A method and device for value traceability based on a short-circuit impedance test instrument

Abstract

The present invention belongs to the technical field of short-circuit impedance testing, and particularly relates to a method and device for value traceability based on a short-circuit impedance testing instrument, including the following steps: S1, obtaining the sampled voltage and current of the device circuit; S2, obtaining the standard measurement voltage and current of the device circuit; S3, calculating the cross error and the standard error respectively; S4, calculating the loss value; S5, obtaining the value traceability result of the short-circuit impedance testing instrument. By using multiple different standard short-circuit impedance meters to perform fast Fourier mean sampling on the device circuit, the present invention obtains the standard measurement voltage and current of the device circuit. The error values of the standard measurement voltage and current of the device circuit are small, the fault tolerance rate is large, and the calculation results are more accurate. The method, device, electronic device and computer-readable storage medium for value traceability based on a short-circuit impedance testing instrument proposed by the present invention solve the problem of low accuracy of the short-circuit impedance tester.

Description

Technical Field

[0001] The present invention belongs to the technical field of short - circuit impedance testing, and particularly relates to a method and device for value traceability based on a short - circuit impedance testing instrument. Background Art

[0002] The short - circuit impedance is the resistance formed by the short - circuit of an electrical appliance, such as eddy current, etc. Generally, the short - circuit impedance of a transformer refers to the equivalent series impedance between the terminals of a certain winding in a pair of windings at the rated frequency and reference temperature. Since the impedance of a large - capacity transformer is mainly inductive reactance, the reactance of the transformer winding can be approximately obtained from the short - circuit voltage. Therefore, the short - circuit impedance is a very important item in the performance indicators of the transformer, and the deviation requirements between the measured value and the specified value at the time of factory are very strict.

[0003] Existing short - circuit impedance testers usually directly use the measured data. For example, the short - circuit impedance of a transformer is directly used based on the measured current and voltage to determine whether there is deformation in the transformer winding. This method only relies on the data of the short - circuit impedance tester for judgment, which is prone to errors, thus reducing the accuracy of the short - circuit impedance testing instrument.

[0004] In view of this, the present invention proposes a method and device for value traceability based on a short - circuit impedance testing instrument to solve the problem of low accuracy during the measurement of the short - circuit impedance tester. Summary of the Invention

[0005] In order to solve or improve the problem of low accuracy during the measurement of the short - circuit impedance tester, the present invention provides a method and device for value traceability based on a short - circuit impedance testing instrument. The specific technical solutions are as follows:

[0006] The present invention provides a method and device for value traceability based on a short - circuit impedance testing instrument, including the following steps:

[0007] S1, Use a short - circuit impedance meter to perform fast Fourier mean sampling on a preset device circuit to obtain the sampled voltage and current of the device circuit;

[0008] S2, Use multiple groups of different standard short - circuit impedance meters to perform fast Fourier mean sampling on the device circuit to obtain the standard measured voltage and current of the device circuit;

[0009] S3, Calculate the cross - error between each group of different standard measured voltages and currents, and calculate the standard error corresponding to all groups of standard short - circuit impedance meters according to the cross - error;

[0010] S4, Calculate the standard mean of all groups of standard measured voltages and currents, and calculate the loss value between the sampled voltage and current and the standard mean;

[0011] S5. Coefficient-correct the sampled voltage and current according to the standard error and the loss value to obtain the value traceability result of the short-circuit impedance tester.

[0012] Preferably, in S1, use a short-circuit impedance meter to perform fast Fourier mean sampling on a preset device circuit to obtain the sampled voltage and current of the device circuit. It is necessary to use a short-circuit impedance meter to obtain the circuit signal of the device circuit, perform signal sampling at a preset number of points within the unit time of the circuit signal to obtain a sampled signal, then perform a fast Fourier transform on the sampled signal to obtain a frequency-domain array, and finally perform a preset number of array moving averages on the frequency-domain array to obtain the sampled voltage and current of the device circuit.

