Method, system and storage medium for detecting voltage sensor accuracy

Abstract

The application relates to the technical field of precision detection, and discloses a detection method and system for the precision of a voltage sensor and a storage medium. The method comprises the following steps: through a closed-loop measurement and control system composed of a withstand voltage instrument, a detection and calibration instrument, a relay control board and computer terminal automatic test software, automatic testing of all voltage test points of all poles is completed at one time; the steps comprise the following steps in sequence: communication handshake confirmation, automatic generation of a test script, sequential switching of the relay control board, standard voltage output of the withstand voltage instrument, high-speed sampling of the detection and calibration instrument, stable determination based on instantaneous curvature, double-filter amplitude estimation of Kalman and sliding average, calculation of ratio difference and angle difference, encrypted saving of test records, and determination of overall qualification based on maximum error. The application realizes rapid batch detection with high precision, the whole process is free of manual intervention, and data can be digitally traced.

Description

Technical Field

[0001] This application relates to the field of accuracy detection technology, and in particular to methods, systems and storage media for detecting the accuracy of voltage sensors. Background Technology

[0002] The internal components of a deeply integrated circuit breaker include: an arc-extinguishing switch, a voltage sensor, a current sensor, and a spring-operated mechanism. The voltage signal is acquired by a voltage acquisition box and a voltage sensor. Due to the inherent errors in the actual hardware, and the requirement for high accuracy in voltage acquisition, the matching sensors need to be calibrated on the voltage acquisition box to achieve a voltage acquisition accuracy of 0.5S. This necessitates a method to quickly measure the accuracy deviation between the voltage acquisition box and the voltage transformer.

[0003] A similar prior art patent application, CN109143145A, provides an AC withstand voltage testing system suitable for smart energy meters and electricity consumption information collection terminals. The system includes: an industrial control computer, an AC withstand voltage tester, and an AC withstand voltage test bench. The industrial control computer is connected to the control terminal of the AC withstand voltage tester, controlling the tester to generate different voltage output levels according to different withstand voltage testing schemes. The industrial control computer is also connected to the control terminal of the AC withstand voltage test bench, controlling the crimping and releasing of different meter positions on the test bench and the opening and closing of high-voltage relays. The AC withstand voltage tester is connected to the AC withstand voltage test bench, outputting the generated voltage levels to the test bench. The AC withstand voltage test bench includes four testing positions and four sets of high-voltage relay switching units corresponding to each testing position.

[0004] Similar prior art includes Chinese patent application CN107064853A, which provides a withstand voltage testing system and method for an energy meter with automatic test voltage switching function. The system includes: an AC voltage tester with multiple voltage output terminals for outputting different voltages; each voltage output terminal of the AC voltage tester corresponds to a relay, each relay has a control input terminal and a control output terminal, each control output terminal includes a common terminal and an output connection terminal, and the output connection terminal of each relay is connected to one voltage output terminal of the AC voltage tester; all the common terminals of the relays are interconnected to form a test voltage output terminal connected to the energy meter under test; the control input terminal of each relay is connected to a controller; during testing, the controller controls one relay to be in a conducting state while the other relays are in a de-energized state, thereby achieving selection of the test voltage and applying the selected test voltage to the energy meter under test for withstand voltage testing.

[0005] However, the two technical solutions mentioned above only focus on the voltage switching and insulation strength of a single electricity meter withstand voltage test, without involving multi-channel accuracy calibration and full-process data encryption and traceability. Therefore, this invention provides a method, system and storage medium for detecting the accuracy of voltage sensors. Summary of the Invention

[0006] This application provides a method, system, and storage medium for detecting the accuracy of voltage sensors, enabling rapid and accurate accuracy detection of voltage sensors.

[0007] In a first aspect, this application provides a method for detecting the accuracy of a voltage sensor, the method comprising:

[0008] The computer-based automatic testing software sends handshake frames to the withstand voltage tester, calibration instrument, and relay control board. If a correct response is received within a predetermined time, the communication link is determined to be normal; otherwise, the test is terminated and a communication fault code is displayed.

[0009] A test script is generated based on the preset pole number, voltage test point, and accuracy threshold. Each voltage test point of each pole is tested according to the test script, including: the relay control board closes the pole circuit according to the test sequence, controls the calibrator to collect the pole sequence data at a preset sampling frequency, determines that the stable stage has been reached based on the sequence data, the calibrator collects stable sequence data at a predetermined sampling frequency, and obtains the amplitude mean and phase based on the stable sequence data and Kalman and moving average double filtering. The withstand voltage tester outputs the standard voltage of the corresponding voltage test point.

[0010] Based on the standard voltage, average amplitude, and phase, the ratio difference and angle difference are calculated. After each voltage value test point is completed, a test record is generated and saved, including the pole number of the voltage value test point, the percentage of test points, the standard voltage, the measured voltage, the ratio difference, the angle difference, the qualified status, the test timestamp, and the MD5 check value.

[0011] After all voltage values ​​of all poles are tested, multiple ratio differences and angle differences are obtained. The maximum ratio difference and maximum angle difference are obtained. The maximum ratio difference is compared with the preset first accuracy threshold, and the maximum angle difference is compared with the preset second accuracy threshold. Based on the comparison results, it is determined whether the voltage sensor accuracy is qualified.

