1. State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology, Tianjin 300130, China
2. Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province Hebei University of Technology, Tianjin 300130, China
3. College of Electrical Engineering and New Energy, China Three Gorges University, Yichang 443002, Hubei, China