Value of variable sources on power systems

The author examines the value of variable power sources, such as wind and tidal energy, on electricity supply systems. A statistical approach is developed for assessing the operational impacts, including thermal plant cycling and operating reserve requirements. It is shown from this analysis that operating penalties are negligible when the capacities involved are small relative to the overall system, as long as reserve is optimally scheduled. Simplified equations are also presented for estimating operating penalties from limited data. The author then discusses the impact of variable sources at higher system penetrations, and uses modelling studies to examine the possible economic value of wind energy up to very high capacities. Finally, the author examines the contribution of variable sources to system reliability and the nature of capital savings arising from this