1. School of Electrical and Information Engineering, Tianjin University, Nankai, Tianjin, China
2. Second Academy of China Aerospace Science and Industry Corporation Limited, Haidian, Beijing, China
3. Department of Electrical Engineering, Key Laboratory of Control of Power Transmission and Conversion, Ministry of Education, Shanghai Jiao Tong University, Shanghai, China
4. State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, China