A low voltage ride-through technique for grid-connected converters of distributed energy resources

With more and more distributed energy resources (DERs) being connected to the grid through interface converters, the utility requires the DER generation system to remain grid-connected during voltage sags to ensure the operating stability of the AC power system. These low voltage ride-through requirements also suggest that the DER generation system injects reactive power to support grid voltages. In this paper, a positive and negative sequence reactive current injection method is proposed to meet the low voltage ride-through requirement. Its operation principle and control method are explained and analyzed. Experimental results are presented to validate the effectiveness of the proposed method. Comparisons of the proposed method and other low voltage ride-through techniques are also presented.