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CN-122017334-A - Ubiquitous metering-oriented self-adaptive alternating current-direct current wide-range electric energy metering system and method

CN122017334ACN 122017334 ACN122017334 ACN 122017334ACN-122017334-A

Abstract

The invention belongs to the technical field of digital circuits, and discloses a ubiquitous metering-oriented self-adaptive alternating current-direct current wide-range electric energy metering system and a ubiquitous metering-oriented self-adaptive alternating current-direct current wide-range electric energy metering method, wherein the system comprises a PGA, an ADC, a waveform extreme point judging module, a PGA multiple calculating module and a two-dimensional alternating current-direct current identifying module; the method comprises the steps of dynamically adjusting the PGA gain based on the effective bit width occupancy rate to enable the signal amplitude to be adaptively matched with the optimal range of the ADC, constructing a two-dimensional identification logic by combining the frequency and the amplitude characteristics to accurately distinguish the AC/DC signals, and establishing a cooperative feedback mechanism of gain adjustment and AC/DC identification to realize differential power calculation. The method solves the problems of rigidity of gain configuration, low extremum extraction precision, high alternating current/direct current misjudgment rate and poor system cooperativity of the traditional scheme, and has the advantages of strong self-adaption, accurate identification, good real-time performance and flexible scene adaptation.

Inventors

  • HUANG KAI
  • LI JINWANG

Assignees

  • 浙江大学

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. A ubiquitous metering-oriented adaptive AC/DC wide-range electric energy metering system is characterized by comprising a programmable gain amplifier control module, an analog-to-digital converter, a waveform extreme point judging module, an extreme point and extreme point position processing module, a programmable gain amplifier multiple calculating module and a two-dimensional AC/DC signal identifying module, wherein the programmable gain amplifier control module is used for amplifying an input voltage or current signal according to configured amplification factors, the analog-to-digital converter is used for collecting a signal amplified by the programmable gain amplifier and outputting a discretized signed sampling data sequence, the waveform extreme point judging module is used for processing the sampling data sequence through a sliding window extreme value judging method, extracting global maximum values, global minimum values and corresponding position information of the global maximum values and the global minimum values, the extreme point and extreme point position processing module is used for calculating the period and the amplitude of the signal according to the maximum values, the minimum values and the position information of the maximum values, the programmable gain amplifier multiple calculating module is used for adaptively calculating and adjusting the optimal amplification factors of the programmable gain amplifier according to the bit width occupation conditions of the maximum values, and the two-dimensional AC/DC signal identifying module is used for comprehensively judging whether the signal is an AC signal or a DC signal according to the period and the amplitude of the signal and the amplitude combined with a preset frequency range and a threshold.
  2. 2. The ubiquitous metering-oriented adaptive ac/dc wide-range power metering system according to claim 1, further comprising a data format processing module for binding the sampled data of the analog-to-digital converter with the current programmable gain amplifier multiple identification and normalizing the sampled data under different gains to unify signal amplitude references.
  3. 3. The ubiquitous metering-oriented adaptive ac/dc wide-range power metering system according to claim 2, further comprising a delay circuit for delaying reading of updated sampling data according to a preset delay parameter when the programmable gain amplifier multiple adjustment is detected, so as to avoid invalid data of the gain switching transition period.
  4. 4. A ubiquitous metering-oriented adaptive AC/DC wide-range electric energy metering method is applied to a system according to any one of claims 1-3 and is characterized by comprising the following steps of S1, collecting signals amplified by a programmable gain amplifier through an analog-to-digital converter to obtain a discretized signed sampling data sequence, S2, traversing the sampling data sequence by adopting a sliding window extremum discrimination method to extract global maximum value, global minimum value and corresponding position information thereof, S3, calculating a signal period according to the position information of the maximum value and the minimum value, calculating a signal amplitude according to the difference value of the maximum value and the minimum value, S4, analyzing the binary effective bit width of the maximum value and the minimum value, calculating the bit width occupancy rate, and adaptively adjusting the amplification factor of the programmable gain amplifier according to the comparison result of the bit width occupancy rate and a preset optimal interval, S5, judging that the input signals are AC signals or DC signals are judged to be the AC signals through a two-dimensional logic according to the calculated frequency range and the preset amplitude value, and S6, and determining the subsequent sampling data type is carried out based on the subsequent sampling data.
  5. 5. The adaptive ac/dc wide-range electric energy metering method for ubiquitous metering according to claim 4, wherein the sliding window extremum discrimination method in step S2 further comprises setting the window length to be 5 sampling points, traversing the sampling sequence, judging whether each intermediate sampling point is the maximum value or the minimum value in the 5-point window, screening the extremum points in all windows, taking the point with the maximum value as a global positive peak value, taking the point with the minimum value as a global negative peak value, and recording the corresponding position index.
  6. 6. The adaptive ac/dc wide-range power metering method for ubiquitous metering according to claim 4, wherein said step S4 further comprises taking absolute values of the global maximum and minimum values, respectively, calculating the effective bit width thereof by means of leading zero counts, taking the maximum effective bit width of the two to calculate the bit width occupancy, increasing the amplification factor if the bit width occupancy is lower than the first hysteresis threshold and the current gain is lower than the maximum gain, decreasing the amplification factor if the bit width occupancy is higher than the second hysteresis threshold and the current gain is higher than the minimum gain, and repeating the process until the bit width occupancy is stabilized within the preset optimal interval.
  7. 7. The adaptive ac/dc wide-range power metering method according to claim 4, wherein the two-dimensional logic determination in step S5 further comprises determining that the signal is a dc signal if the frequency corresponding to the signal period is not within a preset ac frequency range and the signal amplitude is less than a preset amplitude threshold, and determining that the signal is an ac signal if the frequency corresponding to the signal period is not within the preset ac frequency range.
  8. 8. The adaptive ac/dc wide-range power metering method for ubiquitous metering according to claim 4, wherein the power metering calculation in step S6 further comprises binding the sampled data of the analog-to-digital converter with a current programmable gain amplifier multiple identifier, performing gain normalization on the sampled data according to the multiple identifier, restoring the sampled data to a real signal amplitude, calculating a voltage effective value and a current effective value according to the normalized data, and selecting corresponding dc or ac power calculation logic according to the identification result in step S5 to calculate active power, reactive power and apparent power.
  9. 9. The adaptive ac/dc wide-range power metering method for ubiquitous metering of claim 8, wherein said power calculation logic further comprises calculating an average value of normalized voltage and current in a single period when it is determined as a dc signal, and taking the product of said average value of voltage and average value of current as dc active power.
  10. 10. The adaptive ac/dc wide-range power metering method for ubiquitous metering according to claim 8, wherein said power calculation logic further comprises calculating apparent power by multiplying voltage effective value and current effective value, calculating active power by averaging instantaneous power accumulation in a period, and deriving reactive power by power triangle relation based on said apparent power and active power.

