A smart metering front-end optimization method and system

Abstract

This application discloses a method and system for optimizing the metering front end of a smart meter. The method includes: setting a near-linear phase anti-aliasing network at the front end of the metering channel and sampling synchronously; determining a range switching window based on zero crossover or a preset voltage change rate, performing automatic range switching within the window, and performing overlapping sampling and digital stitching on the samples before and after the switching; determining a rectification conduction gap based on rectification conduction prediction, pausing sampling within the gap, and compensating for missing samples; injecting a reference signal into the channel in a calibration injection window, obtaining a correction coefficient based on the response, and performing online correction; the above three types of windows do not overlap and are uniformly scheduled by synchronous timing; and completing power and energy calculations based on the corrected voltage and current sequences. The system includes units such as an anti-aliasing network, range control, rectification conduction detection and gap gating, injection and online correction, synchronous timing, and metering calculation. This invention can achieve low-distortion, wide-range, and consistent metering output in practical applications.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a method and system for optimizing the metering front end of a smart meter. Background Technology

[0002] The metering front end of a smart meter typically consists of a voltage channel and a current channel. The voltage channel, after voltage division and buffering, enters the anti-aliasing network and analog-to-digital converter (ADC). The current channel is sampled by a shunt, current transformer, and Hall effect device, and then enters the ADC after pre-amplification and the anti-aliasing network. The digital side calculates active power, reactive power, apparent power, and related harmonic parameters based on the synchronous sampling results. With the increase in distributed power sources, nonlinear loads, and low power factor operating conditions, the metering front end needs to maintain amplitude and phase accuracy over an extremely wide dynamic range, while suppressing the impact of power supply rectification, switching noise, surges, and temperature drift on the metering link.

[0003] Existing solutions often employ fixed or simple stepped range configurations and conventional anti-aliasing networks, correcting front-end errors through offline calibration. In engineering applications, the following problems easily arise: range switching often occurs at arbitrary times, introducing steps and phase abrupt changes during switching, leading to jumps in power and energy calculations; the phase response of conventional anti-aliasing networks is nonlinear, and combined with channel device errors, causes voltage and current phase mismatch, amplifying errors in low power factor and harmonic scenarios; the rectification and conduction of the internal power supply and ripple can couple to the metering chain via common-mode or differential-mode paths, disturbing critical sampling moments; offline calibration struggles to track long-term drift caused by temperature and aging; and the lack of unified timing orchestration for sampling, range switching, and calibration operations easily leads to mutual interference.

[0004] Therefore, it is necessary to propose a systematic optimization scheme for the metering front end to improve the accuracy, stability and maintainability of metering in complex power consumption environments. Summary of the Invention

[0005] The embodiments of this application provide a method and system for optimizing the metering front end of a smart meter to address the issues of metering accuracy and robustness in complex electricity usage environments.

[0006] To address the aforementioned technical problems, embodiments of this application disclose the following technical solutions: On one hand, a smart meter metering front-end optimization method is provided, comprising: setting a near-linear phase anti-aliasing network at the front end of the voltage and current channels to synchronously sample the anti-aliased voltage and current signals; determining a range switching window based on zero crossover or a preset voltage change rate, performing automatic range switching within the range switching window, and performing overlapping sampling and digital splicing before and after switching to avoid steps; determining a rectification conduction gap based on the rectification conduction prediction of the metering front end, pausing metering sampling within the rectification conduction gap and compensating for missing samples; injecting a reference signal into the voltage channel and / or the current channel within a calibration injection window, obtaining a correction coefficient based on the response of the reference signal, and performing online calibration of the metering channel based on the correction coefficient; performing metering calculations based on the corrected voltage and current signals to obtain metering results; wherein the range switching window, the rectification conduction gap, and the calibration injection window are all non-overlapping and are scheduled by a synchronous timing sequence.

[0007] Furthermore, the anti-aliasing network is a near-linear phase passive network, employing a T-type or equivalent structure, maintaining an approximately linear phase response within the measurement bandwidth, and the network's cutoff frequency is set to a range higher than the power frequency fundamental frequency but lower than the analog-to-digital conversion sampling Nyquist frequency, in order to reduce aliasing and decrease phase distortion.

