Performance evaluation of SRF-based dynamic voltage restorer for mitigation of various power quality problems

Abstract

Dynamic voltage restorer (DVR) is used to protect sensitive loads from harmonic distortion, sag/swell, and unbalance in supply voltage economically. In this paper, synchronous reference frame (SRF) theory-based algorithm has been developed for the production of compensating voltages for controlling DVR. Linear as well as nonlinear loads can be controlled by this algorithm. A three-phase programmable voltage source is taken for producing voltage sag/swell and voltage harmonic distortion and this voltage is compared with a reference voltage of same magnitude. At the time of any disturbance, an error signal is generated which is processed by controller based on SRF theory. The controller generates the gate pulses for PWM inverter energised by a DC source and inverter injects the missing voltage into the distribution line and tightly regulates the voltage at the load terminals. By extensive simulation studies in MATLAB/Simulink and SimPowerSystems environment, the above control strategy is tested. The simulation results for voltage harmonic distortion, voltage sag/swell, and voltage unbalanced mitigation using the proposed control algorithm prove the effectiveness of DVR.