on the complex permittivity according to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and generating the error function, includes:
[0020] Obtain the complex dielectric constants corresponding to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and select the corresponding real and imaginary dielectric parts;
[0021] An error function is generated by calculating the error based on the real and imaginary parts of the dielectric.
[0022] Preferably, the step of using the steepest descent method to perform nonlinear optimization based on the error function to obtain the water content parameters of the transformer bushing includes:
[0023] Construct the objective function based on the error function;
[0024] The initial parameters of the transformer bushing are set according to the frequency domain dielectric spectrum model curve;
[0025] Based on the initial parameters, the objective function is solved nonlinearly using the steepest descent method to minimize its residual and obtain the water content parameters of the transformer bushing.
[0026] The second aspect of this application provides a transformer bushing insulation performance evaluation device, comprising:
[0027] The curve generation unit is used to determine the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a preset XY model.
[0028] The error calculation unit is used to calculate the error based on the complex dielectric constant according to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and generate an error function.
[0029] The parameter solving unit is used to perform nonlinear optimization solution based on the error function using the steepest descent method to obtain the water content parameters of the transformer bushing;
[0030] An insulation assessment unit is used to assess the insulation performance of transformer bushings based on the moisture content parameters and obtain insulation assessment results.
[0031] Preferably, the curve generation unit specifically includes:
[0032] Obtain the conductivity of the epoxy resin in the transformer bushing;
[0033] The actual dielectric constants of the cardboard, support strips, and epoxy resin in the transformer bushing are determined based on the frequency domain dielectric spectrum characteristic curve and the conductivity.
[0034] Input all the actual dielectric constants into the preset XY model to obtain the complex dielectric constant;
[0035] Based on the complex permittivity, a frequency domain dielectric spectrum model curve at a preset temperature is generated.
[0036] Preferably, it further includes:
[0037] The test unit is used to perform frequency domain dielectric spectrum testing on transformer bushings at a preset temperature, obtain the test complex dielectric constant, construct frequency domain dielectric spectrum test curves, and generate a preset database.
[0038] The calibration unit is used to perform temperature correction on the test complex permittivity in the preset database using the Arrhenius formula, and generate a frequency domain dielectric spectrum characteristic curve at the reference temperature.
[0039] Preferably, the error calculation unit is specifically used for:
[0040] Obtain the complex dielectric constants corresponding to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and select the corresponding real and imaginary dielectric parts;
[0041] An error function is generated by calculating the error based on the real and imaginary parts of the dielectric.
[0042] A third aspect of this application provides a transformer bushing insulation performance evaluation device, the device including a processor and a memory;
[0043] The memory is used to store program code and transmit the program code to the processor;
[0044] The processor is used to execute the transformer bushing insulation performance evaluation method described in the first aspect according to the instructions in the program code.
[0045] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:
[0046] This application provides a method for evaluating the insulation performance of transformer bushings, comprising: determining a frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a pre-set XY model; calculating an error based on the complex dielectric constant based on the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and generating an error function; performing nonlinear optimization solution based on the error function using the steepest descent method to obtain the water content parameter of the transformer bushing; and evaluating the insulation performance of the transformer bushing based on the water content parameter to obtain the insulation evaluation result.
[0047] The transformer bushing insulation performance evaluation method provided in this application uses a pre-set XY model for data analysis, which can integrate multiple sets of characteristic data and transform them into dielectric response curves of the overall bushing insulation. By deeply considering the physicochemical properties of the transformer bushing, the dielectric constant is selected as the evaluation parameter, which better reflects the actual situation of the bushing and ensures the accuracy of the evaluation results. Furthermore, the difference in dielectric constant between the two curves is quantified by an error function, and the steepest descent method is used for rapid optimization, which can convert the degree of fit into a numerical index and quickly determine the optimization direction. While ensuring the accuracy of the solution results, it can also take into account the estimation efficiency. Therefore, this application can solve the technical problem that existing transformer bushing insulation degradation evaluation parameters lack specificity and ignore the physicochemical properties of the bushing, resulting in low accuracy of insulation performance evaluation. Attached Figure Description
[0048] Figure 1 A flowchart illustrating a method for evaluating the insulation performance of transformer bushings, provided as an embodiment of this application;
[0049] Figure 2 This is a schematic diagram of the structure of a transformer bushing insulation performance evaluation device provided in an embodiment of this application;
[0050] Figure 3The first curve of dielectric constant solution provided for the model in the embodiments of this application;
[0051] Figure 4 The second curve of dielectric constant solution provided for the embodiments of this application. Detailed Implementation
[0052] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.