[0008] Furthermore, the automatic range switching includes: pre-activating the input switch of the target range channel and maintaining continuous sampling of the current range channel at the start of the range switching; after the target range channel stabilizes, disconnecting the output switch of the current range channel and activating the output switch of the target range channel to form a transition zone, wherein the transition zone is the entirety or a sub-interval of the range switching window; within the transition zone, performing weighted splicing or minimum error splicing on the current range sample before switching and the target range sample after switching, so that the output waveform is continuous in amplitude and phase, thereby avoiding steps.

[0009] Furthermore, the rectification stage at the metering front end employs a full-wave rectifier branch composed of multiple low-junction-capacitance small-signal diodes to reduce capacitive coupling to the metering channel during the rectifier switching process. The determination of the rectifier conduction window includes: determining the half-cycle start point based on grid zero-crossing detection; establishing a conduction period estimation model by combining the conduction threshold of the small-signal diodes with the rising / falling slope of the energy storage capacitor voltage; or identifying the conduction interval by detecting the rising / falling edge of the conduction current of the rectifier branch or the peak and valley moments of the ripple voltage at the energy storage capacitor terminal. Based on the conduction interval, a gate signal corresponding one-to-one with its start and end times is generated to control the suspension of metering sampling within the interval and the resumption of sampling outside the interval.

[0010] Furthermore, the injected amplitude of the reference signal is no higher than one percent of the rated amplitude of the metering signal, and the frequency selection avoids the main frequency point of the metering calculation and its integer multiples; the online correction includes: calculating the gain ratio and phase difference of the injected channel output relative to the reference signal, obtaining the amplitude correction coefficient and phase correction coefficient respectively, and triggering an update when the temperature change exceeds the preset temperature threshold or the load condition change exceeds the preset load threshold.

[0011] Furthermore, the synchronous timing scheduling arranges the start and end times of the range switching window, the rectifier conduction window and the calibration injection window in each power grid cycle based on the power grid frequency estimation, ensuring that the three types of windows do not overlap. The range switching window is preferentially placed near the voltage zero crossing or in the range where the voltage change rate is lower than the preset voltage change rate. A minimum time safety interval is set between the calibration injection window and the rectifier conduction window to avoid mutual interference.

[0012] Furthermore, the compensation for missing samples includes: within the effective sampling interval before and after the rectification conduction window, using interpolation or fitting extrapolation based on the time and amplitude relationship of adjacent samples to recover the missing samples, and using the compensated continuous sequence in the measurement calculation.

[0013] Furthermore, the current channel adopts a four-terminal sampling structure to reduce the error introduced by wiring voltage drop, and the temperature coefficient of the shunt is compensated by temperature measurement in the metering calculation to reduce the linear error under high current and temperature rise conditions.

[0014] Furthermore, the metering calculation includes calculating active power, reactive power, apparent power, and power factor based on synchronously sampled voltage and current signals, and completing energy accumulation and power index output after applying the correction coefficient.

[0015] On the other hand, a smart meter metering front-end optimization system is provided, comprising: a near-linear phase anti-aliasing network configured at the front end of the voltage and current channels; a range control unit for performing range switching and overlapping sampling and digital splicing in intervals with zero crossover or voltage change rate lower than a preset voltage change rate; a rectifier conduction detection and window gating unit for electrically connecting to a rectifier branch composed of a low junction capacitance small-signal diode array, identifying conduction intervals based on the conduction current of the rectifier branch or the ripple voltage at the energy storage capacitor end, and outputting a gating signal corresponding to the interval to pause sampling and trigger missing sample compensation; an injection and online calibration unit for injecting reference signals into the calibration injection window and calculating amplitude and phase correction coefficients; a synchronization timing unit for scheduling the range switching window, rectifier conduction window, and calibration injection window in each power grid cycle; and a metering calculation unit for calculating and outputting metering results.

