Measurements of power system nominal voltage, frequency and voltage flicker parameters

We present, in this paper, an approach for measuring the frequency and amplitude of voltage signal in the presence of voltage flicker as well as the flicker parameters; flicker amplitude and frequency. The proposed algorithm performs the estimation in two steps; while in the first step the voltage signal is shifted forward and backward by an integer number of samples, one sample in this paper. The new generated signal from such shift together with the original one are used to estimate the amplitude of the voltage signal that composed of the nominal voltage and flicker voltage. Averaging this amplitude produces the amplitude of the nominal voltage; this amplitude is subtracted from the original identified signal amplitude to obtain the samples of the flicker voltage. In the second step, the argument of the signal is calculated by simply dividing the magnitude of signal samples with the estimated amplitude in the first step. Calculating the arccosine of the argument, the frequency of the nominal signal as well as the phase angle can be calculated using the least error square estimation algorithm. Simulation examples are given within the text to show the features of the proposed approach.