1. State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources, North China Electric Power University, Beijing, China
2. State Grid Dalian Power Supply Company, Dalian, Liaoning, China
3. State Grid Langfang Power Supply Company, Langfang, Hebei, China
4. Tibet Yangbajing High Altitude Electrical Safety and Electromagnetic Environment National Observation and Research Station, Lhasa, Tibet, China
5. Electrical Engineering Division, University of Cambridge, Cambridge, U.K