Weighted least squares dynamic synchrophasor estimation in the case of harmonically distorted sine-waves

In this paper the accuracies of synchrophasor estimates obtained by two real-valued Taylor-based Weighted Least Squares (TWLS) algorithms are compared when harmonically distorted sine-waves are analyzed. Both algorithms estimate the waveform frequency runtime and only the effect of 2nd harmonic on returned phasor estimates is considered. The first algorithm, called TWLS-RH(2), applies the classical TWLS procedure to the signal obtained by removing the 2nd harmonic from the acquired data. The second one, called TWLS-H(2), applies the TWLS procedure to a signal model containing both the fundamental and the 2nd harmonic. Both algorithms are implemented avoiding the run-time computation of pseudoinverse matrices, so reducing the computational effort. Estimation accuracy is quantified by the parameters suggested in the IEEE Standard C37.118.1-2011 for synchrophasor measurements for power systems, that is, the Total Vector Error (TVE), the Frequency Error (FE), and the Rate-of-change-of-Frequency Error (RFE). Results obtained through computer simulations are reported and compliance with the M-class of performance is investigated.