Performance Analysis of Transmission Line Using Upfc With Pi and Fuzzy Controller

Abstract

High quality power and high efficient power is an apprehension for now days due to advancement in electrical technology. Today’s power systems are highly composite and require suitable design when new effective and consistent devices are to be introduced in the liberalized electric power industry. This is done in order to flexibly control the power flow. In the early 1980s, the Electric Power Research Institute (EPRI) framed a new strategy in order to resolve the difficult of designing, adjusting and functioning the power systems: the projected concept came to be known as Flexible AC Transmission Systems (FACTS). It is reckoned conceptually as a target for the long term development in order to offer new opportunities for controlling the power in addition to enhancing the capacity of the present as well as new lines in the coming decades. Its main objectives are to raise power transmission capability, voltage control, voltage stability enrichment and power system stability improvement.
There are several FACTS controllers. Among them the UPFC is the most adaptable and proficient device which was introduced in 1991. In UPFC, the transmitted power can be controlled by changing three parameters namely the magnitude of the transmission voltage, the impedance and the phase angle. The Unified Power Flow Controller (UPFC) is the most prominent member of the FACTS family which has the capability to control parameters such as voltage, impedance and phase angle. By the use of UPFC a superior power flow control over the existing power line is not only possible but also it will work nearer to its thermal stability limit making the system more efficient and reliable.
FACTS devices controls the power flow in a systematic manner by which not only the power flow is controlled but also the stability of the system is always maintained in a space region. The control mechanism incorporated with the UPFC has an edged control over the power flow and the system stability. The performance is varied for different control mechanism used for the control of UPFC. The performance of each controller must be properly studied before implementing to the power system. The two controllers are PI and Fuzzy. On comparing we can say that Fuzzy Logic Controller based UPFC gives better voltage sag compensation than PI Controller based UPFC.