High precision harmonic measurement method based on all phase FFT algorithm
Aiming at the technical problem of accurately measuring the spectrum characteristics of harmonic signals in power systems,this paper proposes a high-precision harmonic measurement method based on all phase FFT algorithm.The measured signal is conditioned by a low drift signal conversion circuit and a programmable filter,and then converted into a digital quantity by a high-precision A/D converter and transmitted to MCU for all phase FFT transformation.Two spectral lines with the largest amplitude in the discrete spectrum are selected for correction to obtain accurate signal measurement results.Using LTspice circuit and Matlab algorithm,the results show that the proposed method can achieve accurate measurement of signal frequency and amplitude when the input signal is ideal harmonic,complex harmonic and interharmonic,and the fundamental wave of superimposed white noise signal.Compared with the traditional FFT bispectral line correction and windowed FFT bispectral line correction,the measurement method proposed in this paper has higher accuracy,better noise resistance,stronger spectrum leakage suppression ability,and is suitable for high-precision measurement of power signals.
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