Controle de um ciclo aplicado em sistemas fotovoltaicos autônomos em um Microgrid de corrente contínua

摘要

The integration of units with primary energy sources, energy storage and loads, is expected to play a promising role in the future for the electricity supply. The interconnection of such units providing medium and low voltage makes a microgrid system. The distributed energy sources are the basic units for storage and distribution in microgrids. These sources can be of a hybrid type, which includes a primary energy source and storage simultaneously. A hybrid type proposed in this paper 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 Buck-Boost converter that controls the energy flow in the system, charging or discharging a battery bank. The control of these converters should consider the protection of the battery against voltage transients and spikes, as well as the protection of loads connected to the microgrid main bus when the battery supplies the stored energy. Conventional control techniques used on the converters of these units use the pulse width modulation, which has the disadvantage of produce undesirable transient due to the slow response to changes in the system input source, or the loads resistance connected to microgrid the main bus. These transients can damage other loads and batteries connected to the microgrid main bus. Thus, one-cycle control technique is applied to the switching converters to allow fast response to transient without overshoots and zero steady-state error. The objective of this work is to use this technique in controlling these converters in order to quickly track the maximum power point of the photovoltaic panel, charge the batteries when they are discharged, and provide power from the batteries to the loads when needed, ensuring the protection of the batteries and the loads connected to the microgrid main bus.