A strategy for suppressing the second harmonic of output power for photovoltaic grid-connected inverters with low voltage ride-through

When an unbalanced voltage drop occurs in the grid system , output power of distributed photovoltaic grid-connected system will generate second harmonics. In order to suppress the second harmonic, a new low voltage ride-through control strategy is proposed, which can adjust the harmonic suppression target according to the degree of voltage drop. This strategy can suppress the second harmonic of active power when the voltage drop is low, and suppress the second harmonic of reactive power when the voltage drop is large. The control strategy is simulated in MATLAB, and the results testified its effectiveness.