Flexible AC Transmission Systems,
called FACTS, got in the recent years a well-known term for higher
controllability in power systems by means of power electronic devices. Several
FACTS-devices have been introduced for various applications worldwide.Rapid advances
in high power semiconductor devices and control technology, recently made it
possible to provide fast voltage support by dynamic reactive compensation of
the transmission system and power flow control in transmission corridors. Electrical
loads both generate and absorb reactive power. Since the transmitted load
varies considerably from one hour to another, the reactive power balance in a
grid varies as well. The result can be unacceptable voltage amplitude
variations or even a voltage depression, at the extreme a voltage collapse. A
rapidly operating Static Var Compensator (SVC) can continuously provide the
reactive power required to control dynamic voltage oscillations under various
system conditions and thereby improve the power system transmission and
distribution stability. Installing an SVC at one or more suitable points in the
network can increase transfer capability and reduce losses while maintaining a
smooth voltage profile under different network conditions. In addition an SVC
can mitigate active power oscillations through voltage amplitude modulation.
SVC installations consist of a number of building blocks. In the present pace
of power system restructuring, transmission systems are being required to
provide increased power transfer capability to accommodate a much wider range
of possible generation patterns. There are several problems associated with
power transmission network expansion. Hence, there is an increased interest in
better utilization of available power system capacities by installing new
device such as Flexible AC Transmission systems (FACTS). The FACTS devices can
reduce the flow of power in heavily loaded lines, resulting in an increased
loadabilty, low system loss, improved stability of the network, reduced cost of
production. The increased interest in these devices is essentially due to two
reasons. Firstly, the recent development in high power electronics has made
these devices cost effective and secondly, increased loading of power systems,
combined with deregulation of power industry, motivates the use of power flow
control as a very cost-effective means of dispatching specified power

Industrial Perspective:

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Electric arc furnaces, SAG-Mills, and many other loads cause
dynamically fluctuating disturbances to the feeding network. Penalties or shut
downs by the utility can be the result. Fact devices  help and even boost plant productivity.

Voltage stabilization and
flicker reduction:

Stable power supply and power quality improve
production. Static Var Compensators like SVC Classic or STATCOM (SVC PLUS)
compensate for quickly varying loads, stabilize voltage and reduce flicker.

Reduction of harmonic voltage distortion:

Filter circuits
compensate for unwanted harmonics caused by nonlinear loads. Low distortions
and stable voltage improve efficiency of customer assets and ensures compliance
with utility requirements.

Improvement of power factor:

Filters, SVC, and SVC PLUS compensate for
reactive loads and thus improve the power factor. Efficient power transmission
and prevention of penalty charges for reactive power consumption are achieved.

• power flow control,

• increased stability limits,
damping of power system oscillation

• increase of transmission

 • voltage control

 • reactive power compensation

 • stability improvement

 • power quality improvement

• Minimising the transmission

• Minimising the environmental


using TSC in Pakistan:

§  Siemens

§  Pak
Elektron limited (PEL)


Domestic Usage of the



Literature Survey:

Flexible AC Transmission Systems
(FACTS) controllers have been used in power systems since the 1970s with the
objective of improving system dynamic performance. Power quality is an issue
that is becoming increasingly important to electricity consumers at all levels
of usage. Sensitive power electronic equipment and non-linear loads are widely
used in industrial, commercial and domestic applications leading to distortion
in voltage and current waveforms. Due to the environmental, right-of-way, and
cost problems in both bundled and unbundled power systems, many transmission
lines have been forced to operate at almost their full capacities worldwide.
FACTS controllers enhance the static performance viz. increased loading,
congestion management, reduced system loss, economic operation, etc., and
dynamic performance viz. increased stability limits, damping of power system
oscillation, etc. In this paper, an overview of FACTS controllers is explained.
Various FACTS controller several devices in FACTS family are also discussed.

Problem Statement:

Low power issue of
electrical causes high power consumption in power distribution system.