[0013] Preferably, voltage-current synchronous AC sampling is used for sampling the device circuit signal.

[0014] Preferably, performing a fast Fourier transform on the sampled signal to obtain a frequency-domain array specifically includes using the following equation:

[0015]

[0016] where X k is the frequency-domain array, N is the number of signal samplings, m is the count of the signal sampling, i is another count different from m of the sampled signal, e is the current sampling signal, x is the voltage signal sampling, and k is the parameter of the fast Fourier transform formula.

[0017] Preferably, in S3, calculate the cross error between each group of different standard measured voltages and currents respectively, including the following steps:

[0018] S301. Pool all groups of standard measured voltages and currents together to form a data pool;

[0019] S302. Select a group of standard measured voltage and current as the target voltage and current from the data pool one by one without replacement;

[0020] S303. Calculate the relative error values between the target voltage and current measured in S302 and each group of unselected standard voltages and currents respectively until all the standard measured voltages and currents in the data pool are selected;

[0021] S304. Calculate the mean value of the relative error values from the results of S303 to obtain the cross error.

[0022] Preferably, in S302, selecting a group of standard measured voltage and current as the target voltage and current from the data pool one by one without replacement includes the following steps:

[0023] S3021. Extract a standard measurement voltage from the data pool using a random function;

[0024] S3022. Find the corresponding standard measurement current according to the standard measurement voltage drawn in S3021;

[0025] S3023. Delete the used standard measurement voltage and current in S3022 from the data pool;

[0026] S3024. Return to the step of S3021 to extract a standard measurement voltage from the data pool using a random function until there is no such standard measurement voltage in the data pool.

[0027] Preferably, in S3, calculating the cross - error between each group of different standard measurement voltages and currents includes the following steps:

[0028] S3001. Select different groups of standard measurement voltages and currents pairwise without repetition;

[0029] S3002. Calculate the difference value between the two selected different groups of standard measurement voltages and currents;

[0030] S3003. Until all groups of standard measurement voltages and currents are calculated, and calculate the mean value of the difference values to obtain the cross - error.

[0031] Preferably, in S5, according to the standard error and the loss value, coefficient correction is performed on the sampled voltage and current to obtain the value traceability result of the short - circuit impedance tester, including the following steps:

[0032] S501. Calculate the error coefficient according to the loss value;

[0033] S502. Calculate the error range of the sampled voltage and current according to the error coefficient and the standard error;

[0034] S503. Use the error range to numerically adjust the sampled voltage and current to obtain the value traceability result of the short - circuit impedance tester.

[0035] Preferably, in S502, calculating the error range of the sampled voltage and current according to the error coefficient and the standard error includes: calculating the error range of the sampled voltage and current using the following error algorithm:

[0036]

[0037] where s(Δε) is the error range of the voltage and current, Δε is the standard error, n is the total number of the voltage and current, i is the counting number of the voltage and current, Δεi is the error coefficient, is the standard deviation corresponding to the standard error.

[0038] The present invention also provides a quantity value traceability device based on a short-circuit impedance test instrument, which is characterized in that it includes a first sampling module and a second sampling module for data sampling, a calculation error module for calculating the cross error between each group of different standard measurement voltages and currents, a calculation loss module for calculating the loss value of the standard mean, and a correction module for coefficient correction of the sampled voltage and current.