[0012] In conjunction with the first aspect, in the first implementation of the first aspect of this application, the closed-loop measurement and control system is connected in the following manner:

[0013] Connect the high-voltage output terminal of the withstand voltage tester to the common input terminal of the relay control board. Connect each output terminal of the relay control board to the primary side of the corresponding pole. Connect the secondary side small signal output terminal of each pole to the multi-channel input terminal of the calibrator. The withstand voltage tester and the calibrator establish a bidirectional communication connection with the computer-based automated testing software via RS232. The relay control board establishes a bidirectional communication connection with the computer-based automated testing software via Ethernet.

[0014] In conjunction with the first aspect, in the second implementation of the first aspect of this application, after determining that a stable stage has been reached based on sequence data, the following steps are included:

[0015] Read the real-time sampling data of the most recent sampling period of the calibrator, perform a discrete Fourier transform on the real-time sampling data, and obtain a complex vector by extracting the fundamental component. When a new sampling data is acquired, delete the earliest sampling data, add the new sampling data, perform a discrete Fourier transform again, and obtain a new complex vector by extracting the fundamental component. Calculate the instantaneous curvature of each sampling data based on the complex vector. Calculate the instantaneous curvature of each sampling data in two consecutive periods. If the instantaneous curvature of two consecutive periods is less than a preset threshold, it is determined that a stable stage has been reached.

[0016] In conjunction with the first aspect, in the third implementation of the first aspect of this application, the instantaneous curvature of each sampled data is calculated based on a complex vector, including:

[0017] For the i-th sampled data, obtain the preceding and following sampled data. The complex vectors corresponding to these three adjacent sampled data are Z and Z, respectively. i-1 Z i and Z i+1 Calculate the first vector X=Z i -Z i-1 Calculate the second vector Y=Z i+1 -Z i The instantaneous curvature k corresponding to the i-th sampled data is calculated based on the first vector and the second vector. i The calculation formula is: , where lm represents taking the imaginary part of the complex number.

[0018] In conjunction with the first aspect, in the fourth implementation of the first aspect of this application, the amplitude mean and phase are obtained based on stable sequence data and Kalman averaging plus moving average dual filtering, including:

[0019] Using a sampling period as a sliding window and a sampled data as a step size, the discrete Fourier transform is performed on the stable sequence data within the corresponding sliding window each time the sliding window slides to obtain the fundamental complex vector corresponding to each period. The amplitude and phase of the corresponding period are obtained based on the fundamental complex vector.

[0020] The amplitude values ​​of multiple cycles form an amplitude sequence. The amplitude sequence is then subjected to Kalman and moving average double filtering to obtain the mean amplitude value for each cycle.

[0021] In conjunction with the first aspect, in the fifth implementation of the first aspect of this application, the amplitude sequence is subjected to Kalman and moving average double filtering to obtain the amplitude mean, including:

[0022] The state vector is set as an amplitude sequence. The process noise covariance is configured based on the prior thermal noise statistics. The observation noise covariance is estimated in real time during the no-load calibration phase. The Kalman filter performs prior estimation, prior covariance calculation, Kalman gain calculation, posterior estimation, and posterior covariance calculation once in each sampling cycle to output the real-time optimal estimate at each time step. All optimal estimates form the optimal estimate sequence. The optimal estimate sequence is input into a moving average filter with a window length of a preset length. The coefficients of the moving average filter are determined based on the equal-weighted average measurement of the optimal estimates within the window. All outputs of the moving average filter are summed and averaged to obtain the final amplitude mean.

[0023] In conjunction with the first aspect, in the sixth implementation of the first aspect of this application, the ratio difference and angle difference are calculated based on the standard voltage, the average amplitude, and the phase, including:

[0024] Obtain the sampling period corresponding to the average amplitude, obtain the standard voltage of the withstand voltage tester corresponding to the sampling period, perform discrete Fourier transform on the standard voltage to obtain the corresponding standard amplitude and standard phase, subtract the average amplitude from the standard amplitude and take the absolute value to obtain the first difference, and then divide the first difference by the standard amplitude to obtain the ratio difference.

[0025] The phase corresponding to the average amplitude is called the measured phase. The angle difference is obtained by subtracting the measured phase from the standard phase and taking the absolute value.

[0026] In conjunction with the first aspect, in the seventh implementation of the first aspect of this application, determining whether the sensor accuracy is qualified based on the comparison result includes:

[0027] If the maximum ratio difference is less than the first accuracy threshold and the maximum angle difference is less than the second accuracy threshold, the sensor accuracy is considered qualified; otherwise, the sensor accuracy is considered unqualified.

[0028] Secondly, this application provides a detection system for the accuracy of a voltage sensor, the system comprising:

[0029] In the communication establishment module, the computer-side automatic testing software sends handshake frames to the withstand voltage tester, calibrator, and relay control board. If a correct response is received within a predetermined time, the communication link is determined to be normal; otherwise, the test is terminated and a communication fault code is displayed.

