1. Department of Electrical Engineering, North China Electric Power University, Baoding, Hebei, China
2. Marketing Service Center, State Grid Hebei Electric Power Co., Ltd, Shijiazhuang, Hebei, China
3. Yangtze Ecology Environment Co., Ltd, Shanghai, China
4. State Grid Shandong Electric Power Company Taian Power Supply Company, Taian, Shandong, China