Abstract:
Everywhere in the world, the demand for electric power is increasing substantially while the expansion
of power generation and transmission systems is being hindered by limited resources and environmental
restrictions. As a consequence, some transmission lines are heavily loaded and system stability and
performance are becoming power transfer-limiting factors. The eastern region of Ethiopian HVAC
transmission line is one of such loaded lines in Ethiopia. There are different ways of mitigation of
dynamic performance and stability problems; namely, constructing new transmission lines,
interconnecting different power systems, and installing static manual methods such as phase-shifting
transformers and reactors. The problem is: - constructing new transmission lines requires huge
investment whereas installing manual methods does not significantly improve dynamic performance and
stability as phase-shifting transformers and reactors are not robust. This study investigates the effects of
SVC, TCSC and UPFC controllers on voltage profile, loss, small-signal stability and transient stability
of the Eastern Regional Network of the Ethiopian Power System. The network has been modeled and
simulated in PSAT of MATLAB. Rotor angle, angular frequency, voltage profile and line loss responses
of the network are investigated with and without FACTS (SVC, TCSC and UPFC) controllers.
Simulation results have demonstrated that SVC, TCSC and UPFC controllers can significantly improve
the voltage profile, small signal stability, line losses and transient stability of the Eastern Regional
Network of the Ethiopian Power System. It is found from this study that the FACTS (SVC, TCSC and
UPFC) controllers can improve line losses by 9.54%,37.24%,37.47% respectively. The simulation
results indicate that for practical long line, FACTS controllers are very import devices for improving
transient stability, line losses, small signal stability and voltage stability of power system. In conclusion,
the results indicated a UPFC controller outperformed both SVC and TCSC controllers in enhancing the
dynamic performance and stability of the Eastern Regional Network of the Ethiopian Power System.
