A revised interpolated DFT is proposed to estimate the harmonic parameters accurately. Firstly, a 4-order Hann self-convolving window is employed to restrain the interferences caused by spectral leakage and sidelobes. The corresponding error can be restrained at a degree of 10⁻¹⁵ theoretically. Then, an equidistant two-point interpolated formula is proposed to deal with the picket-fence effect. It avoids the systematic error caused by the polynomial fitting in common interpolation method. For estimating precision, the theoretical relative errors of harmonic parameters would approximate 10⁻¹¹. The relative frequency error of the fundamental wave is about 10⁻⁷ in a 50-dB-noise environment. Moreover, in a 20-dB-noise background, the signal reconstructed could reduce the variances to 0.001 of its own, which is feasible and useful in practical harmonic detection.

中文翻译：

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基于Hann自卷积窗和等距两点插值DFT的电力系统谐波参数在线估计

提出了一种修正的插值DFT来准确估计谐波参数。首先，采用4阶Hann自卷积窗来抑制由频谱泄漏和旁瓣引起的干扰。理论上，相应的误差可以限制在10 ^-15度。然后，提出了等距两点插值公式来处理栅栏效应。避免了普通插值法中多项式拟合引起的系统误差。为了估计精度，谐波参数的理论相对误差将接近10 ^-11。基波的相对频率误差约为10 ^-7在50 dB的噪声环境中。此外，在20 dB噪声的背景下，重建的信号可以将方差减小到其自身的0.001，这在实际的谐波检测中是可行且有用的。