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The paper presents a measurement method for power quality analysis in electrical power systems. The method is the evolution of an iterative procedure already set up by the authors and allows the most relevant disturbances in electrical power systems to be detected, localized and estimated automatically. The detection of the disturbance and its duration are attained by a proper application, on the sampled signal, of the Continuous Wavelet Transform (CWT). Disturbance amplitude is estimated by decomposing, in an optimized way, the signal in frequency subbands by means of the Discrete Time Wavelet Transform (DTWT). The proposed method is characterized by high rejection to noise, introduced by both measurement chain and system under test, and it is designed for an agile disturbance classification. Moreover, it is also conceived for future implementation both in a real-time measurement equipment and in an off-line analysis tool. In the paper firstly the theoretical background is reported and briefly discussed. Then, the proposed method is described in detail. Finally, some case-studies are examined in order to highlight the performance of the method. © 1998 IEEE

a b s t r a c tA Wind power forecasting method based on the use of discrete time Markov chain models is developed starting from real wind power time series data. It allows to directly obtain in an easy way an estimate of the wind power distributions on a very short-term horizon, without requiring restrictive assumptions on wind power probability distribution. First and Second Order Markov Chain Model are analytically described. Finally, the application of the proposed method is illustrated with reference to a set of real data.

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This paper presents the results of comprehensive testing, and subsequent detailed analysis of obtained test results, evaluating harmonic and interharmonic performance of PV inverters (PVInvs) for a range of different operating conditions. The presented results indicate significant power-dependent changes in harmonic and interharmonic emissions of tested PVInvs for different supply voltage conditions (presence of voltage waveform distortions and various source impedance values). To correctly quantify and describe these changes inPVInvs' performance, the paper discusses and applies measurement procedures and metrics for evaluating harmonic and interharmonic emission recommended in existing standards, as well as some additional metrics and indicators. For some operating conditions, tested PVInvs significantly increase both harmonic and interharmonic emission, and paper also discusses impact of PVInvs' controls (e.g. maximum power point tracking control) as a possible origin of the interharmonic distortion.

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