Research on LVRT Based on Maximum Power Point Tracking Strategy

The primary researches are mainly of two measures focused on a suitable control strategy and an additional hard-ware circuit to enhance the LVRT capability of photovoltaic (PV) system. In this paper, according to the Grid Integration Technical Regulation of PV station published by state grid crop, a hybrid control method composed of software and hardware are presented to enhance the capacity of low-voltage ride-through (LVRT). With the action of the hybrid control strategy, the PV system, in the fault condition, can quickly suppress the fault current and fluctuation of its DC-link. The method also can effectively improve the grid voltage sag and significantly reduce the adjustable range of power factor according to the depth of the grid voltage dip. Therefore, the transient performance of PV system is significantly strengthened. The simulation model of a two-stage three-phase PV system is built in MATLAB and the validity of the proposed method is demonstrated through the different scenarios.