ac–dc power converter; HVDC transmission; Multilevel converter; Scheduling; State feedback Controllers; DC power transmission; Electric power transmission; Feedback; Feedback linearization; Linearization; Power converters; Scheduling; State feedback; DC power converter; Direct current control; Feedback linearization controllers; High-voltage direct-current transmission systems; HVDC transmission; Input output linearization; Multilevel converter; Three-level neutral-point-clamped converter; HVDC power transmission