A systematic design methodology for DC-link voltage control of single phase grid-tied PV systems

PI controllers are commonly used for the DC-link voltage control of single phase grid-tied inverters. This DC-link voltage is characterized by double-line frequency ripples, which are natural by-product of single phase AC systems. These ripples, if not controlled properly, can adverse the performances of the grid-tied PV system at the AC side, particularly the grid current THD. On the other hand, random and sudden changes of the active power produced by PV panels, during sudden shadow or lighting of PV panels, can lead to high DC-link voltage fluctuations. This paper presents a systematic design methodology to tune the gains of the PI-based DC-link voltage controller so that the DC-link voltage fluctuations as well as the grid current THD are reduced to tolerable limits. Several simulation results are presented and discussed to show the effectiveness of the proposed design methodology.