Time-optimal operation of a predictive current controller for voltage source converters

This paper presents an optimization approach in predictive control of voltage source converters (VSC). Basic predictive controllers are derived in discrete time domain and use the approximate mathematical models of the VSC based device to predict its electrical response. The proposed optimization approach, the time-optimal current controller (TOCC), predicts the state of electrical variables also for more sampling periods ahead This results in better dynamics of the device. Predicting the current path during current transients allows the estimation of transient duration which is (considering the predefined operation boundaries of the VSC device) used as the optimization function. The instantaneous reference voltage vector defined with the optimization procedure generates current vector which follows the predicted optimal current path that demands the shortest time to reach stationary state The simulations of the TOCC prove stable, robust and relatively simple operation, while showing evident advantages in comparison with other fast controllers.