Abstract
Power quality (PQ) disturbances are becoming an important issue in smart grids (SGs) due to the significant economic consequences that they can generate on sensible loads. However, SGs include several distributed energy resources (DERs) that can be interconnected to the grid with static converters, which lead to a reduction of the PQ levels. Among DERs, wind turbines and photovoltaic systems are expected to be used extensively due to the forecasted reduction in investment costs and other economic incentives. These systems can introduce significant time-varying voltage and current waveform distortions that require advanced spectral analysis methods to be used. This paper provides an application of advanced parametric methods for assessing waveform distortions in SGs with dispersed generation. In particular, the Standard International Electrotechnical Committee (IEC) method, some parametric methods (such as Prony and Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT)), and some hybrid methods are critically compared on the basis of their accuracy and the computational effort required.
Highlights
Significant modifications are taking place in distribution systems as they move toward the future use of smart grids (SGs)
The high-frequency emissions basically are due to the photovoltaic system (PVS) inverter and they are due to the pulsewidth modulation (PWM) technique that is used
The sampling rate was 100 kHz in order to provide the most appropriate operating conditions for the parametric methods that were used so that they could provide estimates of the spectral components around the order 2mf, which are the most significant introduced by the aforesaid type of PWM and whose amplitudes were fixed up to 12% of the fundamentala
Summary
Significant modifications are taking place in distribution systems as they move toward the future use of smart grids (SGs). The high-frequency emissions basically are due to the PVS inverter and they are due to the pulsewidth modulation (PWM) technique that is used These emissions are always present during the power production of the system, and they are null when the inverter is turned off; for the current waveform of a single photovoltaic plant in ideal operating conditions, the amplitudes of these high-frequency spectral components are higher than those of the low-frequency spectral components [18,19]. In this scheme, the emission of spectral components is caused mainly by the static converter, but unlike the previous case, there is no direct influence on the airgap flux, so the spectral content of the waveforms at the PCC is less. A given sequence of sampled data x(n) of size N is approximated by [37]: x^ðnÞ
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