[1] Clemson Univ, Real Time Power & Intelligent Syst Lab, Clemson, SC 29634 USA
[2] Univ KwaZulu Natal, Eskom Ctr Excellence HVDC Engn, ZA-4041 Durban, South Africa
[3] NEC Labs Amer Inc, Energy Management Dept, Cupertino, CA 95014 USA
[4] Spirae Inc, Ft Collins, CO 80524 USA
[5] Clemson Univ, Dept Elect & Comp Engn, Clemson, SC 29634 USA