1. Energy Technology Engineering Research Center of Ministry of Education of Renewable, Hohai University, Nanjing, Jiangsu Province 210098, China
2. Department of Wind Energy, Technical University of Denmark, Lyngby 2800, Denmark
3. Jiangsu Key Laboratory of Hi-Tech Research for Wind Turbine Design, Nanjing University of Aeronautics and Astronautics. Nanjing, Jiangsu Province 210016, China