Nonrecursive methods for real-time determination of basic waveforms of voltages and currents

Using the Fourier technique, Kalman filter theory and Walsh functions, nonrecursive algorithms for online determination of basic waveforms of signals are introduced, investigated and compared. The Fourier algorithms very efficiently reject the higher harmonics. For nonharmonic random noise of higher frequencies the new nonrecursive algorithms based on the Kalman filter theory have better filter properties than Fourier ones. The Walsh methods are very simple for computer implementation, but their filter properties are not very convenient, especially for the odd harmonics.