Module Power Balancing Mechanism for a Single-Phase Single-Stage Grid-Connected Photovoltaic Cascaded H-Bridge Inverter

This article presents a grid support-based module power balancing strategy for a grid-connected photovoltaic (PV) system fed with a modular cascaded H-bridge inverter. Power imbalance occurs in the PV system because of partial shading, aging effect, damage, and dusting of panels, etc., and results in overmodulation of the H-bridge modules (HBM). Overmodulation of HBM increases the distortion in grid current. The majority of the solutions in literature to handle the power imbalance are limited by the need for a modulation index more than
$4/\pi$
. Therefore, a methodology for utilizing a part of the grid power to take care of the severe power imbalance in the system through a supportive H-bridge module is presented in this article. The proposed method is validated with simulation and experimental studies on PV panels.