A method and system for evaluating the uncertainty of a transformer tester
By establishing an evaluation function based on the measurement uncertainty representation guideline and a Bayesian evaluation method, the accuracy problem of transformer measurement uncertainty assessment was solved, and the measurement accuracy and reliability of the transformer tester were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ELECTRIC POWER RES INST OF GUANGXI POWER GRID CO LTD
- Filing Date
- 2022-08-01
- Publication Date
- 2026-07-31
AI Technical Summary
The uncertainty of transformer measurements is difficult to assess accurately, affecting the accuracy and reliability of transformer measurements. Especially under the requirement of high-precision measurement, existing technologies are unable to effectively reduce the uncertainty of load loss.
A first evaluation function is established based on the measurement uncertainty representation guide. Then, by combining the measurement object and the uncertainty source correction function, and using the Bayesian evaluation method of maximum entropy measurement uncertainty, a third evaluation function is obtained to evaluate the uncertainty of the testing instrument.
This improves the accuracy and scientific rigor of uncertainty assessment for transformer testers, aligns with current judgment standards, and enhances the reliability and acceptability of assessment results.
Smart Images
Figure CN115408825B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of measuring equipment, and in particular relates to a method and system for evaluating the uncertainty of a transformer tester. Background Technology
[0002] The analysis of transformer no-load loss, capacity, and short-circuit impedance relies primarily on measured values, which are not precise figures and possess inherent uncertainty. The extent of this uncertainty depends on the quality of the testing equipment, particularly the measurement system, operator skill, the type of test sample, and the difficulty of the measurement. Chapter 10 of GB1094.1-2013 provides the permissible deviations for the specified loss parameters of transformers in test verification. The national standard GB20052—2013, "Energy Efficiency Limits and Energy Efficiency Grades for Three-Phase Distribution Transformers," specifies the Level 3 energy efficiency limit as a guaranteed value. Systematic error analysis of the aforementioned loss measurement tests reveals that, considering only the systematic factors of the measuring equipment, under conventional measurement conditions, the uncertainty in load loss measurement after calibration at the reference temperature reaches 2.9%. In reality, this value would be even higher due to random factors such as temperature measurement and operator skill levels. Therefore, reducing load loss uncertainty is particularly important and urgent for further high-precision transformer measurements. Furthermore, this type of uncertainty analysis helps relevant laboratories to reasonably assess their own testing capabilities, accurately judge the results of the tested samples, and provide reliable data support for the market supervision and management system's supervision and inspection, arbitration and determination, thereby minimizing or avoiding misjudgments of the tested samples and providing strong support for resolving testing disputes.
[0003] Meanwhile, in practical applications, the evaluation and prediction results of transformer measurement uncertainty can effectively reflect the latest state of the measurement system in real time, making the evaluation results of transformer measurement uncertainty more scientific and reasonable, and improving the reliability of product inspection results. Therefore, the research on high-precision transformer measurement methods and uncertainty evaluation methods for transformer parameter measuring instruments is very important for transformer measurement research. Summary of the Invention
[0004] To solve or improve the above problems, the present invention provides a processing method for a transformer tester uncertainty evaluation method, the specific technical solution of which is as follows: This invention provides a method for evaluating the uncertainty of a transformer tester, comprising: establishing a first evaluation function based on a guide to measurement uncertainty representation; determining the source of uncertainty according to the measurement object of the tester; modifying the first evaluation function according to the source of uncertainty to obtain a second evaluation function; and obtaining a third evaluation function for evaluating the uncertainty of the tester based on the second evaluation function and a Bayesian evaluation method for maximum entropy measurement uncertainty.
[0005] Preferably, the measurement objects of the measuring instrument include no-load loss, capacity, and short-circuit impedance; the uncertainty sources include transformer environmental parameters, voltage waveform parameters, winding voltage and current values, uncertainty of the voltage and current transformer used for measurement, and standard uncertainty; correspondingly, determining the uncertainty sources according to the measurement objects of the measuring instrument includes: selecting at least one of the uncertainty sources according to the measurement objects of the measuring instrument.
[0006] Preferably, selecting at least one source of uncertainty based on the object being measured by the measuring instrument includes: selecting at least one source of uncertainty based on the properties of the transformer and the object being measured by the measuring instrument.
[0007] Preferably, the attributes of the transformer include applicable scenarios; correspondingly, the step of selecting at least one source of uncertainty based on the attributes of the transformer and the measurement object of the measuring instrument includes: selecting and assigning a weight corresponding to the source of uncertainty based on the applicable scenario, wherein the weight is used to modify the first evaluation function to obtain a second evaluation function.