[0016] The above-mentioned technical solutions have at least the following beneficial effects: By using a near-linear phase anti-aliasing network and implementing synchronous sampling at the front end of the voltage and current channels, automatic range switching is completed within the zero-crossing or low voltage change rate window, and output continuity is ensured by overlapping sampling and digital splicing; a sampling window is set within the predicted rectification conduction interval and missing samples are compensated; a reference signal is injected into the channel through a dedicated calibration injection window and the amplitude and phase correction coefficients are calculated in real time; finally, the three types of windows are scheduled non-overlapping in each power grid cycle with a unified synchronous timing sequence; through the collaborative mechanism, on the one hand, the disturbance of range switching and power supply rectification to key sampling moments is significantly reduced, and output steps and phase changes are eliminated; on the other hand, online tracking and correction of front-end errors are achieved without affecting the continuity of metering, thereby improving the consistency and stability of active power, reactive power, apparent power, and energy metering in wide dynamic range, low power factor, and harmonic scenarios.

[0017] The above-mentioned technical solutions also have the following advantages: the near-linear phase anti-aliasing network significantly reduces phase distortion within the metering bandwidth, reducing the impact of phase mismatch between channels on power calculation; range switching triggered by zero-crossing or low voltage change rate windows, combined with overlapping sampling and digital stitching, ensures continuity of amplitude and phase before and after switching, avoiding energy calculation errors caused by range jumps; the sampling window and missing sample compensation in the rectifier conduction interval suppress the transient interference of rectifier switch noise and ripple on the metering chain, balancing interference immunity and data integrity; reference injection and online calibration enable adaptive tracking of amplitude and phase errors, reducing long-term deviations caused by temperature and aging drift; synchronous timing scheduling ensures that the range switching window, rectifier conduction window, and calibration injection window do not overlap, avoiding cross-influence between windows, and comprehensively improving the anti-interference capability, accuracy maintenance capability, and engineering feasibility of the metering front end. Attached Figure Description

[0018] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0019] Figure 1 A schematic diagram of an exemplary smart meter metering front-end optimization method provided in this application.

[0020] Figure 2 A block diagram of an exemplary smart meter metering front-end optimization system provided in this application.

[0021] Figure 3 This is a schematic diagram of the range switching window and overlapping sampling provided in this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this application. It should be understood that the specific embodiments described in this specification are merely for explaining this application and are not intended to limit it.

[0023] In the description of this application, it should be noted that the terms "first," "second," etc., used in the specification and claims are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such designations can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, meaning that a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those explicitly listed, but may also include other steps or units not explicitly listed or inherent to the process, method, system, product, or apparatus. In this document, "used for" indicates the configuration and capability to implement the described function, but does not limit the specific implementation form; "and / or" is used to indicate a parallel relationship, and can mean "and", "or", or any combination of "and / or"; the order of the method steps described does not constitute a restriction on the actual execution order without affecting the technical logic; terms such as "module", "unit", and "device" can be implemented by hardware, software, or a combination of hardware and software, and their deployment location can be within the same device or distributed among different devices. The terms "installation", "connection", and "linking" should be interpreted broadly, for example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections, direct connections, or indirect connections through an intermediate medium; they can be the internal connection of two components or the interaction relationship between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0024] In the description of this application, "smart meter metering front end" refers to the analog and interface circuits directly related to voltage and current signal measurement, as well as their supporting synchronous sampling, window scheduling, and digital correction logic, excluding upper-level business functions not directly related to settlement and communication. "Voltage channel" and "current channel" refer to the links that convert the measured grid voltage and current into sampleable electrical signals, typically including voltage dividers or sensing elements, buffers / amplifiers, and anti-aliasing networks, and working in conjunction with analog-to-digital converters. "Anti-aliasing network" refers to a front-end filtering network that suppresses spectral components higher than the target bandwidth before sampling to reduce aliasing errors. "Near-linear phase" indicates that the phase-frequency relationship within the metering bandwidth is approximately linear, thereby reducing phase distortion introduced by filtering; this application may use a T-type or equivalent topology as an implementation method, but is not limited to this. "Synchronous sampling" refers to the simultaneous or equivalent simultaneous acquisition of voltage and current channels under a unified time base, ensuring the timing consistency of power calculation. "Zero crossing" refers to the instantaneous crossing of the voltage waveform across the reference zero level; "voltage change rate" refers to the rate of voltage change per unit time (dV / dt). "Range" refers to the programmable range of channel gain or voltage division ratio; "Automatic Range Switching" refers to switching between different ranges based on the input amplitude to expand the dynamic range; "Overlap Sampling and Digital Stitching" refers to simultaneously retaining valid samples of the old and new ranges for a short period before and after switching, and forming a continuous output in the digital domain through weighted or error minimization; "Step" indicates that there is a step change in amplitude and phase of the output waveform after switching. "Rectifier On-Conduction Prediction" refers to timing estimation of the conduction interval of devices in the power supply rectification stage of the metering front end; "Interpolation or Fitting Extrapolation Compensation" refers to recovering missing samples based on valid samples before and after the gap using interpolation or fitting methods to form a continuous metering sequence.

