Fractional order direct current control algorithm for three-phase grid-connected PV system

This paper integrates a suitable controller in DC-bus voltage regulation loop of the direct current control (DCC) algorithm for three-phase grid-connected PV system. The proposed controller named fractional order PI (FO-PI) controller adjust the integration order from integer to real value. The FO-PI controller provides a faster settling time and stands the parameters variation and the external disturbances. Thus, the improved algorithm (FO-DCC) ensures a smooth injection of appropriate energy from the PV system (PV emulator, boost converter and P&O MPPT) to the electrical grid with high power quality and unity power factor. The validity of the FO-DCC algorithm has been investigated through real time bench. The obtained results confirm the high performances in static and dynamic regimes. Thus, the proposed algorithm (FO-DCC) could be an interesting alternative solution to grid-connected PV systems.