The invention provides a low-
voltage ride through (LVRT)
control system of a
photovoltaic inverter and a method thereof. The
system comprises a
solar cell panel, a
photovoltaic inverter, a
power grid and a controller, wherein the
solar cell panel, the
photovoltaic inverter and the
power grid are sequentially connected; and the controller is respectively connected with the photovoltaic
inverter and the
power grid. The
system and the method have the advantages that 1) when the power grid breaks down to cause power
grid voltage balance sag, good dynamic response is provided, and grid-connected current can be steadily outputted by three phases of
current sharing of the photovoltaic
inverter; and 2) in unbalanced
voltage sag, the positive and negative sequence
voltage influence of the power grid can be eliminated by the
control system, only the positive sequence current component is outputted, and the three-phase
current sharing is ensured and has a lower
harmonic component, so that the loss caused by the faults of the power grid is reduced, and the power supply reliability of the power grid is improved. The special situation of the unbalanced power grid is supported by the
system, and the stable operation of the normal three-phase
current sharing is guaranteed.