Synchrophasor Estimation Using Prony's Method

Prony's method can be used as a dynamic phasor estimator. It can be regarded as the adaptive approximation of its complex exponential signal model to the dynamic phasor of an oscillation over a finite time interval. Equipped with a closed signal model, it is possible to implement it in one cycle. In its first adaptive stage, it estimates the best damping and frequency for its signal model; and, in the second one, the best phasor over the considered time window. This paper compares the performance of Prony's method with that of the very well-known one-cycle Fourier filter. With a higher flexibility, due to its adaptive nature, Prony estimates improve the Fourier ones under oscillation conditions. The Fourier filter can be considered as a static subclass of the Prony filters. With its static signal model, it is unable to accurately follow oscillations when the frequency fluctuates. Additionally, the Prony filter, together with its phasor estimates, provides instantaneous estimates of damping and frequency, corresponding to the first derivative of amplitude and phase, which are very useful to assess the power system stability. Finally, by being implemented in one-cycle windows, and its good rejection of the dc or exponentially attenuated components, it can also be used in protection applications.