Analysis of Periodic Clock Errors in Synchrophasor Ambient Data

Synchrophasor data from real world power systems are exposed to numerous adverse cyber-and-physical conditions that can negatively impact its fitness for use in PMU applications. While the most significant impairments like GPS signal loss, instrument transformer failures, data drop-offs, etc., have been studied in the literature, it is challenging to address other more complex nuisances that impact data quality. This is the case of differences in how clock synchronization, time-disciplining and phasor estimation is performed by different PMU vendors, that while frequently disregarded, have important implications on the data’s fitness for use in PMU applications. In particular, ambient data applications, which have increasingly become a focus for tracking grid performance indicators, are extremely sensitive to periodic clock errors. Using synchrophasor and waveform data from Dominion Energy’s power system, this article gives an in-depth analysis of the substaintial effect of seemingly minor device clock errors on measurement signal content.