Adaptive synchronization of grid-connected three-phase inverters by using virtual oscillator control

This paper presents an adaptive synchronization for current-controlled grid-connected inverter based on a timedomain virtual oscillator controller (VOC). Inspired by the phenomenon of dynamics of adaptive oscillator under the perturbation effect. Firstly, the fast learning rule of the oscillator frequency is derived in order to make the oscillator evolve to the grid voltage. Thus realizing a phase-locking behavior, but without requiring the use of a dedicated phase-locked loop (PLL). Then, the unit orthogonal components are obtained to generate the current reference, and a current loop is designed by using a PR controller in the αβ frame. Experimental results were obtained with comparison to PI current controller, showing the salient performances of the proposed method in front of grid frequency variations, voltage sags and swells.