[0053] The embodiments of this application, when using the XY model to estimate the water content of the transformer bushing under test, mainly involve three key aspects: First, estimating the ratio between insulating paper and epoxy resin in the transformer bushing; second, using the Arrhenius formula to convert the frequency domain dielectric spectrum (FDS) test results to an FDS curve at the main temperature; and third, obtaining the epoxy conductivity through methods such as field measurements, and using the various parameters to obtain the error function, thus transforming the problem into an extremum problem.
[0054] For easier understanding, please refer to Figure 1 An embodiment of a method for evaluating the insulation performance of transformer bushings provided in this application includes:
[0055] Step 101: Determine the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using the preset XY model.
[0056] Further, step 101 includes:
[0057] Obtain the conductivity of the epoxy resin in the transformer bushing;
[0058] The actual dielectric constants of the cardboard, support strips, and epoxy resin in the transformer bushing are determined based on the frequency domain dielectric spectrum characteristic curves and conductivity.
[0059] Input all actual dielectric constants into the preset XY model to obtain the complex dielectric constant;
[0060] The frequency domain dielectric spectrum model curve at a preset temperature is generated based on the complex dielectric constant.
[0061] Furthermore, step 101, preceding the following, also includes:
[0062] The transformer bushing is subjected to frequency domain dielectric spectrum testing at a preset temperature to obtain the complex dielectric constant, and frequency domain dielectric spectrum test curves are constructed to generate a preset database.
[0063] The Arrhenius formula is used to perform temperature correction on the test complex permittivity in the pre-set database to generate the frequency domain dielectric spectrum characteristic curve at the reference temperature.
[0064] It should be noted that the preset temperature can be set according to actual conditions and is not limited here. At the preset temperature, the complex dielectric constant of the transformer bushing at different moisture contents can be obtained, forming a preset database. Simultaneously, the corresponding frequency domain dielectric spectrum test curves can also be constructed.
[0065] The Arrhenius formula can be used to convert the real and imaginary parts of the dielectric constant at different temperatures for each frequency point into temperature-dependent equivalent parameters, establishing a linear relationship model. For each frequency measured in practice, the corresponding complex dielectric constant data at different temperatures are extracted and substituted into the Arrhenius correction formula. Through linear fitting, the slope and intercept of the real and imaginary parts of the dielectric constant at that frequency as a function of temperature are obtained, and then the conversion coefficient from the measurement temperature to the reference temperature is calculated to ensure that the correction coefficient reflects the degree of influence of temperature on the dielectric response. For each frequency point in the actual measured FDS data, the calculated correction coefficient is used to convert the complex dielectric constant at the measurement temperature to the corresponding value at the reference temperature. After completing the correction for all data points across the entire frequency range, a curve is plotted with frequency as the horizontal axis and the corrected real and imaginary parts as the vertical axes, respectively, to obtain the frequency domain dielectric spectrum characteristic curve at the reference temperature.
[0066] The actual dielectric constants of the cardboard, support strips, and epoxy resin at a reference temperature are collected, including the real and imaginary parts of the complex dielectric constant of each material across the entire frequency range. Specifically, after obtaining the conductivity of the epoxy resin in the transformer bushing, the dielectric constant of the epoxy resin can be determined based on the conductivity. The dielectric constant of the cardboard can be extracted from the temperature-corrected frequency domain dielectric spectrum characteristic curve. The dielectric constants of the support strips and epoxy resin can also be obtained through separate testing or from a database.
[0067] The preset XY model in this embodiment is expressed as follows:
[0068]
[0069] in, This represents the complex permittivity calculated using the XY model. This indicates the dielectric constant corresponding to the support bar. This represents the dielectric constant of the paperboard. This represents the dielectric constant of the epoxy resin. , These represent the first insulation structure parameter and the second insulation structure parameter, respectively. For temperature.
[0070] For each frequency point, the initial epoxy resin conductivity corresponding to the transformer bushing, the complex dielectric constant of the paperboard, the actual dielectric constant of the support strip, the actual dielectric constant of the epoxy resin, and the proportional parameters X and Y are substituted into the XY model equation. The total complex dielectric constant of the composite insulation system at that frequency is calculated through the equation. This process is repeated across the entire frequency range, calculating the complex dielectric constant of the composite system at each frequency point to form a complete frequency dielectric constant dataset. By plotting frequency on the horizontal axis and the calculated complex dielectric constant on the vertical axis, connecting the data points to form a continuous curve, the frequency domain dielectric spectrum model curve of the XY model can be obtained.