[0025] In the description of this application, "Kelvin four-terminal sampling" refers to a four-terminal connection method where current and voltage sampling leads are respectively set at both ends of the shunt, in order to reduce the influence of wire and solder joint resistance on voltage measurement and improve current measurement accuracy. "Per grid cycle" or "grid cycle" refers to a time interval with the grid fundamental frequency as the period (e.g., one cycle corresponding to 50Hz or 60Hz). "Metering calculation" and "metering results" refer to indicators such as active power, reactive power, apparent power, power factor, and energy accumulation calculated based on the voltage and current signals obtained by synchronous sampling. The specific scope can be described in the embodiments according to the standard or implementation selection.

[0026] The term "nearby" as used in this application refers to the neighborhood surrounding a reference point, reference time, reference frequency, or reference location, and does not require precise overlap with the reference quantity; it is a non-limiting term. Unless otherwise explicitly defined, the range of "nearby" can be determined by system parameters or control resolution, and can be represented as a time window, a range window, or a spatial window. For example, "near zero crossover" can be understood as a bounded time window centered on the zero crossover moment and defined by a voltage threshold or a voltage change rate threshold; "near a low voltage change rate" can be understood as an interval where |dV / dt| is lower than a preset threshold; the specific width of "nearby" can be set by a threshold, a ratio, or a number of sampling periods, but is not limited thereto.

[0027] Unless otherwise specified in the context, the terms used above shall be interpreted as those defined in this section; terms not mentioned in this section but commonly used in the field shall be interpreted as those generally accepted in the field.

[0028] In smart meters, the metering front end needs to simultaneously acquire voltage and current signals and participate in the calculation of parameters such as active power, reactive power, and apparent power. However, common problems in engineering sites include: large measurement ranges leading to amplified front-end errors or voltage divider networks being prone to step and phase abrupt changes during switching; traditional anti-aliasing networks exhibiting significant phase distortion within the target bandwidth, affecting power accuracy under low power factor conditions; the auxiliary power supply rectifier devices in the meter coupling common-mode or differential-mode interference to the metering link at the moment of conduction, causing synchronous sampling jitter; and device temperature drift and aging causing amplitude and phase errors to drift over time. The combination of these factors makes it difficult for existing solutions to maintain stable metering accuracy and consistency in the long term under complex power grid environments with light and heavy load switching and rectifier ripple and harmonics.

[0029] To address this, this application proposes a smart meter metering front-end optimization method and system. Near-linear phase anti-aliasing networks are configured at the voltage and current channel front-ends, and synchronous sampling is implemented. Range switching windows are determined based on zero crossover or low voltage change rate, and automatic range switching is performed within these windows. Overlapping sampling and digital splicing before and after switching ensure continuous output and avoid step-like fluctuations. A rectification conduction window is set based on the prediction of the rectification conduction period, during which critical sampling is paused and missing samples are compensated, reducing power supply and metering coupling. A reference signal is injected into the channel through a calibration injection window, and the channel response is extracted to obtain amplitude and phase correction coefficients for online correction. The aforementioned range switching window, rectification conduction window, and calibration injection window are scheduled synchronously within each power grid cycle and do not overlap. Through systematic metering front-end optimization, amplitude and phase errors and coupling noise can be significantly reduced in wide dynamic range and complex harmonic / ripple environments, improving the accuracy, stability, and traceability of power and energy metering.

