Setup and state based energy control of a grid-connected multipurpose hybrid hydrogen system

Grid connected hybrid hydrogen systems consisting of an electrolyzer, a fuel cell and a battery may become major parts of local energy systems in future. System setup is quite challenging due to different electric constraints and the need for a gas management system. This paper presents planning for a technical setup using a DC micro grid and a hydrogen pressure tank and the development of a new control strategy. In order to ensure grid stability a multi-level control strategy with decentralized and centralized control loops is used. A state-based energy control algorithm was developed to provide services to the electric grid and to optimize the system. Simulation results covering a real office and research building proved the energy control system to be feasible and revealed which control parameters are critical such as hydrogen tank pressure. It can be shown that by using a hybrid hydrogen system the maximum peak load of the building can be reduced by 33 % This reduction can be maintained for more than 8650 hours a year and feeding excess energy into the mains can be avoided completely.