Localized Spectral Analysis of Fluctuating Power Generation from Solar Energy Systems
- PDF / 935,336 Bytes
- 8 Pages / 600.03 x 792 pts Page_size
- 16 Downloads / 165 Views
Research Article Localized Spectral Analysis of Fluctuating Power Generation from Solar Energy Systems Achim Woyte,1 Ronnie Belmans,2 and Johan Nijs2, 3 1 3E
sa, Rue du Canal 61, 1000 Brussels, Belgium Elektrotechniek, Katholieke Universiteit Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium 3 Photovoltech sa, Grijpenlaan 18, 3300 Tienen, Belgium 2 Departement
Received 27 April 2006; Revised 20 December 2006; Accepted 23 December 2006 Recommended by Alexander Mamishev Fluctuations in solar irradiance are a serious obstacle for the future large-scale application of photovoltaics. Occurring regularly with the passage of clouds, they can cause unexpected power variations and introduce voltage dips to the power distribution system. This paper proposes the treatment of such fluctuating time series as realizations of a stochastic, locally stationary, wavelet process. Its local spectral density can be estimated from empirical data by means of wavelet periodograms. The wavelet approach allows the analysis of the amplitude of fluctuations per characteristic scale, hence, persistence of the fluctuation. Furthermore, conclusions can be drawn on the frequency of occurrence of fluctuations of different scale. This localized spectral analysis was applied to empirical data of two successive years. The approach is especially useful for network planning and load management of power distribution systems containing a high density of photovoltaic generation units. Copyright © 2007 Achim Woyte et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1.
INTRODUCTION
Most applications of wavelet decomposition in the field of electrical power engineering concern the analysis of load profiles [1, 2], the electrical power supply quality and its measurement [3–6], and also protection issues [7]. The primary objective in most of these applications is the isolation of transient phenomena from steady-state phenomena in the electricity grid, usually the fundamental 50 or 60 Hz component and its harmonics [7]. A new area of application is presented with the analysis of time series of solar radiation in order to quantify the intermittent power supplied by solar energy systems, mainly photovoltaics (PV). In this case, the power supply quality can be deteriorated as a consequence of power variations due to a varying cloud coverage of the sky. This leads to variable power output of the PV system, which introduces voltage dips to the distribution system. Typically these fluctuations persist seconds up to a fraction of an hour. The intermittent nature of solar radiation is one of the drawbacks of the large-scale application of photovoltaics. With a high density of PV generation in a power distribution grid, irradiance fluctuations introduced by moving clouds can lead to unpredictable variations of node voltages and power and finally cause a breakdown of distribution grids.
Distribu
Data Loading...