[0030] Figure 1 A schematic diagram illustrating an exemplary smart meter metering front-end optimization method provided in this application. Figure 1 As shown, the exemplary metering front-end optimization method provided in this application includes the following steps: S1, setting a near-linear phase anti-aliasing network at the front end of the voltage and current channels to synchronously sample the anti-aliased voltage and current signals; S2, determining a range switching window based on zero crossover or a preset voltage change rate, performing automatic range switching within the range switching window, and performing overlapping sampling and digital splicing before and after switching to avoid steps; S3, determining a rectification conduction gap based on the rectification conduction prediction of the metering front end, pausing metering sampling within the rectification conduction gap, and compensating for missing samples; S4, injecting a reference signal into the voltage channel and / or the current channel within the calibration injection window, obtaining a correction coefficient based on the response of the reference signal, and performing online calibration of the metering channel based on the correction coefficient; S5, performing metering calculations based on the corrected voltage and current signals to obtain the metering result. In the above steps, the range switching window, the rectification conduction gap, and the calibration injection window do not overlap and are scheduled by synchronous timing.

[0031] Figure 2 A block diagram of an exemplary smart meter metering front-end optimization system provided in this application. Figure 2 As shown, the exemplary smart meter metering front-end optimization system 100 provided in this application includes: a near-linear phase anti-aliasing network 101 configured at the front end of the voltage channel 11 and the current channel 12; a range control unit 102, used to perform range switching and overlap sampling and digital splicing in the range of zero crossover or voltage change rate lower than the preset voltage change rate; a rectifier conduction detection and window gating unit 103, used to be electrically connected to the rectifier branch 20 composed of a low junction capacitance small signal diode array, identify the conduction range based on the conduction current of the rectifier branch 20 or the ripple voltage at the energy storage capacitor end, and output a gating signal corresponding to the range to pause sampling and trigger missing sample compensation; an injection and online correction unit 104, used to inject a reference signal in the calibration injection window and calculate the amplitude and phase correction coefficients; a synchronization timing unit 105, used to schedule the range switching window, rectifier conduction window and calibration injection window in each power grid cycle; and a metering calculation unit 106, used to calculate and output the metering results of the metering channel 10.

[0032] Combination Figure 1 and Figure 2The detailed process of the exemplary smart meter metering front-end optimization method provided in this application is as follows. First, in the sampling preparation of metering channel 10, a near-linear phase anti-aliasing network 101 is introduced at the front end of voltage channel 11 and current channel 12 to perform bandwidth constraint and phase shaping on the analog signal entering the analog-to-digital conversion, so that the phase response of the power frequency and its effective band is basically consistent, thereby reducing the amplitude and phase distortion caused by the front-end network. The cutoff frequency of the anti-aliasing network 101 is set to be higher than the fundamental frequency of the power frequency and lower than the Nyquist frequency of the analog-to-digital conversion, so as to suppress aliasing and control the phase distortion within the band. The voltage and current paths are sampled synchronously under the same sampling clock. The clock source is managed by the synchronization timing unit 105 to ensure that the two channels are time-aligned at each sampling moment, providing a consistent time reference for subsequent power synthesis and harmonic analysis.

[0033] The synchronization timing unit 105 establishes a timeline plan for the power grid cycle based on power grid zero-crossing detection or frequency estimation. Near zero-crossing or in areas where the voltage change rate is lower than a preset voltage change rate, it triggers the range control unit 102 to open the input branch of the target range channel, allowing it to enter the stable region ahead of time. Simultaneously, it maintains continuous sampling of the current range channel, switching the output branch to the target range only after the target range stabilizes. Both ranges are simultaneously acquired in the transition region. The digital side performs weighted splicing or minimum error splicing on the overlapping samples, ensuring the waveforms before and after the switch are continuous in amplitude and phase, fundamentally avoiding the steps and instantaneous phase jumps caused by range switching.

