Drivers for sub-hourly scheduling in unit commitment models

Growing shares of wind and solar power increase the sub-hourly variability of the net load, leading to higher and more frequent ramping. Sub-hourly unit commitment and economic dispatch modelling may be beneficial in certain regions given that it may capture the increase in short-term ramping requirements. However, sub-hourly scheduling comes at a computational cost. This paper questions the extent to which sub-hourly modelling may be of benefit for regions of different size and and different make-up and dispersion of renewable energy resources. Moreover, the individual impact that wind and solar power may have on sub-hourly net-load ramping is assessed in order to determine whether high-resolution modelling is of equal value in high-wind and high-solar power scenarios. It was found that the short-term net-load variability captured by sub-hourly modelling depends on the geographic dispersion of wind and solar resources, the size of the power system and the make-up of its renewable energy portfolio, and therefore, so may the benefits obtained from sub-hourly modelling for a given power system.