Robust H_∞ Current Control of Three-Phase Grid-Connected Voltage Source Converters Using Linear Matrix Inequalities

This paper proposes a robust H∞ current control of a three-phase LCL-filtered grid-connected voltage source converter (VSC). As main contributions, new modeling for three-phase grid-connected VSC is presented that considers control input delay and grid impedance variations. The linear matrix inequalities (LMIs) formulation and polytopic type uncertainty representation are employed to achieve this goal. The performance of the proposed control strategy is investigated under different grid short circuit ratios (SCRs). Simulation and experimental results confirm the excellent performance of the proposed control method under different grid conditions.