PV System with Battery Storage Using Bidirectional DC-DC Converter

Abstract

With the increase in demand for generating power using renewable energy sources, energy storage and interfacing the energy storage device with the load has become a major challenge. Energy storage using batteries is most suitable for renewable energy sources such as solar, wind etc. A bi-directional DC-DC converter provides the required bidirectional power flow for battery charging and discharging mode. The duty cycle of the converter controls charging and discharging based on the state of charge of the battery and direction of the current. In this paper, a nonisolated bi-directional DC-DC converter is designed and simulated for energy storage in the battery and interfacing it with the DC grid. The power extracted from the solar panel during the daytime is used to charge the batteries through the DC-DC converter operating in buck mode and when solar power is unavailable, the battery discharges to supply power to DC load through the converter operating in boost mode. Solar arrays connected through a DC bus to a load. Due to the instantaneous changes of solar irradiance and temperature, maximum power point tracking (MPPT) is integrated in the inverter control. The technique of maximum power point tracking (MPPT) is used in photovoltaic systems to extract the maximum power. The most popular MPPT techniques are reviewed and studied, such as: Perturb and Observe, Increment of Conductance and control based on fuzzy logic (LF). The simulation is done in matlab/simulink and results are presented.