Zusammenfassung
The irradiance fluctuations and the subsequent variability of the
power output of a PV system are analysed with some mathematical tools
based on the wavelet transform. It can be shown that the irradiance
and power time series are nonstationary process whose behaviour resembles
that of a long memory process. Besides, the long memory spectral
exponent alpha is a useful indicator of the fluctuation level of
a irradiance time series. On the other side, a time series of global
irradiance on the horizontal plane can be simulated by means of the
wavestrapping technique on the clearness index and the fluctuation
behaviour of this simulated time series correctly resembles the original
series. Moreover, a time series of global irradiance on the inclined
plane can be simulated with the wavestrapping procedure applied over
a signal previously detrended by a partial reconstruction with a
wavelet multiresolution analysis, and, once again, the fluctuation
behaviour of this simulated time series is correct. This procedure
is a suitable tool for the simulation of irradiance incident over
a group of distant PV plants. Finally, a wavelet variance analysis
and the long memory spectral exponent show that a PV plant behaves
as a low-pass filter.
Nutzer