Optimization of off-grid hybrid PV-wind-diesel power supplies with multi-technology battery systems taking into account battery aging

This thesis presents an optimization tool for off-grid systems to find the economically and ecologically optimal design. It allows finding the optimal sizing of the system components and the optimal operation conditions as well. The developed tool in this thesis allows various combinations of energy sources (sun, wind and diesel generator) and different electrochemical energy storage systems (Li-ion, lead-acid and redox-flow). Furthermore, the possibility to use any input data (weather data, load profile and considered costs) allows designing for any application anywhere in the world an appropriate power supply system. This includes optimized energy management strategies. Optimization is done with regard to life cycle costs' including various constrains including CO2 emissions, area restrictions, life cycle assessment issues and local technology exclusions. All components must be represented by technical, economic and lifetime models. A versatile and generic energy management system (EMS) developed in the frame of this thesis manages the power flow among the system components and assures that the load demand is completely met at every point in time. Moreover, the EMS regulates the charging and discharging strategies of the three different battery technologies used in the system. Practical results for the case studies in Germany and Syria have been obtained for system simulations and overall system optimization. The optimization results and sensitivity analyses for different criteria are then analysed. The user of this tool can freely define the components involved in the system (PV, wind turbine, diesel generator, li-ion battery, lead-acid battery and redox-flow battery) and the site (weather data of the selected site) and related costs for each component.