Improving PV System Power Harvesting in Partial Shading Environment using Decentralised Modular Multilevel Converter

Partial shading and its effect is an important consideration in any photovoltaic (PV) system, as any PV system will experience a drop in power and efficiency when exposed to uneven radiation. Using multilevel power electronic converters is a viable approach to minimise the impact of partial shading on a PV system. The Modular Multilevel Converter (MMC) is a perfect topology for this kind of application due to its modularity, effectiveness, and high efficiency. This research paper investigates the performance of two MMC based PV systems under different shading patterns. The traditional MMC PV system has the entire PV array connected to the MMC leg terminals through a central DC/DC converter. An alternative MMC system divides the PV array into smaller groups, each integrated into the MMC submodules (SMs) through decentralised DC/DC converters. Both systems are examined in terms of their effectiveness, performance, and power harvesting under different shading conditions. In comparison to the conventional MMC system topology, simulation results show that the proposed MMC has the potential to improve the power harvested from the PV array under partial shading. The findings show that by using the proposed topology, almost 50% extra power can be gained under nonuniform radiation compared to the traditional system.