An Analysis of Transient Stability Enhancement Capability of UPFC in a Multi machine Power System
This study presents the transient stability enhancement capability of Unified power flow controller (UPFC) as an effective Flexible AC Transmission System (FACTS) device in a multi machine power system. The test system was a reduced Nigerian 330kV power system and the focus was on the effect of disturbances on the largest generating unit (Egbin) in the system. The analysis was conducted by simulating a 3 phase fault at two locations; on the terminal of the largest generator unit at Egbin bus and the bus with the largest load at Ikeja west. The response of the system in both cases was compared with and without the device in operation. Simulations were carried out using the Power System Simulation for Engineering (PSS/E) software. Results showed that, with the UPFC in the network, system transient stability was enhanced considering that critical clearing time of the system was increased from 380ms to 590ms when the fault was at Egbin generator terminal and from 470ms to 510ms following the fault at Ikeja west. In addition, the device was able to damp power oscillations resulting from the disturbance created by the faults.