An Error Demodulation Technique for Single-Phase Grid Synchronization/LVRT Applications

This paper proposes a nonadaptive error demodulation technique with which to track the amplitude, the phase and the frequency information of the grid voltage for single-phase applications. A nonadaptive comb filter, Lyapunov’s estimation law, and half-cycle moving average filters are exploited in order to reconstruct the fundamental orthogonal components. The proposed nonadaptive Lyapunov filter has good bandpass filtering characteristics, thus allowing the rapid rejection of the dc-offset and the harmonics. The proposed open-loop phase angle deviation algorithm is, moreover, a rescuer as regards estimating the fundamental frequency deviation, signifying that it correctly compensates the estimated amplitude and the phase angle information through the use of a mathematical regression approach under off-nominal frequency conditions.