[0071] Step 102: Calculate the error based on the complex dielectric constant according to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and generate the error function.
[0072] Further, step 102 includes:
[0073] The complex dielectric constants corresponding to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve are obtained respectively, and the corresponding real part and imaginary part of the dielectric are selected.
[0074] Error is calculated based on the real and imaginary parts of the dielectric, and an error function is generated.
[0075] It should be noted that the complex dielectric constants corresponding to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve can be extracted separately. The real and imaginary parts of these dielectric constants can be determined. Based on the real and imaginary dielectric parts corresponding to the model curve and the test curve, the error function of this embodiment can be constructed.
[0076]
[0077] in, , These are the real and imaginary dielectric parts corresponding to the dielectric constant of the frequency domain dielectric spectrum test curve, respectively. , These are the real and imaginary dielectric parts corresponding to the dielectric constant of the frequency domain dielectric spectrum model curve, respectively.
[0078] Step 103: Using the steepest descent method, nonlinear optimization is performed based on the error function to obtain the water content parameters of the transformer bushing.
[0079] Further, step 103 includes:
[0080] Construct the objective function based on the error function;
[0081] The initial parameters of the transformer bushing are set based on the frequency domain dielectric spectrum model curve;
[0082] Based on the initial parameters, the steepest descent method is used to perform nonlinear optimization of the objective function to minimize its residuals and obtain the water content parameters of the transformer bushing.
[0083] It should be noted that in the comparative analysis of the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, the analysis is conducted from both the perspective of image processing and the perspective of formulas. Then, combined with the error function, the corresponding objective function can be constructed. The steepest descent method is then used to perform nonlinear optimization of the objective function to minimize its residual, thereby determining the water content of the transformer bushing, i.e., the water content parameter. However, the solution process is an iterative optimization process, so a set of initial parameters needs to be set at the beginning of the iteration process.
[0084] The initial parameters in this embodiment are set based on the frequency domain dielectric spectrum model curve, and include at least the ratio of insulating paper to epoxy resin in the transformer bushing, for example, X=20%, Y=32%; the initial moisture content mc=1% and the epoxy numerical conductivity σ. oil =1.0×10 -12 One of the parameters in S / m. The objective function can be solved using initial parameters and a nonlinear optimization algorithm to obtain the water content parameters.
[0085] During this process, the initial parameters can be incremented, and the increment can be expressed as... Based on the parameters after incremental processing, an updated model curve is generated, and the error between the updated model curve and the measured frequency domain dielectric spectrum curve is determined. The directional derivatives corresponding to each parameter are determined, and the directions corresponding to the directional derivatives are used as the directions that cause the error between the model curve and the measured frequency domain dielectric spectrum curve to decrease most rapidly. The initial parameters after incremental processing are used as the moisture detection results, and the moisture detection results are used again as the initial values for iteration. The incremental processing is repeated until the iteration results meet the error requirements or the number of iterations overflows, thus obtaining the final moisture content parameter detection results.
[0086] Furthermore, this implementation can improve the moisture content parameter detection process. Based on initial parameters, a model curve is fitted, and other parameters are solved based on a preset number of iterations and a preset moisture content. Based on the error curve corresponding to the solution results, the error value is determined. If the error value does not meet the preset error requirements, the temperature range is divided, and different increments are set for different error requirements and iteration numbers. When the total error obtained from the iterative calculation is less than the error threshold or the maximum number of iterations is reached, the iteration stops and the final parameters are output.
[0087] Specifically, using Python programming, we first set the initial values X=0.2, Y=0.32, and the conductivity of the epoxy resin is 1×10⁻⁶. -12 The model curve was obtained by fitting a value of S / m and a moisture content of 1.0%, with the iteration count set to 10,000. Assuming a moisture content of 1%, and neglecting the effect of temperature, other parameters were solved using programming. A set of frequency domain dielectric spectrum curves were selected for testing, and the data was recorded in a text file to test whether the program could run smoothly and to verify the accuracy of the results.
[0088] like Figure 3 As shown, the curves marked with squares represent the dielectric parameters of the model curves, while the curves marked with circles represent the dielectric parameters of the measured curves (database curves). From Figure 3 As can be seen, there are still some errors in the real and imaginary parts of the dielectric constant between the model curve and the measured curve, especially in the high-frequency range, with a total error of 0.45838. The calculation results are: insulation structure parameters X=0.19781, Y=0.14831, and paper moisture content mc=1%.
