Novel battery / supercapacitor hybrid energy storage control strategy for battery life extension in isolated wind energy conversion systems

In most autonomous off-grid wind energy systems it is necessary to store energy at times when there is an excess and release it at times when there is a deficit. Typically, for small off grid applications such as rural electrification, this is achieved using a conventional battery and in many cases a VRLA (valve regulated lead acid) battery. Replacement costs factor significantly into the life-cycle costs of battery systems and one of the shortcomings of the conventional battery is its relatively short cycle life. This paper proposes a novel control methodology by which a supercapacitor / battery hybridised energy storage system can be implemented to yield a benefit in terms of reduction in quantifiable aging factors that lead to the reduction in battery life cycle.