[0034] Figure 3 This application provides a schematic diagram of the range switching window and overlapping sampling. Based on the above overlapping sampling process, this application provides an exemplary voltage signal curve for an overlapping sampling process, such as... Figure 3 As shown, for voltage signal sampling, three different ranges, A, B, and C, are provided. Range B can measure the largest voltage amplitude, exceeding v3; range C can measure the smallest voltage amplitude, with an accuracy of v1; and range A can measure a voltage amplitude in the middle, v2. When the current range channel corresponds to range A, the range control unit 102, based on the planning of the synchronization timing unit 105, opens the input branch of the target range channel in advance at point t1 near the zero-crossing point, i.e., the corresponding... Figure 3The start time for range B is t1. Simultaneously, the range channel corresponding to range A is maintained as the effective output of the ADC. When the range channel of range B stabilizes, i.e., at time t2, the output switch of the range channel corresponding to range A is disconnected, and the output switch of the range channel corresponding to range B is turned on, forming a transition region [t1, t2]. Within this transition region, weighted splicing or minimum error splicing is performed on the samples before and after switching from range A to range B, ensuring the output waveform is continuous in amplitude and phase, thus avoiding step-like transitions. Similarly, during the overlapping sampling process from range B to range C, the transition region is [t3, t4], which will not be elaborated further. In this embodiment, the range switching window planned by the synchronization timing unit 105 is determined by zero-crossing detection. In other embodiments, it can also be determined based on whether the voltage change rate is less than a preset voltage change rate, i.e., a low voltage change rate is required as the range switching criterion. In this embodiment, the range switching window is equivalent to the transition zone; in other embodiments, the range switching window may also include a time margin for stability, and the transition zone is a sub-interval used for overlapping sampling and splicing. Digital splicing is performed on the two simultaneously acquired sequences within the transition zone. Taking the aforementioned transition zone [t1, t2] as an example, the weight function w[n] is monotonically transitioned from 0 to 1 within [t1, t2] (it can be a linear or Hanning window), and the output y[n] = (1-w[n])·y_old[n] + w[n]·y_new[n], where y_old[n] is the output of the current range channel, and y_new[n] is the output of the target range channel; or, the two channels are first fitted with least squares to ensure amplitude alignment before splicing, thereby guaranteeing the continuity of the waveform in amplitude and phase before and after switching, avoiding steps and instantaneous phase jumps. In addition, in the current measurement path, in order to reduce the impact of wiring voltage drop on the measurement results, the current channel 12 adopts a Kelvin four-terminal sampling structure to detect the voltage of the shunt. The measurement lead is separated from the current-carrying lead to reduce the system error caused by parasitic resistance. At the same time, the operating temperature of the shunt is obtained by combining the temperature sensor, and the resistance value is compensated according to the calibrated temperature coefficient to maintain the linearity of the meter under high current and temperature rise conditions.

[0035] To reduce crosstalk to the measurement link during the rectification process of the metering power supply, the rectifier branch 20 is composed of a small-signal diode array with low junction capacitance. The rectifier continuity detection and window gating unit 103 identifies the conduction interval within each half-cycle by monitoring the rectifier branch current or the ripple voltage at the energy storage capacitor terminal. When no sensor monitoring is configured, the interval boundary can also be obtained by establishing an equivalent conduction model based on the zero-crossing time, device threshold, and energy storage capacitor discharge curve. The identification result is converted into a gating signal, pausing key metering sampling within the conduction interval and resuming sampling outside the interval. To avoid energy deviation caused by the pause in sampling, the digital post-processing stage interpolates or fits extrapolates the effective samples before and after the window according to the relationship between time and amplitude, replenishing the missing samples, so that the sequence participating in the metering calculation is continuous in time and has no significant bias in energy.

