Voltage dip detection and power system transients

Recently developed power quality mitigation equipment, like the static transfer switch, needs methods for fast and reliable detection of voltage dips. Such a detection scheme must be able to detect a voltage dip as fast as possible and be immune to other types of disturbances. In this paper, the authors address the problem of voltage dip detection regarding Kalman filtering, the characteristics of fault-induced voltage dips and other power system disturbances. They investigate how the voltage dip characteristics influence the speed of detection and show that disturbances other than fault-induced dips could trigger a detection scheme. Special attention is given to trans former-related events. Their characteristics are presented using measurements. Kalman filtering modelling issues are discussed. Statistics on the characteristics of fault-induced dips and transformer events are presented from medium voltage networks.