1. Department of Mechanical Engineering, North China Electric Power University, Baoding 071003, China
2. Hebei Engineering Research Center for Advanced Manufacturing & Intelligent Operation and Maintenance of Electric Power Machinery, North China Electric Power University, Baoding 071003, China
3. Suzhou Institute of North China, Electric Power University, Suzhou 215000, China
4. State Grid Hebei Electric Power Research Institute, Shijiazhuang 050021, China