International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 08 Issue: 04 | Apr 2021 www.irjet.net p-ISSN: 2395-0072 © 2021, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 1514 Power Quality Enhancement in Distribution System Using D-STATCOM Anita Y. Solanki 1 , Dr. Sanjay R. Vyas 2 1 PG Scholar, LDRP Institute of Technology and Research, Gujarat, India 2 Professor, Department of Electrical Engineering, LDRP Institute of Technology and Research, Gujarat, India ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract –. This paper deals with the Power Quality enhancement in distribution system using distribution static compensator(D-STATCOM). Power Quality (PQ) has become very important aspect for the utility because electricity customer demands high quality power with reliability. Industrial consumers are highly affected due to PQ issues in terms of loss of revenue. In this paper Voltage sag is considered as PQ problem which can be experienced by different types of faults. D-STATCOM injects current into a system to mitigate the voltage sag at distribution side. The D-STATCOM model is based on Voltage source converter (VSC) principle. The simulations were performed in MATLAB/SIMULINK model R20007b with and without insertions of D-STATCOM. Key Words: Power quality, Voltage sag, Custom power device, D-STATCOM, Voltage source converter (VSC) 1. INTRODUCTION Power Quality (PQ) has become important for industrial and commercial electric power customers, particularly as today’s manufacturing and control processes rely on computerized equipment which are very sensitive to power system disturbances. Power quality problems such as transient, Voltage sags, swells interruptions, Harmonics and noise can affect the performance of the equipment at consumer. The types of PQ problems frequently experienced by customers are voltage sags and harmonics while the less frequent ones include transient, flicker and noise. Due to PQ disturbances the sensitive electronic equipment/devices may malfunction or fail to operate at all, which causes huge loss of revenue for the industrial consumers. Voltage sag is frequently experienced due to utility faults, transformer charging or heavy motor starting. Various custom power devices are available to mitigate PQ problems. Evolution has been seen in custom power devices such as D-STATCOMs for power factor correction, voltage regulation, compensation of excessive neutral current, and load balancing; DVRs for mitigating voltage quality problems in transient and steady- state conditions; and UPQCs as a combination of D-STATCOM and DVR for mitigating current and voltage quality problems in a number of applications. The voltage sag/swell magnitude is ranged from 10% to 90% of nominal voltage and with duration from half a cycle to 1 min. Distribution Static Compensator (D-STATCOM) is proposed for mitigation of voltage sag which is the most frequently experienced PQ issue. 2. Distribution Static Compensator A D-STATCOM consists of a two-level VSC, a dc energy storage device, controller and a coupling transformer connected in shunt to the distribution network. Figure 2.1 shows the schematic diagram of D-STATCOM. It replaces conventional voltage and reactive power control elements. It can improve the voltage profile along feeders, reduce losses and is also capable of compensating for real power fluctuations on account of the presence of an energy storage system connected to the DC side. When voltage fluctuations occur, the D-STATCOM responds by injecting currents, With the proper phase angle and magnitude. Figure 2.1 shows the schematic diagram of D-STATCOM. Iout =IL -Is (2.1) Where, Is =Vth-VL (2.2) Zth Iout =output current, IL=load current, Is=source current  = o oe, ℎ = ℎ eei oe, ℎ = i ee Fig.2.1 Schematic Diagram of D-STATCOM As per equation 2.2,  will correct the voltage sags by adjusting the voltage drop across the system impedance, (ℎ =R+jX). T he effectiveness of D- STATCOM in correcting voltage sags depends on:The value of Impedance, ℎ= R+jX ,The fault level of the load bus. 2.1 Voltage Source Converter (VSC) It is an electronic device. VSC is the most important component in D-STATCOM and it can generate a sinusoidal