This paper presents power quality issues, and ways to resolve these problems. There are a number of custom power devices which are used to resolve these issues. The Dynamic Voltage Restorer (DVR) is a special device that is used nowadays. To detect the voltage drop system, park transform is utilized and applied to the voltage regulator as a control system function, that detects the voltage amplitude at the sensitive load constantly in DVR (using a three-phase voltage source inverter with voltage loop control (PI)) (Martiningsih & Prakoso, 2018). This paper is about basic working of DVR with simulation results. MATLAB is used in this work, and confirmed the convincingness of the DVR.