Use of Ultracapacitors and Batteries for Efficient Energy Management in Wind-Diesel Hybrid System

The interconnection of the wind generator (WG) and the diesel generator (DG) induces some interactions on the common coupling point. These interactions are studied in this paper with the aim of identifying the system limits in performance and proposing an alternative solution. Due to the fast fluctuations of the WG and the DG slow dynamics, ultracapacitors and batteries are used for improving the hybrid system performances and reducing the fuel consumption. The dc-bus voltage is controlled by the diesel engine while providing a smoothed current. To ensure optimized life cycle cost and performance, a lifetime-estimation-based method is proposed. In this method, a rainflow counting method is applied to size the storage devices by taking into account the actual conditions of the system operation. The experimental test bench is designed in a reduced scale. Some simulations and experimental results are presented and analyzed.