Calibration phase value determination method and device, storage medium and electric metering equipment

Abstract

The invention provides a calibration phase value determination method and device, a storage medium and electric metering equipment, and relates to the technical field of electric metering equipment. The determination method comprises the following steps: sampling a target signal to obtain an original sampling data sequence; interpolation resampling processing is carried out on the original sampling data sequence to obtain a resampling data sequence, and the resampling data sequence comprises continuous whole-cycle wave data; performing fast Fourier transform processing on the continuous whole cycle data to obtain harmonic data of each harmonic in the resampling data sequence; determining absolute phase information of the target signal according to the harmonic data; a calibration phase value is determined based on the hardware phase difference of the electrical metrology device and the absolute phase information. The problem of deviation between the phase value obtained by the electric measurement equipment and the actual value under the condition that the frequency of the measured signal is non-standard can be solved on the software level, and the accuracy of phase measurement of the electric measurement equipment is improved with low cost and high compatibility.

Description

Technical Field

[0001] The present application relates to the technical field of electric metering equipment, and in particular, to a method and device for determining a calibration phase value, a storage medium, and an electric metering equipment. Background Art

[0002] In the related art, for electric metering equipment such as an AC standard meter, it is necessary to be able to measure voltage and current signals simultaneously. For a three-phase AC energy meter with a single-channel ADC, it samples a total of 6 signals, namely 3-phase voltage signals and 3-phase current signals, through a time-division multiplexing sampling method.

[0003] The above time-division multiplexing sampling method will have a direct impact on the calculation of the phase value. Therefore, when calibrating the phase meter, it is necessary to calibrate and eliminate the hardware phase difference together. When measuring a signal to be measured with a non-standard frequency, such as an electrical signal with a frequency other than 50 Hz, through the above energy meter, since the frequency of the measured signal changes, even if the hardware phase difference remains unchanged, the sampling phase difference will inevitably change, resulting in the invalidation of the phase calibration coefficient and finally a deviation in the calculated phase value, leading to inaccurate phase measurement results. Summary of the Invention

[0004] The present application aims to at least solve the problem that the phase measurement result is inaccurate when measuring a signal with a non-calibrated frequency by a single-channel ADC asynchronous sampling AC standard meter in the prior art or related art.

[0005] To this end, a first aspect of the present application provides a method for determining a calibration phase value of an electric metering equipment.

[0006] A second aspect of the present application provides a device for determining a calibration phase value of an electric metering equipment.

[0007] A third aspect of the present application provides a device for determining a calibration phase value of an electric metering equipment.

[0008] A fourth aspect of the present application provides a readable storage medium.

[0009] A fifth aspect of the present application provides an electric metering equipment.

[0010] In view of this, a first aspect of the present application provides a method for determining a calibration phase value of an electric metering equipment, and the determining method includes: sampling a target signal to obtain an original sampling data sequence; performing interpolation resampling processing on the original sampling data sequence to obtain a resampled data sequence, where the resampled data sequence includes continuous full-cycle data; performing fast Fourier transform processing on the continuous full-cycle data to obtain harmonic data of each harmonic in the resampled data sequence; determining the absolute phase information of the target signal according to the harmonic data; and determining the calibration phase value based on the hardware phase difference and the absolute phase information of the electric metering equipment.

[0011] In this technical solution, the electrical metering device includes, but is not limited to, an AC standard meter, an oscilloscope, a portable watt-hour meter, etc. The electrical energy standard meter can measure multiple signals simultaneously. Taking the three-phase AC standard meter as an example, the three-phase AC standard meter needs to be able to simultaneously measure a total of 6 signals including 3-phase voltage and 3-phase current.

[0012] The working principle of the three-phase AC standard meter is to cyclically and sequentially select the independent input / output terminals, including terminals X0 to X5, to be gated with the common output / input terminal X through the input values of three address lines A, B, and C controlled by the MCU (Micro Controller Unit), so as to realize time-division multiplexing access of 6 sampling signals to the sampling input port of the ADC.

[0013] In addition, within the time interval between the sequential gating of two adjacent channels of the multi-channel analog switch chip, the MCU needs to output a conversion trigger signal to the single-channel ADC (analog to digital converter) chip and read the AD (analog to digital) conversion value of the gated signal through the connected SPI (Serial Peripheral Interface) data bus. By continuously executing the above process, the sampling data of 6 voltage and current signals can be continuously input into the MCU, so that the MCU can calculate the frequency, amplitude, phase, and power values of each signal.

[0014] Theoretically speaking, when the measured voltage and current signals are all sine waves and the sampling rate is much higher than the frequencies of each signal, such a time-division multiplexing sampling method has no influence on the calculated values of the frequency, amplitude, and power of the measured signal, but has a direct influence on the phase value. The reason is that there is a sampling trigger interval for the other 5 phases relative to the A-phase voltage, and the interval time increases sequentially from the first to the last. Using such sampling data that is not synchronized in time will inevitably result in a phase difference caused by the sampling trigger interval between the other 5 phases and the A-phase voltage, that is, there is a sampling phase difference. And this sampling phase difference is positively correlated with the frequency value of the measured voltage and current signals. The higher the frequency, the greater the sampling phase difference.

[0015] When the measured signal is a single-frequency signal, such as only used in an environment of 50 Hz, the above sampling phase difference can be calibrated and eliminated together with the hardware phase difference during phase calibration. However, once the frequency of the measured signal changes, even if the hardware phase difference remains unchanged, the sampling phase difference will inevitably change, resulting in the invalidation of the phase calibration coefficient and finally a deviation in the calculated phase value.

[0016] In view of the above problems, the present application performs interpolation resampling on the original sampled data sequence obtained by sampling the target signal, so as to obtain a resampled data sequence in which exactly one cycle satisfies a specific number of sampling points, that is, including continuous full-cycle data. Among them, the target signal is also the signal to be measured. Through such an operation, the data in the resampled data sequence can satisfy the requirements for fast Fourier transform (FFT) processing.

