The Ragone plots guided sizing of hybrid storage system for taming the wind power

The fluctuant behaviors of wind power, and so as their effects on the stability of grid, span across different time scales. Hence, single type of electrical energy storage (EES) cannot level the fluctuation effectively. The high energy density sources (e.g. lead-acid batteries) and high power density sources (e.g. supercapacitors) are complementary in merits such as power density and energy density. As a result, the employment of the hybrid EES (HEES) is hoped to level wind power output more effectively. This work proposes a sizing strategy for determining the capacity allocation between the high energy density sources and high power density sources. The traits of this employed strategy are the introduction of energy-power relationships (Ragone plots) of EES as constraints and taking of the minimization of life cycle cost (LCC) of HESS as objective function; which respectively considers the power and energy storage characteristics of EES integrally, and reflects the economic need of renewable energy integration. The analytical process of the sizing strategy is described in detail. A case study for an analysis of specific wind power output, with the types of EES we adopted in project, is illustrated graphically based on the developed programming software platform.