1. School of Automation, Key Laboratory for Intelligent Control and Decision on Complex Systems, Beijing Institute of Technology, Beijing 100086, P. R. China
2. State Grid East Inner Mongolia Economic Research Institute, Hohhot 010020, P. R. China
3. Department of Electronic and Information Engineering, Hong Kong Polytechnic University, Hong Kong
4. School of Automation, Beijing Institute of Technology, Beijing 100086, P. R. China
5. China Electric Power Research Institute, Beijing 100192, P. R. China