1. Center for Wind Energy, Department of Electrical and Computer Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
2. Department of Electrical and Computer Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
3. Center for Wind Energy, Department of Mechanical Engineering, University of Texas at Dallas, Richardson, TX 75080, USA
4. Xcel Energy, Minneapolis, MN 55401, USA