An advanced control strategy of PV system for low-voltage ride-through capability enhancement

• No additional hardware is required.
• The coordinated LVRT control strategy of the active and reactive power.
• The active power control can increase the energy captured from the PV array.
• The reactive power control can help the voltage recovery during the grid faults.
• A feed forward compensation is applied to smooth the DC-link voltage fluctuation.

This paper presents a novel control strategy of the two-stage three-phase photovoltaic (PV) system to improve the low-voltage ride-through (LVRT) capability according to the grid connection requirement. With the help of the new strategy, the PV array can generate active power as much as possible according to the depth of the grid voltage dip and the power rating of the grid inverter to keep power balance between the two sides of the inverter by operating in different modes. It is worthy of special mention that the proposed strategy can ensure the reactive power support when a low voltage fault occurs at the point of common coupling (PCC) without additional device. Besides, the new control method introduces a feed forward compensation reflecting the instantaneous current injecting into the DC-link from the PV array to smooth the DC-link voltage fluctuations during the grid fault. The effectiveness of the proposed control strategy has been demonstrated through various simulation scenarios. Compared with the conventional protection, the proposed control strategy can not only enhance the LVRT capability of the PV system, but also provide grid support through the active and reactive power control.