Noise Analysis of Power System Frequency Estimated From Angle Difference of Discrete Fourier Transform Coefficient

The frequency deviation of an electric power system is a reflection of its operating state. This frequency deviation can be estimated from angle variations of the discrete Fourier transform coefficient of the positive fundamental frequency. Most errors of the frequency estimate can arise from noise in the power system signal and the leakage effect of the negative fundamental frequency. This paper analyzes errors of the frequency estimates and the measured angle variations due to the noise. Their means and variances are derived theoretically with respect to signal-to-noise ratios and verified and analyzed through simulations.