Uncertainity and Disturbance Estimator based Control of Transformerless DVR

This paper presents Uncertainty and Disturbance Estimator (UDE) based control for Transformerless Dynamic Voltage Restorer (TDVR). The proposed UDE based control algorithm for TDVR mitigate the voltage disturbances and maintain robustness during parameter (filter) variations. The control equation of UDE is derived based on the dynamic model of a voltage source inverter along with the LC filter. The proposed UDE control estimates the uncertainties and disturbances by an appropriate filter (loop filter involved in the derived UDE control law) and used for further synthesis, thus accounts for robustness. The simulation studies are performed for 230 V low voltage (LV) system in MATLAB to verify the efficacy of UDE control for symmetric and asymmetric voltage sags along with the parameter mismatch (inverter filter) conditions.