Two-Loop Controller for Maximizing Performance of a Grid-Connected Photovoltaic-Fuel Cell Hybrid Power Plant

The study started with the requirement that a photovoltaic (PV) power source should be integrated with other supplementary power sources whether it operates in a stand-alone or grid-connected mode. First, fuel cells for a backup of varying PV power were compared in detail with batteries and were found to have more operational benefits. Next, maximizing performance of a grid-connected PV-fuel cell hybrid system by use of a two-loop controller was discussed. One loop is a neural network controller for maximum power point tracking, which extracts maximum available solar power from PV arrays under varying conditions of insolation, temperature, and system load. A real/reactive power controller (RRPC) is the other loop. The RRPC meets the system's requirement for real and reactive powers by controlling incoming fuel to fuel cell stacks as well as switching control signals to a power conditioning subsystem. The RRPC is able to achieve more versatile control of real/reactive powers than the conventional power sources since the hybrid power plant does not contain any rotating mass. Results of time-domain simulations prove not only effectiveness of the proposed computer models of the two-loop controller, but also their applicability for use in transient stability analysis of the hybrid power plant. Finally, environmental evaluation of the proposed hybrid plant was made in terms of plant's land requirement and lifetime CO 2 emissions, and then compared with that of the conventional fossil-fuel power generating forms. iii ACKNOWLEDGEMENTS First of all, I would like to express my sincere gratitude to my advisor, Dr. Saifur Rahman. His kind guidance, thorough comments and constant support have made it possible for me to make my dissertation complete. His teaching of the course " Alternate Energy Systems " had a great influence on my idea for this dissertation. I would also like to thank Dr. for their time and advice as my advisory committee. During my Ph.D. program, I have been associated with my colleagues at the Center for Energy and the Global Environment. I would like to list here some of them to memorize and thank them: would like to specially thank Mr. Teklu for his support to capture solar data from the photovoltaic test facility located on the roof of Whittemore Hall in the Virginia Tech campus. I would like to show my great appreciation to my wonderful parents, brothers and sister for their encouragement and support until I obtain a doctorate degree. I want …