A Fast and Reliable Switching Strategy for Parallel Dynamic Voltage Restorers

ABSTRACT Ensuring a smooth voltage transition during dynamic voltage restorers (DVRs) switching is critical for addressing voltage sags, particularly for sensitive loads. Existing techniques often induce load voltage fluctuations when bypass thyristors are switched, leading to prolonged response times or even failed transitions due to incorrect current polarity detection. To address these issues, this paper establishes a mathematical model of the DVR during switching, analyzes conventional switching methods and their operating mechanisms, and identifies key factors affecting response time. Based on this analysis, a fast and reliable switching strategy (FRSS) is proposed. The presented thyristor turn‐off method significantly reduces response time while ensuring reliable operation despite current sampling errors in adverse conditions. Moreover, it effectively suppresses load voltage spikes during DVR cutout. A 50‐kW parallel DVR prototype is developed, and experimental results validate the effectiveness and robustness of the proposed commutation strategy.