ISSN: 2277-9655 [Mehta* et al., 6(8): August, 2017] Impact Factor: 4.116 IC™ Value: 3.00 CODEN: IJESS7 http: // www.ijesrt.com© International Journal of Engineering Sciences & Research Technology [348] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY DESIGN AND IMPLEMENTATION OF UNIFIED POWER QUALITY CONTROLLER N. D. Mehta *1 , Dr. A. M. Haque 2 & R. Ramesh 3 *1 Assistant Professor, Vishwakarma Government Engineering College, Chandkheda India. 2 Assistant Professor, Vishwakarma Government Engineering College, Chandkheda India. 3 Manager (R & D) and Guide, Veeral Control P. Ltd , Gandhinagar DOI: 10.5281/zenodo.845306 ABSTRACT Power line disturbances such as voltage dips and fluctuations, momentary interruptions, harmonics and transients incur a heavy loss to electric utility customer. Except the power outages and transients due to lightning , other power quality problems like sags, swells, short term interruption, harmonics , distortions occur either due to some faults in distribution feeders or interference from loads. During short circuits or fault clearing process in feeder, the neighboring feeders can get affected with sags or swells in the supply voltage. In this paper authors have proposed new Unified Power Quality controller (UPQC) that protects the load from these power quality issues as well as regulates the terminal voltage of the load. Authors have also explained the system configuration, control strategy and practical implementation of the UPQC. KEYWORDS: Dynamic Voltage Restorer (DVR), Power Quality, STATCOM, Unified Power Quality Controller. I. INTRODUCTION Increased use of non-linear loads, such as uncontrolled/controlled rectifiers, converters, arc furnaces has caused an increase in harmonic injection and reactive power into the power distribution system. To solve these problems shunt active filters have been developed [1] [2]. Another cause for the degradation of power quality in the utility or industrial power system is the distortion/harmonics present in the voltage at the distribution substation. The power quality problems in voltage encompass voltage sag, voltage swell, flicker, voltage outage, harmonics distortion and voltage is expected to be within certain limit specified by the supplier. Voltage sags are the one of the common power quality issues encountered by the industrial customers [3]. UPQC is an active series / shunt power line conditioner. It is combination of a STATCOM as well as a series compensating stage connected before the load in series with the mains using a matching transformer. UPQC is used to compensate voltage and current harmonics, control input power factor to near unity as well as regulate the load voltage. It can be installed by the electric utilities to damp out harmonic propagation caused by resonance with line impedance and passive shunt compensators. The UPQC is made out of two voltage-source inverters one inverter is connected to the power system through a shunt transformer, whereas the other inverter is inserted into the transmission line through a series transformer. These two voltage-source inverters are coupled on their dc sides through a common dc capacitor link. From the control perspective, the UPQC can be decoupled into two branches; the parallel branch formed by the shunt transformer, voltage source inverter and dc capacitor operating as a STATCOM, and the series branch composed of the series transformer, a voltage source inverter and the dc capacitor which behaves as a SSSC. The basic UPQC structure is shown in Fig. 1.