[0036] In a time slice that does not overlap with the aforementioned window, the synchronization timing unit 105 triggers the injection and online correction unit 104 to couple a small-amplitude reference signal to the voltage channel 11 and / or the current channel 12. The frequency of the reference signal avoids the fundamental frequency and its integer multiples, and the amplitude is controlled to a very small proportion of the rated metering amplitude, so as not to affect normal metering. On the digital side, using the injected signal as a reference, the gain ratio and phase difference of the injected channel relative to the reference are calculated to obtain the online correction coefficients for amplitude and phase. When the temperature or load condition changes to a preset load threshold, the coefficients are automatically refreshed to achieve adaptive compensation for long-term drift caused by operational amplifier offset, device temperature drift, and aging. The correction coefficients correct the voltage and current data obtained by synchronous sampling in real time in the digital domain, and together with the fixed phase characteristics of the anti-aliasing network 101, ensure the phase and amplitude matching of the two signals.

[0037] After the three types of windows—range switching, rectifier conduction window, and calibration injection—are arranged non-overlapping within each power grid cycle by the synchronization timing unit 105, the metering calculation unit 106 performs power and energy calculations on the corrected voltage and current sequences according to the same time base, outputting active power, reactive power, apparent power, power factor, and harmonic indicators as needed. In this process, front-end anti-aliasing and phase shaping ensure frequency domain consistency, overlapping sampling and digital stitching guarantee waveform continuity across ranges, rectifier conduction window and missing sample compensation suppress coupling interference from power supply rectification to the measurement, and online calibration via reference injection continuously calibrates amplitude and phase errors. Each unit is driven by the same timing framework, thereby achieving low-distortion, wide dynamic range, and high-consistency output from the metering front-end under engineering conditions.

[0038] In summary, the smart meter metering front-end optimization scheme proposed in this application optimizes the metering front-end by configuring a near-linear phase anti-aliasing network 101 at the front end of the voltage channel 11 and the current channel 12 and implementing synchronous sampling. It performs automatic range switching with overlapping sampling and digital splicing in the zero-crossing or low voltage change rate range. Based on the conduction identification or prediction of the rectifier branch 20, it sets a rectifier conduction window and compensates for missing samples. Reference signals are injected into the metering channel within time slices that do not overlap with the aforementioned window to obtain amplitude and phase correction coefficients for online correction. Furthermore, a unified synchronous timing sequence schedules the range switching window, the rectifier conduction window, and the calibration injection window. At the system level, it employs a low-junction capacitance small-signal diode array or an equivalent low-coupling rectifier structure, timing gating, and digital compensation to achieve coordinated decoupling and error self-correction between the power supply and measurement chains. This solution can significantly reduce front-end phase amplitude distortion and rectification coupling noise while ensuring consistency of source and caliber. It avoids range switching steps and instantaneous phase jumps, expands the dynamic range, and improves the accuracy and stability of active power, reactive power, apparent power and energy measurement under low power factor and harmonic conditions. It also takes into account the robustness and maintainability of engineering implementation.

[0039] The embodiments provided above are merely illustrative of the methods, systems, and core ideas of this application. Those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A method for optimizing the metering front end of a smart meter, characterized in that, include: Near-linear phase anti-aliasing networks are set at the front end of the voltage and current channels to synchronously sample the anti-aliased voltage and current signals. The range switching window is determined based on zero crossover or a preset voltage change rate. Automatic range switching is performed within the range switching window, and overlapping sampling and digital stitching are performed before and after the switching to avoid steps. The rectifier stage at the metering front end uses a full-wave rectifier branch composed of multiple low-junction capacitance small-signal diodes to reduce capacitive coupling of the metering channel during the rectifier switching process. Determining the rectification conduction window based on the rectification conduction prediction of the metering front end includes: determining the half-cycle start point based on grid zero-crossing detection; establishing a conduction period estimation model by combining the conduction threshold of the small-signal diode and the rising / falling slope of the energy storage capacitor voltage; or identifying the conduction interval by detecting the rising / falling edge of the conduction current of the rectifier branch or the peak and valley moments of the ripple voltage at the energy storage capacitor terminal; generating a gate signal corresponding one-to-one with the start and end times of the conduction interval to control the suspension of metering sampling within the interval and the resumption of sampling outside the interval; suspending metering sampling within the rectification conduction window and processing missing samples. Compensation is performed; a reference signal is injected into the voltage channel and / or the current channel within the calibration injection window, and a correction coefficient is obtained based on the response of the reference signal. The metering channel is then calibrated online based on the correction coefficient. Metering calculations are performed based on the calibrated voltage and current signals to obtain the metering results. The range switching window, the rectifier conduction window, and the calibration injection window do not overlap and are scheduled by a synchronous timing sequence. The synchronous timing sequence schedules the start and end times of the range switching window, the rectifier conduction window, and the calibration injection window within each power grid cycle based on the power grid frequency estimate.

