Energy storage for improvement of wind power characteristics

Abstract

1--Results from simulation of the influence of energy storage on the variability and availability of wind energy are presented here. Simulations have been done using a mathematical model of energy storage implemented in MATLAB. The obtained results show the quality improvement, of energy delivered by a combination of wind and energy storage, in relation to the size of the energy storage. The introduction of storage enables suppression of wind power fluctuations up to a timescale proportional to the storage energy capacity. Energy storage cannot provide availability of wind power at all times, but it can guarantee that a certain fraction of average wind power will be available within a given timeframe. The amount of storage energy capacity necessary for significant improvement of wind power availability, within a given period, is found to be approximately 20% of the energy produced in that period. The necessary storage power is found to be approximately equal to the average wind power of that same period. Index terms--Energy storage, Energy management, Wind energy, Power systems, Power system stability, Simulation I. INTRODUCTIONWind power is a rapidly growing and very promising renewable source of electric energy. But with a large fraction of wind power in the electric power system, the stochastic nature of wind power will start to play a significant role. A controllable and non-fluctuating supply is needed to fully secure availability, but this cannot be achieved with wind power alone.Introducing an energy storage element in relation to a wind power plant changes the spectrum and statistical distribution of the output power. A gradual increase in the amount of storage (power and energy) associated with a wind power plant, will make the output more controllable, predictable and less variable.A variety of energy storage technologies with diverse properties and attributes are available. In order to determine, which storage technologies that are most relevant in connection to wind power the required power-and energy levels of storage must be determined. The aim of using energy storage is to improve the overall quality of wind energy, but the actual improvement will always be subject to an objective judgment.Storage technologies and their ability to create actual value in terms of production cost reductions have been analyzed in various ways, [9], [10], [11] and [12]. The outcome of such an analysis depends on a large number of parameters and assumptions. It therefore seems relevant to try to obtain some C.N. Rasmussen is Associate Professor at the Technical University of Denmark, Department of Electrical Engineering. DK-2800 Lyngby, Denmark. cnras@elektro.dtu.dk basic measures of the wind energy quality improving effect of a given amount of energy storage.What is presented here is the result of an effort to determine the energy quality improving effects of energy storage on wind power, on medium timescales, from minutes to weeks. Three possible indicators of a general improvement in the quality of wind ene...

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