Performance Enhancement of PV–DG–BS Distributed Generation System in Islanded Mode

Abstract

The photovoltaic (PV)-based distributed generation systems are being promoted for electrification of remote and hilly areas. In the absence of grid, the continuity, quality, and reliability of the power supply need to be regulated through deployment of auxiliary generators, energy storage systems, etc., which is the focus area of this work. The aim of this paper is to address multiple challenges of power management, power quality, maximum energy harvesting from renewable source, battery current control, and load balancing in a diesel generator (DG)–photovoltaic (PV)–battery energy storage (BES)-based standalone system, with reduced number of converters. A voltage source converter (VSC) is used for implementing a modified system identification technique of normalized robust mixed norm (NRMN), which is found better for improving the power quality index as compared to the conventional methods. Further, the given VSC control scheme also achieves balancing of DG currents in case of unbalanced load and coordinates the power obtained from PV array, and DG, to feed the loads at all times. The PV array is connected in single-stage manner, i.e., without interlinking DC–DC converter, for making the system economic and efficient. The function of MPPT operation of PV array, thus, is achieved here through the buck-boost converter (BBC) which is a bidirectional converter connected between BES and the DC side of VSC. The BBC control scheme in this paper is unified with the battery current control to regulate the battery charging/discharging current within permissible limits. The robustness of control is successfully tested in the laboratory for various scenarios on an experimental prototype.