[0017] After obtaining the resampled data sequence including continuous full-cycle data, perform fast Fourier transform processing on this data sequence to obtain the harmonic data of each harmonic, including the harmonic data of the first harmonic, the harmonic data of the second harmonic... and the harmonic data of the nth harmonic.

[0018] After obtaining the harmonic data of each harmonic, the absolute phase information of the target signal, that is, the signal to be measured, can be calculated based on the harmonic data. Combining the known hardware phase difference of the electrical metering device, the calibrated phase value can be obtained.

[0019] By separately processing the sampling phase difference and the hardware phase difference in the present application, and processing the sampling phase difference separately after each sampling, it is possible to solve the problem that the phase value obtained by the electrical metering device deviates from the actual value when the frequency of the signal to be measured is non-standard at the software level. This method does not require modification of the original hardware of the electrical metering device, such as the hardware of a three-phase AC energy meter, does not increase the hardware cost, and does not change the original calibration process, and can improve the accuracy of the phase measurement of the electrical measurement device with low cost and high compatibility.

[0020] In addition, the method for determining the calibrated phase value of the electrical metering device in the above technical solution provided by the present application may further have the following additional technical features:

[0021] In some technical solutions of the present application, optionally, the target signal includes multiple signals; sampling the target signal includes: separately sampling the multiple signals according to a preset sampling interval; determining the calibrated phase value based on the hardware phase difference and the absolute phase information of the electrical metering device includes: determining the number of sampling points per cycle of the original sampled data sequence; according to the number of sampling points per cycle, determining the sampling phase difference between each of the multiple signals; and determining the calibrated phase value corresponding to each sampled signal according to the hardware phase difference, the sampling phase difference, and the absolute phase information.

[0022] In this technical solution, taking the target signal as a three-phase electrical signal as an example, the target signal includes 3 voltage signals and 3 current signals. Among them, the 3 voltage signals are the phase A voltage signal, the phase B voltage signal, and the phase C voltage signal. The 3 current signals are the phase A current signal, the phase B current signal, and the phase C current signal.

[0023] When sampling the target signal, time-division multiplexing sampling is performed on the above six signals based on fixed sampling detection.

[0024] Exemplarily, each signal is sampled at equal intervals according to a fixed sampling rate to obtain an original sampling sequence, and this sampling rate is denoted as f s , according to the Nyquist theorem, the sampling rate is denoted as f s satisfies the following formula (1):

[0025] f s ≥2f Max ; (1)

[0026] where, f s is the sampling frequency for sampling the target signal, and f Max is the highest frequency value that needs to be detected in the target signal. For example, when analyzing the parameters of the 64th harmonic at the mains frequency (50 Hz), f Max = 50 × 64 = 3200 Hz. Optionally, the sampling frequency is 2.56 times to 4 times the above highest frequency value, then f s = 3200 × 4 = 12800 Hz.

[0027] At a sampling rate of 12800 Hz, if the fundamental frequency of the target signal is 50 Hz, the number of sampling points per cycle is 256 points.

[0028] Exemplarily, by detecting the zero-crossing position of the original sampling data, an accurate cycle sampling circuit can be obtained, and then through the following formula (2), the fundamental frequency is calculated according to the original sampling rate and the accurate number of cycle points:

[0029]

[0030] where, f b is the fundamental frequency of the target signal, f s is the sampling frequency, and N b is the number of cycle sampling points.

[0031] Based on the above number of cycle sampling points, the sampling phase difference between each signal in the multiplexed signals can be calculated.

[0032] Let the hardware phase difference be the absolute phase information be the sampling phase difference be then the calibration phase value corresponding to each sampled signal can be calculated through the following formula (3)

[0033]

[0034] where, To calibrate the phase value, is the absolute phase information, is the sampling phase difference, is the hardware phase difference.

[0035] This application can improve the accuracy of phase measurement by separately processing the hardware phase difference and the sampling phase difference.

[0036] In some technical solutions of this application, optionally, interpolating resampling processing is performed on the original sampling data sequence to obtain a resampled data sequence, including:

[0037] Interpolating resampling processing is performed through the following formula (4):

[0038] y m = x n + (x n+1 - x n ) × (Δm - n); (4)

[0039] where y m is the m-th data in the resampled data sequence, x n is the n-th data in the original sampling data, x n+1 is the (n + 1)-th data in the original sampling data, Δ is the step value of the interpolating resampling processing, Δm is the resampling time of the m-th resampling point, n is the floor value of Δm.

[0040] In this technical solution, at a set resampling frequency, interpolating resampling processing is performed on the original sampling data sequence obtained by equally spaced sampling to obtain a resampled sequence with exactly 256 points in one cycle. The purpose of this operation is to make the obtained resampled data sequence meet the conditions for subsequent FFT operations, that is, the number of operation points is a power of 2, and the data participating in the operation is data of a whole cycle.

[0041] The principle of resampling is to use the original sampling data sequence whose number of cycle points may not be the set value, and use the interpolation algorithm to calculate a resampled sequence with the number of cycle points being the set value. Assume that the actual number of cycle points of the original sampling data sequence is N b , and the set value of the number of cycle points to be obtained is 256. Then, the step value Δ of the interpolating resampling can be determined through the following formula (5), and the resampling frequency f s ′ can be determined through the following formula (6):

[0042]

[0043] f s ′ = 256f b ; (6);

[0044] Among them, Δ is the step value of interpolation resampling, and N b is the actual number of cycle points of the original sampling data sequence, and f s ′ is the resampling frequency, and f b is the fundamental frequency of the target signal.

[0045] The formula used for interpolation resampling is as shown in the above formula (4).

[0046] By performing interpolation resampling on the original sampling data sequence in this application, the obtained resampled data sequence can meet the format requirements of FFT operations, thereby improving the calculation accuracy and calculation efficiency of the calibration phase value.

[0047] In some technical solutions of this application, optionally, the harmonic data includes the real part data and the imaginary part data of each harmonic; determining the absolute phase information of the target signal according to the harmonic data includes:

[0048] Determining the absolute phase information through the following formula (7):

[0049]

[0050] Among them, is the absolute phase information of the nth harmonic, im n is the imaginary part data of the nth harmonic, and re n is the real part data of the nth harmonic.

