Classification and comparison of interfacing schemes for connecting fuel cells to a single-phase utility line

Based on a systematic classification of dc source to utility interfacing schemes, this paper presents six major interfacing schemes for connecting fuel cells to a single-phase utility line using high-frequency transformer isolated power converters. The operation, advantages and disadvantages are discussed for each scheme with examples and operating waveforms. Several features e.g., utility line power factor, line current THD, size, ease of connection to utility line and simplicity of control, are compared. Based on their performance and fuel cell characteristics, a suitable scheme is selected. The selected scheme (#4) uses a dc/dc converter followed by a current controlled voltage source inverter. Details of the power conditioning unit (PCU) based on the selected scheme are given with some PSIM simulation results.

Keywords: power processing, power control, utility interfacing, high-frequency power conversion, fuel cells, classification, single-phase utility lines, power conditioning units, simulation