Detection of Sags, Swells, and Interruptions Using the Digital RMS Method and Kalman Filter with Fast Response

A fast detection algorithm for sags, swells and interruptions is developed in this paper. The proposed method is based on the combination of the digital RMS technique and the Kalman filter. The union of these methods allows using the main advantages of Kalman filter and RMS techniques and helps rejecting the extreme drawbacks of Kalman filter. The proposed approach can be applied to dynamic voltage restorers, dynamic sag correctors, uninterruptible power supplies, and other compensation topologies for power quality improvement