[0039] The beneficial effects of the present invention are as follows: By using multiple groups of different standard short-circuit impedance meters to perform fast Fourier mean sampling on the device circuit, the standard measurement voltage and current of the device circuit are obtained. The error values of the standard measurement voltage and current of the device circuit are small, the error tolerance rate is large, and the calculation results are more accurate, with high reference value; Calculate the cross error between each group of different standard measurement voltages and currents, and calculate the standard error corresponding to all groups of standard short-circuit impedance meters according to the cross error. The mean value of the scattered difference values can reduce the systematic error caused by the calculation formula, improve the accuracy of the numerical value, the reliability of the experimental results, and the applicability of the calculation method, and improve the calculation accuracy while ensuring the efficiency. Coefficient correction is performed on the sampled voltage and current according to the standard error and the loss value to obtain the quantity value traceability result of the short-circuit impedance test instrument. Therefore, the quantity value traceability method, device, electronic device and computer-readable storage medium based on the short-circuit impedance test instrument proposed by the present invention can solve the problem of low accuracy of the short-circuit impedance tester. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flowchart of a quantity value traceability method based on a short-circuit impedance test instrument;

[0041] Figure 2 is a structural diagram of a quantity value traceability device based on a short-circuit impedance test instrument. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0043] 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, wholes, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0044] It should also be understood that the terms used in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0045] It should be further understood that the term "and / or" used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0046] In order to solve the problem of relatively low accuracy during the measurement of a short-circuit impedance tester, a method and device for value traceability of a short-circuit impedance test instrument as shown in Figure 1 are provided, including the following steps:

[0047] S1. Using a short-circuit impedance meter to perform fast Fourier mean sampling on a preset device circuit to obtain the sampled voltage and current of the device circuit;

[0048] S2. Using multiple different standard short-circuit impedance meters to perform fast Fourier mean sampling on the device circuit to obtain the standard measured voltage and current of the device circuit;

[0049] S3. Respectively calculating the cross errors between each group of different standard measured voltages and currents, and calculating the standard errors corresponding to all groups of standard short-circuit impedance meters according to the cross errors;

[0050] S4. Calculating the standard means of all groups of standard measured voltages and currents, and calculating the loss values between the sampled voltage and current and the standard means;

[0051] S5. Performing coefficient correction on the sampled voltage and current according to the standard errors and the loss values to obtain the value traceability result of the short-circuit impedance test instrument.

[0052] The fast Fourier transform is a fast algorithm for the discrete Fourier transform. It is obtained by improving the algorithm of the discrete Fourier transform according to the odd, even, imaginary, real and other characteristics of the discrete Fourier transform. The amount of computation of the fast Fourier transform is only 1% of that of the discrete Fourier transform for the same number of points. The more points there are, the greater the savings in the amount of computation. In the present invention, it can save the sampling time and increase the sampling efficiency.

[0053] As a specific implementation manner of the present invention, in S1, a short-circuit impedance meter is used to perform fast Fourier mean sampling on a preset device circuit to obtain the sampled voltage and current of the device circuit. It is necessary to use a short-circuit impedance meter to obtain the circuit signal of the device circuit, perform signal sampling at a preset number of points within the unit time of the circuit signal to obtain a sampled signal, then perform a fast Fourier transform on the sampled signal to obtain a frequency-domain array, and finally perform a preset number of array moving averages on the frequency-domain array to obtain the sampled voltage and current of the device circuit. Performing a fast Fourier transform on the sampled signal to obtain a frequency-domain array specifically includes using the following equation:

[0054]

[0055] wherein, X k is the frequency-domain array, N is the number of signal samplings, m is the count of signal samplings, i is another count different from m of the sampled signal, e is the current sampled signal, x is the voltage signal sampling, and k is the parameter of the fast Fourier transform formula.

[0056] In Embodiment 1, in S3, the cross errors between each group of different standard measured voltages and currents are calculated respectively, including the following steps:

[0057] S301: Pool all groups of standard measured voltages and currents together to form a data pool;

[0058] S302: Select a group of standard measured voltage and current from the data pool without replacement one by one as the target voltage and current;

[0059] S303: Calculate the relative error values between the target voltage and current measured in S302 and each group of standard voltages and currents that have not been selected until all the standard measured voltages and currents in the data pool have been selected;

[0060] S304: Calculate the mean value of the relative error values from the results of S303 to obtain the cross error.

