Hybrid energy storage approach for renewable energy applications

•Overview of the innovative field of hybrid energy storage systems (typical applications, storage coupling architectures and energy management concepts).•Discussion of an hierarchical control- and optimization-based energy management concept (for the example of a fuel cell − battery − hybrid system).•Discussion of hybrid energy storage configurations suitable for the application in decentralized PV-systems.•Presentation of a principle approach for the power flow decomposition based on peak shaving and double low-pass filtering.•Description of structure, functionality and components of a modular experimental test-bed for hybrid energy storage systems.

The paper gives an overview of the innovative field of hybrid energy storage systems (HESS). An HESS is characterized by a beneficial coupling of two or more energy storage technologies with supplementary operating characteristics (such as energy and power density, self-discharge rate, efficiency, life-time, etc.). The paper discusses typical HESS-applications, energy storage coupling architectures and basic energy management concepts including a hierarchical control- and optimization-based energy management. Four HESS-configurations, suitable for the application in decentralized PV-systems: (a) power-to-heat/battery, (b) power-to-heat/battery/hydrogen, (c) supercap/battery and (d) battery/battery, are presented along with a principle approach for the power flow decomposition based on peak shaving and double low-pass filtering. A modular experimental test-bed for hybrid energy storage systems is described in its components, structure and functionality.