Metrological characterization of algorithms adopted for voltage dip measurement

This paper analyzes accuracy of algorithms commonly adopted in instrument devoted to the detection and the characterization of voltage dips (also called sags). This analysis is particularly interesting because the results of dip measurements are utilized for calculation of severity levels and the site index assessment that are parameters adopted in determination of quality level of power supply but also in developing planning and design criteria of new electrical power grid or for selecting equipment with proper intrinsic immunity. Anyway there is a certain degree of freedom is left to instrument manufacturers (f.i. the choice of dip detection algorithm) and it can be found that, different instruments significantly disagree in some actual measurements. The paper analyzes most diffused dip detection algorithms presenting the introduced systematic deviations in event characterization. The obtained results are aimed to be taken into account and applied to performance verification of a commercial dip monitoring instrument.