[0030] The data processing module generates a test script based on the preset pole number, voltage test point, and accuracy threshold. It performs tests on each voltage test point of each pole based on the test script, including: the relay control board closes the pole circuit according to the test sequence, controls the calibrator to collect the pole sequence data at a preset sampling frequency, determines that the stable stage has been reached based on the sequence data, the calibrator collects stable sequence data at a predetermined sampling frequency, and obtains the amplitude mean and phase based on the stable sequence data and Kalman and moving average double filtering. The withstand voltage tester outputs the standard voltage of the corresponding voltage test point.

[0031] The data storage module calculates the ratio difference and angle difference based on the standard voltage, average amplitude, and phase. After each voltage value test point is completed, it generates and saves a test record by including the pole number of the voltage value test point, the percentage of test points, the standard voltage, the measured voltage, the ratio difference, the angle difference, the pass status, the test timestamp, and the MD5 check value.

[0032] After all voltage value test points of all poles are completed, the accuracy judgment module obtains multiple ratio differences and angle differences. It then obtains the maximum ratio difference and the maximum angle difference, compares the maximum ratio difference with the preset first accuracy threshold, and compares the maximum angle difference with the preset second accuracy threshold. Based on the comparison results, it determines whether the voltage sensor accuracy is qualified.

[0033] A third aspect of this application provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the above-described method for detecting the accuracy of a voltage sensor.

[0034] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0035] The technical solution provided in this application uses a closed-loop measurement and control system consisting of a withstand voltage tester, a calibration instrument, a relay control board, and computer-based automatic testing software to complete automated and traceable accuracy testing of all voltage test points of all poles in one go. It uses an instantaneous curvature algorithm to dynamically determine stability, Kalman and moving average dual filtering to improve amplitude estimation accuracy, and determines overall qualification by the maximum ratio difference and the maximum angle difference, which significantly shortens the testing time and improves data reliability and production efficiency. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1This is a schematic diagram of one embodiment of a method for detecting the accuracy of a voltage sensor in this application.

[0038] Figure 2 This is a schematic diagram of the connection method of the closed-loop measurement and control system in the embodiments of this application;

[0039] Figure 3 This is a schematic diagram of one embodiment of a voltage sensor accuracy detection system in this application. Detailed Implementation

[0040] This application provides a method, system, and storage medium for detecting the accuracy of a voltage sensor. The terms "first," "second," "third," "fourth," etc. (if present)," in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" or "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0041] For ease of understanding, the specific process of the embodiments of this application is described below. Please refer to [link / reference]. Figure 1 One embodiment of the method for detecting the accuracy of a voltage sensor in this application includes:

[0042] Step S1: The computer-side automatic testing software sends handshake frames to the withstand voltage tester, calibrator, and relay control board. If a correct response is received within the predetermined time, the communication link is determined to be normal; otherwise, the test is terminated and a communication fault code is displayed.

[0043] Specifically, in order to quickly and accurately detect the accuracy of the sensor, based on, for example Figure 2 The method shown integrates a withstand voltage tester, a calibration instrument, a relay control board, and computer-based automatic testing software into a closed-loop measurement and control system. This system is used to perform automated and traceable accuracy testing on all pole voltage acquisition channels in the deeply integrated circuit breaker. Before testing, the computer-based automatic testing software sends handshake frames to the withstand voltage tester, the calibration instrument, and the relay control board. If a correct response is received within a predetermined time, the communication link is considered normal; otherwise, the test is terminated and a communication fault code is displayed, ensuring normal communication between the automatic testing software and each device.

[0044] Step S2: Generate a test script based on the preset pole number, voltage test point, and accuracy threshold. Perform tests on each voltage test point of each pole based on the test script, including: the relay control board closes the pole circuit according to the test sequence, controls the calibrator to collect the pole sequence data at a preset sampling frequency, determines that a stable stage has been reached based on the sequence data, the calibrator collects stable sequence data at a predetermined sampling frequency, obtains the amplitude mean and phase based on the stable sequence data and Kalman and moving average double filtering, and outputs the standard voltage of the corresponding voltage test point by the withstand voltage tester.

[0045] Specifically, the automated testing software also generates test scripts based on preset pole numbers, voltage test points, and accuracy thresholds. A pole refers to... Figure 2 The voltage test points shown as Ua, Ub, Uc, U0, Ua2, Ub2, and Uc2 refer to multiple test points at 5%, 20%, 50%, 100%, and 105% of the voltage. The accuracy thresholds include a first accuracy threshold and a second accuracy threshold. These thresholds can be set according to standards. Standard IEC 61869 defines 0.5S class as having an absolute difference of ≤0.5% and an absolute angle difference of ≤20′ (arc-min) within 5%–120% of the rated voltage. Therefore, the first accuracy threshold can be 0.5%, and the second accuracy threshold can be 20′. The test script automatically performs tests on each voltage test point. In automated testing, the relay control board closes the pole circuit according to the test sequence, and controls the calibrator to collect the sequence data of the pole at a preset sampling frequency. Based on the sequence data, it is determined that a stable stage has been reached. The specific method for determining whether a stable stage has been reached will be explained in detail later. The calibrator collects stable sequence data at a predetermined sampling frequency. Based on the stable sequence data and Kalman and moving average double filtering, the amplitude mean and phase are obtained. The withstand voltage tester outputs the standard voltage of the corresponding voltage test point. Automated testing can achieve the purpose of quickly testing the pole voltage acquisition unit, improve testing efficiency, and reduce inaccurate test results caused by human factors.

