Power Quality improvement using FACTS devices

Abstract

Power Quality is a measure of how well a system supports reliable operation of its loads. A power disturbance or event can involve voltage, current, or frequency variations. Power disturbances can originate in consumer power systems, consumer loads, or the utility because of non-linear loads, adjustable speed drives, traction drives, start of large motor loads, arc furnace, lightning etc. Typical power quality disturbances are voltage variation (voltage swelling, voltage sag) frequency variation & waveform distortion. In this Thesis voltage variation is the focal point. Since the change in voltage at the receiving end of a line depends on reactive power loading, so voltage sag/swell can be reduced by supplying/absorbing reactive power locally rather through transmission line. Number of ways has been proposed which includes number of controllers to meet the reactive power of load and allow the source to supply power at unity power factor. In this thesis a subset of controllers are discussed and there simulation were carried out in Simulink software, steady state and dynamic effects of these controllers are simulated by taking detailed model and average model. Simple systems are also taken into consideration to show the performance. Between the basic two types of controllers, one being converter based and other being variable impedance or admittance based, the converter based controllers shows good dynamic and steady state behavior, since their application strictly depend on the system requirement and economic point of view. There is a need of analyzing both, which is presented in this study.