Indirect current control for seamless transfer of three-phase utility interactive inverters

This paper proposes an indirect current control algorithm for seamless transfer of three-phase utility-interactive inverters. With the proposed method the inverter is able to provide critical loads with a stable and seamless voltage during the whole transition period including both clearing time and control mode change. The LCL filter design which is suitable for the indirect current control is also proposed to meet the harmonic limits. The proposed control method is validated through simulation and experiment.