FCS-MPC Current Control of Parallel Photovoltaic Grid Connected Inverter with Common AC and DC Buses

As the growth penetration of photovoltaic (PV) renewable power generation systems connected into grid increases, high power quality and good efficiency are needed. Hence, in photovoltaic grid-connected systems, parallel two-level inverters (VSIs) connected with common AC and DC buses are largely used to ensure high power quality and efficiency. Besides, such a solution rises a number of concerned issues, especially, zero sequence circulating current (ZSCC) which will distort the performance of the system. This study proposes a finite set control model predictive method for suppressing the ZSCC, and controlling currents with rapid transient response. The causes of the zero-sequence circulating current are presented in detail. The proposed current controller is realized by minimizing the cost function and pick the optimal vector to generate the control requirement. Finally, Simulation results show that the proposed control scheme achieves to ensure power quality, suppression of circulating currents, and also maintains the DC-link voltage constant.