Optimization, design and application of a hybrid wind turbine/photovoltaic/fuel cell/battery system for stand alone applications

The increase in energy demand in the whole world as well as the rapid depletion of fossil fuels has given increase to the studies on alternative and renewable energy sources. Besides, the growing concerns on the negative environmental effects of fossil fuels have provided a growing importance of the studies on renewable sources of energy. There are many advantages of renewable energy sources, however there are some problems to be solved for the renewable energy issue. One of the most important drawbacks of renewable energy options such as wind, solar, etc., is their unpredictable nature and dependence on weather and climatic changes. Thus, in order to overcome this problem and satisfy the load demand in all conditions, hybrid energy systems that combine the renewable energy sources with energy storage (or ?back-up?) units have been implemented. Traditionally, batteries have been used in this regard. However, due to the size and cost problems of battery systems, the use of fuel cell technology as back-up unit through an electrolyzer system is recommended in recent studies. Such a hybrid system can be used to provide power to energy consumption centers (residential loads, industrial loads, the demand of telecommunication systems, etc.) without grid connection. Thus, the negative impacts of the use of fossil fuels in such systems can be prevented and efficiency improvement xvi and cost reduction can be obtained. The optimum sizing of such hybrid systems shows great importance in terms of obtaining minimum cost. In the concept of the realized thesis, it is aimed to design, realize an optimum sizing and experimentally verify a stand alone hybrid system for supplying the power demand of a stand alone load unit. The mentioned hybrid system consisting of wind turbine/photovoltaic/fuel cell/battery units are evaluated in the simulation environment in the first part of the study. Then, experimental studies of the mentioned system are conducted on a test platform. A new perspective considering the performance degradations of hybrid system components during optimum sizing process is presented. Thus, it is aimed to make contributions to the existing literature especially on hybrid alternative energy systems. Key words: Battery, dynamic modeling, electrolyzer, energy management system, fuel cell, hybrid system, optimum sizing, photovoltaic panel, wind turbine.