1. State Grid Ningxia Electric Vehicle Service Co., Ltd., Yinchuan 750000, China
2. State Grid Ningxia Electric Power Co. Ltd., Yinchuan 750000, China
3. Marketing Service Center of State Grid Ningxia Power Co., Ltd., (Measurement Center of State Grid Ningxia Power Co., Ltd.), Yinchuan 750000, China
4. State Key Lab of Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University), Baoding 071003, China