1. State Grid Jibei Electric Power Co. Ltd, Research Institute, North China Electric Power Research Institute Co. LtdBeijing100045People's Republic of China
2. Department of Electrical EngineeringState Key Lab of Power System, Tsinghua UniversityBeijing100084People's Republic of China
3. Department of Electrical and Computer EngineeringUniversity of ConnecticutStorrsConnecticut06269USA