Smart Energy Research. At the Crossroads of Engineering, Economics, and Computer Science : 3rd and 4th IFIP TC 12 International Conferences, SmartER Europe 2016 and 2017, Essen, Germany, February 16-18, 2016, and February 9, 2017, Revised Selected Papers ; Dynamic Aggregation of Virtual Power Plants with a Registry for Distributed Energy Resources - Tim Dethlefs and Thomas Preisler and Wolfgang Renz (Cham ; Springer International Publishing, 2017)