Fault ride through control with voltage compensation capability for utility interactive inverter with critical load

Simultaneous disconnection of a large amount of DG systems could cause instability in the grid. Therefore, during a grid fault DG systems are required to remain connected to the grid for a certain period of time. Rather, it is necessary for DG systems to supply reactive power variably depending on actual voltage level for grid support. Further, during the grid fault the utility-interactive inverter with a critical load should not only supply reactive power to the grid but also provide well regulated voltage to the critical load. This paper proposes a reactive current injection algorithm for FRT with voltage compensation capability for the critical load. A design guideline is provided considering the increase of apparent power. The proposed algorithm is validated through simulation and experiment.