Maximizing Power Output of Photovoltaic Power Plants Based on the Cascaded H-Bridge Converter During Unbalanced Generation

In a large-scale photovoltaic (PV) power plant based on the cascaded H-bridge (CHB) converter, PV arrays are distributed among the CHB submodules (SMs). In such distributed power plants, the PV arrays can have different maximum available powers due to uneven irradiance and/or temperature. If all the PV arrays operate at their maximum power points (MPPs), the consequent PV power imbalance can exceed the tolerance of the CHB converter, leading to dc-link capacitor voltages divergence. To address this challenge, several control strategies have been presented to curtail PV power generation under extreme imbalance scenarios. However, existing strategies primarily focus on single-stage CHB-PV power plants and can lead to unnecessary PV power curtailments. In sight of these drawbacks, this article proposes a novel PV power management strategy for two-stage CHB-PV power plants. The proposed strategy operates all the PV arrays at their MPPs under normal conditions for maximum power generation. In scenarios of extreme power imbalance, it minimally curtails the power generation of certain PV arrays to prevent capacitor voltage divergence. Simulation and experimental results are obtained to validate the proposed strategy.