一种用于分布式光伏接入中压交流电网且消除功率失配的并联型多端口多电平逆变器

The Cascaded H-bridge (CHB) multilevel inverter stands out as an optimal topology for integrating large-scale photovoltaic (PV) power systems into the grid. Due to its multiport characteristic, each submodule directly interfaces with distributed PV strings. Nonetheless, PV power generation often experiences mismatches among three phases and between arms of one phase due to factors such as nonuniform irradiation, partial shading, and temperature variations. Addressing these challenges, this study introduces a novel CHB multilevel inverter with a parallel structure. Consequently, the added power circulation paths facilitate phase power exchange through circulating current injection (CCI), effectively eliminating phase power mismatch and power mismatch between arms in one phase. By transitioning the power exchange mode from voltage-driven to current-driven, the prevalent voltage overmodulation issue associated with the traditional CHB multilevel inverter is resolved. Additionally, this study offers a quantitative assessment of the power balancing capability of the suggested inverter in PV applications. Evidence suggests that, by employing CCI, the proposed inverter significantly enhances power balance capabilities compared to the traditional CHB multilevel inverter that utilizes zero-sequence voltage injection (ZSVI). Both simulation and experimental results validate the proposed approach.