The growth in the demand of electrical energy is leading to load on the Power system which increases the occurrence of frequent oscillations in the system. The reason for the oscillations is due to the lack of damping torque which is required to dominate the disturbances of Power system. By using FACT devices, such as Unified Power Flow Controller (UPFC) can control power flow, reduce sub-synch...

Long distance AC transmission is often subject to stability problems , which limits the transmission capability.Large interconnected power systems often suffer from weakly damped swings between synchronous generators and subsystems.This paper presents two methods , based on the use of nonlinear system model , to improve transient stability and damping of power swings using UPFC. A statevariable...

This paper proposes a sensitivity based technique for optimal placement of Unified Power Flow Controller (UPFC) to enhance voltage stability margin under contingencies. The sensitivity of system loading factor with respect to the reactive power flowing through lines computed for the system intact case and critical contingency cases have been used to decide optimal location for the placement of ...

Weakly damped power swings are one of the main problems endangering secure operation of power systems. This paper presents two methods , based on the use of nonlinear system model , to improve damping of power swings using UPFC. A statevariable control strategy has been derived using local available signals of real and reactive power. The results of simulation tests of two control methods, unde...

The unified power flow controller (UPFC) is a typical FACTS (Flexible AC Transmission Systems) device that is capable of instantaneous control of transmission line parameters. This paper presents the transient model and control system of UPFC. The presented control system enables the UPFC to following the exchanges of line active and reactive power reference values, regulating the DC link and b...

In this paper the performance of unified power flow controller is investigated in controlling the flow of po wer over the transmission line. Voltage sources model is utilized to study the behaviour of the UPFC in regulating the active, reactive power and voltage profile. This model is incorporated in Newton Raphson algorithm for load flow studies. Simultaneous method is employed in which equati...

In this paper a multi objective optimal power flow (OPF) is obtained by using BAT search algorithm (BAT) with Unified power flow controller (UPFC). UPFC is a voltage source converter type Flexible Alternating Current Transmission System (FACTS) device. It is able to control the voltage magnitudes, voltage angles and line impedances individually or simultaneously. UPFC along with BAT algorithm i...