Power quality indices for aperiodic voltages and currents

Abstract-The authors show that the use of high-resolution spectrum estimation methods instead of Fourier-based techniques can improve the accuracy of measurement of spectral parameters of distorted waveforms encountered in power systems, in particular the estimation of the power quality indices (such as inter/harmonic groups and subgroups) .The comparison of the frequency and amplitude estimation error, based on numerical simulations is presented. Presentation of selected power quality indices is then followed by comparison of estimation error in the case of application of FFT-based algorithms and parametric methods.Investigated waveforms are typical for dc arc furnace plant. MUSIC and ESPRIT high-resolution methods are used to analyze waveforms in a supply system of a DC arc furnace. Reduction of variance of results is achieved by using robust averaging procedure (winsorized mean).

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“…The main application of spectral components in the field of Power Quality refers to the calculation of waveform distortion indices [2,3].…”

Section: Power Quality Indicesmentioning

confidence: 99%

Power Quality Evaluation using Advanced Spectrum Estimation Methods

Leonowicz

Łobos

2006

2006 International Conference on Power System Technology

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“…Based on the WDFT the Short Term Harmonic Distortion (STHD) index can be defined for each window and calculated as [7]:…”

Section: Index Definitionmentioning

confidence: 99%

“…One of the most commonly used index is the total harmonic distortion (THD) [2], that is based on harmonic components of currents or voltages that are periodic signals. Thus, the condensation of information associated with signals that contain aperiodic, quasi periodic, or non integer multiples of power frequency terms may be misinterpreted, which happens in many industrial loads [7].…”

Section: Introductionmentioning

confidence: 99%

Hybrid Power Quality Harmonic Indices

Lima

Reinieri²,

Magnago³

2005

REPQJ

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Abstract:In this paper the most frequently used power quality indices are reviewed, and an hybrid algorithm for power quality index determination is proposed. The algorithm is based on the wavelet transform and is not limited to stationary waveforms. The wavelet transform is used to detect, classify the signals and to calculate the Total Harmonic Distortion (THD). In cases where the wavelet transform is not applicable, its detection capability allows to identify the signals and the choice of another index is done to calculate the harmonic distortion. Advantages of the new index are highlighted and its performance is compared with the traditional set of indices.

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“…The resolution of these methods is to high degree independent on signal-to-noise ratio and on the initial phase of the harmonic components. The author argues that the use of high-resolution spectrum estimation methods instead of Fourier-based techniques can improve the accuracy of measurement of spectral parameters of distorted waveforms encountered in power systems, in particular the estimation of the power quality indices [6].…”

Section: Introductionmentioning

confidence: 99%