[0046] Step S3: Calculate the ratio difference and angle difference based on the standard voltage, average amplitude, and phase. After each voltage test point is completed, generate a test record and save it by including the pole number of the voltage test point, the percentage of test points, the standard voltage, the measured voltage, the ratio difference, the angle difference, the pass / fail status, the test timestamp, and the MD5 check value.

[0047] Specifically, the ratio difference and angle difference are calculated based on the standard voltage, average amplitude, and phase. The specific calculation method will be explained in detail later. To ensure that the test results are verifiable and to provide a basis for tracking product issues, after each voltage test point is tested, a test record is generated and saved, including the pole number of the voltage test point, the percentage of test points, the standard voltage, the measured voltage, the ratio difference, the angle difference, the pass / fail status, the test timestamp, and the MD5 checksum. The ratio difference refers to the percentage error between the measured amplitude and the amplitude corresponding to the standard voltage, which is used to quantify the amplitude linearity. The angle difference refers to the difference between the measured phase and the standard phase, which is used to quantify the phase delay. The MD5 checksum is a 128-bit hash of each test record, which is used to ensure that the test record is not tampered with and to meet the requirements of digital traceability.

[0048] Step S4: After all voltage value test points of all poles are completed, multiple ratio differences and angle differences are obtained. The maximum ratio difference and the maximum angle difference are obtained. The maximum ratio difference is compared with the preset first accuracy threshold, and the maximum angle difference is compared with the preset second accuracy threshold. Based on the comparison results, it is determined whether the voltage sensor accuracy is qualified.

[0049] Specifically, in order to determine whether the sensor is qualified, after all voltage value test points of all poles are completed, multiple ratio differences and angle differences are obtained. The maximum ratio difference and maximum angle difference are obtained. The qualification of the entire sensor can be determined by a single comparison, avoiding point-by-point screening.

[0050] In one specific embodiment, the closed-loop measurement and control system is connected in the following manner:

[0051] Connect the high-voltage output terminal of the withstand voltage tester to the common input terminal of the relay control board. Connect each output terminal of the relay control board to the primary side of the corresponding pole. Connect the secondary side small signal output terminal of each pole to the multi-channel input terminal of the calibrator. The withstand voltage tester and the calibrator establish a bidirectional communication connection with the computer-based automated testing software via RS232. The relay control board establishes a bidirectional communication connection with the computer-based automated testing software via Ethernet.

[0052] Specifically, such as Figure 2 The diagram shows the connection method of the closed-loop measurement and control system. The high-voltage output terminal of the withstand voltage tester is connected to the common input terminal of the relay control board. Each output terminal of the relay control board is connected to the primary side of the corresponding pole. The small signal output terminal of the secondary side of each pole is connected to the multi-channel input terminal of the calibrator. The withstand voltage tester and the calibrator establish a bidirectional communication connection with the computer-based automated testing software through RS232. The relay control board establishes a bidirectional communication connection with the computer-based automated testing software through Ethernet.

[0053] In one specific embodiment, determining whether a stable stage has been reached based on sequence data includes the following steps:

[0054] Read the real-time sampling data of the most recent sampling period of the calibrator, perform a discrete Fourier transform on the real-time sampling data, and obtain a complex vector by extracting the fundamental component. When a new sampling data is acquired, delete the earliest sampling data, add the new sampling data, perform a discrete Fourier transform again, and obtain a new complex vector by extracting the fundamental component. Calculate the instantaneous curvature of each sampling data based on the complex vector. Calculate the instantaneous curvature of each sampling data in two consecutive periods. If the instantaneous curvature of two consecutive periods is less than a preset threshold, it is determined that a stable stage has been reached.

[0055] Specifically, since the withstand voltage tester outputs a standard voltage, which is a set value, not the true value, it is theoretically equal to the target value. However, the high voltage generator, feedback network, and load changes can cause transient overshoot, oscillation, or drift at the actual output of the withstand voltage tester. The calibration instrument itself is a low-voltage precision measuring instrument that collects the physical true value in real time. Only by using the true value can the reliability of the calibration results be guaranteed. Therefore, it is necessary to determine whether the stability stage has been reached based on the calibration instrument.

