1. Department of Electrical Engineering, Tsinghua University, Beijing, China
2. Tianjin University of Technology, Tianjin, China
3. School of Electrical Engineering and Automation, Wuhan University, Wuhan, China
4. State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, China
5. Department of Electronic Engineering, Tsinghua University, Beijing, China