J. of Advancement in Engineering and Technology Voume2/Issue1 ISSN: 2348-2931 1 Enhancement of Power System Voltage Stability with the Aid of Reactive/Capacitive Power Switching Mechanism (A Case Study of Oweeri Transmission Company of Nigeria) Folorunso O. 1 , Osuji C.C. 1 , Ighodalo O.S. 2 1. Electrical/Electronic Department, University of Benin, Benin-City, Edo State, Nigeria. 2. Federal University of Petroleum Resources, Effuru, Nigeria *Corresponding author: Folorunso O, E-mail: oladipofolorunso@yahoo.com Received: September 4, 2014, Accepted: October 8, 2014, Published: October 8, 2014. ABSTRACT The focus of this paper is on the application of Static Var Compensator in enhancing voltage stability in power system. In other to achieve this, the Owerri transmission substation is used as a case study. Owerri transmission substation receives its power from Alaoji transmission station at a voltage level of 132kV. This substation is made up of three power transformers, two steady transformers and a mobile transformer with ratings of 60MVA and 40 MVA. ETAP 7.0 was the major tool used in achieving this aim. It was clearly observed that with SVC out of service bus voltage at Owerri was far below regulated value and very high loss occurred along the transmission line leading to high voltage drop. But with the SVC in service the bus voltage experienced a boost in voltage to a regulated value with corresponding reduction in voltage drop, drop in reactive power from the sending end and increase in real power supplied. Also the model was tested with light loads and it was observed that bus voltage was more than the source without the SVC but with the SVC the bus voltage was kept at a regulated value by the reverse flow of reactive power into the SVC. This again showed the dynamic nature of the SVC, absorbing reactive power in period of high voltage and supplying reactive power when low voltage occurs. Keyword: Static Var Compensator, reactive power, active power, and voltage INTRODUCTION The Nigeria power system is associated with epileptic supply, poor system stability, high losses, weak bus voltages, line overloads, inappropriate location of generating stations, long transmission lines among orders (Onohaebi O.S asnd Kuale P.A, 2007). These affect the overall power quality (Omorogiuwa, 2013). Every day, the power transmission and distribution systems face increasing demands for more power, with expecting for better power quality, reliability at lower cost, and as well as low environmental effect. Under these conditions, transmission networks are called upon to operate at high transmission levels, which invariably turn the system to unstable condition. An approach towards solving tackling this problem among others will include placement of Static Var Compensator optimally by the use of any optimization tool. An inherent characteristic of electric energy transmission and distribution by alternating current (AC) is that real power is generally associated with reactive power. AC transmission and distribution associated with reactive power. AC transmission and distribution lines are dominantly reactive networks, characterized by their per-mile series inductance and shunt capacitance. Thus, load and load power factor changes alter the voltage profile along the transmission lines and can cause large amplitude variations in the receiving end voltage. For passive compensation, shunt capacitors have been extensively used since the 1930s. They are either permanently connected to the system, or switched, and they contribute to voltage control by modifying characteristics of the network. They are either permanently connected to the system, or switched, and they contribute to voltage control by modifying characteristics of the network (Kundur et al., 1994). Improvements in the field of power electronics have had a major impact on the development of shunt active compensators, which are Static Var Compensator (SVC) and Static Compensator (STATCOM) devices. One of the most important applications of such devices is to keep system voltage profiles at desirable levels by compensating for the system reactive power. By employing these devices for reactive power compensation, both the stress on the heavily loaded lines and losses are easily reduced as a consequence of line loadability, which is increased. The Electric Power Research Institute (EPRI) has initiated the development of Flexible AC Transmission Systems (FACTS) in which power flow is dynamically controlled by various power electronic devices. The two main objectives of FACTS are to increase the transmission capacity of lines and control power flow over designated transmission routes (Laszlo, 1994) Flexible AC Transmission System (FACTS) controllers, such as the Static Var Compensator (SVC), employ the latest technology of power electronic switching devices in electric power transmission systems to control voltage and power-flow, and improve voltage regulation. Static Var Compensators are being increasingly applied in electric transmission systems to economically improve voltage control and post-disturbance recovery voltages that can lead to system instability. An SVC provides such system improvements and benefits by controlling JOURNAL OF ADVANCEMENT IN ENGINEERING AND TECHNOLOGY Journal homepage: http://scienceq.org/Journals/JAET.php Research Article Open Access