More stability and robustness with the multi-loop control solution for dynamic voltage restorer (DVR)

This paper presents the application of dynamic voltage restorers (DVR) on power distribution systems for mitigation of voltage sags/swells at critical loads. DVR is one of the compensating types of custom power devices. An adequate modeling and simulation of DVR, including controls in MATLAB, based on forced-commutated voltage source converter (VSC), has been proved suitable for compensating the voltage sags/swells. In this paper, a double loop control method is proposed for the improvement of the stability of DVR during the load current variation. For the main loop (Outer Voltage Loop), we use a PI controller for the regulation of the filter condenser voltage. The second loop (Inner Current Loop) also uses a PI controller to control the disturbances current during load variation. Simulation results are presented to illustrate and understand the performances of DVR in the compensation of voltage sags/swell even with variation load condition.