Grid synchronisation technique without using trigonometric functions for accurate estimation of fundamental voltage parameters

Abstract

This study proposes a single-phase grid voltage synchronisation technique combining a quadrature signal generator and a frequency estimator to avoid the use of the computationally demanding trigonometric functions of a conventional phase-locked loop. The quadrature signal generator consists of an anticonjugate decomposition process and a cascaded delayed signal cancellation (ACDSC) strategy. The technique can provide accurate estimation of the fundamental voltage amplitude, frequency and phase angle, and can also reject the negative effects caused by the presence of DC offset and harmonics. When compared with a phase-locked loop based on the ACDSC, the proposed technique avoids the evaluation of the trigonometric functions, removes the phase loop, thus does not require tuning of loop filter, and also provides comparable estimation accuracy and dynamics. Simulation and experimental results are provided to verify the performance of the proposed technique.