A Novel Method for Despiking Spectra from Synchrophasor Measurements

Periodic corrections to phase angle estimates are performed inside PMUs to compensate for the internal clock drift with respect to the GPS clock that PMUs experience. In the frequency domain, this results in narrow bandwidth peaks referred to as spikes. The amplitude of these spikes depends on the amount of correction introduced and, consequently, the spikes' amplitude can sometimes be larger than the actual power system's dynamic system response under ambient excitation. These spikes result in spurious poorly damped modes in data-driven small signal analysis. To address this issue, this work proposes a novel approach that removes these spikes from the phase angle signal. The proposed approach is based on a technique for baseline estimation combined with the Whitaker-Hayes method for despiking spectra. The effectiveness of the proposed approach is demonstrated on PMU data from Dominion Energy's substations with significant internal clock issues.