1. School of Energy and Electric Engineer, Hohai University, Nanjing, Jiangsu, China
2. Key laboratory of wind Energy and Solar Energy Technology, Inner Mongolia University of Technology, Hohhot, Inner Mongolia, China
3. Jiangsu Key Laboratory of Hi-Tech Research for Wind Turbine Design, Nanjing University of Aeronautics & Astronautics, Nanjing, Jiangsu, China