A Large-Scale PV-Storage Generation System and Control Strategies Based on Triple Active Bridge and Modular Multilevel Converters

With the rapid advancement of renewable energy, large-scale photovoltaic (PV) energy storage systems for medium- and high-voltage applications have gained significant attention. Achieving high efficiency, enhanced flexibility, galvanic isolation, and compact system design is crucial for the development of PV power generation architectures. To address these demands, this paper proposes a large-scale PV energy storage generation architecture and its associated control strategy, in which the system comprises a Triple Active Bridge (TAB) converter and a Modular Multilevel Converter (MMC). The TAB converter interfaces the PV modules and energy storage units with the submodule capacitors of the MMC, while the inherent modular structure of the MMC enables direct connection to medium- or high-voltage AC grids. Mathematical models of both the TAB converter and the MMC are developed, and a small-signal model is derived to characterize the power coupling behavior of the TAB. Based on this model, a decoupled power control strategy is designed for the TAB. By coordinating the decoupled control of the TAB with the grid-connected control of the MMC, a comprehensive control framework for the proposed system is established. The proposed topology offers distributed maximum power point tracking (MPPT), electrical isolation, and eliminates the need for bulky line-frequency transformers. Simulation results confirm the feasibility and effectiveness of the proposed system architecture and control strategy.