A Reconfigurable Modular Topology for Grid-Forming PV-ESS to Improve Overcurrent Capacity and Flexibility

Grid-forming (GFM) photovoltaic (PV) converters have been widely investigated owing to their ability to provide frequency and voltage support for power grids. However, GFM converters should have high overcurrent capacity to provide short-circuit current during grid fault, and substantial hardware redundancy is needed in conventional implementations based on fixed topology. This paper proposes a reconfigurable modular topology for GFM photovoltaic-energy storage system (PV-ESS), in which flexible modules can be dispatched to PV, grid, and energy storage (ES) sides via flexible switches. This reconfiguration enables adaptive capacity allocation based on instantaneous power across different conversion stages, thus enhance grid-side overcurrent capacity and improve light-load efficiency. A common-mode suppression circuit is designed to prevent flexible switch from high voltage stress caused by common-mode voltage. The proposed topology and its hierarchical control system are validated by simulation in MATLAB/Simulink.