A frequency locked loop strategy for synchronization of inverters used in distributed energy sources

Abstract

A technique has been developed that incorporates the advantages of the cascaded delayed signal cancellation and dual second order generalized integrator schemes, the first one being used now as a pre-filter for the second element. A reconstructor block is applied as well to prevent unreal changes in the estimated frequency in case of phase angle jumps of the grid voltage. Experimental results are evaluated in terms of quality of the positive voltage sequence, frequency and phase angle identification for the grid voltage disturbed by harmonic and negative sequence components as well as for amplitude, frequency, and phase angle jumps in the voltage.