1. School of AutomationHangzhou Dianzi University Hangzhou 310018 PR China
2. Center for Operations Research and EconometricsUniversité catholique de Louvain Voie du Roman Pays 34 Louvain la Neuve Belgium
3. Center for Electric Power and Energy (CEE), Department of Electrical EngineeringTechnical University of Denmark Kongens Lyngby 2800 Denmark