Low voltage ride through of two-stage photovoltaic inverter with enhanced operational performance

This paper proposed a novel low voltage ride-through (LVRT) strategy applied in two-stage photovoltaic (PV) inverter with enhanced operational performance. The dc-link voltage will be controlled to follow the change of grid voltage to maintain the high modulation ratio operation unlike the conventional control method so that the high frequency harmonic injected into grid can be attenuated significantly. In case where the modulation ratio cannot be decreased, for example, the single-phase voltage drop, the proposed control strategy will alternatively compensate the double-line-frequency ripple of DC-link voltage induced by the unbalanced output power to avoid the operation failure. The theoretical findings were verified by Matlab simulations.