An efficient robust MPPT control for grid-connected photovoltaic systems with reduced DC link capacitance

This paper presents a novel robust maximum power point tracking (MPPT) control for a grid connected photovoltaic (PV) system with reduced DC link capacitance. The voltage source inverter (VSI) integrating the PV system to the grid introduces a double line frequency ripple or current variation into the PV system. This ripple or current variation results in oscillation of operating point around the MPP, introducing an extra power loss from the extracted panel power. In order to reduce this ripple content, large electrolytic capacitors are used as power decoupling units in grid connected PV systems. However, these electrolytic capacitors are bulky and less reliable affecting the reliability of the entire PV system. These electrolytic capacitors can be replaced by highly reliable thin film capacitors, if the energy storage requirement could be reduced. So, a novel DC-DC converter control is proposed to reduce the PV ripple variation along with MPPT control under reduced DC link capacitance. The method proposed is implemented and verified in MATLAB/Simulink software under varying sun conditions. The results obtained from the proposed control clearly show the increase in power extracted from the PV system under reduced DC link capacitance making the system more reliable and economical.