This document discusses FACTS (Flexible AC Transmission System) devices. It defines FACTS as using static power electronics controllers to control reactive power and enhance AC transmission system controllability. The document outlines the necessity of FACTS devices to compensate for reactive power and improve power transmission efficiency. It describes different types of FACTS controllers including shunt controllers like STATCOM, TCR, TSR, and TSC. The benefits of FACTS in providing fast, flexible control of transmission parameters and improving power flow capability are also summarized.

1. NAME : Ravirajsinh Solanki
ENROLLMENT NO: 150990109011
SUBJECT : Advance Power Electronics
TOPIC : FACTS Devices
BRANCH: Electrical Engineering
SEM:7th
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2. CONTENT
 Introduction
 Definition of FACTS system
 Necessity of facts devices
 Shunt connected controllers
 Types of facts controllers
 Shunt connected controllers
 Benefits of FACTS
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3.  INTRODUCTION
 The concept of FACTS (Flexible AC Transmission System)
refers to a family of power electronics based devices able to
enhance AC system controllability and stability and to increase
power transfer capability.
 The design of the different schemes and configurations of
FACTS devices is based on the combination of traditional
power system components (such as transformers, reactors,
switches, and capacitors) with power electronics elements
(such as various types of transistors and thyristors).
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4.  Necessity OF FACTS DEVICES
 Power System network consist of three kinds of powers,
namely, active, reactive and apparent power. Active power is
the useful or true power that performs a useful work in the
system or load.
 Reactive power is caused entirely by energy storage
components and the losses due to reactive power may be
considerable, although reactive power is not consumed by the
loads.
 The presence of reactive power reduces the capability of
delivering the active power by the transmission lines. And the
apparent power is the combination of active and reactive
power.
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5.  In order to achieve maximum active power
transmission, the reactive power must be
compensated. This compensation is necessary for
 Improving the voltage regulation
 Increasing system stability
 Reducing the losses associated with the system
 Improving the power factor
 Better utilization of machines connected to the system
 The compensation techniques of the power system
supplies the inductive or capacitive reactive power (to
its particular limits) in order to improve the quality
and efficiency of the power transmission system.
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6.  Definition of FACTs
 The flexible AC transmission system (FACTs) uses static
controllers . power electronic based static controllers are used
to control the reactive power across AC transmission system.
 This enhances controllability and increases power transfer
capability of AC transmission line.
 The IEEE definition for FACTS controller is stated as , it is a
power electronic based system and other static equipment that
provides the control of one or more AC transmission
parameters (such as voltage, impedance, phase angle and
power).
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7. Shunt
Controller
 TYPES OF FACTs CONTROLLERS
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8. • SERIES CONNECTED CONTROLLERS
 These controllers inject a voltage in series with the line. If
this voltage is in phase quadrature with the current, the
controller consumes or supplies variable reactive power to the
network.
 Series controller may be a variable capacitor or variable
inductor or may be a source of variable frequency
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9. • SHUNT CONNECTED CONTROLLERS
 Similar to the series connected controllers, these controllers
could be a variable reactor or capacitor or a power electronic
based variable source.
 Examples of the shunt controllers include TCR, STATCOM,
TSR, TCBR and TSC.
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10. • COMBINED SERIES-SERIES CONTROLLERS
 These controllers are the combination of individual series
controllers that are controlled in a coordinated manner in
multiple power transmission systems.
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11. • COMBINED SERIES-SHUNT CONTROLLERS
 These are the combination of separate series and shunt
controllers that are controlled in a coordinate manner with
series and shunt elements.
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12.  SHUNT CONNECTED CONTROLLERS
 Different type of shunt controllers are as follows :
1) SSG –static synchronous generator
2) TCR – Thyristor controller reactor
3) TSR – Thyristor switched reactor
4) TSC – Thyristor switched capacitor
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13. 1. SSG –STATIC SYNCHRONOUS GENERATOR
 The static synchronous generator is the combination of
STATCOM and energy source to supply or absorb power.
 Battery, fly wheel, super conducting magnet, large d.c
generator, other rectifier or inverter can be used as the energy
source.
 Electronic chopper circuit is connected between the energy
source and the converter.
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14. 2. TCR – THYRISTOR CONTROLLER REACTOR
 As shown in Fig an inductor is connected in series with the
back to back connected thyristors. Effective reactance is
changed by changing the firing angle or thyristors.
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15. 3. TSR – THYRISTOR SWITCHED REACTOR
 In this more than one inductor are used and thyristors are
completely switched on or off depending upon the requirement.
No change in firing angle or thyristor is made.
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16. 4. TSC – THYRISTOR SWITCHED CAPACITOR
• In this thyristor based switches are used with the help of
which the shunt capacitors are switched on and off
depending upon the requirement. So the reactive power
supplied to the system can be changed.
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17.  BENEFITS OF FACTS
1. Power flow in the range of few tens to few hundreds of
mega watts is controlled.
2. Series impedance, shunt impedance, current, voltage, phase
angle are controlled at various frequencies.
3. The control and response of FACTs is faster.
4. The FACTs are compact and cost effective.
5. FACTs solve technical problems in interconnected power
systems and improve their synchronous operation.
6. Voltage quality is improved by harmonic control.
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