Control and Operation of Dynamic Voltage Restorer With Online Regulated DC-Link Capacitor in Microgrid System

This article presents a dynamic voltage restorer (DVR) topology based on the adaptive noise canceling (ANC) technique, which can be used for both voltage compensation and harmonic mitigation. Furthermore, this article aims to investigate the DVR performance when installed in a microgrid (MG) during both normal operation of the utility and during utility disturbances. One of the main objectives of this article is to reduce the cost of inverter-based DVR by reducing both the size of the dc-link capacitor and rating of switching elements. The voltage of the dc-link capacitor is regulated to low voltage level using a transformer and a pulsewidth modulation (PWM) rectifier to achieve both effective voltage regulation and drawing a sinusoidal line current from the grid and thus not to contribute to the increase of the THD of the utility current. Furthermore, the voltage across the switches can be limited to low value by an adequate design of dc-link capacitor size, capacitor voltage, and sag level to be compensated. Finally, the effectiveness and fast response of the proposed DVR for the compensation of voltage disturbances and current harmonics is confirmed by simulation using MATLAB/Simulink during the steady-state and transient operations to analyze the performance of the scheme under different operating conditions.