The International Journal of Engineering and Science (IJES) || Volume || 8 || Issue || 6 Series I || Pages || PP 53-64 || 2019 || ISSN (e): 2319 – 1813 ISSN (p): 23-19 – 1805 DOI:10.9790/1813-0806015364 www.theijes.com Page 53 A Review of Power Quality Improvements by using FACTS devices Harendra Pal Singh 1 , Dr. A.K. Swami 2 1 Electrical Engineering, College of Technology Pantnagar, Uttarakhand, India 2 Electrical Engineering, College of Technology Pantnagar, Uttarakhand, India Author: Harendra Pal Singh --------------------------------------------------------ABSTRACT----------------------------------------------------------- In a recent trend for controlling of most of the industrial loads is mainly based on semiconductor devices which cause such loads to be more sensitive against power system disturbances. Thus, the power quality problems have gained more interest recently. This paper presents a review of some of the disturbances, on the source side that may cause problems on the load side. The focus is given on problems associated with voltage dips as voltage dips have been reported to be the most severe problems to industrial loads. The power quality has an important role in the power supply industry. As the power providers are turning to smart grid and smart meters, the standards for power quality needs to be revisited. The power quality can be categorized into two groups, one addressing the standard for the power quality supplied at the grid level and the other group which deals with the factors that affect the power quality at user level. These factors include harmonics, voltage changes, sags, transients, voltage unbalance, etc. These factors will provide us in- depth details about the power system network. In this paper, an overview of various factors will be presented in order which can affect the power quality of the system. KEYWORDS;- Power quality, Flexible AC transmission system (FACTS) devices, UPFC, SVC, STATCOM. --------------------------------------------------------------------------------------------------------------------------------------- DATE OF SUBMISSION: 21-06-2019 DATE OF ACCEPTANCE: 05-07-2019 ------------------------------------------------------------------------------------------------------------------------------------ I. INTRODUCTION Utilities aim to provide their customers with an ideal sinusoidal voltage waveform. By definition, ideal sinusoidal voltage waveform has the characteristics: constant magnitude at the required level, constant frequency and balance in case of three phase operation. Naturally, this is not always possible because of normal system variations and due to the unavoidable incidents that temporarily can affect the operation, such as short- circuits faults. On the other hand, utilities require that customers should draw sinusoidal current. SOLID- STATE control of AC power using thyristors and other semiconductor switches is widely employed to feed controlled electric power to electrical loads, such as adjustable speed drives (ASD‟s), furnaces, computer power supplies, etc. Such controllers are also used in HVDC systems and renewable electrical power generation. As nonlinear loads, these solid-state converters draw harmonic and reactive power components of current from ac mains. In three-phase systems, they could also cause unbalance and draw excessive neutral currents. The injected harmonics, reactive power burden, unbalance, and excessive neutral currents cause low system