Modeling and Control of PV and Multiple Batteries based DC Microgrid

This article explores the integration of photovoltaic (PV) systems and multiple Battery Energy Storage Systems (BESSs) through DC-DC converters connected to a common DC bus. It presents an averaged nonlinear model of the converter system, which incorporates a PV system and two distinct BESSs. The model is linearized and validated around a specified operating point. A comprehensive control scheme is discussed that encompasses (i) An outer voltage controller which maintains a constant DC bus voltage, (ii) A battery reference current generation block, and (iii) Inner current controllers which regulate the battery currents or inductor currents to their reference values calculated based on the State of Charges (SOCs). The reference current generation scheme ensures that batteries with a higher SOC discharge at a higher rate and charge at a lower rate, while the opposite is true for batteries with lower SOC. Simulations are conducted in MATLAB/Simulink under varying irradiance and load conditions.