Reactive power estimation based control of self supported dynamic voltage restorer (DVR)

The dynamic voltage restorer (DVR) is an attractive solution to protect sensitive loads from voltage sag, swell, unbalance and voltage harmonics. When the injected voltages by the DVR are in quadrature with line currents, the DVR can be supported by a capacitor on DC side. In this paper, a new and simple control algorithm based on reactive power estimation is proposed for a self-supported DVR. The DVR is controlled by tracking the load voltages to their reference values computed by the proposed control algorithm in the stationary reference frame. Furthermore, a proportional-resonant (PR) controller is utilized to avoid any reference frame transformation. Moreover, the PR controller has very high gain at both positive and negative sequence frequencies and thus it is used to achieve a better unbalance compensation without using two separate positive and negative sequence controllers. The proposed control strategy is validated by performing simulation studies in MATLAB environment. The simulation results for voltage sag, swell, harmonic and unbalance compensation using the proposed control algorithm are discussed.