ABSTRACT
The study of the transient stability enhancement capability of Unified power flow controller (UPFC) in a multi-machine power system is presented. The test system was Nigerian 330kV power system and the focus was on the effect of disturbances on the largest generating unit (Egbin) in the system. The original network was reduced to retain the area of interest (i.e. South West buses including Egbin generator). The UPFC was connected between Egbin and Ikeja-west buses and the analysis was conducted by simulating a 3-phase fault at three locations; on the terminal of the largest generator unit at Egbin bus, the bus with the largest load at Ikeja-west and the bus at Benin. The response of the system for the three cases with and without the device in operation was observed. The dynamic model for the series part of the device was developed in Python programme using the application program interface (API) in Power System Simulation for Engineering (PSS/E) software used for the analysis. Simulation results showed that, with the UPFC in the network, the steady state voltage profiles of some buses were improved by as much as 4.9% especially those close to the point of connection. In addition, the device was able to damp power oscillation and the system transient stability was enhanced. The enhancement is from the critical clearing time of the system which was increased from 380ms to 590ms when the fault was at Egbin generator terminal, from 470ms to 510ms following the fault at Ikeja-west, and from 770ms to 830ms when the fault was at Benin bus.