Cascaded H-bridge MV grid and power balance control for PV systems

Abstract

In this paper, a new centralized cascaded H-bridge medium-voltage (MV) grid topology model based on the three-phase power system is established and presented, including its control strategy. The influence that the power supply imbalance between three phases which caused by PV array partial shading or module mismatch of Cascaded H-Bridge is analyzed as well, based on which the power balance control algorithm is put forward. Simulation and experimental results show that the algorithm is effective and reliable, it improves the conversion efficiency and grid-connected power quality, solves the key problem of cascaded H-bridge topology used in three-phase system, provides a theoretical basis for the development of new high-power photovoltaic grid-connected inverter.