全相位FFT算法高精度谐波测量方法

High precision harmonic measurement method based on all phase FFT algorithm

针对电力系统精确测量谐波信号频谱特性这一技术问题,该文提出一种基于全相位FFT算法的高精度谐波测量方法。通过低漂移信号转换电路和程控滤波器对被测信号进行调理,再经高精度A/D转换器变换成数字量传至MCU进行全相位FFT变换,选择离散频谱中幅值最大的两根谱线进行校正得到信号精确测量结果。利用LTspice电路与Matlab算法协同仿真,结果表明:在输入信号为理想谐波、复杂谐波与间谐波、叠加白噪声信号的基波情况下,所提出的方法均可实现对信号频率和幅值的准确测量。在与传统FFT双谱线校正和加窗FFT双谱线校正相比,该文提出的测量方法精度更高、抗噪性更好,频谱泄漏抑制能力更强,适用于对电力信号的高精度测量。

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.