Stability Analyses of a Multifunctional PV and Battery Integrated UPQC System

The proposed research is focused on stability dynamics and power flow control of a hybrid renewable energy system consisting of a photovoltaic array and a battery energy storage unit, and the coordination is made possible by the means of a Unified Power Quality Conditioner (UPQC). It is a two-way interface that exchanges energy between a hybrid generation system, utility grid, and downstream loads. The issues of power quality, considering voltage dip, harmonic distortion, and large reactive power consumption, are enhanced because of the presence of renewable generation and nonlinear load. The system is designed to handle these shortcomings with flexible AC transmission system (FACTS) devices. In this paper, a control scheme based on closed-loop control architecture combined the Grey Wolf Optimization algorithm and two control types, i.e., Grey Wolf Optimization Algorithm-Proportional Integral Derivative Controller (GWA-PID) and Grey Wolf Optimization Algorithm-Fuzzy Logic Controller (GWA-FLC) is presented. The battery side buck-boost converter and the UPQC unit, developed specifically for power quality improvement, as well as the PV side boost converter, controlled by the corresponding controllers, are also included in the system. This structure plays an important role in stabilizing voltage levels, minimizing Total Harmonic Distortion (THD), and controlling dynamic real and reactive power flow. Under the simulation models created from MATLAB/Simulink, it has been found that the GWA-FLC controller outperforms the GWA-PID controller in terms of transient behavior and enhancement of global power quality indices.