1. College of Electrical and Information Engineering, Hunan University, Changsha, China
2. Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK, Canada
3. Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong
4. Power Delivery & Utilization, Electric Power Research Institute, Palo Alto, CA, USA
5. Melentiev Energy Systems Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia