Power Generation Curtailment in Cascaded H-Bridge Converter-Based Solar Farms under Unbalanced Generation

The cascaded H-bridge (CHB) converter is a promising topology for integrating large-scale photovoltaic (PV) systems into the grid. However, significant power imbalance among individual PV arrays can cause stability issues, often requiring PV power curtailment. To date, the extent of power curtailment under various imbalance conditions and modulation strategies has not been thoroughly quantified. This paper investigates the required PV power curtailment in CHB-PV systems across a range of imbalance scenarios. The results show that substantial curtailment may be necessary, especially when multiple PV arrays have relatively low available power. In extreme cases, the system may be unable to deliver any active power to the grid. Furthermore, the study examines the potential of mitigating curtailment by injecting harmonics into the submodule ac-side output voltages.