摘要：Now a days power system network operates at different states due to variation in load demand.
As a result, the power flow in transmission line keeps on changing which needs to be controlled
precisely. Therefore, in this paper an attempt to control power flow in transmission line at
various operating states of power system network using Unified power flow controller (UPFC) is
considered. Fuzzy logic controller (FLC) has been employed to provide dynamic control of
series and shunt converters of UPFC because it adapts wide range of dynamic changes of power
sys-tem operations easily. The performance of the FLC based UPFC to control power flow
under three operating states (nominal loading, variable loading and different referencing of
power) of IEEE-14 bus system has been observed in PSCAD environment. The results show that
FLC based UPFC is capable of controlling power flow in transmission line in whatever states
the power system network is operating. In addition, to validate the statement that FLC based
UPFC cope up with networks variation flexibly, the simulation results are compared with
proportional integral (PI) based UPFC. The results show that the FLC based UPFC has better
power flow capability compared to PI controller.
关键词：FACTS; UPFC; Power Flow Control; Fuzzy Logic; PSCAD.
