Abstract
Fault current introduces voltage and reactive
power imbalances which are major problems in power systems.
This study shows the ability of Unified Power Flow Controller
(UPFC) to clear a single line to ground fault and improves
transmission system stability. The device under review is one of
the most advanced classes of Flexible Alternating Current
Transmission System (FACTS) devices. A 30-bus transmission
line system is modelled with MATLAB/Simulink software. Two
cases were simulated to evaluate the performance of UPFC. In
Case 1, the 30-bus network system is modelled and simulated
without a compensating device whilst Case 2, the system is
modelled with UPFC. The system models are designed to have a
single line to ground fault with resistance 0.010Ω and ground
resistance of 0.001Ω occurring at bus 1. The fault is expected to
cause instability in the system and be cleared after 0.04s in both
cases. The simulated results of the two cases were compared to
determine the performance of UPFC in improving the voltage
stability and power profile of the system. The results show that
UPFC has the ability of stabilizing voltage and power profile of
transmission system. The study has thus, increased insight on the
use of the device in transmission system stability and control.