A Novel Circuit Configuration for The Integration of Modular Multilevel Converter with Large-Scale Grid-Connected PV Systems

In this paper, a novel modular circuit configuration to integrate the large-scale photovoltaic (PV) systems to the grid using the modular multilevel converter (MMC) is proposed. The proposed circuit is modular, scalable, and has excellent performance during PV shading conditions. Unlike other PV-MMC circuits, this circuit configuration diminishes the power unbalance between the arms of the converter allowing the control to deal with the power unbalance occurred between the converter phases. It also eases the control process and assures a wide range of power balancing capability of the MMC. The control strategy can balance the power between the MMC phases by only injecting the dc circulating current component while the ac component is kept minimal which increases the stability and reduces the internal losses of the converter. The proposed circuit configuration and the control strategy are designed and simulated. The corresponding results are presented to demonstrate their effectiveness during different PV power generation conditions.