Dimensioning and control of energy storage systems for renewable power leveling

The objective of this paper was to level out the fluctuations of renewable power generation by applying different energy storage systems. The range of the supplied power was kept within predefined values, thereby achieving a guaranteed minimum and maximum power feed-in. Based on a new integration method, in which renewable energy sources are clustered and combined to a single grid connection point, the energy storage systems were dimensioned in terms of power and capacity. Droop control provided a simple and reliable system operation without the need for communication. By adjusting the droops dynamically, appropriate power sharing between the different energy storage systems could be achieved. Simulation results of a sample wind and photovoltaic configuration showed that the power range could be kept within 5% and 22% of the nominal installed power throughout a whole year. The efficiency of the system including energy storage reached a high value of 88%.