Power Quality Improvement and Sag Voltage Correction by Dynamic Voltage Restorer

Abstract

Power quality is a very important topic of the recent power system network topics. It refers to maintaining a sinusoidal waveform of bus voltages. Unfortunately, the power system faces many disturbances which affect the supply waveform, such as under voltage, notching, harmonics, sag and swell voltages. In practice, sag voltage and harmonics are the major problems which can cause malfunctioning or tripping of equipment and many other problems on the system. One of the causes of these events is the inrush current during the energization of no-load transformers. This paper presents an effective and economic solution for the protection of sensitive loads from sags and harmonics using the dynamic voltage restorer (DVR). It also highlights the full functions of the DVR, showing that it can be considered as a proper solution to overcome the inrush current effects. Sag indices concepts on the distribution system are also presented, showing the performance of the DVR to get better results. The increasing of the DVR effectiveness as well as its simplicity and low cost are reasons for considering it as the best solution for many quality disturbances. Simulation results using MATLAB/SIMULINK are presented to verify the effectiveness of the proposed scheme.