Modelling and control of high-voltage AC–DC power systems

In this paper, a systematic procedure is presented for the design of a controller for HVDC transmission links. The design objective is to attain fast stabilization against transient oscillations. The system dynamic equations have been cast into the frame of nominally linear model with norm-bounded non-linearities. A two-stage approach has been developed to meet the cited objective. In the first stage, a multiloop optimal state-feedback controller containing an adjustable parameter has been synthesized for the nominal system. The adjustable parameter is then tuned to accommodate the nonlinearities. Numerical simulation on a typical system has verified the developed theory.