[0056] Traditional methods for determining whether a stable phase has been reached are based on standard requirements, assuming a preset time has elapsed. The upper limit of these requirements is typically 5 seconds. This application aims to quickly and accurately determine whether a withstand voltage tester has reached its output stability phase. It reads real-time sampling data from the most recent sampling period of the calibration instrument. This real-time data includes both amplitude and phase. To compress the effective signal output by the calibration instrument into a complex number for easier curvature calculation, a Discrete Fourier Transform (DFT) is performed on the real-time sampling data from the most recent sampling period, and the fundamental component is extracted to obtain a complex vector. For example, for any time i (corresponding to the i-th sampling point), assuming N sampling cycles, N recent consecutive sampling data points are obtained. A DFT is then performed on these N sampling data points, and the fundamental component is retained to obtain the complex vector Z. i =a i +jb i ,in, , Where N represents the number of sampled data in one sampling period, k is an integer ranging from 0 to N-1, and x k Refers to the k-th sampled data, a i Let b represent the i-th fundamental cosine component. i This represents the i-th fundamental sine component, with an instantaneous amplitude of... Phase is After performing Fourier decomposition on the periodic signal, the lowest frequency sine component is the fundamental component, and the other integer multiples of the frequency are harmonics. The fundamental component represents the effective voltage amplitude and effective phase, while the harmonics represent interference. By taking the fundamental component, the interference of high-frequency noise on the stability judgment can be eliminated. As the calibration instrument continuously samples, each time a new sample data is acquired, the earliest sample data is deleted, the new sample data is added, and a discrete Fourier transform is performed again to obtain a new complex vector by taking the fundamental component. The instantaneous curvature of each sample data is calculated based on the complex vector sequence. The instantaneous curvature of each sample data in two consecutive cycles is calculated. If the instantaneous curvature of two consecutive cycles is less than the preset threshold, the stability stage is determined to be reached.

[0057] The above method replaces the fixed delay with an adaptive calculation method, which can quickly and accurately determine whether the withstand voltage meter has reached the stable output stage.

[0058] In one specific embodiment, calculating the instantaneous curvature of each sampled data based on a complex vector includes the following steps:

[0059] For the i-th sampled data, obtain the preceding and following sampled data. The complex vectors corresponding to these three adjacent sampled data are Z and Z, respectively. i-1 Z i and Z i+1 Calculate the first vector X=Z i -Z i-1 Calculate the second vector Y=Z i+1 -Z i The instantaneous curvature k corresponding to the i-th sampled data is calculated based on the first vector and the second vector. i The calculation formula is: , where lm represents taking the imaginary part of the complex number.

[0060] Specifically, instantaneous curvature is considered as a two-dimensional geometric problem of directional rotation angle per unit arc length. The degree of curvature is measured using the cross product of vectors in the complex plane. The first vector X is the first segment chord, the second vector Y is the second segment chord, and lm represents taking the imaginary part of the complex number. It is the cross product modulus, representing the area of ​​the parallelogram formed by the first and second chords. The larger the area, the more drastic the change in direction, i.e., the greater the curvature. The denominator is... It is an equivalent arc length represented by the sum of approximate chord lengths multiplied by the total chord length, used for normalization so that the curvature is independent of the curve length.

[0061] In one specific embodiment, the amplitude mean and phase are obtained based on stable sequence data and Kalman averaging plus moving average dual filtering, specifically including the following steps:

[0062] Using a sampling period as a sliding window and a sampled data as a step size, the discrete Fourier transform is performed on the stable sequence data within the corresponding sliding window each time the sliding window slides to obtain the fundamental complex vector corresponding to each period. The amplitude and phase of the corresponding period are obtained based on the fundamental complex vector.

[0063] The amplitude values ​​of multiple cycles form an amplitude sequence. The amplitude sequence is then subjected to Kalman and moving average double filtering to obtain the mean amplitude value for each cycle.

[0064] Specifically, assuming there are 40 samples of stable sequence data within one period, the 40 samples are subjected to Discrete Fourier Transform (DFT) to extract the fundamental component. The magnitude of the fundamental component is taken and normalized to obtain the voltage amplitude. One sampling period is used as a sliding window, and one sample is used as the sliding step size. Each time the sliding window slides, a DFT is performed based on the stable sequence data within the sliding window to obtain the fundamental complex vector corresponding to each sliding window (each period). Based on the fundamental complex vector, the amplitude and phase of the corresponding period are obtained. After multiple slidings, an amplitude sequence composed of amplitudes from multiple periods can be obtained. The amplitude sequence is subjected to Kalman averaging and moving average double filtering to obtain the average amplitude corresponding to each period. The specific method for obtaining the average amplitude will be explained in detail later.

[0065] In one specific embodiment, the amplitude sequence is subjected to Kalman and moving average double filtering to obtain the amplitude mean, specifically including the following steps:

[0066] The state vector is set as the amplitude, the process noise covariance is configured based on the prior thermal noise statistics, and the observation noise covariance is estimated in real time through the no-load calibration stage. The Kalman filter performs prior estimation, prior covariance calculation, Kalman gain calculation, posterior estimation, and posterior covariance calculation once in each sampling cycle to output the real-time optimal estimate at each time step. All optimal estimates form the optimal estimate sequence. The optimal estimate sequence is input into a moving average filter with a window length of a preset length. The coefficients of the moving average filter are determined based on the equal-weighted average measurement of the optimal estimates within the window. All outputs of the moving average filter are summed and averaged to obtain the final amplitude mean.

