Robust Model Predictive Control (MPC) for large-scale PV plant based on paralleled three-phase inverters

Abstract

In this contribution a robust Model Predictive Control (MPC) is proposed to enhance the power quality of a large-scale PV plant connected to the grid through Paralleled Voltage Source Inverters (PVSIs) with common AC and DC buses. Paralleling inverters allow handling high-power export and offer advantages in terms of redundancy which ensure the system reliability. However, due to the physical differences and parameter disparities between the inverters, zero sequence circulating currents will flow through it, which will disturb the performance of the system. Hence, the control goal is to regulate the currents injected into the grid, suppress the zero-sequence circulating current (ZSCC). Consequently, this study proposes an MPC algorithm that is based on optimization approach which allows minimizing circulating currents. In order to show its effectiveness and performance of the proposed control, a comparison with linear PI controller is included. In addition, design control and tuning procedure are detailed. Simulation results show the performance of the proposed controller in ensuring power quality, and suppressing circulating currents. To verify the real-time feasibility of the proposed control scheme, Hardware-In-the-Loop (HIL) setup is carried out with means of Opal-RT and dSPACE rapid prototyping systems.