Instantaneous Complex Power Control of a Grid-Tie VSC Supplying a Constant Power Load

Abstract

In this paper a nonlinear controller for a grid-tie VSC supplying a constant power load is introduced. The control law combines a feedback loop and a feedforward compensator. The feedback loop strategy uses a feedback linearizing method for compensating nonlinearities appearing in the VSC model. The performance in presence of changes between two different values of constant power is improved by including a fast feedforward compensation. This compensator uses estimates of power load and its time derivative obtained from a nonlinear observer. The resultant strategy is validated via simulation and experimental tests. These experiments show that the proposed scheme performs in a very good way.