2. The smart meter metering front-end optimization method as described in claim 1, characterized in that, The anti-aliasing network is a near-linear phase passive network with a T-type or equivalent structure. The phase response within the measurement bandwidth remains approximately linear, and the cutoff frequency of the network is set to be higher than the fundamental power frequency but lower than the Nyquist sampling frequency of the analog-to-digital conversion, in order to reduce aliasing and decrease phase distortion.

3. The smart meter metering front-end optimization method as described in claim 1, characterized in that, The automatic range switching includes: at the start of the range switching, pre-connecting the input switch of the target range channel and maintaining continuous sampling of the current range channel; after the target range channel stabilizes, disconnecting the output switch of the current range channel and connecting the output switch of the target range channel to form a transition zone, wherein the transition zone is the entirety or a sub-interval of the range switching window; within the transition zone, performing weighted splicing or minimum error splicing on the current range sample before switching and the target range sample after switching, so that the output waveform is continuous in amplitude and phase, thereby avoiding steps.

4. The smart meter metering front-end optimization method as described in claim 1, characterized in that, The injected amplitude of the reference signal is no higher than one percent of the rated amplitude of the metering signal, and the frequency selection avoids the main frequency point of the metering calculation and its integer multiples; the online correction includes: calculating the gain ratio and phase difference of the injected channel output relative to the reference signal, obtaining the amplitude correction coefficient and phase correction coefficient respectively, and triggering an update when the temperature change exceeds the preset temperature threshold or the load condition change exceeds the preset load threshold.

5. The smart meter metering front-end optimization method as described in claim 1, characterized in that, The range switching window should be placed near the zero voltage crossover or in the range where the voltage change rate is lower than the preset voltage change rate. A minimum time safety interval should be set between the calibration injection window and the rectification conduction window to avoid mutual interference.

6. The smart meter metering front-end optimization method as described in claim 1, characterized in that, The compensation for missing samples includes: within the effective sampling interval before and after the rectification conduction window, using interpolation or fitting extrapolation based on the time and amplitude relationship of adjacent samples to recover the missing samples, and using the compensated continuous sequence in the measurement calculation.

7. The smart meter metering front-end optimization method as described in claim 1, characterized in that, The current channel adopts a four-terminal sampling structure to reduce the error introduced by wiring voltage drop, and the temperature coefficient of the shunt is compensated by temperature measurement in the metering calculation to reduce the linear error under high current and temperature rise conditions.

8. The smart meter metering front-end optimization method as described in claim 1, characterized in that, The metering calculation includes calculating active power, reactive power, apparent power, and power factor based on synchronously sampled voltage and current signals, and completing energy accumulation and power index output after applying the correction coefficient.

9. A smart meter metering front-end optimization system, characterized in that, include: Near-linear phase anti-aliasing networks configured at the front ends of the voltage and current paths; The range control unit is used to switch the range and perform overlapping sampling and digital stitching in the range of zero crossover or voltage change rate lower than the preset voltage change rate; the rectifier conduction detection and gap gating unit is used to be electrically connected to the rectifier branch composed of a low junction capacitance small signal diode array, identify the conduction interval based on the conduction current of the rectifier branch or the ripple voltage at the energy storage capacitor end, and output a gating signal corresponding to the interval to pause sampling and trigger missing sample compensation. An injection and online correction unit is used to inject a reference signal into the calibration injection window and calculate the amplitude and phase correction coefficients; The synchronous timing unit is used to schedule the range switching window, the rectifier conduction window, and the calibration injection window within each power grid cycle; The measurement calculation unit is used to calculate and output measurement results.

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