Modelling, control, and performance study of cascaded inverter based grid connected PV system

This paper describes a three-phase grid-connected photovoltaic (PV) generation system, using a vector controlled cascaded two-level inverter (CTLI). The system is operated to supply different active power, with variable solar irradiance. Two different schemes have been considered here to operate the inverters with either equal or unequal dc-link voltages. The unequal voltage is chosen to reduce certain harmonics in the output. In both the cases, the solar radiation has been changed in the input of solar modules, and the proposed control scheme is shown to achieve satisfactory voltage regulation for the inverters. The effects of connecting LCL filters, to the vector controlled systems, are also studied here in the simulation environment.