[1] Univ Ghent, Dept Elect Energy Syst & Automat, B-9052 Ghent, Belgium
[2] Univ Bordeaux 1, IMS LAPS Automat Prod Signal & Image, ENSEIRB, UMR CNRS 5218, F-33405 Talence, France
[3] Inst Engn Polytech Porto, Dept Elect Engn, P-4200072 Oporto, Portugal