Modeling and grid connection of a solid oxid fuel cell (SOFC) based on P-Q theory for stationary loads

This paper presents the dynamic modeling of a Solid Oxid Fuel Cell (SOFC) and the device necessary to perform its grid connection. Since there is a voltage drop with increasing load, the DC/DC Converter boosts the cell´s output voltage and keeps it regulated. The DC/AC inverter interfaces the DC output of the converter side with the AC grid side. In order to control the injection of active and reactive power into the grid, the inverter control is based on the p-q theory. It is also shown that the inherent slow response of the fuel cell would make it improper for sudden load changes, but the addition of power electronics makes the presented set feasible for such load behaviors. Simulation in Power System Computer Aided Design (PSCAD) helps validate the stated above, including the attempt to generate more power than the cell´s rated power capacity, which is taken into consideration.