[0061] The method of Embodiment 1 is to calculate the error values by comparing each group of standard measured voltages and currents one by one. The advantage of this method is to ensure that the selected data can be compared with all other data one by one, without missing a group of data that has not been compared, increasing the accuracy of the calculation result.

[0062] In S302, selecting a group of standard measured voltage and current from the data pool without replacement one by one as the target voltage and current includes the following steps:

[0063] S3021. Extract a standard measurement voltage from the data pool using a random function;

[0064] S3022. Find the corresponding standard measurement current according to the standard measurement voltage drawn in S3021;

[0065] S3023. Delete the used standard measurement voltage and current from the data pool;

[0066] S3024. Return to the step of extracting a standard measurement voltage from the data pool using a random function in S3021 until there is no such standard measurement voltage in the data pool.

[0067] In the second embodiment, in S3, the steps of respectively calculating the cross - error between different groups of standard measurement voltages and currents include the following:

[0068] S3001. Select different groups of standard measurement voltages and currents pairwise without repetition;

[0069] S3002. Calculate the difference value between the selected two different groups of standard measurement voltages and currents;

[0070] S3003. Until all groups of standard measurement voltages and currents are calculated, and calculate the mean value of the difference values to obtain the cross - error.

[0071] The advantage of the method in the second embodiment is that the calculation amount of the second embodiment is relatively smaller than that of the first embodiment. There is no need to compare one by one, and the accuracy of the calculation result is relatively low, but the calculation speed is fast and the efficiency is high. Users can choose to use the method of the first or second embodiment according to their needs.

[0072] As a specific implementation manner of the present invention, in S5, coefficient correction is performed on the sampled voltage and current according to the standard error and the loss value to obtain the value traceability result of the short - circuit impedance tester, including the following steps:

[0073] S501. Calculate the error coefficient according to the loss value;

[0074] S502. Calculate the error range of the sampled voltage and current according to the error coefficient and the standard error;

[0075] S503. Numerically adjust the sampled voltage and current using the error range to obtain the value traceability result of the short - circuit impedance tester.

[0076] In S502, calculating the error range of the sampled voltage and current according to the error coefficient and the standard error includes: calculating the error range of the sampled voltage and current using the following error algorithm:

[0077]

[0078] Among them, s(Δε) is the error range of the voltage and current, Δε is the standard error, n is the total number of the voltage and current, i is the counted number of the voltage and current, and Δε i is the error coefficient, is the standard deviation corresponding to the standard error.

[0079] To implement the method of the present invention, the present invention also provides a value traceability device based on a short-circuit impedance tester, which is characterized in that it includes a first sampling module and a second sampling module for data sampling, a calculation error module for calculating the cross error between each group of different standard measurement voltages and currents, a calculation loss module for calculating the loss value of the standard mean, and a correction module for coefficient correction of the sampled voltage and current.

[0080] Those of ordinary skill in the art can realize that the units of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components of each example have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0081] In the embodiments provided in the present application, it should be understood that the division of units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units can be combined into one unit, one unit can be split into multiple units, or some features can be ignored, etc.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements 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 by the scope of the claims and the description of the present invention.

Claims

1. A method for the traceability of measurement values based on a short-circuit impedance testing instrument, characterized in that, Including the following steps: S1. Use a short-circuit impedance meter to perform fast Fourier mean sampling on a preset device circuit to obtain the sampled voltage and current of the device circuit; S2. Use multiple groups of different standard short-circuit impedance meters to perform fast Fourier mean sampling on the device circuit to obtain the standard measured voltage and current of the device circuit; S3. Calculate the cross errors between the standard measured voltages and currents of each group respectively, and calculate the standard errors corresponding to the standard short-circuit impedance meters of all groups according to the cross errors; S4. Calculate the standard means of the standard measured voltages and currents of all groups, and calculate the loss values between the sampled voltage and current and the standard means; S5. Perform coefficient correction on the sampled voltage and current according to the standard errors and the loss values to obtain the value traceability result of the short-circuit impedance test instrument.

