Virtual RL Damping and Harmonic Suppression for Current-Source Inverter-Based Photovoltaic Systems

This paper proposes a virtual RL damper in series with the passive filter inductor of the grid-connected current-source inverter (CSI)-based photovoltaic (PV) systems. The virtual damper actively applies a supplementary feedback from the inductor current to the pulse-width modulator via a proportional-derivative (PD) controller. The details of the proposed PD controller and its practical design are also presented in this paper. Theoretical analysis and simulation results demonstrate that the proposed control strategy adequately suppresses the current oscillations and mitigates the low-order harmonics.