Wideband harmonic scene-based high-precision ac sampling method for low-voltage power grid

By capturing the rising edge of the grid voltage in a low-voltage grid to calculate the true cycle length, configuring the sampling time interval and performing hardware calibration, the problem of misalignment between the sampling point and the grid cycle in broadband harmonic scenarios is solved. This achieves high-precision synchronous signal acquisition and distortion elimination, satisfies the Nyquist sampling theorem, and improves the stability and accuracy of the sampling system.

CN122259944APending Publication Date: 2026-06-23STATE GRID SHANGHAI MUNICIPAL ELECTRIC POWER CO
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Patent Information

Authority / Receiving Office
CN Β· China
Patent Type
Applications(China)
Current Assignee / Owner
STATE GRID SHANGHAI MUNICIPAL ELECTRIC POWER CO
Filing Date
2026-05-21
Publication Date
2026-06-23

AI Technical Summary

Technical Problem

Existing low-voltage power grid AC sampling methods cannot adapt to the dynamic fluctuations of the actual power grid cycle in broadband harmonic scenarios, resulting in misalignment between sampling points and the power grid cycle, reduced accuracy of signal synchronization acquisition, amplification errors due to uncalibrated hardware parameters, and mismatch between sampling timing and the actual power grid cycle, leading to prominent sampling distortion problems.

Method used

The rising edge of the grid voltage is captured by a zero-crossing comparator circuit, the true period length is calculated, the sampling time interval is configured according to the true period, hardware parameter calibration and environmental monitoring are performed, a dynamic compensation parameter set is generated, the sampling process is corrected in real time, and signal reconstruction is performed by applying fast Fourier transform and digital filtering techniques.

Benefits of technology

It achieves high-precision synchronous acquisition of voltage and current signals in broadband harmonic scenarios, eliminates period deviation, optimizes the hardware foundation of signal acquisition, reduces sampling signal distortion, satisfies the Nyquist sampling theorem, and improves the accuracy and stability of the sampling system.

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Abstract

This invention relates to the field of low-voltage power grid sampling technology, specifically a high-precision AC sampling method for low-voltage power grids in broadband harmonic scenarios. The method includes: after the sampling system starts, completing hardware initialization calibration, configuring the reference frequency of the real-time clock, setting the full-scale reference voltage of the analog-to-digital converter, and setting the gain coefficients of the secondary signal input channels of the voltage and current transformers; converting the original AC voltage into a square wave of the same frequency through a zero-crossing comparator circuit, capturing the rising edge time using a real-time clock counter, and calculating the true period of the power grid voltage; dividing the true period equally according to a preset number of sampling points per period to obtain the sampling interval; configuring a programmable timer to trigger the analog-to-digital converter to synchronously acquire the secondary signals of the voltage and current transformers via a timer interrupt to obtain the original sampling sequence. This method can match the actual period of the power grid, improving the sampling accuracy and signal synchronization under broadband harmonics.
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