The electricity grid finds itself at the start of what might become big changes. These changes are driven by a number of developments in society, where the transition to a sustainable society is the most important one. Without serious changes in the way in which the grid is designed and operated, it may become a barrier against this transition. The changes in society translate in new challenges for the electricity network. Using existing technology will not always allow these challenges to be solved, and even when it is possible to solve them, new technology may do the job better and cheaper.