A new modular multilevel converter based on photovoltaic system: power mismatch elimination and its control strategy

Colque J.C.; Delgado-Huayta I.; Ruppert E.; Azcue J.L. · 2023 15th IEEE International Conference on Industry Applications, INDUSCON 2023 - Proceedings (2023) · DOI: 10.1109/induscon58041.2023.10374737

Resumen

The modular multilevel converter (MMC) became attractive for photovoltaic solar energy applications due to its intrinsic characteristics such as modular structure and flexible operation, achieving high efficiency compared to other multilevel converter topologies. In this way, being able to adapt the converter in topologies derived from the MMC, in which the number of components varies, isolated dc-dc stage, common DC bus or with separate sources, high-frequency transformers instead of inductors and modifications of other passive elements; to improve energy production or to balance the energy generated between the arms. In this paper, a new topology for an MMC-based PV system is proposed, in which, the PV panels are used to energize an isolated DC-DC converter which in turn is connected to a submodule, a redundant submodule (rSM) is also placed in each arm to balance the possible power mismatch in each phase of the MMC, each isolated DC-DC converter is controlled individually and a local MPPT (Maximum power point tracking) is also included which optimizes the energy extraction in each PV submodule. Finally, the dq-reference frame control is used for the output current control and the electrical grid connection to validate the proposed system. The time-domain simulations are performed using the Simulink/Matlab software.