Modeling, Control Design And Simulation Ofgrid Connected Single-Phase Solar Microinverter

This paper represents the mathematical modeling, control design and simulation of grid connected single phasesolar micro inverter. A system level approach is exploited to establish an upper-level block diagram that depicts the various blocks of the solar inverter. These blocks are PV panel, boost converter, inverter, ac grid and control system along with their coordination in power and signal flow. In mathematics modeling, complete state space model is developed, having three states of the system, magnetizing current, output voltage current and voltage. Photovoltaic voltage and duty ratio is taken as input to the state space model. A transfer function model between output ac voltage and input duty ratio is established and time domain analysis is conducted for its stability analysis. Frequency domain analysis is also carried out and a PI controller is designed to improve it relative stability. Feedback compensator and feed forward loop both are used to improve the system performance. The complete model along with its controller is developed in Simulink. Results of the model reveal the accurate operation of the inverter. DC rail output of the fly back converter produces 350V in steady state. In the startup phase of the inverter, it took 0.03 sec to synchronize the inverter output to the grid voltage. The peak voltage of the inverter is kept high than the grid voltage for the power injection to the grid.