Combining Steady-State Accuracy and Responsiveness of PMU Estimates: An Approach Based on Left and Right Taylor–Fourier Expansions

Modern power systems are characterized by fast dynamics, due to the massive presence of power electronics-based converters. In this scenario, the present article proposes an approach for measuring synchrophasor, frequency, and rate of change in frequency (ROCOF) that allows to effectively cope with abrupt transients. The method is based on Taylor-Fourier models, which typically consider an observation interval centered on the reporting instant. In this article, the Taylor expansion is performed on asymmetric windows, which look either at the left or at the right of the measurement instant. A reconstruction algorithm enables a seamless blend between left and right estimates that, while preserving accuracy during steady-state or slowly varying conditions, leads to an exemplary behavior in amplitude and phase step tests, also in the presence of wideband noise. In particular, an M-class compliant estimator is designed to highlight the potentialities of the proposed approach. Zero synchrophasor, frequency, and ROCOF response times are obtained, since steady-state accuracy limits are never exceeded in the presence of step variations. From a different point of view, the proposed technique does not return invalid estimates, thus it is capable of also tracking abrupt transitions.