Uncertain models of renewable energy sources

To quantitatively depict the statistical regularity of uncertain renewable energy power uncertainty, this study not only defines the concept of statistical forecast uncertainty but also proposes a δ function model system to illustrate the relationship between statistical forecast uncertainty and look‐ahead forecast time. First, δ functions are employed to describe the uncertainties in the wind and solar power generations. Second, all power grid δ functions are combined into a δ sum function with multiple time coefficients. Third, the δ sum function is then turned into an equivalent δ function with a single time constant via order reduction. Finally, the equivalent δ function is finally turned into a profile δ function by ascertaining the single time coefficient function. The amplitude and time constant are the two numerical characteristics of the δ function that characterise the statistical regularity of uncertain renewable energy power uncertainty. Two propositions that guarantee the rigorousness of the proposed δ function model system are further proposed and illustrated.