[0089] After initially completing the moisture estimation of the XY model based on the steepest descent method, it was found that there was still a certain error between the measured curve and the model curve, with the error reaching 0.45838. Therefore, the steepest descent method was improved by considering the influence of temperature, dividing the temperature range, and setting different increments δ for different error requirements and iteration numbers. The maximum number of iterations was set to 500, with initial values X=0.2, Y=0.32, and oil conductivity of 1×10⁻⁶. -12 S / m, moisture content is 1.0%.
[0090] To further reduce errors, the steepest descent method was used to solve for each parameter separately, resulting in an improved calculation of the moisture content of the resin-impregnated paper insulation using the steepest descent method. For example... Figure 4 As shown, when using the improved steepest descent method for moisture estimation, the model curve and the measured curve show good consistency, and the real and imaginary parts of the complex permittivity are basically in agreement. The total error is 0.00729, and the calculated results are: insulation structure parameters X = 0.20947, Y = 0.20327, transformer bushing moisture content mc = 0.47914%, epoxy resin conductivity σ... oil =6.81292×10-13S / m.
[0091] Step 104: Evaluate the insulation performance of the transformer bushing based on the water content parameters to obtain the insulation evaluation results.
[0092] The transformer bushing insulation performance evaluation method provided in this application uses a pre-set XY model for data analysis, which can integrate multiple sets of characteristic data and transform them into a dielectric response curve of the overall bushing insulation. By deeply considering the physicochemical properties of the transformer bushing, the dielectric constant is selected as the evaluation parameter, which better reflects the actual situation of the bushing and can ensure the accuracy of the evaluation results. Furthermore, the difference in dielectric constant between the two curves is quantified by an error function, and the steepest descent method is used for rapid optimization, which can convert the degree of fitting into a numerical index and quickly determine the optimization direction. While ensuring the accuracy of the solution results, it can also take into account the estimation efficiency. Therefore, this application embodiment can solve the technical problem that the existing transformer bushing insulation degradation evaluation parameters lack specificity and ignore the physicochemical properties of the bushing, resulting in low accuracy of insulation performance evaluation.
[0093] For easier understanding, please refer to Figure 2 This application provides an embodiment of a transformer bushing insulation performance evaluation device, comprising:
[0094] The curve generation unit 201 is used to determine the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a preset XY model.
[0095] The error calculation unit 202 is used to calculate the error based on the complex dielectric constant according to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and generate an error function;
[0096] The parameter solving unit 203 is used to perform nonlinear optimization solution based on the error function using the steepest descent method to obtain the water content parameters of the transformer bushing;
[0097] Insulation assessment unit 204 is used to assess the insulation performance of transformer bushings based on water content parameters and obtain insulation assessment results.
[0098] Furthermore, the curve generation unit 201 specifically includes:
[0099] Obtain the conductivity of the epoxy resin in the transformer bushing;
[0100] The actual dielectric constants of the cardboard, support strips, and epoxy resin in the transformer bushing are determined based on the frequency domain dielectric spectrum characteristic curves and conductivity.
[0101] Input all actual dielectric constants into the preset XY model to obtain the complex dielectric constant;
[0102] The frequency domain dielectric spectrum model curve at a preset temperature is generated based on the complex dielectric constant.
[0103] Furthermore, it also includes:
[0104] Test unit 205 is used to perform frequency domain dielectric spectrum testing on transformer bushings at a preset temperature, obtain the test complex dielectric constant, construct frequency domain dielectric spectrum test curves, and generate a preset database;
[0105] The correction unit 206 is used to perform temperature correction on the test complex permittivity in the preset database using the Arrhenius formula, and generate the frequency domain dielectric spectrum characteristic curve at the reference temperature.
[0106] Furthermore, the error calculation unit 202 is specifically used for:
[0107] The complex dielectric constants corresponding to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve are obtained respectively, and the corresponding real part and imaginary part of the dielectric are selected.
[0108] Error is calculated based on the real and imaginary parts of the dielectric, and an error function is generated.
[0109] This application also provides a transformer bushing insulation performance evaluation device, the device including a processor and a memory;
[0110] The memory is used to store program code and transfer the program code to the processor;
[0111] The processor is used to execute the transformer bushing insulation performance evaluation method in the above method embodiment according to the instructions in the program code.
[0112] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.
[0113] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0114] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.
[0115] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods described in the various embodiments of this application through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.
