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Modern power frequency converters generate not only a wide spectrum of characteristic harmonics but also non-characteristic harmonics and interharmonics. Interharmonics are considered more damaging than ordinary harmonic components of the distorted signals. Usual tools of the harmonic analysis based on Fourier transform assume that only harmonics are(More)
The diagnosis of cryptococcal infection was established in 3 patients with AIDS. Infection was meningo-encephalic in all and presented a violent outset. The chemical characteristics of the CSF were normal. Detection of cryptococcal antigen, presence of encapsulated yeast forms revealed by india-ink staining and positive cultures allowed a definitive(More)
— Modern frequency power converters generate a wide spectrum of harmonics components. Standard tools of harmonic analysis based on the Fourier transform assume that only harmonics are present and the periodicity intervals are fixed, while periodicity intervals in the presence of interharmonics are variable and very long. A novel approach to harmonic and(More)
– IEC Standards characterize the waveform distortions in power systems with the amplitudes of harmonic and interharmonic groups and subgroups. These groups/subgroups utilise the waveform spectral components obtained by using a fixed frequency resolution DFT; while this choice represents a good compromise among different aims such as the need of good(More)
—This paper considers applying nonparametric and parametric methods for the calculation of the time–frequency representation of nonstationary signals in power electronics. A space phasor is proposed as a complex representation of a three-phase signal to calculate the spectrum of positive-and negative-sequence components. The developed methods are tested(More)
– A novel approach to harmonic and interharmonic analysis, based on the " subspace " methods, is proposed. Min-norm harmonic retrieval method is an example of high-resolution eigenstructure-based methods. The Wigner-Ville representation was also tested for time-frequency analysis of electric signals. The high-resolution methods do not show the disadvantages(More)
In this paper time-frequency methods have been investigated for complex investigations of transient states in wind power plants. Application of parallel processing in time and frequency domain brought new findings in description of wind power plants working under transient conditions. Proposed algorithms represents standard Short-Time Fourier Transform(More)
A new method of fault analysis and detection by signal classification in industrial frequency converters is presented. The Wigner-Ville time frequency distribution is used to produce the representation of the signal and the probabilistic neural network as a classifier. The accuracy and robustness of the proposed method is investigated on signals obtained(More)