[0051] In this technical solution, by performing a fast Fourier transform operation on the resampled data sequence, the real part data re n and the imaginary part data im n of each harmonic can be obtained, and then the absolute phase information of each harmonic can be calculated through the above formula (7)

[0052] Among them, due to the characteristics of the FFT algorithm, the harmonic frequency resolution f n of the operation result satisfies the following formula (8):

[0053]

[0054] Among them, f n is the harmonic frequency resolution after FFT operation, f s ′ is the resampling frequency, f b is the fundamental frequency of the target signal, N is the number of resampled points for FFT operation, and k is the number of cycles for FFT operation. Among them, when k = 1, f n = f b , that is, the harmonic frequency resolution is equal to the fundamental frequency.

[0055] Substitute it into Equation (7), and the harmonic frequency resolution \(f\) calculated according to Equation (8) n , when \(k = 1\), \(f\) n = \(f\) b . At this time, when \(n = 0\), it represents the data of the DC component, and when \(n = 1\), it represents the data of the fundamental wave. The absolute phase of the fundamental wave, that is, the above absolute phase information, is denoted as

[0056] In some technical solutions of the present application, optionally, determining the sampling phase difference between each path of signals among multiple paths of signals includes:

[0057] Determine the sampling phase difference through the following Equation (9):

[0058]

[0059] where is the sampling phase difference, \(k\) is the phase difference multiple of multiple paths of signals, and \(N\) b is the number of sampling points per cycle.

[0060] In this technical solution, calculate the sampling phase difference between each path of signals through the above Equation (9). Among them, the derivation process of Equation (9) is shown in the following Equation (10):

[0061]

[0062] where is the sampling phase difference, and \(m\) is the phase difference multiple of each path of signals.

[0063] Taking the single-channel ADC multi-path signal asynchronous sampling circuit structure as an example, the cyclic sampling order is \(U_a\), \(U_b\), \(U_c\), \(I_a\), \(I_b\), \(I_c\), then the phase difference multiples of each path are 0, 1, 2, 3, 4, 5 in turn.

[0064] In some technical solutions of the present application, optionally, after determining the calibration phase value based on the hardware phase difference and the absolute phase information of the electrical metering device, the determination method further includes: obtaining the standard phase value; correcting the hardware phase difference according to the standard phase value and the calibration phase value.

[0065] In this technical solution, for the hardware phase difference it can be calibrated after determining the relative phase value. Exemplarily, the hardware phase difference can be calibrated through the following Equation (11): The calibration is as follows:

[0066]

[0067] where is the hardware phase difference after calibration, is the hardware phase difference before calibration, is the relative phase value, is the obtained standard phase value. Exemplarily, the standard phase value is a relative value and can be obtained through external input.

[0068] In some technical solutions of the present application, optionally, the target signal includes multiple signals, and the multiple signals include a first signal; after determining the calibration phase value based on the hardware phase difference and the absolute phase information of the electrical metering device, the determination method further includes: determining the relative phase value corresponding to each signal in the multiple signals according to the first calibration phase value corresponding to the first signal.

[0069] In this technical solution, taking the target signal as a three-phase electrical signal as an example, among the multiple signals of the three-phase electrical signal, there are 3-phase voltage signals and 3-phase current signals. Let the first signal be the A-phase voltage signal Ua, and the first calibration phase value corresponding to the first signal is Then, the relative phase value corresponding to each signal is calculated respectively through the following formulas (12) to (17):

[0070]

[0071] wherein, is the relative phase value of the A-phase voltage signal, is the calibration phase value corresponding to the A-phase voltage signal. is the relative phase value of the B-phase voltage signal, is the calibration phase value corresponding to the B-phase voltage signal. is the relative phase value of the C-phase voltage signal, is the calibration phase value corresponding to the C-phase voltage signal. is the relative phase value of the A-phase current signal, is the calibration phase value corresponding to the A-phase current signal. is the relative phase value of the B-phase current signal, is the calibration phase value corresponding to the B-phase current signal. is the relative phase value of the C-phase current signal, is the calibration phase value corresponding to the C-phase current signal.

[0072] The second aspect of the present application provides a device for determining the calibration phase value of an electrical metering device. The determining device includes: a sampling module for sampling a target signal to obtain an original sampling data sequence; a processing module for performing interpolation resampling processing on the original sampling data sequence to obtain a resampled data sequence, the resampled data sequence including continuous full-cycle data; and performing fast Fourier transform processing on the continuous full-cycle data to obtain harmonic data of each harmonic in the resampled data sequence; a determining module for determining the absolute phase information of the target signal according to the harmonic data; and determining the calibration phase value based on the hardware phase difference and the absolute phase information of the electrical metering device.

[0073] In this technical solution, the electrical metering device includes but is not limited to an AC standard meter, an oscilloscope, a portable watt-hour meter, etc. The electrical energy standard meter can simultaneously measure multiple signals. Taking a three-phase AC standard meter as an example, the three-phase AC standard meter needs to be able to simultaneously measure a total of 6 signals including 3-phase voltage and 3-phase current.

[0074] The working principle of the three-phase AC standard meter is to cyclically and sequentially select the independent input / output terminals, including terminals X0 to X5, and the common output / input terminal X by controlling the input values of the three address lines A, B, and C controlled by the MCU (Micro Controller Unit), so as to realize the time-division access of the 6 sampling signals to the sampling input port of the ADC.

[0075] In addition, within the time interval between the sequential selection of two adjacent channels of the multi-channel analog switch chip, the MCU needs to output a conversion trigger signal to the single-channel ADC (analog to digital converter) chip and read the AD (analog to digital) conversion value of the selected signal through the connected SPI (Serial Peripheral Interface) data bus. By continuously executing the above process, the sampling data of the 6 voltage and current signals can be continuously input into the MCU, so that the MCU can calculate the frequency, amplitude, phase, and power values of each signal.