2. A method for the traceability of the measured value of a short-circuit impedance testing instrument according to claim 1, characterized in that: In S1, when using a short-circuit impedance meter to perform fast Fourier mean sampling on a preset device circuit to obtain the sampled voltage and current of the device circuit, it is necessary to use the short-circuit impedance meter to obtain the circuit signal of the device circuit, perform signal sampling at a preset number of points within the unit time of the circuit signal to obtain a sampled signal, then perform a fast Fourier transform on the sampled signal to obtain a frequency domain array, and finally perform an array moving average on the frequency domain array a preset number of times to obtain the sampled voltage and current of the device circuit.

3. A method for the traceability of the measured value based on a short-circuit impedance test instrument according to claim 2, characterized in that: The voltage-current synchronous AC sampling method is adopted for sampling the device circuit signal.

4. A method for value traceability of a short - circuit impedance test instrument according to claim 2, characterized in that: Performing a fast Fourier transform on the sampled signal to obtain a frequency domain array specifically includes using the following equation: Among them, is the frequency domain array, is the number of signal samplings, is the count of signal samplings, is another count of the sampling signal different from and is the current sampling signal, is the voltage signal sampling, is the parameter of the fast Fourier transform formula.

5. A value traceability method based on a short-circuit impedance test instrument according to claim 1, characterized in that: In S3, calculating the cross errors between the standard measured voltages and currents of each group respectively includes the following steps: S301. Pool all the standard measured voltages and currents of all groups together to form a data pool; S302. Select a group of standard measured voltage and current as the target voltage and current from the data pool one by one without replacement; S303. Calculate the relative error values between the target voltage and current measured in S302 and each group of standard voltages and currents that have not been selected until all the standard measured voltages and currents in the data pool have been selected; S304. Calculate the mean value of the relative error values from the results of S303 to obtain the cross error.

6. A method for value traceability of a short-circuit impedance test instrument according to claim 5, characterized in that: In S302, selecting a group of standard measured voltage and current as the target voltage and current from the data pool one by one without replacement includes the following steps: S3021. Use a random function to draw a standard measured voltage from the data pool; S3022. Find the corresponding standard measured current according to the standard measured voltage drawn in S3021; S3023. Delete the standard measured voltage and current used in S3022 from the data pool; S3024. Return to the step of using a random function to draw a standard measured voltage from the data pool in S3021 until there is no such standard measured voltage in the data pool.

7. A method for value traceability of a short-circuit impedance test instrument according to claim 1, characterized in that: In S3, the calculation of the cross errors between the standard measured voltages and currents of each group respectively includes the following steps: S3001. Select the standard measured voltages and currents of different groups pairwise without repetition; S3002. Calculate the difference value between the standard measured voltages and currents of the two selected different groups; S3003. Until the standard measured voltages and currents of all groups are calculated, and calculate the mean value of the difference values to obtain the cross error.

8. A value traceability method based on a short-circuit impedance test instrument according to claim 1, characterized in that: In S5, perform coefficient correction on the sampled voltages and currents according to the standard error and the loss value to obtain the value traceability result of the short-circuit impedance tester, including the following steps: S501. Calculate the error coefficient according to the loss value; S502. Calculate the error range of the sampled voltages and currents according to the error coefficient and the standard error; S503. Use the error range to perform numerical adjustment on the sampled voltages and currents to obtain the value traceability result of the short-circuit impedance tester.

9. A value traceability method based on a short-circuit impedance test instrument according to claim 8, characterized in that: In S502, calculating the error range of the sampled voltages and currents according to the error coefficient and the standard error includes: calculating the error range of the sampled voltages and currents by using the following error algorithm: wherein, is the error range of the voltage and current, is the standard error, is the total number of the voltage and current, is the counted number of the voltage and current, is the error coefficient, is the standard deviation corresponding to the standard error.

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