Robust control of two-stage photovoltaic inverter for unbalanced low voltage ride-through operation

Since low voltage ride-through (LVRT) was proposed, its improvements have never been stopped, especially the improvements for operation under unbalanced faults. In this paper, an overall control strategy is proposed to solve the problem that the output current quality and dc-link voltage quality cannot be guaranteed at the same time. For this propose, a current control method is employed to guarantee the symmetrical and sinusoidal output current and a dc-link voltage regulation method is proposed for two-stage PV inverter to improve the performance of dc-link voltage either. The Matlab simulation results prove the effectiveness of proposed method.