[0076] Theoretically speaking, when the measured voltage and current signals are both sine waves and the sampling rate is much higher than the frequencies of all signals, such a time-division multiplexing sampling method has no impact on the calculated values of the frequency, amplitude, and power of the measured signals, but has a direct impact on the phase value. The reason is that there is a sampling trigger interval for the other 5 channels relative to the A-phase voltage, and the interval time increases sequentially from the first to the last. Using such asynchronously sampled data in time will inevitably result in a phase difference caused by the sampling trigger interval between the other 5 phases and the A-phase voltage, that is, there is a sampling phase difference. Moreover, this sampling phase difference is positively correlated with the frequency value of the measured voltage and current signals. The higher the frequency, the greater the sampling phase difference.

[0077] When the measured signal is a single-frequency signal, such as only used in an environment of 50 Hz, the above sampling phase difference can be calibrated and eliminated together with the hardware phase difference during phase calibration. However, once the frequency of the measured signal changes, even if the hardware phase difference remains unchanged, the sampling phase difference will inevitably change, resulting in the invalidation of the phase calibration coefficient and finally a deviation in the calculated phase value.

[0078] To address the above problems, the present application performs interpolation resampling processing on the original sampling data sequence obtained by sampling the target signal, so as to obtain a resampled data sequence in which exactly one cycle satisfies a specific number of sampling points, that is, including continuous integral cycle data. Among them, the target signal is also the measured signal. Through such an operation, the data in the resampled data sequence can meet the requirements for fast Fourier transform (FFT) processing.

[0079] After obtaining the resampled data sequence including continuous integral cycle data, perform fast Fourier transform processing on this data sequence to obtain the harmonic data of each harmonic, including the harmonic data of the first harmonic, the harmonic data of the second harmonic... and the harmonic data of the nth harmonic.

[0080] After obtaining the harmonic data of each harmonic, the absolute phase information of the target signal, that is, the measured signal, can be calculated based on the harmonic data. Combining the known hardware phase difference of the electrical metering device, the calibrated phase value can be obtained.

[0081] The present application separates the sampling phase difference from the hardware phase difference and processes the sampling phase difference separately after each sampling. Therefore, it can solve the problem that the phase value obtained by the electrical metering device deviates from the actual value when the frequency of the measured signal is non-standard at the software level. This method does not require modification of the original hardware of the electrical metering device, such as the hardware of a three-phase AC energy meter, does not increase the hardware cost, and does not change the original calibration process, and can improve the phase measurement accuracy of the electrical measurement device with low cost and high compatibility.

[0082] The third aspect of the present application provides a device for determining a calibration phase value of an electric metering device, including: a memory for storing programs or instructions; a processor for implementing the steps of the method for determining the calibration phase value of the electric metering device provided in any of the above technical solutions when executing the programs or instructions, and thus can also achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0083] The fourth aspect of the present application provides a readable storage medium, on which programs or instructions are stored. When the programs or instructions are executed by a processor, the steps of the method for determining the calibration phase value of the electric metering device provided in any of the above technical solutions are implemented, and thus can also achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0084] The fifth aspect of the present application provides an electric metering device, including: the device for determining the calibration phase value of the electric metering device provided in any of the above technical solutions, and / or the readable storage medium provided in any of the above technical solutions, and thus can also achieve the same technical effects. To avoid repetition, it will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] The above and / or additional aspects and advantages of the present application will become apparent and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:

[0086] Figure 1 A flowchart of a method for determining a calibration phase value of an electric metering device according to some embodiments of the present application is shown;

[0087] Figure 2 A schematic structural diagram of a single-channel ADC multi-channel signal asynchronous sampling circuit according to some embodiments of the present application is shown;

[0088] Figure 3 A schematic diagram of the phase calculation logic of a single-channel ADC asynchronous sampling AC standard meter according to some embodiments of the present application is shown;

[0089] Figure 4 A schematic diagram of an original sampling data sequence according to some embodiments of the present application is shown;

[0090] Figure 5 A schematic diagram of a resampled data sequence according to some embodiments of the present application is shown;

[0091] Figure 6 A block diagram of the structure of a device for determining a calibration phase value of an electric metering device according to some embodiments of the present application is shown;

[0092] Figure 7 A block diagram of the structure of a device for determining a calibration phase value of an electric metering device according to some embodiments of the present application is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0093] In order to more clearly understand the above-mentioned objects, features, and advantages of the present application, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0094] In the following description, many specific details are set forth in order to fully understand the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0095] The following refers to Figures 1 to 7 Describe a method and device for determining a calibration phase value, a storage medium, and an electrical metering device according to some embodiments of the present application.

[0096] In some embodiments of the present application, a method for determining a calibration phase value of an electrical metering device is provided. Figure 1 The flowchart of the method for determining the calibration phase value of the electrical metering device according to some embodiments of the present application is shown. As Figure 1 shown, the determination method includes:

[0097] Step 102, sampling the target signal to obtain an original sampling data sequence;

[0098] Step 104, performing interpolation resampling processing on the original sampling data sequence to obtain a resampled data sequence, and the resampled data sequence includes continuous full-cycle wave data;

[0099] Step 106, performing fast Fourier transform processing on the continuous full-cycle wave data to obtain harmonic data of each harmonic in the resampled data sequence;

[0100] Step 108, determining the absolute phase information of the target signal according to the harmonic data;

[0101] Step 110, determining the calibration phase value based on the hardware phase difference and the absolute phase information of the electrical metering device.

[0102] In this embodiment, the electrical metering device includes, but is not limited to, an AC standard meter, an oscilloscope, a portable electric energy meter, etc. The electric energy standard meter can measure multiple signals simultaneously. Taking a three-phase AC standard meter as an example, the three-phase AC standard meter needs to be able to measure a total of 6 signals including 3-phase voltage and 3-phase current simultaneously.

