Increased uncertainty a new challenge for power system planners

A few years ago it was the opinion that, in the field of system planning, uncertainty was increasing. The author believes that in many countries this opinion has not changed. This increasing uncertainty has to be incorporated in the planning process. The scenario technique is presently widely used. However, as illustrated in this paper, it has limits and drawbacks. The author argues that there is still a need for new tools which can deal with real-size problems and which do not impose drastic and unrealistic simplifications