MMC-Based Distributed Maximum Power Point Tracking for Photovoltaic Systems

This paper proposes a novel topology for grid connected photovoltaic (PV) system based on modular multilevel converter (MMC). In this topology, a PV array is connected to capacitors of each submodule (SM) of the MMC through a DC-DC boost converter with maximum power point tracking (MPPT) control. This topology will maximize the efficiency of the system in the case of partial shading conditions, as it can regulate the SM capacitor voltages independently from each other to realize distributed MPPT. A model predictive control is used to track the AC output current, balance the SMs capacitor voltages, and to mitigate the circulating current. The proposed PV generation topology with 7 level MMC system validity has been verified by simulations via MATLAB/Simulink toolbox under normal operation, partial shading and PV array failure.