[0103] Figure 2 The structural schematic diagram of the single-channel ADC multi-channel signal asynchronous sampling circuit according to some embodiments of the present application is shown. As Figure 2As shown, the working principle of the three-phase AC standard meter is to cyclically and sequentially select the independent input / output terminals, including terminals X0 to X5, to be gated with the common output / input terminal X through the input values of the three address lines A, B, and C controlled by the MCU (Micro Controller Unit), so as to implement time-division access of the six sampling signals to the sampling input port of the ADC.

[0104] In addition, within the time interval when two adjacent channels of the multi-channel analog switch chip are sequentially gated, the MCU needs to output a conversion trigger signal to the single-channel ADC (analog to digital converter) chip and read the AD (analog to digital) conversion value of the gated signal through the connected SPI (Serial Peripheral Interface) data bus. By continuously executing the above process, the sampling data of the six voltage and current signals can be continuously input into the MCU, so that the MCU can calculate the frequency, amplitude, phase, and power values of each signal.

[0105] Theoretically speaking, when the measured voltage and current signals are both sine waves and the sampling rate is much higher than the frequencies of each signal, such a time-division multiplexing sampling method has no effect on the calculated values of the frequency, amplitude, and power of the measured signal, but has a direct impact on the phase value. The reason is that there is a sampling trigger interval for the other five phases relative to the A-phase voltage, and the interval time increases sequentially from the first to the last. Using such asynchronously sampled data in terms of time will inevitably result in a phase difference caused by the sampling trigger interval between the other five phases and the A-phase voltage, that is, there is a sampling phase difference. Moreover, this sampling phase difference is positively correlated with the frequency value of the measured voltage and current signals. The higher the frequency, the greater the sampling phase difference.

[0106] When the measured signal is a single-frequency signal, such as only used in an environment of 50 Hz, the above sampling phase difference can be calibrated and eliminated together with the hardware phase difference during phase calibration. However, once the frequency of the measured signal changes, even if the hardware phase difference remains unchanged, the sampling phase difference will inevitably change, resulting in the invalidation of the phase calibration coefficient and finally a deviation in the calculated phase value.

[0107] In response to the above problems, exemplarily, Figure 3 shows a schematic diagram of the phase calculation logic of the single-channel ADC asynchronous sampling AC standard meter according to some embodiments of the present application, as Figure 3As shown, the present application performs interpolation resampling on the original sampling data sequence obtained by sampling the target signal, so as to obtain a resampled data sequence in which exactly one cycle satisfies a specific number of sampling points, that is, including continuous integral cycle data. Among them, the target signal is also the measured signal. Through such an operation, the data in the resampled data sequence can satisfy the requirements for performing fast Fourier transform (FFT) processing. Among them, the fast Fourier transform is an efficient algorithm for discrete Fourier transform, which can transform a discrete sequence in the time domain to the frequency domain for analyzing the amplitude and phase parameters of each harmonic frequency point contained in the original signal.

[0108] After obtaining the resampled data sequence including continuous integral cycle data, perform fast Fourier transform processing on this data sequence to obtain harmonic data of each harmonic, including harmonic data of the first harmonic, harmonic data of the second harmonic... and harmonic data of the nth harmonic.

[0109] After obtaining the harmonic data of each harmonic, the absolute phase information of the target signal, that is, the measured signal, can be calculated based on the harmonic data. Combining the known hardware phase difference of the electrical metering device, the calibrated phase value can be obtained.

[0110] By separately processing the sampling phase difference and the hardware phase difference in the present application and processing the sampling phase difference separately after each sampling, it is possible to solve the problem that the phase value obtained by the electrical metering device deviates from the actual value when the frequency of the measured signal is non-standard at the software level. This method does not require modification of the original hardware of the electrical metering device, such as the hardware of a three-phase AC energy meter, does not increase the hardware cost, and does not change the original calibration process, and can improve the phase measurement accuracy of electrical measurement devices with low cost and high compatibility.

[0111] In some embodiments of the present application, optionally, the target signal includes multiple signals; sampling the target signal includes: separately sampling the multiple signals according to a preset sampling interval; determining the calibrated phase value based on the hardware phase difference and absolute phase information of the electrical metering device includes: determining the number of sampling points per cycle of the original sampling data sequence; according to the number of sampling points per cycle, determining the sampling phase difference between each of the multiple signals; and determining the calibrated phase value corresponding to each sampled signal according to the hardware phase difference, sampling phase difference, and absolute phase information.

[0112] In this embodiment, taking the target signal as a three-phase electrical signal as an example, the target signal includes 3 voltage signals and 3 current signals. Among them, the 3 voltage signals are the phase A voltage signal, phase B voltage signal, and phase C voltage signal. The 3 current signals are the phase A current signal, phase B current signal, and phase C current signal.

[0113] When sampling the target signal, time-division multiplexing sampling is performed on the above six signals based on fixed sampling detection.

[0114] Exemplarily, each signal is sampled at equal intervals according to a fixed sampling rate to obtain an original sampling sequence, and this sampling rate is denoted as f s , according to the Nyquist theorem, the sampling rate is denoted as f s satisfies the following formula (1):

[0115] f s ≥2f Max ; (1)

[0116] where f s is the sampling frequency for sampling the target signal, and f Max is the highest frequency value that needs to be detected in the target signal. For example, when analyzing the parameters of the 64th harmonic at the mains frequency (50 Hz), f Max = 50 × 64 = 3200 Hz. Optionally, the sampling frequency is 2.56 times to 4 times the above highest frequency value, then f s = 3200 × 4 = 12800 Hz.

[0117] At a sampling rate of 12800 Hz, if the fundamental frequency of the target signal is 50 Hz, the number of sampling points per cycle is 256 points.

[0118] Exemplarily, by detecting the zero-crossing position of the original sampling data, an accurate cycle sampling circuit can be obtained, and then through the following formula (2), the fundamental frequency can be calculated according to the original sampling rate and the accurate number of cycle points:

[0119]

[0120] where f b is the fundamental frequency of the target signal, f s is the sampling frequency, and N b is the number of cycle sampling points.

[0121] Based on the above number of cycle sampling points, the sampling phase difference between each signal in the multiple signals can be calculated.

