Improved Strategy for Dynamic Voltage Restorers Considering Voltage Sag Duration

This paper proposes an improved compensation strategy for dynamic voltage restorers (DVR) to solve the voltage sag problem of different duration. Based on the detailed analysis of the traditional compensation strategies, an improved compensation strategy adapting to voltage sags is proposed, which can gradually switch from pre-sag voltage compensation strategy to minimum energy compensation strategy. This proposed strategy not only avoids the impact of phase angle jumps on sensitive loads, but also achieves long-term voltage compensation. In addition, to further reduce the energy consumption during the compensation process, the load reference voltage is appropriately reduced considering the voltage sag tolerance of loads. The simulation experiment results prove the effectiveness of this strategy in reducing the phase angle jump and extending the compensation time.