AN OPTIMAL CONTROL TECHNIQUE FOR SINGLE PHASE GRID CONNECTED INVERTER USING SIMULINK

Abstract

This paper will optimize the control technique based on Digital Pulse Width Modulation for single phase grid connected inverter application. Model-Based Design workflow was adopted in two approaches for implementing and testing the designed digital control of the system. In the first approach simulation is adopted using Matlab/Simulink and for the second approach, a co-simulation test bench with the Simulink model of the System is adopted using ModelSim. It was found that, the control technique based on digital pulse width modulation synchronized a sinusoidal output voltage of the utility grid with the inverter current and also control the power injected to the utility grid. The result from simulation and co-simulation are in good agreement with minimal error, and it can be seen clearly that the HDL co-simulator was able to optimize the designed control. From the harmonic analysis it can be observed that the THD for the grid current does not to exceed the 5% specified limit for THD as suggested by the International Standard for both two approaches, while for the inverter current it exceeds the specified limit and this can be attributable to the use of Zero Crossing Detection technique in the synchronization module of the inverter control system, due to it poor harmonic filtering capability and inability to accurately extract the utility grid parameters. Therefore, technique to control the System need to be explored in other to inject quality power to the utility grid with less distortions.