[0008] This invention provides a transformer tester uncertainty assessment system, comprising: a first unit for establishing a first assessment function based on a measurement uncertainty representation guideline; a second unit for determining the uncertainty source according to the measurement object of the tester; a third unit for modifying the first assessment function according to the uncertainty source to obtain a second assessment function; and a fourth unit for obtaining a third assessment function for assessing the uncertainty of the tester based on the second assessment function and a Bayesian evaluation method for maximum entropy measurement uncertainty.
[0009] Preferably, the measurement objects of the measuring instrument include no-load loss, capacity, and short-circuit impedance; the uncertainty sources include transformer environmental parameters, voltage waveform parameters, winding voltage and current values, uncertainty of the voltage and current transformer used for measurement, and standard uncertainty; correspondingly, determining the uncertainty sources according to the measurement objects of the measuring instrument includes: selecting at least one of the uncertainty sources according to the measurement objects of the measuring instrument.
[0010] Preferably, selecting at least one source of uncertainty based on the object being measured by the measuring instrument includes: selecting at least one source of uncertainty based on the properties of the transformer and the object being measured by the measuring instrument.
[0011] Preferably, the attributes of the transformer include applicable scenarios; correspondingly, the step of selecting at least one source of uncertainty based on the attributes of the transformer and the measurement object of the measuring instrument includes: selecting and assigning a weight corresponding to the source of uncertainty based on the applicable scenario, wherein the weight is used to modify the first evaluation function to obtain a second evaluation function.
[0012] The beneficial effects of this invention are as follows: A first evaluation function based on the measurement uncertainty representation guideline is established, which conforms to current mainstream judgment standards and improves the acceptability of the evaluation results; the source of uncertainty is determined according to the measurement object of the measuring instrument; the first evaluation function is modified according to the source of uncertainty to obtain a second evaluation function, which can improve the accuracy of the evaluation results; based on the second evaluation function and the Bayesian evaluation method of maximum entropy measurement uncertainty, a third evaluation function for evaluating the uncertainty of the testing instrument is obtained, which can further improve the accuracy of the evaluation results. Attached Figure Description
[0013] Figure 1 This is a schematic diagram of the uncertainty assessment method for transformer testers according to the present invention; Figure 2 This is a schematic diagram of the transformer tester uncertainty assessment system according to the present invention.
[0014] Explanation of key figure labels: 1-Unit 1, 2-Unit 2, 3-Unit 3, 4-Unit 4. Detailed Implementation
[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0016] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.
[0017] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.
[0018] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.
[0019] To address or improve the uncertainty problem of transformer testers, the following suggestions are proposed: Figure 1 The method for evaluating the uncertainty of a transformer tester includes: S1, establishing a first evaluation function based on the measurement uncertainty representation guideline; S2, determining the source of uncertainty according to the measurement object of the tester; S3, modifying the first evaluation function according to the source of uncertainty to obtain a second evaluation function; S4, obtaining a third evaluation function for evaluating the uncertainty of the tester based on the second evaluation function and the Bayesian evaluation method of maximum entropy measurement uncertainty.
[0020] How to reasonably and objectively evaluate measurement accuracy has always been an important part of measurement science and metrological practice. There are many terms or expressions used to describe the quality of measurement results in different fields and contexts, but the most commonly used in practice are measurement error and measurement uncertainty. With the promulgation and implementation of the Guide to Expression of Uncertainty in Measurement (GUM) and its positive results over the past 20 years, especially its recognition by national physics laboratories and metrology research institutions, measurement uncertainty has become a widely accepted consensus in the academic community to replace measurement error in characterizing the accuracy of measurement results. Based on the Guide to Expression of Uncertainty in Measurement (GUM), a first evaluation function / evaluation model is established. This can provide preliminary, basic formulas / functions for evaluating the uncertainty of testing instruments, allowing for the judgment of the uncertainty of the testing instrument to be evaluated.
[0021] The objects measured by a measuring instrument can be varied, including voltage, current, capacitance, and impedance. The measurement principles of the instrument differ depending on the object being measured, and the external factors influencing the object also vary. Based on the object being measured, the sources of uncertainty can be determined by combining experience or experimental results.
[0022] The second evaluation function is obtained by modifying the first evaluation function based on the sources of uncertainty. Specifically, this includes: adding the measurement object as a correction parameter based on the measurement uncertainty representation guidelines, modifying the parameters of the first evaluation function, and adding or subtracting functions, which can improve the accuracy of the evaluation.
