An adaptive direct power control for multi-terminal HVDC transmission system under unbalanced conditions

In this paper, the model-based direct power controller (DPC) is proposed for a multi-terminal high voltage direct current (HVDC) using Voltage source converter (VSC), which is able to control directly the instantaneous power and reactive power. Moreover, this DPC is able to handle the unbalanced network condition, that is unequal AC voltage due to unbalanced power supplies, unbalanced loads and unavoidable faults in the AC side. In addition the DPC includes an adaptation mechanism to cope with uncertain parameters. Numerical simulation has been performed to illustrate the merits of the proposed solution.