A Two Stage Stand Alone Solar PV System

Abstract

Stand-alone systems based on solar photovoltaic (PV) have developed as a sustainable alternative pertaining to issue of electrification in areas particularly where the grid is not present. Main challenges in scheming this kind of systems are 1) Maximum power extraction from PV array 2) Dc to ac conversion 3) Protecting battery from over discharging and overcharging and 4) Facilitating satisfactory stepping up of voltage. As many objectives are needed to be met, schemes hitherto for standalone systems need a minimum of three converter stages, resulting in significant decline in efficiency and reliability of system. To tackle this problem, a two stage stand-alone topology comprising a novel transformer coupled dual input converter (TCDIC) is connected to a normal full bridge inverter is discussed in this thesis. Discussed TCDIC can facilitate charge control of battery while tracking maximum power point and keeping proper voltage level at load terminal. Mathematical model of TCDIC through small signal based approach is also included. A suitable control strategy for TCDIC is also presented to generate pulses. The operational efficiency of this topology is verified by performing simulation studies in detail.