Current-Controller Effectiveness for Grid-Connected Converters: Comparative Case Studies

Abstract

This paper describes the implementation and comparison of two current-control strategies for a three-phase voltage source inverter (VSI) system grid connected via a LCL filter and used in distributed power generation systems (DPGS) applications. The performance of a proportional integrator (PI) current controller in the dq-synchronous reference frame and a proportional resonant (PR) controller in the αβ stationary reference frame are evaluated and compared. A voltage source (playing the role of a generic renewable energy source) is connected to the grid using a two-level inverter in order to verify the performance of the proposed approach. Both methods are implemented and tested at the laboratory-level using a dSPACE setup. The comparative study is performed to demonstrate the stability and effectiveness of the control algorithms across a wide range of operating conditions. The experimental results confirm that the proposed control achieves good current tracking, thus satisfying the grid-connection harmonics standards.