Voltage Sag Classification with Consideration of Phase Shift

Voltage sag has become one of the major power quality concerns in recent years. To accurately evaluate the voltage sag, it is necessary to obtain its sag type. In this paper, a more generalized voltage sag classification method with consideration of phase shift is proposed compared to the traditional classification method. This new method can be used in the accurate discrimination of sag types. Moreover, the effects of transformers on phase shift are studied on the basis of the proposed classification method.