[0122] Let the hardware phase difference be the absolute phase information be the sampling phase difference be then the calibration phase value corresponding to each sampled signal can be calculated through the following formula (3)

[0123]

[0124] where To calibrate the phase value, is the absolute phase information, is the sampling phase difference, is the hardware phase difference.

[0125] By separately processing the hardware phase difference and the sampling phase difference, this application can improve the accuracy of phase measurement.

[0126] In some embodiments of this application, optionally, interpolation resampling processing is performed on the original sampling data sequence to obtain a resampled data sequence, including:

[0127] Interpolation resampling processing is performed through the following formula (4):

[0128] y m = x n +(x n+1 - x n ) × (Δm - n); (4)

[0129] Where y m is the mth data in the resampled data sequence, x n is the nth data in the original sampling data, x n+1 is the (n + 1)th data in the original sampling data, Δ is the step value of the interpolation resampling processing (such as Figure 5 shown by the difference step value), Δm is the resampling time of the mth resampling point (i.e., the coordinate position of the mth sampling point on the Figure 5 shown time axis), n is the floor value of Δm.

[0130] In this embodiment, with a set resampling frequency, interpolation resampling processing is performed on the original sampling data sequence obtained by equally spaced sampling to obtain a resampled sequence with exactly 256 points in one cycle. The purpose of this operation is to make the obtained resampled data sequence meet the conditions of subsequent FFT operations, that is, the number of operation points is a power of 2, and the data participating in the operation is data of an integer cycle. Exemplarily, Figure 4 shows a schematic diagram of the original sampling data sequence in some embodiments of this application, Figure 5 shows a schematic diagram of the resampled data sequence in some embodiments of this application, as Figure 4 and Figure 5 shown, where X 0 , X 1 ... X n+1 are the original sampling data points, and Y 0 , Y 1 ... Y m are the resampled data points. By performing interpolation resampling, the conditions of FFT operations can be met.

[0131] The principle of resampling is to use the original sampling data sequence with a possible non-set number of cycle points, and use an interpolation algorithm to calculate the resampled sequence with a set number of cycle points. Assume that the actual number of cycle points of the original sampling data sequence is N b , if the set value of the number of cycle points to be obtained is 256, the step value Δ of interpolation resampling can be determined by the following formula (5), and the resampling frequency f s ′ can be determined by the following formula (6):

[0132]

[0133] f s ′ = 256f b ; (6);

[0134] where Δ is the step value of interpolation resampling, N b is the actual number of cycle points of the original sampling data sequence, f s ′ is the resampling frequency, and f b is the fundamental frequency of the target signal.

[0135] The formula used for interpolation resampling is as shown in the above formula (4).

[0136] By performing interpolation resampling on the original sampling data sequence, the obtained resampled data sequence can meet the format requirements of the FFT operation, thereby improving the calculation accuracy and calculation efficiency of the calibration phase value.

[0137] In some embodiments of the present application, optionally, the harmonic data includes the real part data and the imaginary part data of each harmonic; determining the absolute phase information of the target signal according to the harmonic data includes:

[0138] Determining the absolute phase information by the following formula (7):

[0139]

[0140] where is the absolute phase information of the nth harmonic, im n is the imaginary part data of the nth harmonic, and re n is the real part data of the nth harmonic.

[0141] In this embodiment, by performing a fast Fourier transform operation on the resampled data sequence, the real part data re n and the imaginary part data im n of each harmonic can be obtained, and then the absolute phase information of each harmonic can be calculated through the above formula (7).

[0142] Among them, due to the characteristics of the FFT algorithm, the harmonic frequency resolution f of the operation result n satisfies the following formula (8):

[0143]

[0144] where f n is the harmonic frequency resolution after FFT operation, f s ′ is the resampling frequency, f b is the fundamental frequency of the target signal, N is the number of resampling points for FFT operation, and k is the number of cycles for FFT operation. Among them, when k = 1, f n = f b , that is, the harmonic frequency resolution is equal to the fundamental frequency.

[0145] Substituting into formula (7), the harmonic frequency resolution f n calculated according to formula (8), when k = 1, f n = f b , at this time, when n = 0, it represents the data of the DC component, and when n = 1, it represents the data of the fundamental wave. The absolute phase of the fundamental wave, that is, the above absolute phase information, is denoted as

[0146] In some embodiments of the present application, optionally, determining the sampling phase difference between each path of signals among multiple paths of signals includes:

[0147] Determining the sampling phase difference through the following formula (9):

[0148]

[0149] where is the sampling phase difference, k is the phase difference magnification factor of multiple paths of signals, and N b is the number of sampling points per cycle.

[0150] In this embodiment, the sampling phase difference between each path of signals is calculated through the above formula (9).

[0151] Among them, the derivation process of formula (9) is shown in the following formula (10):

[0152]

[0153] where is the sampling phase difference, and m is the phase difference magnification factor of each path of signals.

[0154] Taking the single-channel ADC multi-path signal asynchronous sampling circuit structure as an example, the cyclic sampling order is Ua, Ub, Uc, Ia, Ib, Ic, then the phase difference magnification factors of each path are 0, 1, 2, 3, 4, 5 in sequence.

[0155] In some embodiments of the present application, optionally, after determining the calibration phase value based on the hardware phase difference and the absolute phase information of the electrical metering device, the determination method further includes: obtaining a standard phase value; and correcting the hardware phase difference according to the standard phase value and the calibration phase value.

[0156] In this embodiment, for the hardware phase difference it is possible to calibrate the hardware phase difference after determining the relative phase value. Exemplarily, the hardware phase difference can be calibrated by the following formula (11): for calibration:

[0157]

[0158] where, is the calibrated hardware phase difference, is the hardware phase difference before calibration, is the relative phase value, is the obtained standard phase value. Exemplarily, the standard phase value is a relative value and can be obtained through external input.

[0159] In some embodiments of the present application, optionally, the target signal includes multiple signals, and the multiple signals include a first signal; after determining the calibration phase value based on the hardware phase difference and the absolute phase information of the electrical metering device, the determination method further includes: determining the relative phase value corresponding to each signal in the multiple signals according to the first calibration phase value corresponding to the first signal.

