Nonlinear coordinated control of multiple HVDC links

This paper is concerned with the investigation of a new control technique for the conventional High Voltage Direct Current (HVDC) link. The proposed technique relies upon nonlinear state feedback linearization of the AC/DC power system. The idea in nonlinear exact feedback linearization is to algebraically transform system dynamics into a linear control problem using a nonlinear pre-feedback loop, and then for the linearized power system one can design another feedback loop using a well established technique, such as a linear quadratic regulator. The primary goal of the controllers presented in this paper is to contribute to the enhancement of both the transient and the small-signal stability of the power system. Since the proposed state feedback linearization does not rely on assumption that there is only a small deviation of the states from an equilibrium, the enhancement of both is feasible.