[0023] Bayesian evaluation method for maximum entropy measurement uncertainty: The probability density function of the sample information is solved using the maximum entropy principle; then, combined with prior information, the probability density function of the posterior information is obtained using the Bayesian evaluation method; finally, the uncertainty of the measurement result is calculated.
[0024] The second evaluation function allows modification of prior information, as well as the probability density function of the prior information or the probability density function of the posterior information. Specifically, it first obtains the basic probability density function, the probability density functions of the prior information, and the probability density functions of the posterior information based on the Bayesian evaluation method for maximum entropy measurement uncertainty. Then, according to the formula of the second evaluation function itself or the function result, the coefficients and constants in the probability density functions of the prior information and the posterior information are modified. The third evaluation function obtained in this way can be used to evaluate the uncertainty of the testing instrument.
[0025] The measuring instrument measures no-load loss, capacity, and short-circuit impedance; the sources of uncertainty include transformer environmental parameters, voltage waveform parameters, winding voltage and current values, uncertainty of the voltage and current transformer used for measurement, and standard uncertainty; correspondingly, determining the sources of uncertainty based on the measuring instrument's measuring objects includes selecting at least one of the sources of uncertainty based on the measuring instrument's measuring objects.
[0026] Transformers are crucial components of power systems. Therefore, accurately measuring various transformer parameters is essential for maintaining grid stability. The measuring instruments measure no-load loss, capacity, and short-circuit impedance. This is primarily because these parameters are critical for transformers, and high accuracy is required for the measurement results.
[0027] Uncertainty sources are the causes / factors considered to lead to high uncertainty in the measurement results. Specifically, these include transformer environmental parameters, voltage waveform parameters, winding voltage and current values, uncertainty of the voltage and current transformers used for measurement, and standard uncertainty. Transformer environmental parameters include the transformer's operating environment, specifically factors such as temperature and humidity. Voltage waveform parameters include factors such as voltage waveform distortion and frequency fluctuations. Winding voltage and current values include winding voltage and winding current. Uncertainty of the voltage and current transformers used for measurement includes the uncertainties of the voltage and current transformers themselves, and can be preset values. Standard uncertainty refers to the uncertainty of the standard transformer and calibrator, and can also be preset values.
[0028] By collecting historical and real-time data corresponding to the sources of uncertainty, and combining them with the first evaluation function and / or the second evaluation function and / or the third evaluation function, the accuracy of the final uncertainty assessment can be improved.
[0029] The step of selecting at least one source of uncertainty based on the object being measured by the measuring instrument includes: selecting at least one source of uncertainty based on the properties of the transformer and the object being measured by the measuring instrument.
[0030] The transformer's attributes include applicable scenarios; correspondingly, selecting at least one source of uncertainty based on the transformer's attributes and the measuring object of the measuring instrument includes: selecting and assigning a weight corresponding to the uncertainty source based on the applicable scenario, wherein the weight is used to modify the first evaluation function to obtain a second evaluation function.
[0031] This invention provides a transformer tester uncertainty assessment system, comprising: a first unit 1 for establishing a first assessment function based on a measurement uncertainty representation guideline; a second unit 2 for determining the uncertainty source according to the measurement object of the tester; a third unit 3 for modifying the first assessment function according to the uncertainty source to obtain a second assessment function; and a fourth unit 4 for obtaining a third assessment function for assessing the uncertainty of the tester based on the second assessment function and a Bayesian evaluation method for maximum entropy measurement uncertainty.
[0032] The system's operating principle includes: establishing a first evaluation function / evaluation model based on the Guide to Measurement Uncertainty (GUM). It can provide preliminary, basic instrument uncertainty evaluation formulas / functions to determine the uncertainty of the instrument to be evaluated.
[0033] The objects measured by a measuring instrument can be varied, including voltage, current, capacitance, and impedance. The measurement principles of the instrument differ depending on the object being measured, and the external factors influencing the object also vary. Based on the object being measured, the sources of uncertainty can be determined by combining experience or experimental results.
[0034] The second evaluation function is obtained by modifying the first evaluation function based on the sources of uncertainty. Specifically, this includes: adding the measurement object as a correction parameter based on the measurement uncertainty representation guidelines, modifying the parameters of the first evaluation function, and adding or subtracting functions, which can improve the accuracy of the evaluation.
[0035] Bayesian evaluation method for maximum entropy measurement uncertainty: The probability density function of the sample information is solved using the maximum entropy principle; then, combined with prior information, the probability density function of the posterior information is obtained using the Bayesian evaluation method; finally, the uncertainty of the measurement result is calculated.
