1. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, China
2. Department of Electrical Engineering, North China University of Science and Technology, Tangshan, China
3. State Key Laboratory of Operation and Control of Renewable Energy and Storage Systems, China Electric Power Research Institute, Beijing, China
4. Department of Electrical and Computer Engineering, Baylor University, Waco, TX, USA