[1] North China Elect Power Univ, State Key Lab Alternate Elect Power Syst Renewabl, Baoding 071003, Peoples R China
[2] Univ Illinois, Dept Elect & Comp Engn, Urbana, IL 61801 USA
[3] China Elect Power Res Inst, State Key Lab Operat & Control Renewable Energy &, Beijing 100192, Peoples R China
[4] Univ Beira Interior, C MAST, P-6201001 Covilha, Portugal
[5] Univ Porto, INESC TEC, P-4200465 Porto, Portugal
[6] Univ Porto, Fac Engn, P-4200465 Porto, Portugal
[7] Univ Lisbon, Inst Super Tecn, INESC ID, P-1049001 Lisbon, Portugal