Npc Based 5 Level Two-Stage Energy Storage Solar Photovoltaic-Based Stand-Alone Scheme for Rural Deployment

Abstract

In this PV-based stand-alone scheme for application in rural areas is proposed. Photovoltaic (PV) has become one of the most promising candidates among the available RESs. However, the availability of PV power is intermittent in nature, and hence, PV-based stand-alone systems need an energy storage element which is generally realized by utilizing a battery bank. The major challenges in designing such systems are as follows: 1) extraction of maximum power from the PV array 2) protection of the battery from overcharge and over discharge 3) dc to ac conversion and 4) provision for adequate voltage boosting.  As multiple objectives are required to be satisfied, the existing schemes for stand-alone systems require a minimum of multi converter stages, leading to considerable reduction in the reliability and efficiency of the system. In order to address this issue, a two-stage stand-alone scheme consisting of a novel transformer coupled dual-input converter (TCDIC) followed by a NPC based five level inverter is proposed. The proposed TCDIC can realize maximum power point tracking and battery charge control while maintaining the proper voltage level at the load terminal. A suitable control strategy for the proposed TCDIC devised for manipulating the TCDIC to realize the first two aforementioned objectives, while the third objective is achieved by employing a conventional proportional integral (PI) controller to control the output voltage of the full bridge inverter through sinusoidal pulse width modulation. The simulation results are performed by using Matlab/simulink software.