[0116] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A method for evaluating the insulation performance of transformer bushings, characterized in that, include: The frequency domain dielectric spectrum model curve is determined by using a preset XY model based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing. Based on the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, the error based on the complex dielectric constant is calculated, and an error function is generated; The water content parameters of the transformer bushing are obtained by nonlinear optimization solution based on the error function using the steepest descent method. The insulation performance of the transformer bushing is evaluated based on the water content parameters, and the insulation evaluation results are obtained.
2. The method for evaluating the insulation performance of transformer bushings according to claim 1, characterized in that, The step of determining the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a preset XY model includes: Obtain the conductivity of the epoxy resin in the transformer bushing; The actual dielectric constants of the cardboard, support strips, and epoxy resin in the transformer bushing are determined based on the frequency domain dielectric spectrum characteristic curve and the conductivity. Input all the actual dielectric constants into the preset XY model to obtain the complex dielectric constant; Based on the complex permittivity, a frequency domain dielectric spectrum model curve at a preset temperature is generated.
3. The method for evaluating the insulation performance of transformer bushings according to claim 1, characterized in that, The step of determining the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a preset XY model also includes: The transformer bushing is subjected to frequency domain dielectric spectrum testing at a preset temperature to obtain the complex dielectric constant, and frequency domain dielectric spectrum test curves are constructed to generate a preset database. The test complex permittivity in the preset database is temperature-corrected using the Arrhenius formula to generate a frequency domain dielectric spectrum characteristic curve at the reference temperature.
4. The method for evaluating the insulation performance of transformer bushings according to claim 1, characterized in that, The step of calculating the error based on the complex permittivity according to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and generating the error function, includes: Obtain the complex dielectric constants corresponding to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and select the corresponding real and imaginary dielectric parts; An error function is generated by calculating the error based on the real and imaginary parts of the dielectric.
5. The method for evaluating the insulation performance of transformer bushings according to claim 1, characterized in that, The method of steepest descent is used to perform nonlinear optimization based on the error function to obtain the water content parameters of the transformer bushing, including: Construct the objective function based on the error function; The initial parameters of the transformer bushing are set according to the frequency domain dielectric spectrum model curve; Based on the initial parameters, the objective function is solved nonlinearly using the steepest descent method to minimize its residual and obtain the water content parameters of the transformer bushing.
6. A device for evaluating the insulation performance of transformer bushings, characterized in that, include: The curve generation unit is used to determine the frequency domain dielectric spectrum model curve based on the frequency domain dielectric spectrum characteristic curve of the transformer bushing using a preset XY model. The error calculation unit is used to calculate the error based on the complex dielectric constant according to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and generate an error function. The parameter solving unit is used to perform nonlinear optimization solution based on the error function using the steepest descent method to obtain the water content parameters of the transformer bushing; An insulation assessment unit is used to assess the insulation performance of transformer bushings based on the moisture content parameters and obtain insulation assessment results.
7. The transformer bushing insulation performance evaluation device according to claim 1, characterized in that, The curve generation unit specifically includes: Obtain the conductivity of the epoxy resin in the transformer bushing; The actual dielectric constants of the cardboard, support strips, and epoxy resin in the transformer bushing are determined based on the frequency domain dielectric spectrum characteristic curve and the conductivity. Input all the actual dielectric constants into the preset XY model to obtain the complex dielectric constant; Based on the complex permittivity, a frequency domain dielectric spectrum model curve at a preset temperature is generated.
8. The transformer bushing insulation performance evaluation device according to claim 1, characterized in that, Also includes: The test unit is used to perform frequency domain dielectric spectrum testing on transformer bushings at a preset temperature, obtain the test complex dielectric constant, construct frequency domain dielectric spectrum test curves, and generate a preset database. The calibration unit is used to perform temperature correction on the test complex permittivity in the preset database using the Arrhenius formula, and generate a frequency domain dielectric spectrum characteristic curve at the reference temperature.
9. The transformer bushing insulation performance evaluation device according to claim 1, characterized in that, The error calculation unit is specifically used for: Obtain the complex dielectric constants corresponding to the frequency domain dielectric spectrum model curve and the frequency domain dielectric spectrum test curve, and select the corresponding real and imaginary dielectric parts; An error function is generated by calculating the error based on the real and imaginary parts of the dielectric.
10. A transformer bushing insulation performance evaluation device, characterized in that, The device includes a processor and a memory; The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the transformer bushing insulation performance evaluation method according to any one of claims 1-5 according to the instructions in the program code.