Optimal sizing of energy storage systems: a combination of hourly and intra-hour time perspectives

Storage technology is a key enabler for the integration of renewable energy resources into power systems because it provides the required flexibility to balance, the net load variability and forms a buffer for uncertainties. A solution for sizing of energy storage devices in electric power systems is presented. The considered planning problem is divided into two time perspectives: hourly and intra-hour intervals. For the intra-hour time horizon, the algorithm determines the optimal size of the energy storage devices to provide the adequate ramping capability for the system. This ramping capability guarantees the system ability to follow the load in the intra-hour intervals, as well as to alleviate short-term wind generation and load fluctuations. In the hourly time scale, the optimal size of the storage is determined with respect to having a sufficient generation capacity to support the loads. A 6-bus test power system is studied to show the effectiveness of the proposed algorithm.