A New Topology for the Large-Scale Photovoltaic Systems Grid Connection Based on Modular Multilevel Converter

Modular multilevel converter (MMC) became one of the most popular converters in medium / high power applications. This paper introduces a new topology to connect the large scale photovoltaic (PV) systems to the grid using MMC. The proposed topology capable of concentrating a large PV farm into a single converter which have merits such as a unique control systems, transformer, and line filter. In addition to decrease the losses and cost comparing by using several conventional two-level converters handling the same power. A multi-string PV configuration in which a high gain DC/DC converter is implemented to reach medium voltage operation and to perform the maximum power point tracking (MMPT). The grid connected MMC is controlled by using the finite control-set model predictive control (FCS-MPC) which is a recently powerful control technique used in the power converters. The proposed topology can significantly improve the output power of the PV system under the conditions of constant and changeable solar irradiation in addition to the decoupled active and reactive power regulation. The simulation results are presented to verify the validity of the proposed topology.