Turbulent-like behavior of renewable energies: Its effect on the stability of the power grid
The main renewable energy sources including wind and solar, are highly influenced by weather events and may ramp up or down abruptly in time scales of seconds to minutes. To characterize the stochastic properties of the wind and solar energy sources, we study their spectra and probability density function (PDF) of power increments. We find that the power spectra computed from high frequency time series (with sample rate 1 Hz) of solar irradiance, wind velocity and wind power exhibit a power-law behavior with an exponent ∼ −5/3 (Kolmogorov exponent), indicating that they are turbulent-like sources. To characterize and parametrize the short time fluctuations of these renewable energies a two-points statistics analysis based on increment statistics has been chosen and the analysis show that these renewable resources are severely intermittent. This means that the shapes of increment PDFs, depart largely from the normal (Gaussian) distribution, as they possess exponential-like fat tails (independent of the geographical position and size of the field), with high probability of ’extreme events’.