Description

Ubiquitous metering-oriented self-adaptive alternating current-direct current wide-range electric energy metering system and method Technical Field The invention belongs to the technical field of digital circuits, and particularly relates to a ubiquitous metering-oriented self-adaptive alternating current-direct current wide-range electric energy metering system and method. Background In an electric power system, such as a new energy automobile charging pile (mixed layout of an alternating current pile and a direct current pile), a photovoltaic grid-connected inverter, an energy storage converter, flexible direct current transmission equipment and the like, the amplitude, frequency and alternating current-direct current properties of an electric power signal of the electric power system can be changed rapidly along with the time and working conditions, and the traditional electric energy metering scheme faces serious challenges in the aspects of signal sampling suitability, alternating current-direct current identification accuracy, system instantaneity and the like. The prior art mainly has the following key problems: 1. PGA gain configuration rigidifies and sample amplitude adaptation is poor The amplification factor of the traditional Programmable Gain Amplifier (PGA) needs to be manually calibrated to preset a fixed value or a static configuration mode of segmented fixed gain is adopted, so that the real-time change of the amplitude of the measured signal cannot be dynamically adapted. The method directly causes two problems, namely, when the amplitude of the measured signal is smaller, the effective bit width utilization rate of the ADC is too low (usually lower than 30%), a large number of high bits are invalid zero bits, the quantization precision is seriously lost, the signal details are submerged by noise, and when the amplitude of the measured signal is larger, the gain is too high, the signal is easy to exceed the bipolar range (-V/2 to +V/2) of the ADC, clipping distortion is generated, and signal characteristic distortion is caused. In addition, in the prior art, gain adjustment is not combined with signal attribute identification, and even if gain configuration is unreasonable, alternating current/direct current judgment is still carried out based on distortion or low-precision sampling data, so that identification errors are further amplified. 2. The time domain extremum extraction has weak anti-interference capability and low feature extraction precision In the existing AC/DC identification and signal feature extraction scheme, a simple three-point method (comparing the sizes of the current point and two adjacent points) is mostly adopted for extracting the time domain extremum, and quantization burrs of ADC sampling are not optimized. The quantization step of the high-precision ADC (24 bits for example) is extremely small, tiny jitter of +/-1 to +/-3 quantization units is easy to occur near the vertex, the three-point method is extremely easy to misjudge the quantization burr as an extreme point, or the true extreme point is missed, and the extraction error of the maximum value and the minimum value of the signal is large. Although the frequency domain method (such as FFT/DFT) can avoid the extreme value jitter problem to a certain extent, the computational complexity is high, a large number of complex operations are involved, the realization circuit area is large, the chip power consumption is further increased, and the frequency domain method is difficult to be applied to real-time detection scenes of industrial sites. 3. The AC/DC identification logic is single, and the misjudgment rate is high The existing AC/DC signal identification scheme is mostly dependent on a single judgment dimension, namely whether the signal amplitude fluctuation (peak-to-peak value) is lower than a fixed threshold value or not, or whether the signal frequency deviates from a power frequency range or not. The single-dimension logic has the obvious defects that for low-amplitude alternating current signals (such as weak power frequency signals with peaks close to noise levels), the direct current signals are easily misjudged only by amplitude threshold values, and for direct current signals with larger ripples (such as ripple direct current output by a switching power supply), the direct current signals are easily misjudged only by frequency characteristics. Meanwhile, the influence of sampling quality on the identification result is not considered in the existing scheme, namely when the accuracy of the sampling data is low or distortion is caused by unreasonable gain configuration, the problem of misjudgment is further aggravated, and the identification accuracy is less than 80% in the scenes of low-voltage monitoring, weak signal acquisition and the like. 4. Sampling adaptation and AC/DC identification disjoint, system cooperativity difference In the prior art, signal sampling and AC/DC identification are rega