The use of linear flow estimation in computing codes for long term system planning

In the framework of CEGB, EDF and ENEL collaboration, the three utilities exchanged their point of view, practice and experience on models for long term planning studies, within working group 1/3 `Power system planning´. Two conclusions were drawn: linear flow estimation is still useful in such tools, and is the common core of three models developed by each utility-TRESCO, ORELIA and LODEN respectively; and the design of these models is dependent on the organization of the planning processes, on the predominant problems in each of them, and on the balance between tasks executed by the model and tasks left to the user. The authors discuss these two considerations, and underline four parameters important to the planner. These are: time horizon, geography, system analysis techniques, and uncertainty/variability. Each model is analysed along these four main lines, with an extra mathematical comment