Automation and Operation Strategies in a Stand-Alone Power System that Uses Solar and Wind Energy in Conjunction with Hydrogen Long-Term Storage

The description and analysis of a stand-alone power system that exploits solar and wind energy is presented in this study. More specifically, the integrated system consists of a 10kWp photovoltaic (PV) array and three wind generators rated at 1kWp each. A lead-acid accumulator with nominal capacity of 3,000Ah/48V is used to absorb the short energy fluctuations and to regulate the operation and integrity of the system. Furthermore, the long-term needs are fulfilled via a hydrogen based system. Hydrogen is produced by a 4.2kWp PEM electrolyzer and stored in cylinders under pressure for subsequent use in a 4kWp PEM fuel cell. A diesel engine can also be used to provide power in cases of subsystems failure. In the present study the infrastructure of the control system is presented along with the algorithm for the automatic operation which is used to implement the power management strategy. Moreover, experimental results from the operation of each subsystem will be given and a discussion on them will take place. Finally, two operation strategies will be applied through an one-year simulation study, in order to identify their possible implementation in the real system that currently operates under a system operator either remotely or on site.