[0067] Specifically, although the calibration instrument has reached a macroscopically stable stage, residual disturbances still exist at the microscopic level. Since the amplitude error mainly comes from ADC quantization, temperature drift, and high-frequency noise, its statistical model (zero-mean Gaussian) is suitable for the Kalman hypothesis. Therefore, Kalman and moving average dual filtering is used for secondary noise reduction and extraction of the true value to suppress ADC quantization noise, reduce temperature drift and high-frequency noise interference, and improve statistical confidence. The phase error mainly comes from clock jitter and fixed delay, which usually manifests as systematic deviation rather than random noise. Using Kalman filtering will instead treat the systematic deviation as noise suppression, so no phase filtering is performed.

[0068] The state vector is a one-dimensional scalar containing only the voltage amplitude, used to describe the true voltage amplitude level at each moment, and provides minimal complete information for the Kalman filter to predict and update. The process noise covariance is obtained based on the sensor front-end thermal noise model, which is expressed by the following formula: Where Q is the process noise covariance, and k B It is Boltzmann's constant, T is absolute temperature, and R is... eq This is the equivalent resistance of the front end, obtained by connecting a voltage divider network in parallel with the input impedance. A typical value is 1.2kΩ. Δt is the sampling interval. During the no-load calibration phase, i.e., when the withstand voltage tester outputs 0V and the relay is closed, M sampling data are collected, and the observation noise covariance O is calculated based on the following formula: L n It is the fundamental component corresponding to the nth sampled data. It is the mean of the n fundamental components, and O is the estimated observation noise covariance.

[0069] Taking the calculation of the optimal estimate at time t as an example, at time t, the posterior estimate of the previous time is known. Prior estimation refers to a preliminary estimate or prediction of an unknown quantity based on existing knowledge, theoretical models, or experience before observational or experimental data are obtained. Therefore, the posterior estimate of the previous time is used as the basis for this estimation. As a priori estimate That is The prior covariance at time t is calculated using the following formula. , The posterior covariance at time t-1 is used. Kalman gain represents the reliability of the current actual observation data relative to the prior estimate. A smaller value of 0 indicates a more accurate measurement, and the closer the Kalman gain is to 1. The Kalman gain G is calculated using the following formula: t : O represents the observation noise variance, reflecting the noise level of the calibration instrument measurement, and is estimated posteriorly as... r t It is the noise-included amplitude value output by the calibrator at time t. The observation residuals are multiplied by the Kalman gain and added to the prior estimate to obtain the posterior estimate. The posterior estimate is then used as the real-time optimal estimate, and the posterior covariance is calculated using the following formula. The posterior covariance decreases, indicating the uncertainty of the real-time optimal estimate, which is used for the recursion at the next time step.

[0070] The real-time optimal estimate is input into a moving average filter with a preset window length, assuming the preset length is 5. The specific process of the moving average filter is as follows: For the real-time optimal estimate, the four nearest neighboring optimal estimates are obtained, and the average value of the real-time optimal estimate and these four neighboring optimal estimates is calculated. The final average value is used as the processing result of the moving average filter, and the final average value is used as the amplitude average value of the corresponding period for subsequent calculation of the ratio difference.

[0071] The Kalman filter uses the minimum mean square error criterion and incorporates both process noise and measurement noise into the estimation framework through a state-space model, recursively outputting the real-time optimal estimate. It significantly reduces random errors introduced by ADC quantization, thermal drift, and high-frequency interference at the amplitude and phase levels. By applying a moving average with a fixed window length, it smooths the low-frequency ripple and power frequency harmonics that have not been completely filtered out in the Kalman residual with a finite impulse response, further reducing residual noise and improving the overall signal-to-noise ratio by an order of magnitude. The Kalman filter is good at handling process and measurement noise with known statistical characteristics, while the moving average filter performs secondary suppression of residual colored noise with extremely low computational complexity. The two are complementary and do not introduce additional hardware, enabling the system to effectively reduce extended uncertainty with existing MCU resources, while reducing the total processing delay. The noise removal through the above dual filtering makes the subsequent calculation of the difference more accurate.

[0072] In one specific embodiment, the ratio difference and angle difference are calculated based on the standard voltage, the average amplitude, and the phase, specifically including the following steps:

[0073] Obtain the sampling period corresponding to the average amplitude, obtain the standard voltage of the withstand voltage tester corresponding to the sampling period, perform discrete Fourier transform on the standard voltage to obtain the corresponding standard amplitude and standard phase, subtract the average amplitude from the standard amplitude and take the absolute value to obtain the first difference, and then divide the first difference by the standard amplitude to obtain the ratio difference.

[0074] The phase corresponding to the average amplitude is called the measured phase. The angle difference is obtained by subtracting the measured phase from the standard phase and taking the absolute value.

[0075] Specifically, the ratio difference and angle difference of each voltage value test point are calculated based on the above method, which facilitates subsequent judgment on whether the voltage sensor accuracy is qualified based on the ratio difference and angle difference.

[0076] In one specific embodiment, determining whether the sensor accuracy is qualified based on the comparison result includes the following steps:

[0077] If the maximum ratio difference is less than the first accuracy threshold and the maximum angle difference is less than the second accuracy threshold, the sensor accuracy is considered qualified; otherwise, the sensor accuracy is considered unqualified.

