Classification and characterization of three phase voltage dips by space vector methodology

A new method is presented to identify and to characterize voltage dips measurements from power quality survey. This method is based on the space vector transformation, which describes the three power system voltages by one complex variable - the space vector. Its representation in the complex plane is used to classify voltage dips. Indeed, for a not disturbed system voltages, the space vector represents a circle in the complex plane with a radius equal to the nominal voltage. It follows the same shape for balanced dips, but with a smaller radius. For unbalanced dips, this shape becomes an ellipse with parameters depending on the phase(s) in drop, dip severity and phase angle shift. Further, space vector characteristics and zero sequence voltage are used for a more precise determination of the voltage dip type. The developed algorithm for voltage dips classification is validated by EMTP simulations and measurement data