1. Shanxi Key Laboratory of Mining Electrical Equipment and Intelligent Control, College of Electrical and Power Engineering, Taiyuan University of Technology, Taiyuan 030024, China
2. The State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China
3. Department of Electrical, Electronic, and Information Engineering “Guglielmo Marconi”, University of Bologna, Viale Risorgimento 2, Bologna 40136, Italy