Efficiency Optimization of a Standalone Solar Energy System using Fuzzy Based MPPT

Abstract

This work primarily addresses the design and implementation of a standalone rotary sun tracker with dual maximum power point tracking (MPPT). The objective is to improve the efficiency of the PV system by introducing both physical and MPP tracking. A two-axis rotation mechanism is designed to track the sun over both the azimuth and elevation angles. The position of the sun is determined using a time-based approach, in which preprogrammed derived equations are used to calculate the sun's azimuth and elevation angles continuously throughout the day. The calculated angles are used as set points for two closed-loop control systems with PI controllers implemented in the DSP. The panel power is passed through a power converter that implements a fuzzy logic controller (FLC) based perturb and observe (P&O) MPPT algorithm that keeps the system power operating point at its maximum. In the conventional P&O, the converter input reference voltage is perturbed in fixed steps until the maximum power is reached. However, depending on the step size, the system operating point will oscillate around the MPP resulting in a loss of energy. The proposed controller eliminates the resulting oscillations by adaptively modifying the perturbation step using a fuzzy logic controller. The performance of the proposed system is validated through experiments with a 150-Watt PV system.