1. Rizhao Polytechnic, Rizhao, China
2. Dept. of Electrical Engineering, Furnas Centrais El´etricas S/A, Rio de Janeiro, Brasil
3. Dept. of Electrical Engineering, Federal University of Uberlandia, Uberlandia, Brasil
4. Dept. of Archtecture, Federal University of Uberlandia, Uberlandia, Brasil
5. Dept. of Electrical Engineering, Furnas Centrais Eletricas S/A, Rio de Janeiro, Brasil