An analog based control scheme applied in stand-alone photovoltaic systems for DC power distribution

The integration of units with primary energy sources, energy storage and loads, is expected to play a promising role in the future of the electricity supply. The distributed energy resources are the basic units for storage and distribution in microgrids. A hybrid unit, which includes a primary energy source and storage simultaneously, is proposed in this work. The unit consists of a DC-DC Buck-Boost converter that tracks the maximum power supplied by a photovoltaic panel, a DC-DC Boost converter that regulates the microgrid DC bus voltage and a DC-DC bidirectional converter which controls the energy flow on the system, charging or discharging a battery bank. The control strategy for these converters should consider the protection of the batteries against voltage transients, as well as the protection of the loads at microgrid bus. Thus, this work proposes a coordinated control strategy for maximizing the power supplied to DC microgrids considering the usage of a photovoltaic energy source and a battery bank under different climate conditions. Simulation and experimental results show that the control strategy tracks the maximum power from the photovoltaic module, charges the batteries when they are discharged, and provides power from the batteries when needed, ensuring the protection of the batteries, autonomous loads and the optimization of energy available for the batteries and loads.