[0078] Specifically, if the maximum ratio difference is less than the first accuracy threshold and the maximum angle difference is less than the second accuracy threshold, it indicates that the voltage sensor accuracy meets the predetermined standard; otherwise, it indicates that the voltage sensor does not meet the predetermined standard and needs to be calibrated. Based on the above method, it is possible to quickly and accurately determine whether the sensor accuracy is qualified.

[0079] The method for detecting the accuracy of a voltage sensor in the embodiments of this application has been described above. The system for detecting the accuracy of a voltage sensor in the embodiments of this application is described below. Please refer to [link / reference]. Figure 3 One embodiment of the voltage sensor accuracy detection system in this application includes:

[0080] In the communication establishment module, the computer-side automatic testing software sends handshake frames to the withstand voltage tester, calibrator, and relay control board. If a correct response is received within a predetermined time, the communication link is determined to be normal; otherwise, the test is terminated and a communication fault code is displayed.

[0081] The data processing module generates a test script based on the preset pole number, voltage test point, and accuracy threshold. It performs tests on each voltage test point of each pole based on the test script, including: the relay control board closes the pole circuit according to the test sequence, controls the calibrator to collect the pole sequence data at a preset sampling frequency, determines that the stable stage has been reached based on the sequence data, the calibrator collects stable sequence data at a predetermined sampling frequency, and obtains the amplitude mean and phase based on the stable sequence data and Kalman and moving average double filtering. The withstand voltage tester outputs the standard voltage of the corresponding voltage test point.

[0082] The data storage module calculates the ratio difference and angle difference based on the standard voltage, average amplitude, and phase. After each voltage value test point is completed, it generates and saves a test record by including the pole number of the voltage value test point, the percentage of test points, the standard voltage, the measured voltage, the ratio difference, the angle difference, the pass status, the test timestamp, and the MD5 check value.

[0083] After all voltage value test points of all poles are completed, the accuracy judgment module obtains multiple ratio differences and angle differences. It then obtains the maximum ratio difference and the maximum angle difference, compares the maximum ratio difference with the preset first accuracy threshold, and compares the maximum angle difference with the preset second accuracy threshold. Based on the comparison results, it determines whether the voltage sensor accuracy is qualified.

[0084] This application also provides a computer-readable storage medium, which can be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium, storing instructions that, when executed on a computer, cause the computer to perform steps of a method for detecting the accuracy of a voltage sensor.

[0085] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0086] 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 to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0087] 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 detecting the accuracy of a voltage sensor, characterized in that, A closed-loop measurement and control system, consisting of a withstand voltage tester, a calibration instrument, a relay control board, and computer-based automatic testing software, is used to perform automated and traceable accuracy testing on all pole voltage acquisition channels in a deeply integrated circuit breaker in a single operation. The method includes: The computer-based automatic testing software sends handshake frames to the withstand voltage tester, calibration instrument, and relay control board. If a correct response is received within a predetermined time, the communication link is determined to be normal; otherwise, the test is terminated and a communication fault code is displayed. A test script is generated based on the preset pole number, voltage test point, and accuracy threshold. Each voltage test point of each pole is tested according to the test script, including: the relay control board closes the pole circuit according to the test sequence, controls the calibrator to collect the pole sequence data at a preset sampling frequency, determines that the stable stage has been reached based on the sequence data, the calibrator collects stable sequence data at a predetermined sampling frequency, and obtains the amplitude mean and phase based on the stable sequence data and Kalman and moving average double filtering. The withstand voltage tester outputs the standard voltage of the corresponding voltage test point. Based on the standard voltage, average amplitude, and phase, the ratio difference and angle difference are calculated. After each voltage value test point is completed, a test record is generated and saved, including the pole number of the voltage value test point, the percentage of test points, the standard voltage, the measured voltage, the ratio difference, the angle difference, the qualified status, the test timestamp, and the MD5 check value. After all voltage values ​​of all poles are tested, multiple ratio differences and angle differences are obtained. The maximum ratio difference and maximum angle difference are obtained. The maximum ratio difference is compared with the preset first accuracy threshold, and the maximum angle difference is compared with the preset second accuracy threshold. Based on the comparison results, it is determined whether the voltage sensor accuracy is qualified.

2. The method according to claim 1, characterized in that, The closed-loop measurement and control system is connected in the following manner: Connect the high-voltage output terminal of the withstand voltage tester to the common input terminal of the relay control board. Connect each output terminal of the relay control board to the primary side of the corresponding pole. Connect the secondary side small signal output terminal of each pole to the multi-channel input terminal of the calibrator. The withstand voltage tester and the calibrator establish a bidirectional communication connection with the computer-based automated testing software via RS232. The relay control board establishes a bidirectional communication connection with the computer-based automated testing software via Ethernet.

3. The method according to claim 1, characterized in that, After determining that a stable phase has been reached based on sequence data, the following steps are included: Read the real-time sampling data of the most recent sampling period of the calibrator, perform a discrete Fourier transform on the real-time sampling data, and obtain a complex vector by extracting the fundamental component. When a new sampling data is acquired, delete the earliest sampling data, add the new sampling data, perform a discrete Fourier transform again, and obtain a new complex vector by extracting the fundamental component. Calculate the instantaneous curvature of each sampling data based on the complex vector. Calculate the instantaneous curvature of each sampling data in two consecutive periods. If the instantaneous curvature of two consecutive periods is less than a preset threshold, it is determined that a stable stage has been reached.

