Dynamic phasor estimates for power system oscillations and transient detection

Phasors have been considered as an entirely steady state concept. This assumption has shaped most of the algorithms for phasor estimation. This paper breaks that old paradigm by relaxing the phasor concept to a dynamic one: the dynamic phasor, one complex time function with movement freedom. The paper presents the algorithms to approximate the dynamic phasor by a second-order Taylor polynomial and compares them to the traditional one. The algorithms provide n-th order phasors containing not only the samples of the complex envelope, but also its first and second derivatives. These new phasors add new Taylor details to the estimation process, and provide the way of estimating the oscillation and detecting transients. Errors of the order of 10^-4 are achieved with this approximation in narrowband signals over observation intervals of two-cycles