DC Distribution with Fuel Cells as Distributed Energy Resources

Dedication This dissertation is dedicated to my loving wife. Her continued support and unconditional love have provided me enough energy and time to continue and finish my research. This work is also dedicated to my parents, who have been beyond patient and have always been there when I needed them. Their love for their children is beyond any that I have ever witnessed. 4 Acknowledgments I would like to thank all of the many people that have contributed to my education and research. The journey has been long, but memorable. First and foremost, I greatly appreciate the contributions of my advisor, Dr. Leon M. Tolbert, for his instructions in class and on my dissertation work. His continued support even outside the realm of education and his gentle prodding to keep working have been instrumental in completion of this work. He is a great friend and mentor. Many thanks to my committee members, for reading my work and providing invaluable suggestions and comments. Special thanks to my co-workers at Oak Ridge National Laboratory, Burak Ozpineci and Travis Smith. Their knowledge, support, and leniency were crucial in my completion. Finally, I would like to thank all of my friends, who were able to break me away from my work on the occasion and enjoy life. Abstract In recent years, the idea of a direct current (DC) distribution systems has returned to the public eye as a result of DC based energy sources. The battle between alternating current (AC) and DC began with Thomas Edison and George Westinghouse long ago with AC becoming the victor as a result of the transformer. However, development of power electronics and switching devices and DC based energy sources such as fuel cells has forced the reevaluation of DC systems. This dissertation is focused on once again addressing this topic, but with an examination of the technologies as they stand today. Along with examining basic efficiency of the competing technologies, distributed generation has as well peaked the interest and will be incorporated into the analysis. Optimum placement of this distributed generation (DG) source is vital to obtain the maximum benefit and techniques for optimization are examined. The sensitivity and " rules of thumb " for placement of DG in a DC system are developed. Last, the largest driving factor for system changes is cost. A brief examination of the economic factors that have the potential to drive DC …