A Test For Non-Stationarity Of Synchrophasor Measurements

Synchrophasor measurements are becoming more widely used in control centers. These measurements under ambient power system conditions are frequently modeled as stochastic processes. Statistical stationarity, an assumption made for mathematical expediency of signal processing tools, is almost never completely satisfied in practice. Cogently, a wides-sense-stationarity assumption is made to leverage the powerful techniques developed over recent decades for power system signal analysis. In reality, typical power system operation violates this assumption quite often. Therefore, a detailed study for time-varying statistics of synchrophasor measurements is needed to better understand true system characteristics. The work presented here applies an evolutionary spectrum based non-stationarity test to synchrophasor measurements. The test can provide some useful information such as, overall wide-sense-stationarity of a set of synchrophasor measurements, how long the measurements maintain wide-sense-stationarity, what are the frequency components that violate the assumption, statistical similarity of two or more sets of measurements, etc.