An optimal hybrid supercapacitor and battery energy storage system in wind power application

In this paper, we optimize a hybrid energy storage system that includes a supercapacitor and a battery storage system for economical dispatching of the intermittent wind power source. In the optimal hybrid energy storage system, based on the technical merits of each storage, the supercapacitor is used to compensate a short-term wind power fluctuation, whereas the battery plays as a long-term one to dispatch a stable power into grid. In order to allocate optimally the power flow between two storages, the supercapacitor power is effectively determined based on a zero-phase low-pass filter, and the battery power commits an average dispatching method to stabilize the power dispatch. To obtain the optimal capacity in hybrid energy storage system (HESS), the smoothing time constant of the zero-phase low-pass filter in each dispatching interval is optimized by using the particle swarm optimization (PSO) method. In order to evaluate the proposed optimal system, a numerical example is performed using a 3-MW wind turbine generator with a real wind speed data.