Modeling, control and analysis of cascaded inverter based grid-connected photovoltaic system

This paper proposes a vector controlled isolated source cascaded two-level inverter (CTLI), for grid connected photovoltaic (PV) system. The system is controlled to operate with variable solar irradiance, supplying different levels of active power. The PV systems are designed, modeled and tested with the proposed controller, to provide maximum power output. Additional operation as a reactive power supplier, in the absence of solar radiation, is also tested. A simple sinusoidal pulse width modulation (PWM) technique is used, instead of referred space vector PWM (SVPWM) technique, for the operation. Two different schemes have been considered to operate the inverter with equal and unequal DC-link voltages. The control scheme has been found working, for both active and reactive power supply in steady state and transient conditions. The power supplies of both the schemes are analyzed. The controller performance is found to be satisfactory for both the schemes to extract maximum power at the considered working conditions. (C) 2015 Elsevier Ltd. All rights reserved.