A DC Grid-Connected PV Microgrid Regulated via Digital and MBPC Cascade Control Strategies

Abstract

The current paper focuses on the design of cascade control systems employed in photovoltaic (PV) powered microgrids (MG), which have been well received in remote agricultural farms in Ecuador. The study case is composed of a three-phase inverter powered by a DC-DC converter fed by a PV array and its control system. To simulate the effect of MG peak voltage regulation, a comparison of three cascade schemes was done, using MATLAB/SIMULINK®. These schemes are based on digital control, model-based predictive control (MBPC), and a combination of both. It was found that the best stabilization of voltage although with a fast response and a low overvoltage in the MG are reached with a combined scheme, compound by the classical controller combined with the MBPC. The results were validated using the RT-LAB software and the OPAL-RT real-time (RT) simulator, in the tested microgrid.