Transient analysis of PV-based industrial microgrids between grid-connected and islanded modes

This paper presents a networked control scheme for a photovoltaic-based industrial microgrid to adaptably operate in both grid-connected and islanded modes, and even to transfer smoothly between these two modes. The control scheme is mainly based on the droop method for active and reactive power sharing by means of voltage and frequency regulation. In addition, to get a smooth transfer between islanded and grid-connected modes, a phase-locked loop is also used in the control system. This loop is only activated during islanded mode to eliminate the phase deviation between the voltages in both sides of the point of common coupling switch. The output of this loop is send to all power units following a one-to-all communication scheme with low bandwidth. Finally, selected simulation results are reported in order to prove the effectiveness of the control scheme.