Distributed Power Reserve Control in Grid-Connected Cascaded H-Bridge Converter-Based Photovoltaic Systems

Grid-connected photovoltaic (PV) systems enhance grid stability during frequency fluctuations by adopting power reserve control (PRC) and contributing to frequency regulation. The cascaded H-bridge (CHB) converter is a suitable choice for large-scale photovoltaic systems. This paper introduces a distributed PRC strategy designed for CHB-based PV systems, necessitating minimal inter-module communication and thus simplifying implementation. Each submodule (SM) within the CHB converter periodically engages in maximum power point tracking to assess the system’s total accessible PV power. Through coordinated control, the strategy evenly allocates the necessary power across sub-modules based on their PV power availability, offering a balanced power distribution while acknowledging operational constraints on power disparity among SMs. Simulation and experimental results confirm the efficiency of the proposed approach under various conditions, showcasing accurate PV power estimation, seamless transition between operating modes, fast dynamic response, and regulation of the dc-link voltages.