1. State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources, North China Electric Power University, Beijing, China
2. Tibet Yangbajing High Altitude Electrical Safety and Electromagnetic Environment National Observation and Research Station, Lhasa, China
3. Chongqing Electric Power Research Institute, Chongqing, China
4. State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing, China