Analysis of control strategies in transformerless dynamic voltage restorer

Abstract

In this paper, two control strategies for Transformerless Dynamic Voltage Restorer(TDVR) are analyzed on the basis of its performance under voltage sag, and swell. Eliminating the usage of a transformer for DVR precisely reduces the size and cost. The load voltage profile is controlled using model predictive control, an advanced control which tracks the reference voltage by predicting the future behaviour of the system. Predictive voltage control scheme uses the discrete system model for prediction and hence the nonlinearities of the system are included in the control technique. The proposed control technique is compared with conventional PI control. As the system dynamics are well addressed in the predictive scheme it produces better response compared to PI and reduced THD levels. Simulation results prove the effectiveness of the application of the control scheme to the system.