Title :
Dynamic Phasor and Frequency Measurements by an Improved Taylor Weighted Least Squares Algorithm
Author :
Belega, Daniel ; Fontanelli, Daniele ; Petri, Dario
Author_Institution :
Dept. of Meas. & Opt. Electron., Politeh. Univ. of Timisoara, Timişoara, Romania
Abstract :
One of the most accurate phasor estimation procedures recently proposed in the literature is the so-called Taylor weighted least squares (TWLS) algorithm, which relies on a dynamic phasor model of an electrical waveform at nominal frequency. In this paper, an extension of the TWLS algorithm [called generalized TWLS (GTWLS) algorithm] to a generic (not only nominal) reference frequency is described and the accuracies of the returned estimates are analyzed through meaningful simulations, performed in different steady-state and dynamic testing conditions according to the IEEE Standard C37.118.1-2011 about synchrophasor measurement for power systems and its Amendment IEEE Standard C37.118.1a-2014. It is shown that the accuracy of the total vector error (TVE), frequency error (FE), and rate of change of frequency error (RFE) normally decreases as the deviation between the reference frequency and the true waveform frequency decreases. Furthermore, a two-step procedure for accurate estimation of the phasor parameters is proposed. In the first step, the waveform frequency is estimated by a classical interpolated discrete Fourier transform (IpDFT) algorithm. The second step then returns an estimate of the phasor parameters by applying the TWLS algorithm based on the frequency estimate returned by the first step. It is shown that the proposed procedure, called the GTWLS-IpDFT algorithm, can comply with the P-class or the M-class of performances in all the considered testing conditions when an appropriate number of waveform cycles is considered and the most significant disturbances are removed from the analyzed waveform. Finally, uncertainties of the proposed estimators and the IpD2FT algorithm recently presented in the literature are also compared.
Keywords :
discrete Fourier transforms; frequency estimation; frequency measurement; interpolation; least squares approximations; parameter estimation; phasor measurement; FE; GTWLS algorithm; IEEE standard C37.118.1-2011; IpDFT algorithm; RFE; TVE; amendment IEEE standard C37.118.1a-2014; classical interpolated discrete Fourier transform algorithm; dynamic phasor measurement; dynamic testing condition; electrical waveform frequency estimation; frequency error; frequency measurement; generalized Taylor weighted least square algorithm; phasor parameter estimation; power system measurement; rate of change of frequency error; steady-state testing condition; synchrophasor measurement; total vector error; Accuracy; Frequency estimation; Harmonic analysis; Heuristic algorithms; Standards; Testing; Discrete Fourier transform (DFT); error analysis; harmonic analysis; least squares methods; parameter estimation; power system measurements; signal processing; signal processing.;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
DOI :
10.1109/TIM.2014.2385171