[0160] In this embodiment, taking the target signal as a three-phase electrical signal as an example, among the multiple signals of the three-phase electrical signal, there are 3-phase voltage signals and 3-phase current signals. Let the first signal be the A-phase voltage signal Ua, and the first calibration phase value corresponding to the first signal be Then, the relative phase value corresponding to each signal is calculated respectively through the following formulas (12) to (17):

[0161]

[0162] where, is the relative phase value of the A-phase voltage signal, is the calibration phase value corresponding to the A-phase voltage signal. is the relative phase value of the B-phase voltage signal, is the calibration phase value corresponding to the B-phase voltage signal. is the relative phase value of the C-phase voltage signal, is the calibration phase value corresponding to the C-phase voltage signal. is the relative phase value of the A-phase current signal, is the calibrated phase value corresponding to the A-phase current signal. is the relative phase value of the B-phase current signal, is the calibrated phase value corresponding to the B-phase current signal. is the relative phase value of the C-phase current signal, is the calibrated phase value corresponding to the C-phase current signal.

[0163] In some embodiments of the present application, a device for determining the calibrated phase value of an electrical metering device is provided. Figure 6 shows a structural block diagram of the device for determining the calibrated phase value of the electrical metering device according to some embodiments of the present application, as Figure 6 shown, the determining device 600 includes: a sampling module 602, configured to sample a target signal to obtain an original sampling data sequence; a processing module 604, configured to perform interpolation resampling processing on the original sampling data sequence to obtain a resampled data sequence, the resampled data sequence including continuous full-cycle data; and perform fast Fourier transform processing on the continuous full-cycle data to obtain harmonic data of each harmonic in the resampled data sequence; a determining module 606, configured to determine the absolute phase information of the target signal according to the harmonic data; and determine the calibrated phase value based on the hardware phase difference and the absolute phase information of the electrical metering device.

[0164] In this embodiment, the electrical metering device includes, but is not limited to, an AC standard meter, an oscilloscope, a portable watt-hour meter, etc. The electrical energy standard meter can simultaneously measure multiple signals. Taking a three-phase AC standard meter as an example, the three-phase AC standard meter needs to be able to simultaneously measure a total of 6 signals including 3-phase voltage and 3-phase current.

[0165] The working principle of the three-phase AC standard meter is to cyclically and sequentially select the independent input / output terminals, including terminals X0 to X5, to be connected to the common output / input terminal X through the input values of three address lines A, B, and C controlled by an MCU (Micro Controller Unit), so as to realize time-sharing access of 6 sampling signals to the sampling input port of the ADC.

[0166] In addition, within the time interval between the sequential selection of two adjacent channels of the multi-channel analog switch chip, the MCU needs to output a conversion trigger signal to the single-channel ADC (analog to digital converter) chip and read the AD (analog to digital) conversion value of the selected signal through the connected SPI (Serial Peripheral Interface) data bus. By continuously executing the above process, the sampled data of the six channels of voltage and current can be continuously input into the MCU, so that the MCU can calculate the frequency, amplitude, phase, and power values of each signal.

[0167] Theoretically speaking, when the measured voltage and current signals are all sine waves and the sampling rate is much higher than the frequencies of each signal, such a time-division multiplexing sampling method has no influence on the calculated values of the frequency, amplitude, and power of the measured signal, but has a direct influence on the phase value. The reason is that there is a sampling trigger interval for the other five channels relative to the A-phase voltage, and the interval time increases sequentially from the first to the last. Using such asynchronously sampled data in time will inevitably result in a phase difference caused by the sampling trigger interval between the other five phases and the A-phase voltage, that is, there is a sampling phase difference. Moreover, this sampling phase difference is positively correlated with the frequency value of the measured voltage and current signal. The higher the frequency, the greater the sampling phase difference.

[0168] When the measured signal is a single-frequency signal, such as only used in an environment of 50 Hz, the above sampling phase difference can be calibrated and eliminated together with the hardware phase difference during phase calibration. However, once the frequency of the measured signal changes, even if the hardware phase difference remains unchanged, the sampling phase difference will inevitably change, resulting in the invalidation of the phase calibration coefficient and finally a deviation in the phase calculation value.

[0169] To address the above problems, the present application performs interpolation resampling processing on the original sampled data sequence obtained by sampling the target signal, so as to obtain a resampled data sequence with exactly one cycle satisfying a specific number of sampling points, that is, including continuous full-cycle data. Among them, the target signal is also the measured signal. Through such an operation, the data in the resampled data sequence can meet the requirements for fast Fourier transform (FFT) processing.

[0170] After obtaining the resampled data sequence including continuous full-cycle data, perform fast Fourier transform processing on this data sequence to obtain the harmonic data of each harmonic, including the harmonic data of the first harmonic, the harmonic data of the second harmonic... and the harmonic data of the nth harmonic.

[0171] After obtaining the harmonic data of each harmonic, the target signal, that is, the absolute phase information of the measured signal, can be calculated based on the harmonic data. Combining the known hardware phase difference of the electrical metering device, the calibrated phase value can be obtained.

[0172] In this application, by separately processing the sampling phase difference and the hardware phase difference, and separately processing the sampling phase difference after each sampling, it is possible to solve, at the software level, the problem that the phase value obtained by the electrical metering device deviates from the actual value when the frequency of the measured signal is non-standard. This method does not require modification of the original hardware of the electrical metering device, such as the hardware of a three-phase AC energy meter, does not increase the hardware cost, and does not change the original calibration process, and can improve the accuracy of the phase measurement of the electrical measurement device with low cost and high compatibility.

