Fuzzy logic enhanced control for a single-stage grid-tied photovoltaic system with shunt active filtering capability

In this paper, a three-phase single-stage grid-connected photovoltaic (PV) system with active power filtering capability by means of a three-level T-type inverter is presented. The system is intended to fulfill many functions: harmonic mitigation, unity power factor operation, maximum power extraction from PV source, and so on. For the proposed system to achieve these tasks with a good dynamic performance, a new control strategy based on the fuzzy logic controller is developed. Fuzzy control has three main stages and each one requires many settings or selection of parameters. A new approach of setting the scaling factors which considerably affect the system's response is proposed. Furthermore, a methodology to properly set the fuzzy rules is suggested. The electrical power chain of the system comprises a farm of a PV source, three-level T-type inverter space vector pulse width modulation controlled, inductor filter, non-linear load, and the utility grid. To evaluate the performance of the proposed control, a processor-in-the-loop is performed as a hardware verification of the inverter control algorithm using a low-cost STM32F4 discovery board, while the power circuit plant is modeled in the host computer using Matlab/Simulink. The obtained results are very satisfactory and confirm the role of each component, especially in terms of maximum power tracking, power quality, unity power factor operation, and control robustness.