Study of fuzzy based control algorithm for dynamic voltage restorer

Voltage sags appear in a short time period between half a cycle and 1 minute. The control system of a dynamic voltage restorer should have a fast yet smooth response in detecting, synchronizing, and injecting the appropriate level of compensating voltage to protect sensitive electrical components against probable damages. Moreover, an optimal strategy for the energy storage usage is essential to achieve an extended lifetime for it. This paper proposes an improved control algorithm for a dynamic voltage restorer to address these two issues. The proposed control system significantly reduces the detection and synchronization times during voltage sag by combining the fuzzy logic and the enhanced phase lock loop concepts. Furthermore, an auxiliary control system is introduced to manage the injection strategies during different types of faults to extend the lifetime of the battery.