Electricity grids are facing significant challenges with new energy sources starting to be integrated into grids on a large scale. Distributed generation, changes in load use, and smart grid operation have each caused transformations in grid design. This monograph revisits optimal grid design problems in view of these ongoing transformations in distribution systems. The monograph describes how optimization techniques can be used to plan for a flexible electricity grid that can operate under growing uncertainty. It highlights the trends in grid design to deal effectively with future...