STATE FEEDBACK CONTROL OF DYNAMIC VOLTAGE RESTORER

The dynamic voltage restorer (DVR) is the most advanced mitigation device that has been proposed to protect sensitive loads from the effects of voltage sags. The performance of DVR depends on the ability of PWM scheme to produce the required voltage and the control method. To improve transient and steady state response of DVR, in this paper a new closed 100p control based on the state feedback is proposed. Since the inverter switching using space vector modulation gives some advantages and the control algorithm based on DC signals are much more feasible than those based on sinusoidal signals, we presents a new state space description of DVR in terms of dq quantities that is used to derive a new control scheme, including state feedback and feed-forward path, to eliminate the source disturbance effects and the steady state error. Furthermore, the proposed state space feedback control is completed by integral control to eliminate the steady state error under variable load conditions. To compare the performance of this new control approach with that of some other control methods, some balanced and unbalanced voltage sags have been simulated on a test system in the PSCAD/EMTDC.