Super-twisting Sliding Mode Control for a Multifunctional Double Stage Grid-connected Photovoltaic System

This paper proposes a super-twisting sliding mode control for a multifunctional system that includes a Photovoltaic (PV) system connected to the grid through the Active Power Filter (APF). The latter is implemented to improve the power quality in the grid side, and injecting the provided photovoltaic power into the grid. Sliding mode control is known as a powerful control with good performance in transient and steady-state conditions. In this work, a Super-Twisting Sliding Mode Control (ST-SMC) is applied to extract the maximum power from the PV source, corresponding to the irradiation level, as well as to the threephase inverter-based-APF power control. For the system to inject the generated power from the PV source into the grid with respect to the international standards, fulfilling the active power filtering, synchronous reference frame theory is used to generate the appropriate reference signals for harmonic and reactive power compensation. To test the multi-functionality of the system (PV-APF), this one is connected to a grid supplying nonlinear loads that absorb non-sinusoidal currents. Through the simulation results, it has successfully achieved the multi-functionality of the proposed system under steady-state and dynamic conditions. The results also show the effectiveness and moderation of the proposed super-twisting sliding mode control. Furthermore, a comparative study has been established over the conventional PI controller, showing the clear superiority of the proposed control in every aspect.