Flexible AC Transmission Systems (FACTS)
• Overview Of The Transmission Planning Process
• Role Of Power Electronics Device In Power System
• Introduction Of FACTS
• Benefits Of FACTS Technology
• Types Of FACTS Controllers
• Recants uses FACTS devices
Overview Of The Transmission Planning
• Is A Very Complex Process And Recent Trends And Challenges Make It Even
More Complicated In the past, before the electricity market liberalization.
• Its aim to minimize the generation costs.
• minimizing transmission costs (investment and operation).
• Use of static and dynamic technical constraints.
Role Of Power Electronics Device In
• Switching operation because Availability Of High Power Semiconductor
• Decentralized Renewable Energy Generation Sources
• Increased Power Transfer With Existing Transmission System
• Effective Control Of Power Flow Needed In A Deregulated Environment
• Norms For Power Quality
Introduction On FACTS
• Flexible AC Transmission Systems (FACTS) are the name given to the
application of power electronics devices to control the power flows and
other quantities in power systems.
• “Alternating current transmission systems incorporating power
electronic based and other static controllers to enhance controllability
and 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
Benefits of FACTS
• To increase the power transfer capability of transmission networks.
• To provide direct control of power flow over designated
• Control of power flow as ordered so that it follows on the prescribed
• Increase the loading capability of lines to their thermal
• Static Var Compensator
• Static Synchronous Compensator
•Thyristor Controlled Series Compensator (TCSC)
•Static Synchronous Series Compensator
•Fault Current Limiter (SC+FPD)
•Dynamic Power Flow Controller (DFC)
Static Var Compensator
• The SVC is an excellent tool for achieving dynamic voltage
control of power systems. Increased efficiency in power
• The global trend is towards ever larger power networks,
longer transmission lines, and higher consumption. Energy
is also becoming increasingly expensive. To cope, power
transmission and distribution systems have to become more
efficient. It has increasing power transmission and
distribution capacity at a lower cost.
SVC used as a voltage stabilization
• SVC is the preferred tool for dynamic reactive power support in high
voltage transmission grids. it will counteract the often hazardous voltage
depressions that follow in conjunction with faults in the grid. These highly
dynamic events, where the ever increasing use of induction motors (like
those in air-conditioning units and wind power turbine-generators) stresses
the grid, will need an SVC to maintain the grid voltage and safeguard the
fault ride-through capability.
• Static var compensator includes the following major components
1. Control system
2. Thyristor valves
3. Capacitor banks
Basic SVC schemes
• Thyristor controlled reactor and fixed capacitor,
TCR/FC TCR/FCs are characterized by
– Continuous control
– No transients
– Elimination of harmonics by tuning the FCs as filters
– Compact design
• Thyristor switched capacitor, TSC
TSCs are characterized by
– Stepped control
– No transients
– No harmonics
– Low losses
– Redundancy and flexibility
The Benefits Of SVC To Power
• Stabilized voltages in weak systems
• Reduced transmission losses
• Increased transmission capacity, to reduce, defer or eliminate the need for new lines.
• Higher transient stability limit
• Increased damping of minor disturbances
• Greater voltage control and stability
• Power oscillation damping.
Combined shunt and series connected
Device capabilities SVC STATCOM TCSC SSSC TCPST UPFC
Transmission Capacity Small Small Strong Strong Strong Strong
Power Flow Control Small Small Medium Strong Medium Strong
Transient Stability Small Medium Strong Strong Medium Strong
Voltage stability Strong Strong Small Small Small Strong
Medium Medium Medium Medium Medium Strong
Control of Wind Farm
Reactive Power O/p
Yes Yes No No No Yes
Investment Cost Small Medium Small Medium Medium Strong
• The above discussion reflects various work and philophies are
covered in the area of FACTS. The potential role that FACT may
play towards the development of the future Indian transmission
system. In fact, FACT elements may provide Indian TSOs with
effective solutions to the several criticalities they encounter. Finally,
it has to be noted that in a highly meshed network, as the Indian
FACTS become extensively deployed, they will deliver real benefits
only when subjected to a coordinated and hierarchical control.
 BOOK POWER GENERATION ENGINEERING. AUTHOR R.P AJWALIA
 A. L’ABBATE, G. MIGLIAVACCA, U. HÄGER X, C. REHTANZ X ERSE
(ENEA - RICERCA SUL SISTEMA ELETTRICO) [FORMER CESI RICERCA]
SPA, MILAN, ITALY TECHNICAL UNIVERSITY OF DORTMUND, DORTMUND,
 EUROPEAN TRANSMISSION SYSTEM
 V. KAKKAR, HEAD OF DEPTT (EEE), AND N. K. AGARWAL, ASSIST.
PROF. (EEE) VITS GHAZIABAD.
 L. GYUGYI, N.G. HINGORANI, “UNDERSTANDING FACTS,”
IEEE PRESS, 1ST EDITION, DECEMBER 1999.
 M.H. RASHID, “POWER ELECTRONICS,” PRENTICE HALL, 3RD EDITION,