Power Balancing Strategy for Cascaded H-Bridge Inverter in a Grid-Connected Photovoltaic System Under Asymmetrical Operating Conditions

Cascaded H-bridge multilevel inverter is a well-established technology for photovoltaic systems. Power imbalance occurs in the system because of the environmental dependence of photovoltaic modules, damage and dusting of panels, and the ageing effect. Subsequently, the power handled by H-bridge modules is unequal. As a result of power imbalance, the H-bridge modules carrying higher power are likely to get overmodulated, increasing the distortion in grid current. Due to this, reliability of the system is affected. The ability of existing harmonic compensation techniques to counter this issue is limited to a modulation index of
$4/\pi$
. In the view of this adversity, a voltage alteration method along with an optimization algorithm is proposed in this article to alleviate the power imbalance issue. The presented simulation and experimental results validate the proposed method.