Active power estimation by averaging of the DFT coefficients

The paper proposes and discusses an algorithm to improve the estimation of the active power of electrical systems under incoherent sampling. It is based on smoothing sampled data by windowing, prior to their numeric integration, and then averaging the DFT (discrete Fourier transform) coefficients in the frequency domain to reduce the leakage effects. The simulation and experimental results are presented showing that averaging of DFT coefficients provides better estimation of the active power than by windowing. The spectrum of the used window must have a sine function in the kernel. The use of a suitable algorithm depends on a number of observed periods, on positions of the frequency components, and on signal to noise ratio.