Performance of synchrophasor measurements provided by the Weighted Least Squares approach

In this paper the performances of the synchrophasor estimators provided by the Weighted Least Squares (WLS) algorithm based on the cosine windows are analyzed under steady-state, dynamic, and transient conditions. Two-, three-, and four-cycle observation interval lengths are considered. Specifically, steady-state accuracy is assessed by considering the effect of both off-nominal frequency offsets and harmonics. Conversely, dynamic conditions are modeled as sinusoidal amplitude and/or phase modulations, or linear frequency ramps. According to the IEEE Standard C37.118.1-2011 about synchrophasors for power systems, the Total Vector Error (TVE) is employed as accuracy parameter and the achieved results are compared with the maximum allowed values specified in the Standard for P- or M-class compliance. Finally, estimator response time to amplitude or phase steps is analyzed. The achieved results allow an overall assessment of the WLS synchrophasor estimator performances.