22-06-2012, 04:43 PM
Optimal Placement of Shunt Connected Facts Device in a
Series Compensated Long Transmission Line
Optimal Placement of Shunt Connected Facts Device.pdf (Size: 464.71 KB / Downloads: 110)
Abstract
This paper deals with the optimal location and
parameters of Unified Power Flow Controllers (UPFCs) in
electrical power systems. The UPFC is one of the most
promising FACTS devices in terms of its ability to control
power system quantities. Shunt FACTS devices are used for
controlling transmission voltage, power flow, reducing
reactive losses, and damping of power system oscillations for
high power transfer levels.
INTRODUCTION
The flexible AC transmission system (FACTS) has received
much attention in the last 2 decades. It uses high current
power electronic devices to control the voltage, power flow,
stability, etc. of a transmission system. FACTS
technologies can essentially be defined as highly
engineered power-electronics-based systems, integrating
the control and operation of advanced powersemiconductor-
based converters (or valves) with softwarebased
information and control systems, which produce a
compensated response to the transmission network that is
interconnected via conventional switchgear and
transformation equipment.
TRANSMISSION LINE MODEL
In this study, it is considered that the transmission line
parameters are uniformly distributed and the line can be
modeled by a 2-port, 4-terminal networks as shown in
Figure 1. This figure represents the actual line model. The
relationship between sending end (SE) and receiving end
(RE) quantities of the line can be written as.
SERIES COMPENSATED TRANSMISSION LINE WITH SHUNT
FACTS DEVICES
Consider that the line is transferring power from a large
generating station to an infinite bus and equipped with
series capacitor at center and a shunt FACT device at point
‘m’ as shown in Figure 2. Parameter k is used to show the
fraction of the line length at which the FACTS device is
placed. The shunt FACTS device may be a SVC or
STATCOM and is usually connected to the line through a
step-down transformer as shown in Figures 3 and 4. The
transmission line is divided into 2 sections (1 & 2), and
section 2 is further divided in subsections of length [(0.5-k)
& half-line length].
CONCLUSION
This paper investigates the effect of series compensation
on the optimal location of a shunt FACTS device to get the
highest possible benefit of maximum power transfer and
system stability. Various results were found for an actual
line model of a series compensated 345 kV, 450 km line. It
has been found that the optimal location of the shunt
FACTS device is not fixed as reported by many researchers
in the case of uncompensated lines but it changes with the
change in degree of series compensation.