基于全相位谱线插值的电力谐波检测方法研究

传统基于FFT的谐波检测方法在非同步采样或非整周期截断情况下会产生严重的频谱泄漏,为抑制频谱泄漏对谐波检测精度的影响,提出基于全相位谱线插值的电力谐波检测新方法.该方法使用全相位谱实际频点附近的三根离散谱线获得频率和幅值校正量,并利用离散全相位谱峰值谱线相位即为对应的实际频率相位的特点,无需另加校正即可实现较高的相位精度.利用全相位谱旁谱线相对于主谱线按平方衰减的特性,并结合旁瓣衰减速度快的Nuttall四项五阶余弦窗,可有效抑制基于FFT谱线插值算法相邻谐波成分的相互干扰,提高谐波检测精度.通过与三谱线插值法和全相位时移相位差法的仿真对比实验,结果表明文中提出的算法具有更好的谐波检测精度.

Detection method of harmonics in power system based on spectrum interpolation of apFFT

Aiming at the suppression of spectral leakage caused by non-synchronized sampling or non-integral period truncationin FFT-based harmonics detection method, this paper proposed a new harmonics detection method based on spectrum interpolation of apFFT (all-phase FFT). Three discrete spectral lines near the real frequency component was used to correct the frequency and amplitude of power harmonic. By this method, it is not necessary to perform the harmonic phase correction because the peak spectral line phase of discrete apFFT spectrum was just in correspondence with the actual phase of harmonic component. On the basis of the square attenuation characteristics of the main lines in the apFFT spectrum and the fast sidelobe attenuation characteristics of Nuttall window, the interference between adjacent harmonic components in FFT spectral line was effectively suppressed,resulting in the improvement of harmonics detection accuracy. The simulation results verified that the proposed method performed better than the Triple-spectrum-line Interpolation method and all-phase time-shifting phase difference method.