A dsPic-based measurement system for the evaluation of voltage sag severity through new power quality indexes

In this paper the authors describe the implementation of a smart sensor based on microcontroller for the extraction of new conceived power quality indexes. The work is carried on starting from the improvement of three indexes presented in a previous work (De Capua et al., 2004) for exhaustively detecting voltage sags. After an examination of the loads which could be more susceptible to the duration or to the depth of the sag, an ANOVA analysis has been conducted in order to evaluate the indexes' sensibility to these characteristics of the sag. Then a new measurement algorithm has been implemented, that is considered more rapid for detecting a sag occurrence. Finally a dsPic-based smart sensor has been realized, to monitor the voltage RMS value and extract the indexes values. These values are transmitted to software located on an external peripheral, through serial communication, for the successive data processing stage.