1. Laboratory of Power Systems, Department of Electrical Energy, Federal University of Juiz de Fora, José Lourenço Kelmer St., São Pedro, Juiz de Fora 36036-900, Brazil
2. Department of Geoscience and Petroleum, Norwegian University of Science and Technology, PTS Paviljong, 540, Valgrinda, S.P. Andersens veg 15, 7031 Trondheim, Norway