PMU Measurement Accuracy Awareness Provided by Power Quality Indices

Phasor measurement units (PMUs) are measurement devices capable of monitoring voltage and current phasors, frequency and rate of change of frequency considering an absolute time reference for phase angle evaluation. The absolute reference is provided by coordinated universal time (UTC) through global navigation satellite system signals and distributed to PMUs through appropriate protocols or dedicated receivers. The quality level of time synchronization is directly related to the quality of the measurement as it affects the phase-angle evaluation. This relationship is taken into account and communicated through dedicated fields in the data packets containing the PMU measurements. However, other factors can affect the quality of the measurements, such as changes in the signal or the presence of disturbances. These influencing factors, or, in general, the operating conditions in which the PMUs are immersed while providing measurements, are typically not evaluated in real-time. For this purpose, a real-time estimation of the PMU measurement conditions is presented in this paper. Such estimation is carried out on the basis of the information provided by power quality indices. The goal is to accompany measured quantities with information on the measurement quality that can be helpful for proper use of the collected measurements.