Design of a direct connection scheme of supercapacitors to the grid-tied photovoltaic system

Abstract

A maximum power-point tracking (MPPT) technique needs to be applied to the photovoltaic (PV) system in order to extract maximum possible power output under those varying conditions. The development of supercapacitor (SC) as high power storage device in recent years has created opportunity to replace electrolytic capacitor by SC as dc-link capacitor to provide power during fault ride-through (FRT) condition. However, due to its much bigger capacitance, the voltage dynamics of SC is much slower compared to electrolytic capacitor. Therefore, in this paper, a MPPT technique using a string of supercapacitors which is directly connected to the DC-link of a PV generation system is proposed. The direct connection is proposed to avoid one stage DC-DC power conversion to implement MPPT, so that the efficiency of the system is increased. The proposed direct connection of supercapacitors string configuration along with MPPT strategy is verified by simulation analysis using MATLAB/Simulink where real solar irradiance data is used.