1. College of Electrical and Information Engineering, Hunan University 1 , Changsha 410082, China
2. Skills Training Center of State Grid Sichuan Provincial Electric Power Company (Sichuan Electric Vocational and Technical College) 2 , Chengdu 611133, China
3. State Key Laboratory of Power Grid Environmental Protection, China Electric Power Research Institute 3 , Wuhan 430076, China
4. Shenzhen Power Supply Bureau Co., Ltd, China Southern Power Grid 4 , Shenzhen 518000, China
5. School of Electrical Engineering and Automation, Wuhan University 5 , Wuhan 430072, China