EE8011 – FACTS Unit-1 Introduction
K.RAMAKRISHNAN COLLEGE OF TECHNOLOGY, TRICHY
DEPARTMENT OF EEE
IV Year –VIII SEM
EE8011 – FLEXIBLE AC TRANSMISSION SYSTEMS
UNIT-1 INTRODUCTION
PART-A (Two Marks) Questions and answers
1. What is the necessity of compensation?
The reactive power through the system can significantly improve the performance /
parameters of the power system as follows
Voltage profile
Power angle characteristics
Stability margin
Damping to power oscillations
2. What are the objectives of line compensation?
To increase the power transmission capacity of the line
To keep the voltage profile of the line along its length within acceptable bounds
to ensure the quality of supply to the connected customer as well as to
minimize the line insulation costs
3. How is the reactive power controlled, using FACTS devices?
The SVC is a shunt device of the FACTS group, regulates voltage at its terminals
by controlling the amount of reactive power injected in to or absorbed from the power
system. When a system voltage is low, the SVC generates reactive power (SVC
Capacitive). When a system voltage is high, it absorbs reactive power (SVC inductive)
4. How is reactive power controlled in electrical network?
Traditionally, rotating synchronous condensers and fixed or mechanically
switched capacitors or inductors have been used for reactive power compensation.
However, in recent years static VAR compensators are used to provide or absorb the
required reactive power have been developed.
5. Explain the objectives of FACTS controllers in the power system network.
Better the control of power flow (Real and Reactive) in transmission
lines.
Limits SC current
FINAL EEE (8TH SEM) K.Ramakrishnan College of Technology, Trichy Page 1
EE8011 – FACTS Unit-1 Introduction
Increase the load ability of the system
Increase dynamic and transient stability of power system
Load compensation
Power quality improvement
6. What are the adv. of FACTS controllers?
The flow of power is ordered. It may be as per the contract or as per the
requirements of the utilities
It increases the loading capability of the lines to the thermal capability
It improves the stability of the system and thus make the system
secure.WWW.VIDYARTHIPLUS.C
Provides secure Tie Line connection to the neighboring utilities and
regions , thereby decreasing overall generation reserve requirements on
both sides
Upgrade of lines
7. List the disadvantage of fixed series compensation.
It is effective only during heavy loads
Whenever an outage occurs on a line, with series compensation, the
series compensation is removed. This may cause overloading of other
parallel lines
If series compensation is added to an existing system, it is generally
necessary to have it on all the lines in parallel.
One major drawback in the series capacitance compensation is that
special productive devices are required to protect the capacitors and
bypass the high current produced when a SC occurs
8. What are the diff types of compensation schemes? Mainly two types of compensation
are carried out.
Load compensation
Line compensation
9. What are the diff power electronic switching devices?
SCR
MOSFET
GTO
IGBT
DOIDE
BJT
FINAL EEE (8TH SEM) K.Ramakrishnan College of Technology, Trichy Page 2
EE8011 – FACTS Unit-1 Introduction
10. Define the term FACTS.
Flexible AC Transmission Systems
Alternating current transmission system incorporating power electronics
based and other static controllers to enhance controllability and increase
power transfer capability
11. Compare fixed series compensation and fixed shunt compensation.
Voltage boost due to shunt compensators is uniform throughout the
line.WWW.VIDYARTHIPLUS.COM
Power factor will be improved by the shunt capacitor whereas, series
compensator improves power system stability limit
Protection required for the series compensator is more compared to shunt
compensator.
Amount of voltage boost by the series capacitor is more
12. What are the main areas of application of FACTS devices? FACTS mainly find
application in following areas,
Power transmission
Power Quality
Railway Grid Connection
Wind power grid Connection
Cable Systems
13. What is load compensation?
Load compensation is a management of reactive power to improve the quality of
supply especially the voltage and power factor levels.
Three main objectives of the load compensation are
Better voltage profile
Power factor correction
Load balancing
14. Define VAR compensation.
It is defined as the management of reactive power to improve the performance of
AC power systems: Maximizing stability by increasing flow of active power.
15. List the generation of facts controllers.
The following generation of FACTS controllers for the development of FACTS
controllers
First Generation of FACTS controllers:
Static VAR Compensator (SVC)
FINAL EEE (8TH SEM) K.Ramakrishnan College of Technology, Trichy Page 3
EE8011 – FACTS Unit-1 Introduction
Thyristor Controlled Series Capacitor (TCSC)
Second Generation of FACTS controllers:
Static Synchronous Compensator (STATCOM)
Static Synchronous Series Compensator (SSSC)
Third Generation of FACTS Controllers:
It is designed by combining the features of previous generations Series and shunt
compensation FACTS controllers.
Unified Power Flow Controller (UPFC)
Interline Power Flow Controller (IPFC)
16. What are various categories of FACTS controllers?
Series FACTS controllers
Shunt FACTS controllers
Combined series-series FACTS controllers
Combined series-shunt FACTS controllers WWW.VIDYARTHIPLUS.COM
PART-B Questions
1. Discuss the possible control action to maintain the voltage at rated value in transmission
line.
[Page No: 16-19]
2. Explain the concept and need of reactive power.
[Page No: 16-18]
3. Explain the role of FACTS devices in reactive power compensation.
[Page No: 6-12]
4. What is meant by active and passive compensation? Discuss the effect of shunt and series
compensation on power transmission capacity.
[OR]
What are the objectives of line compensation? Explain the effect of shunt and series
compensation on power transmission capacity of a short symmetrical line.
[OR]
Consider a two machines power system model. Explain the basic concepts of shunt and
series compensation in detail. Also comment about the effect of degree of compensation
on the system with neat sketch.
[Page No: 33-38]
FINAL EEE (8TH SEM) K.Ramakrishnan College of Technology, Trichy Page 4
EE8011 – FACTS Unit-1 Introduction
5. Give the complete analysis of lossless distributed parameter transmission lines and derive
power equations for symmetrical case.
[OR]
Explain the uncompensated transmission line with suitable expressions.
[Page No: 19-23]
6. Explain in detail about the classification of different FACTS controllers.
[OR]
List the various FACTS controller devices and explain briefly any two shunt connected
FACTS devices.
[Refer Unit-1 PPT]
Reference Book:
R.Mohan Mathur, Rajiv K.Varma, “Thyristor – Based Facts Controllers for Electrical
TransmissionSystems”, IEEE press and John Wiley & Sons, Inc, 2002.
FINAL EEE (8TH SEM) K.Ramakrishnan College of Technology, Trichy Page 5
