Power Quality Enhancement of Grid-Tied 7L-PUC Inverter-Based PV System Using a Novel DC-Link Controller

Multistage inverters containing DC-DC converters are more common in grid-tied photovoltaic (PV) systems, because of the low DC voltage value provided by the PV generator, which requires a two-stage topology. The challenge in the latter case is to control the DC-link voltage with an accurate estimation of the current injected into the grid by PV system. In this paper, a two-stage grid-tied PV design based on a high-gain DC-DC converter and a 7 level packed U cells (7L-PUC) inverter, controlled by Finite-Control-Set Model Predictive Control (FCS-MPC) is presented, with the proposal of a novel model for controlling the DC-link voltage by considering system losses. The simulation and experimental results demonstrate the high effectiveness of the proposed control strategy in terms of power quality as well as response time and accuracy under changes in weather conditions and demonstrate the feasibility of the proposed system.