Optimal Power Flow Control in a Stand-Alone PV System With a Battery-Assisted Quasi-Z-Source Inverter

Abstract

This paper presents a photovoltaic (PV) power system with a battery storage unit and the quasi-Z-source inverter (qZSI). This inverter belongs to the group of transformerless single- stage inverters with buck/boost capability. The considered system is designed for autonomous load supply and battery charging in areas isolated from the utility grid. The batteries ensure continuous operation in the case of energy shortage/surplus and compensate for the oscillations of the PV power due to changes in atmospheric conditions. They also enable capturing of the maximum available power from the PV modules. The maximum power point tracking (MPPT) algorithm utilized in this study belongs to the group of perturb-and- observe (P&O) algorithms, which are widely used in commercial PV systems. The state of charge (SOC) of the employed batteries represents an important factor in the context of MPPT operation and is taken into account in the proposed power flow control algorithm. The performance of the proposed system has been tested through simulations in the MATLAB Simulink over wide ranges of solar irradiation, PV module temperatures, and SOC levels.

Mateo Bašić

Full Professor | Department of Power Electronics and Control

Full professor at the Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture in Split, with recent research interests related to the fields of power electronics and renewable energy sources, with a special focus on energy-efficient control of inverters, battery systems, wind turbines, photovoltaic sources and self-excited induction generators in microgrids - both in island operation and in grid-tie operation.

Dinko Vukadinović

Full Professor | Department of Power Electronics and Control

Full professor at the Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture in Split, specialized in modern control systems for power electronic converters, electric motors, and generators. At the Power Electronics Research Laboratory, he leads experimental projects and develops advanced methods for regulating electrical machines and converters, while supervising doctoral research in these areas.

Ivan Grgić

Assistant Professor | Department of Power Electronics and Control

Assistant professor at the Faculty of Electrical Engineering, Mechanical Engineering and Architecture in Split, specialized in the research of power electronic converters in photovoltaic systems and microgrids. Currently, he teaches courses in the areas of control engineering, digital electronics, electrical engineering, electrical machines and transformers.