Reduced Leakage Synchrophasor Estimation: Hilbert Transform Plus Interpolated DFT

Abstract

Synchrophasor estimation is typically performed by means of spectral analysis based on the Discrete Fourier Transform (DFT). Traditional DFT approaches, though, suffer from several uncertainty contributions due to the stationarity assumption, spectral leakage effects and the finite-grid resolution. The present paper addresses these limitations, by proposing a joint application of the Hilbert Transform (HT) and the interpolated DFT (IpDFT) technique. Specifically, the HT enables the suppression of the spectral leakage generated by the negative image of the tones under analysis, whereas the IpDFT limits the effects of spectrum granularity. In order to relax the constraint in terms of measurement reporting latency, the proposed estimator can adopt a window length of 40 ms and yet provides a noticeable estimation accuracy with a worstcase Total Vector Error and Frequency Error equal to 0.02% and 4 mHz, respectively, in steady-state conditions. In this context, the paper discusses the most suitable setting of the algorithm parameters and their effect on spurious component rejection. Moreover, a thorough metrological characterization of the algorithm estimation accuracy and responsiveness with respect to the IEEE Std. C37.118.1 is carried out in order to detect the main uncertainty sources as well as possible room for enhancement. Finally, a comparison with two consolidated IpDFT approaches shows the actual performance enhancement provided by the proposed algorithm.

Accurate phasor and frequency estimation during power system oscillations using least squares

“…and A is given as (see (11)) . The computational window length is considered as 2N + 1 samples with the centre of the window as the reference time.…”

“…Different techniques are available to overcome the errors associated with DFT during changing power system conditions [3][4][5][6][7][8][9][10][11]. A Taylor's expansion-based compensation technique is proposed in [3] to have accurate phasor estimation during dynamic condition of power system.…”

“…Clarke transformation-based DFT algorithm is proposed in [10] to eliminate the estimation errors for a wide frequency range. Both Hilbert transform and IpDFT (HT-IpDFT) techniques are used in [11] to remove the long range spectral leakage effect caused the negative frequency components. The method is compared with available IpDFT algorithms to show the advantages.…”

Applying Directly Modified RDFT Method in Active Power Filter for the Power Quality Improvement of the Weak Power Grid

“…Due to merits such as having no need for load reform, good compensation sampling rate is inconvenient for the control system in practical applications, for many discrete filtering and control parameters should vary with the sampling frequency change to ensure performance and stability. Secondly, in [33,41,42], the interpolating windowed DFT was used to eliminate the errors caused by the spectrum leakage and the picket fence effect. The interpolating algorithm can eliminate errors caused by the picket fence effect, and windowing the signals can reduce the errors produced by the leakage effect.…”

Enhanced Dual-Spectrum Line Interpolated FFT with Four-Term Minimal Sidelobe Cosine Window for Real-Time Harmonic Estimation in Synchrophasor Smart-Grid Technology

“…As per the IEEE Standard C37.118.1a-2014 Phasor Measuring Units (PMUs) are classified as P-class and M-class for fast and accurate estimation of phasors under different abnormal conditions [27]. Recently reduced leakage synchrophasor estimation using Hilbert transform plus the interpolated DFT has been reported in [28]. However, the research is still in progress for developing the unified algorithm for P-and M-class PMUs regarding accuracy and simplicity.…”