[0036] The second evaluation function allows modification of prior information, as well as the probability density function of the prior information or the probability density function of the posterior information. Specifically, it first obtains the basic probability density function, the probability density functions of the prior information, and the probability density functions of the posterior information based on the Bayesian evaluation method for maximum entropy measurement uncertainty. Then, according to the formula of the second evaluation function itself or the function result, the coefficients and constants in the probability density functions of the prior information and the posterior information are modified. The third evaluation function obtained in this way can be used to evaluate the uncertainty of the testing instrument.
[0037] The measuring instrument measures no-load loss, capacity, and short-circuit impedance; the sources of uncertainty include transformer environmental parameters, voltage waveform parameters, winding voltage and current values, uncertainty of the voltage and current transformer used for measurement, and standard uncertainty; correspondingly, determining the sources of uncertainty based on the measuring instrument's measuring objects includes selecting at least one of the sources of uncertainty based on the measuring instrument's measuring objects.
[0038] The step of selecting at least one source of uncertainty based on the object being measured by the measuring instrument includes: selecting at least one source of uncertainty based on the properties of the transformer and the object being measured by the measuring instrument.
[0039] The transformer's attributes include applicable scenarios; correspondingly, selecting at least one source of uncertainty based on the transformer's attributes and the measuring object of the measuring instrument includes: selecting and assigning a weight corresponding to the uncertainty source based on the applicable scenario, wherein the weight is used to modify the first evaluation function to obtain a second evaluation function.
[0040] Those skilled in the art will recognize that the units of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of the invention.
[0041] In the embodiments provided in this application, it should be understood that the division of units is only a logical functional division. In actual implementation, there may be other division methods, such as multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored.
[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.
Claims
1. A method of evaluating the uncertainty of a transformer tester, characterized in that, include: Establish a first evaluation function based on the guidelines for representing measurement uncertainty; The sources of uncertainty are determined based on the measurement objects of the measuring instrument; the measurement objects of the measuring instrument include no-load loss, capacity, and short-circuit impedance. The sources of uncertainty include transformer environmental parameters, voltage waveform parameters, winding voltage and current values, measurement uncertainty of voltage and current transformers, and standard uncertainty. Correspondingly, determining the source of uncertainty based on the object being measured by the measuring instrument includes: Based on the object being measured by the measuring instrument, at least one source of uncertainty is selected; including: Based on the properties of the transformer and the object being measured by the measuring instrument, at least one of the aforementioned sources of uncertainty is selected; The first evaluation function is corrected based on the sources of uncertainty to obtain the second evaluation function; the properties of the transformer include applicable scenarios; correspondingly, The selection of at least one source of uncertainty based on the properties of the transformer and the object being measured by the measuring instrument includes: According to the applicable scenario, select and assign weights corresponding to the sources of uncertainty, and use the weights to modify the first evaluation function to obtain the second evaluation function; Based on the second evaluation function and the Bayesian evaluation method for the maximum entropy measurement uncertainty, a third evaluation function is obtained for evaluating the uncertainty of the testing instrument.
2. A transformer tester uncertainty evaluation system, characterized by, include: The first unit is used to establish the first evaluation function based on the guidelines for representing measurement uncertainty; The second unit is used to determine the source of uncertainty based on the measurement object of the measuring instrument; the measurement object of the measuring instrument includes no-load loss, capacity and short-circuit impedance; The sources of uncertainty include transformer environmental parameters, voltage waveform parameters, winding voltage and current values, measurement uncertainty of voltage and current transformers, and standard uncertainty. Correspondingly, determining the source of uncertainty based on the object being measured by the measuring instrument includes: Select at least one source of uncertainty based on the object being measured by the measuring instrument; The step of selecting at least one source of uncertainty based on the object being measured by the measuring instrument includes: Based on the properties of the transformer and the object being measured by the measuring instrument, at least one of the aforementioned sources of uncertainty is selected; The third unit is used to modify the first evaluation function according to the sources of uncertainty to obtain the second evaluation function; the properties of the transformer include applicable scenarios; correspondingly, The selection of at least one source of uncertainty based on the properties of the transformer and the object being measured by the measuring instrument includes: According to the applicable scenario, select and assign weights corresponding to the sources of uncertainty, and use the weights to modify the first evaluation function to obtain the second evaluation function; The fourth unit is used to obtain a third evaluation function for evaluating the uncertainty of the test instrument based on the second evaluation function and the Bayesian evaluation method of the maximum entropy measurement uncertainty.