Multilevel Inverter Based Single-Stage Grid Connected Photovoltaic System using Cascaded Two-Level Inverter

In the recent trend of using green energy, grid connected Photovoltaic (PV) systems are getting more popular. In this work, the modeling and control of multilevel inverter based single-stage grid connected photovoltaic system based on cascaded two-level inverter (CTLI) is carried out using MATLAB/Simulink. The multilevel inverter topology is developed by the cascade connection of two conventional voltage source inverters (VSI)) using open winding transformer. The inverters are controlled using hysteresis current controller for which the synchronizing reference currents are generated using p-q theory. The maximum power is extracted from the PV array under varying environmental conditions using fuzzy logic controller which generates the change in reference power to be injected into the grid by the CTLI. The CTLI based grid connected PV system is simulated for injecting active power produced by the PV array under varying solar insolation as well as varying load conditions. The simulation is also carried out demonstrating the effective utilization of the PV system by providing reactive power compensation during low or zero insolation conditions. The simulation results demonstrate the effectiveness of the control scheme of the CTLI based grid connected PV system for injecting active as well as reactive power in a controlled manner.