Design and Simulation of a Power System Composed of Grid-tied Five-level Inverter with LCL Filter

Abstract

This paper presents the analysis, design, and simulation of a power system composed of a grid-tied single-phase five-level inverter with an LCL filter. First, the analysis of the proposed system has been carried out in the decoupled Direct-Quadrature frame, where the Phase-Lock-Loop technique has been used for synchronizing the LCL-filter-connected-grid with the five-level inverter. Next, the design of the LCL filter has been discussed. In this paper, we focused on the active power control based on grid current adjustment using a proportional-integral regulator and a high-frequency modulation technique for the switching of a five-level inverter, where the Sinusoidal-Pulse-Width-Modulation technique is selected. All circuit design and control schemes are discussed step by step to provide the effectiveness of the system analysis. The theoretical analysis is verified through simulation results in MATLAB/Simulink environments. An important finding when using the five-level inverter in a grid-connect system is improving the system output voltage; the total standing voltage and the total harmonic distortion are decreased compared to a conventional H-bridge inverter. The results indicate that the total harmonic distortion of grid-current is less than 0.2%, which is according to the international standards.