In order to define an interesting model problem for research work around the assembly of software components, this paper introduces the substation automation domain. Special emphasis is put on those aspects of the application area which make its employment as model problem provider attractive. Firstly, the composition is required to meet several quality requirements besides functionality and must therefore allow for the prediction of these qualities before the final system is assembled and is undergoing a potentially costly factory and/or onsite acceptance test. Secondly, the currently known functionality of the application domain is sufficiently modeled, so that the mapping to components and their quality requirements is straightforward. Thirdly, the upcoming IEC61850 standard, which provides the basis for the functional models as well as the quality requirements, is publicly accessible. It also contains representative sample systems of various complexities.