Control and Operating Range Analysis of an AC-Stacked PV Inverter Architecture Integrated with a Battery

This letter presents a control scheme to operate a battery-integrated ac-stacked photovoltaic (PV) inverter architecture and its operating range analysis. The main operation strategy is the combination of decentralized controls of individual inverter members; PV and battery. In ac-series integration, battery charging and discharging operations affect operating margins of the PV inverter members. The interactive operation needs to be analyzed to identify the system operating range under different conditions. A ramp-rate control, which mitigates PV output variations and improves grid stability, is a suitable application for the PV-battery ac-stacked inverter architecture utilizing a panel-level modular inverter design. In this letter, decentralized ramp-rate control is proposed and demonstrated to analyze the system operating range. The detailed system control and analysis are performed through controller hardware-in-the-loop testing.