1. Department of Electrical Engineering, School of Electronic Information and Electrical EngineeringShanghai Jiao Tong University Shanghai 200240 China
2. Key laboratory of Control of Power Transmission and Conversion (SJTU), Ministry of Education Shanghai 200240 China
3. Department of Electrical EngineeringNational University of Sciences and Technology (NUST) Islamabad 46000 Pakistan
4. Department of Electrical EngineeringUniversity of Engineering and Technology Lahore 54890 Pakistan
5. Goldwind Science and Technology Beijing China