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Abstract
Renewable energy sources such as wind turbines, photovoltaic and fuel cells are becoming more important for standalone as well as distributed generation due to energy consumption growth and pollution. Fuel cells are one of the most promising power sources due to their many advantages which include high efficiency, zero or low emission of pollutant gases, flexible modular structure, higher reliability due to absence of moving parts, and their capability of producing electricity and heat. In this thesis, the performance of proton exchange membrane fuel cell based distributed generation system is investigated. This is achieved by the simulation and modeling of a standalone single stage fuel cell system as well as grid connected fuel cell system using PSCAD/EMTDC simulation software. The single stage fuel cell system consists of proton exchange membrane fuel cell connected directly to a DC/AC inverter which is followed by LC filer and step up transformer. The DC/AC inverter switches are controlled by sinusoidal pulse width modulation which guarantees the full control of the ac voltage frequency, magnitude and phase angle.
The performance of this system has been investigated for different modes of operation. The studied cases include, loading the system with balanced, unbalanced and nonlinear load as well as exposing the system to sudden insertion of balanced and nonlinear load. Moreover, the studies have been extended to examine the system behavior when subjected to line to ground fault. The results obtained from the case studies are presented and discussed.