Abstract
Waveform distortions are an important issue in distribution systems. In particular, the assessment of very wide spectra, that include also components in the 2–150 kHz range, has recently become an issue of great interest. This is due to the increasing presence of high-spectral emission devices like end-user devices and distributed generation systems. This study proposed a new sliding-window wavelet-modified estimation of signal parameters by rotational invariance technique (ESPRIT) method, particularly suitable for the spectral analysis of waveforms that have very wide spectra. The method is very accurate and requires reduced computational effort. It can be applied successfully to detect spectral components in the range of 0–150 kHz introduced both by distributed power plants, such as wind and photovoltaic generation systems, and by end-user equipment connected to grids through static converters, such as fluorescent lamps.
Highlights
Modern distribution systems are characterized by the simultaneous presence of renewable energy sources, storage systems and loads that actively contribute to the operation of such systems, along with an increasingly complex and performing information and communications technology relevant infrastructure
The level Lmax − 1 instead of Lmax was was chosen to avoid the attenuation effects of the overlap introduced by the canonical discrete wavelet transform (DWT) in chosen to avoid the attenuation effects of the overlap introduced by the canonical DWT in the ranges the ranges of frequencies of interest
The sampling frequency of the waveform was 50 kHz, in order to provide the most appropriate operating conditions for the parametric methods; this choice allowed the detection of the spectral operating conditions for the parametric methods; this choice allowed the detection of the spectral components around the order 2mf, that are the most significant introduced by the inverter pulse-width modulation (PWM) and components around the order 2m, that are the most significant introduced by the inverter PWM and whose amplitudes were fixed up fto 2% of the fundamental, in order to emulate the behavior of the whose amplitudes were fixed up to 2% of the fundamental, in order to emulate the behavior of the PV
Summary
Modern distribution systems are characterized by the simultaneous presence of renewable energy sources, storage systems and loads that actively contribute to the operation of such systems, along with an increasingly complex and performing information and communications technology relevant infrastructure. The IEC standard [14] suggests the use of measurement methods according to Comité international spécial des perturbations radioélectriques CISPR 16-1-2 for the evaluation of the high-frequency spectral content; it states that it is not always possible or practical to apply them. Note that low frequency spectral components and high frequency spectral components can be characterized by different behaviours in the frequency and time domain; low frequency components can be stationary while high frequency are usually not stationary Motivated by these issues, the new contribution of this study is in proposing a novel scheme to analyse electrical waveforms with spectral content up to 150 kHz that provides accurate estimation of parameters (mainly, frequencies, amplitudes and initial phases) of spectral components, while maintaining acceptable computational efforts.
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