Control of Single-Phase Grid Connected Inverter System

In this paper, an implementation of the control and the synchronization algorithms for a Voltage Source Inverter used in a grid-connected structure is carried out. The main purpose is to show the combined operation of the control and synchronization algorithm for achieving the proper behavior of the grid inverter for the single phase utility grid system. In order to obtain a proper functionality of the system during perturbation, a proportional integral controller structure along with Second Order Generalized Integrator Phase-Locked Loop (SOGI PLL) is designed and used as synchronization algorithm. Also, the aim is to control power factor at grid, to feed power into the grid, and to decrease phase current distortion of VSI. Secondly, the design of third order LCL output filter will be proposed in this paper. The results of simulations of the inverter system connected to grid (220V, 50 Hz) using MATLAB/Simulink are also shown. Simulation results confirms that the grid input power factor is nearly unity, and the distortion of phase current of the proposed system is reduced, causing the total harmonic distortion for various power conditions falls within 5%.