4. The method according to claim 3, characterized in that, The instantaneous curvature of each sampled data point is calculated based on complex vectors, including: For the i-th sampled data, obtain the preceding and following sampled data. The complex vectors corresponding to these three adjacent sampled data are Z and Z, respectively. i-1 Z i and Z i+1 Calculate the first vector X=Z i -Z i-1 Calculate the second vector Y=Z i+1 -Z i The instantaneous curvature k corresponding to the i-th sampled data is calculated based on the first vector and the second vector. i The calculation formula is: , where lm represents taking the imaginary part of the complex number.

5. The method according to claim 1, characterized in that, The amplitude mean and phase are obtained based on stable sequence data and Kalman and moving average dual filtering, including: Using a sampling period as a sliding window and a sampled data as a step size, perform a discrete Fourier transform on the stable sequence data of multiple sampling periods to obtain the fundamental complex vector corresponding to each period. Based on the fundamental complex vector, obtain the amplitude and phase of the corresponding period. The amplitudes of multiple cycles form an amplitude sequence, and the phases of multiple cycles form a phase sequence. The amplitude sequence is then subjected to Kalman and moving average double filtering to obtain the mean amplitude for each cycle.

6. The method according to claim 1, characterized in that, The amplitude sequence is processed by a Kalman filter and a moving average filter to obtain the amplitude mean, including: The state vector is set as an amplitude sequence. The process noise covariance is configured based on the prior thermal noise statistics. The observation noise covariance is estimated in real time during the no-load calibration phase. The Kalman filter performs prior estimation, prior covariance calculation, Kalman gain calculation, posterior estimation, and posterior covariance calculation once in each sampling cycle to output the real-time optimal estimate at each time step. All optimal estimates form the optimal estimate sequence. The optimal estimate sequence is input into a moving average filter with a window length of a preset length. The coefficients of the moving average filter are determined based on the equal-weighted average measurement of the optimal estimates within the window. All outputs of the moving average filter are summed and averaged to obtain the final amplitude mean.

7. The method according to claim 1, characterized in that, The ratio difference and angle difference are calculated based on standard voltage, average amplitude, and phase, including: Obtain the sampling period corresponding to the average amplitude, obtain the standard voltage of the withstand voltage tester corresponding to the sampling period, perform discrete Fourier transform on the standard voltage to obtain the corresponding standard amplitude and standard phase, subtract the average amplitude from the standard amplitude and take the absolute value to obtain the first difference, and then divide the first difference by the standard amplitude to obtain the ratio difference. The phase corresponding to the average amplitude is called the measured phase. The angle difference is obtained by subtracting the measured phase from the standard phase and taking the absolute value.

8. The method according to claim 1, characterized in that, Determining whether the sensor's accuracy is acceptable based on the comparison results includes: If the maximum ratio difference is less than the first accuracy threshold and the maximum angle difference is less than the second accuracy threshold, the sensor accuracy is considered qualified; otherwise, the sensor accuracy is considered unqualified.

9. A detection system for voltage sensor accuracy, used to implement the detection method for voltage sensor accuracy as described in any one of claims 1-8, characterized in that, The system includes: In the communication establishment module, the computer-side automatic testing software sends handshake frames to the withstand voltage tester, calibrator, and relay control board. If a correct response is received within a predetermined time, the communication link is determined to be normal; otherwise, the test is terminated and a communication fault code is displayed. The data processing module generates a test script based on the preset pole number, voltage test point, and accuracy threshold. It performs tests on each voltage test point of each pole based on the test script, including: the relay control board closes the pole circuit according to the test sequence, controls the calibrator to collect the pole sequence data at a preset sampling frequency, determines that the stable stage has been reached based on the sequence data, the calibrator collects stable sequence data at a predetermined sampling frequency, and obtains the amplitude mean and phase based on the stable sequence data and Kalman and moving average double filtering. The withstand voltage tester outputs the standard voltage of the corresponding voltage test point. The data storage module calculates the ratio difference and angle difference based on the standard voltage, average amplitude, and phase. After each voltage value test point is completed, it generates and saves a test record by including the pole number of the voltage value test point, the percentage of test points, the standard voltage, the measured voltage, the ratio difference, the angle difference, the pass status, the test timestamp, and the MD5 check value. After all voltage value test points of all poles are completed, the accuracy judgment module obtains multiple ratio differences and angle differences. It then obtains the maximum ratio difference and the maximum angle difference, compares the maximum ratio difference with the preset first accuracy threshold, and compares the maximum angle difference with the preset second accuracy threshold. Based on the comparison results, it determines whether the voltage sensor accuracy is qualified.

10. A computer-readable storage medium storing instructions thereon, characterized in that, When the instructions are executed by the processor, they implement the method for detecting the accuracy of a voltage sensor as described in any one of claims 1-8.

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