Minimum current injection method for single-phase dynamic voltage restorer

In this paper, a simple limited current injection method is proposed for the operation of DVR under grid voltage deep sags. The proposed method considers the impact of couplings between load power factor and grid voltage sag depth to calculate the minimum injection current that can preserve satisfaction grid voltage compensation under deep sags, Accordingly, the over current tripping off problems for DVR operating during deep sags can be significantly alleviative. In addition, the approach in this paper has the capability to simultaneously compensate grid voltage harmonics without using additional efforts. Verification results are provided to validate the correctness of the proposed system.