When connected in small amounts, the impact of distributed generation (DG) on distribution system stability will be negligible. However, if its penetration level becomes higher, distributed generation may start to influence the dynamic behavior of the system as a whole. This paper presents a mathematical representation of a solid oxide fuel cell plant that is suitable for use in distribution system stability studies. The model is applied to a distributed utility grid that uses a solid oxide fuel cell plant as distributed resource. Examinations include transient stability and voltage stability of the system. (C) 2003 Elsevier B.V. All rights reserved.