Impact of synchrophasor measurement uncertainty on detecting voltage stability margin in power systems

Phasor Measurement Units (PMUs) provide synchronized phasors (synchrophasors) of voltage and current, usually together with measurements of frequency and rate of change of frequency. One of the main characteristics of the PMUs is to provide synchronized and accurate measurement of all these quantities with a reporting rate much higher than that of traditional measurement systems. Also for this reason, PMUs have been shown have a lot of potential in different applications in power systems, including voltage stability monitoring. As the uncertainty of the PMUs impacts the monitoring performance, it is necessary to perform a thorough analysis before the monitoring system can be designed and its outcome used for control, particularly of critical applications. Hence, this paper presents the analysis of the effect of the uncertainty introduced by the PMUs, on a global method for voltage instability detection. In particular, the Load Margin Index based on wide-area phasor measurements is considered as reference method. Several tests and results obtained on the IEEE 39-bus system are presented and discussed.