Formal energy models have been widely applied to energy systems in the past, but only in few studies nuclear fusion power was included. Since these studies were done, energy system models continued to evolve, new developments took place and improvements in methodology were achieved, resulting in more powerful and flexible tools. The Integrated MARKAL-EFOM System (TIMES), developed by the Energy Technology System Analysis Project of the International Energy Agency, is combining the advantages of two established modelling frameworks including additional new features. This technical-economic model generator was considered to be suitable for modelling fusion as new technology in a future energy system. The aim of this project was the identification of key boundary conditions that either favour or limit the technical-economic potential of fusion power as a new energy supply technology, especially with respect to its application as a large scale, centralised electricity base load option. These key boundary conditions were derived by carrying out energy scenario analyses with a global single regional TIMES model containing the minimum set of options needed to insert fusion power plants. The characteristics of these plants were obtained from existing technical-economic fusion reactor studies. This work, funded by the Friedrich Schiedel Foundation, was an active contribution to the energy studies at the Max-Planck Institute for Plasma Physics in Garching, Germany.