[0173] In some embodiments of this application, a device for determining the calibrated phase value of an electrical metering device is provided. Figure 7 The structural block diagram of the device for determining the calibrated phase value of the electrical metering device according to some embodiments of this application is shown. As Figure 7 shown, the determining device 700 includes: a memory 702 for storing programs or instructions; a processor 704 for implementing the steps of the method for determining the calibrated phase value of the electrical metering device provided in any of the above embodiments when executing the programs or instructions, and thus can also achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0174] In some embodiments of this application, a readable storage medium is provided, on which programs or instructions are stored. When the programs or instructions are executed by a processor, the steps of the method for determining the calibrated phase value of the electrical metering device provided in any of the above embodiments are implemented, and thus the same technical effects can also be achieved. To avoid repetition, it will not be elaborated here.

[0175] In some embodiments of this application, an electrical metering device is provided, including: the device for determining the calibrated phase value of the electrical metering device provided in any of the above embodiments, and / or the readable storage medium provided in any of the above embodiments, and thus the same technical effects can also be achieved. To avoid repetition, it will not be elaborated here.

[0176] The described methods can be implemented in a variety of different ways according to specific features and / or example applications. For example, these methods can be implemented by a combination of hardware, firmware, and / or software. For example, in a hardware implementation, a processor can be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, electronic devices, other device units for performing the above functions, and / or combinations thereof.

[0177] A computer-readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. A computer-readable storage medium can be an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing devices, but is not limited thereto. A non-exhaustive list of more specific examples of computer-readable storage media includes: portable computer floppy disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), or flash memory, static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital versatile discs (DVDs), memory cards, floppy disks, coding mechanical devices (such as punched cards or grooves with raised structures having instructions recorded thereon), and any suitable combination of the foregoing devices. A computer-readable storage medium as used herein should not be construed as a signal per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission medium, or electrical signals transmitted through wires, etc.

[0178] In the description of this application, the term "a plurality of" refers to two or more. Unless otherwise clearly defined, the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship described in the drawings. This is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this application. Terms such as "connection", "installation", and "fixation" should all be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0179] In the description of this application, the description of terms such as "one embodiment", "some embodiments", and "specific embodiments" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this application, the schematic expressions of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0180] The above are only the preferred embodiments of this application and are not used to limit this application. For those skilled in the art, this application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims

1. A method for determining a calibration phase value of an electrical metering device, characterized in that: The determination method comprises: Sampling the target signal to obtain an original sampling data sequence; Performing interpolation resampling processing on the original sampled data sequence to obtain a resampled data sequence, wherein the resampled data sequence includes continuous whole-cycle data; Performing fast Fourier transform processing on the continuous whole cycle data to obtain harmonic data of each harmonic in the resampled data sequence; Determining absolute phase information of the target signal according to the harmonic data; A calibration phase value is determined based on a hardware phase difference of the electrical metering device and the absolute phase information.

2. The determination method according to claim 1, characterized in that: The target signal includes multiple signals; The sampling of the target signal comprises: According to a preset sampling interval, the multiple signals are sampled respectively; The determining of the calibration phase value based on the hardware phase difference of the electrical metering device and the absolute phase information comprises: Determine the number of cycle sampling points of the original sampling data sequence; Determining the sampling phase difference between each signal in the multiple signals according to the number of cycle sampling points; A calibration phase value corresponding to each sampling signal is determined according to the hardware phase difference, the sampling phase difference and the absolute phase information.

3. The determination method according to claim 1, characterized in that: The original sampled data sequence is subjected to interpolation resampling processing to obtain a resampled data sequence, including: The interpolation resampling process is performed using the following formula: y m =x n +(x n+1 -x n )×(Δm-n); Among them, y m is the mth data in the resampled data sequence, x n is the nth data in the original sampled data, x n+1 is the n+1th data in the original sampled data, Δ is the step value of the interpolation resampling process, Δm is the resampling time of the mth resampling point, and n is the rounded-down value of Δm.

4. The determination method according to claim 1, characterized in that: The harmonic data includes real data and imaginary data of each harmonic; and determining the absolute phase information of the target signal according to the harmonic data includes: The absolute phase information is determined by the following formula: in, is the absolute phase information of the nth harmonic, im n is the imaginary part data of the nth harmonic, re n is the real part data of the nth harmonic.

5. The determination method according to claim 2, characterized in that: The determining of the sampling phase difference between each signal in the multiple signals includes: The sampling phase difference is determined by the following formula: in, is the sampling phase difference, k is the phase difference multiplier of the multi-channel signal, N b is the number of sampling points of the cycle.

6. The determination method according to any one of claims 1 to 5, characterized in that: After determining the calibration phase value based on the hardware phase difference of the electrical metering device and the absolute phase information, the determination method further includes: Get the standard phase value; The hardware phase difference is corrected according to the standard phase value and the calibration phase value.

7. The determination method according to any one of claims 1 to 5, characterized in that: The target signal includes multiple signals, and the multiple signals include a first signal; after determining the calibration phase value based on the hardware phase difference of the electrical metering device and the absolute phase information, the determination method further includes: According to the first calibration phase value corresponding to the first signal, a relative phase value corresponding to each signal in the multiple signals is determined.

8. A device for determining a calibration phase value of an electrical metering device, characterized in that: The determining device comprises: A sampling module is used to sample the target signal to obtain an original sampling data sequence; a processing module, configured to perform interpolation resampling processing on the original sampled data sequence to obtain a resampled data sequence, wherein the resampled data sequence includes continuous whole-cycle data; and Performing fast Fourier transform processing on the continuous whole cycle data to obtain harmonic data of each harmonic in the resampled data sequence; a determination module, configured to determine absolute phase information of the target signal according to the harmonic data; and A calibration phase value is determined based on a hardware phase difference of the electrical metering device and the absolute phase information.

9. A device for determining a calibration phase value of an electrical metering device, characterized in that: include: Memory, used to store programs or instructions; A processor, configured to implement the steps of the determination method according to any one of claims 1 to 7 when executing the program or instruction.

10. A readable storage medium having a program or instruction stored thereon, characterized in that: When the program or instruction is executed by a processor, the steps of the determination method according to any one of claims 1 to 7 are implemented.

11. An electrical metering device, characterized in that: include: The device for determining the calibration phase value of an electrical metering device as claimed in claim 8 or 9; and / or The readable storage medium as claimed in claim 10.

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