A robust frequency estimation technique based on three consecutive samples for single-phase systems

This paper proposes a robust technique for fundamental frequency estimation of a single-phase grid voltage waveform under distorted conditions. The technique consists of an improved algorithm based on three consecutive samples (3CSs) and a finite-impulse-response (FIR) filter. The technique can reject the negative effects caused by direct current (dc) offset, harmonics, notches, and spikes. It can also estimate the fundamental frequency for a wide range of variation, thus complying with the standard. Compared with a conventional technique based on 3CSs and an FIR filter, the proposed technique does not require setting a threshold value of the middle sample of 3CSs for removing the ill condition. Moreover, it is less affected by the dc offset, voltage sag, voltage flicker, notches, and spikes compared with the conventional technique. Simulation and real-time experimental results are presented to verify the robustness of the proposed technique.