Reviews on characteristic of renewables: Evaluating the variability and complementarity

Variability and complementarity of the renewables are the most crucial characteristics for the reliability and economics of a highly penetrated power system. Better quantification and understanding of these characteristics are the foundations to achieve a high penetration of renewables. Many efforts have been exerted on the operating and planning of a power system with renewables rather than the essential features of the renewables. To fill the research gap, this review summarized the indexes and methodologies to evaluate the variability and complementarity of the renewables. Firstly, indexes to measure the temporal variability and spatial complementarity are described and formulated. For the complementarity, indexes about the intuitive nature of the renewables and its capacity value to a power system are summarized. And then, methodologies for modelling and analyzing the ramp of the renewables are summarized and discussed, including (a) parameterization and definition of a ramp, (b) ramp detection, and (c) ramp forecasting. This review would give a comprehensive view of the characteristics of the renewables in a quantitative manner and is significant to a future power system with large renewables.