International Research Journal of Engineering and Technology ( I RJET) e-ISSN: 2395 -0056 Volume: 02 Issue: 03 | June-2015 www.irjet.net p-ISSN: 2395-0072 © 2015, IRJET.NET- All Rights Reserved Page 1268 Application of DVR for Power Quality Improvement Shabnam Rukhsar 1 , Dr. D.P. Kuthari 2 1 Student, Electrical Engineering Department, W.C.E.M, Maharashtra, India 2 Director, Electrical Engineering Department, T.G.P.C.E.T, Maharashtra, India ---------------------------------------------------------------------***--------------------------------------------------------------- Abstract -In this paper various power quality problem caused by voltage sag or swell on power system are discussed. These problems will create failure of end user equipments which are sensitive to power quality supply. By the introduction of Custom power devices namely DVR, DSTATCOM, UPQC various problems are reduced. Here an attempt is taken in this paper to review from its establishment to an up to date bibliography on DVR for power quality improvement. Basically the main function of DVR is to eliminate voltage sag. Various control strategies and its improvement is analyzed. Finally, the explorations on DVR incorporating with BESS, different voltage injection method have also been discussed. But PI controller with PWM technique provides good control for sag elimination with reduced voltage. Key Words: DVR, sensitive load, voltage injection technique,voltage sag 1. INTRODUCTION Voltage sag due to fault has become one of the most important power quality problem facing industrial consumers. Any disturbance to the voltage waveform can result in problem related with the operation of electrical and electronics devices which uses need constant sine wave shape, constant frequency and symmetrical voltage with constant RMS value to continue production. This increasing interest to improve overall efficiency and eliminate variation in the industry have resulted more complex instrument that can sensitive to voltage disturbance. Static Ser i es Synchronous Compensator (SSSC) commercially known as Dynamic Voltage Restorer (DVR) inject voltage in series with the system voltage provides most cost effective solution to mitigate voltage sags by improving power quality level that is required by the customer When fault s in a distribution network sudden voltage sag will appear adjacent loads. DVR installed on sensitive load (critical load) resistors the line voltage to its normal value in few milliseconds. The conception of custom power is to use static controller or power electronics devices in the medium voltage distribution system aim to supply reliable & high quality power to the user’s sensitive load. Sensitive load on distribution side like semiconductor manufacturing plant, paper mil, food industries etc, uses DVR for eliminating voltage sag. DVR as a custom power device could be means to overcome some major power quality problems such as voltage sag by the way of injecting active or/ and reactive power into two system. . DVR is connected in series with the transmission line which is shows in figure 1. When source supply voltage changes DVR connected in series injects dynamically controlled voltage in series with supply voltage through a series transformer correct the sag or swell present in system. However in control of DVR not only voltage magnitude (injection) but also active and or reactive power injection is needed. Fig -1 : DVR Location The rating of DVR as module is 2 MVA per module. It compensates 35% of voltage sag for a very less duration of time of half a second. If SLG (single line to ground) fault is occurs than it compensate voltage sag greater than 50%. For Energy storage device capacitor is used which requires 0.2 to 0.4 MJ per MW of load served through a transformer, connected in series with DVR.[6] When the DVR is used as standby mode at that time no voltage is injected and converter is bypassed. At a instant when voltage sag is detected, DVR inject a series voltage of required value this is called as boost mode. DVR can also be used as active filter for isolating harmonics current from source side to load side. In this operation IGBT or IGCT is used with it. 2. DYNAMI C VOLTAGE RESTORER