Improved Performance of Grid-Connected Photovoltaic System Based on Fractional-Order PI Controller and Particle Swarm Optimization

Starting from a benchmark implemented in the Matlab/Simulink development environment for PV array connection to the grid, this article compares the performance of the DC circuit voltage control system using the Proportional Integral (PI) controller, the PI-Particle Swarm Optimization (PSO) controller, and the Fractional-Order (FO)-PI-PSO controller. The article presents the topology and the mathematical description for a connection between a PV array and the main grid. Besides are presented the main elements which assure the connection: the temperature and solar radiation simulation block, which represents the input for the PV array block, supplying DC voltage to the DC-DC (Boost converter block), the DC intermediate circuit, the DC-AC converter receiving DC voltage at the input, the filtering block, and the transformer for the connection to the main grid. The superior performances are obtained through using of the differential and integral fractional calculus and the optimization of the PI/FO-PI controller parameter tuning using the PSO method. The validation of the superiority of FOPI-PSO voltage controller over a benchmark system is carrie out by numerical simulations by using Matlab/Simulink environment.