Virtual flux DPC of three-level multi-terminal VSC-HVDC system using backstepping controller

This paper deals with nonlinear control of multi-terminal voltage source converter HVDC transmission system. The idea of the proposed control is to combine the backstepping control and direct power control with virtual flux concept into one controller able to improve the performance of the studied system. In other hand, the use of the space vector modulation for three-level converter with balancing strategy based on effective use of the redundant switching states of the converters voltage vectors guarantees the objective of maintaining balanced voltages in DC-capacitors. Finally, a simulation of the multi-terminal HVDC system validates the efficiency of the proposed control law, and it is compared with a conventional PI controller. These results allows to exhibit excellent transient response during range of operating conditions.