Intraday dispatch, energy storage and the value of re-scheduling in systems with high wind shares

The combination of increasing uncertainty and decreasing flexibility, brought about by growing shares of wind and solar power, may require a re-thinking of the way in which power systems are modelled and operated. In such systems, it is no longer certain that running a single day-ahead schedule, followed by a balancing dispatch, will make best use of the available flexibility for the system, nor will it necessarily yield the least-cost solution. In this paper, we compare how dispatch decisions and operating costs differ between day-ahead-only simulations, and those that use rolling planning to implement intraday dispatch. The nature and cost of the corrective actions carried out during the balancing dispatch, in order to rectify forecast errors in the day-ahead and intraday simulations, are discussed. Moreover, the impact that day-ahead-only and intraday dispatches have on the way in which energy storage is scheduled, and on how its value to the system is calculated are presented.