Capacity Optimization and Operational Strategy of the Wind-Energy Storage Hybrid Systems for Energy Dispatching

Wind power output fluctuation brings a lot of negative influences on utility grid as a result of increasing penetration level of wind power. A supercapacitor-battery hybrid storage system is proposed to balance the wind power and planned export power of the wind farm. Firstly, using empirical mode decomposition(EMD), the difference between planned export power and the original wind power(unbalanced power, UP) is analyzed to obtain the intrinsic mode functions(IMFs). Secondly, a mathematic method is then developed to confirm a so-called gap frequency to decompose the unbalanced power into high and low frequency components based on the concept of minimum overlap energy. Unbalanced power smoothing is then achieved by dispatching the powers of supercapatiors and batteries to compensate the high- and low-frequency IMFs according to the characteristics of supercapacitor and batteries respectively. Finally, based on a set of data acquired from an existing wind farm, a hybrid storage system(HSS) is designed aiming at minimizing the capital cost and also can make wind power approach the planned export power of the wind farm in a great extent, numerical analysis verifies the efficiency of the developed method.