102 flexible alternating current transmission systems

International Journal of Trend in

International Open Access Journal

ISSN No: 2456 - 6470

@ IJTSRD | Available Online @ www.ijtsrd.com

Flexible Alternating CurrentMatthew N. O. Sadiku, Adedamola A. Omotoso, Sarhan M. Musa, Adebowale E. Shadare

Roy G. Perry College of Engineering

ABSTRACT Flexible AC Transmission System (FACTS) refers to a family of power electronics-based devices designed to increase power transfer capability of power transmission system. The main objective of FACTS is to obtain AC systems with a high level of flexibility just as in high-voltage DC systems. power electronics for controlling power flow in a transmission system. This paper provides a brief introduction to FACTS devices or controllers. KEY WORDS: flexible AC transmission system, power electronics, voltage source converters INTRODUCTION In conventional AC transmission system, of power that can be sent over a transmission line is limited by many factors such as the lengthoverheating, and system stability, transient stability limit, voltage limit, and short circuit current limit.ideal transmission the active power should be equal to the apparent power so that the power factor can be unity. This is where the role of flexible AC transmission system (FACTS) comes inFACS devices can potentially overcome the limitations by using advanced solutions based on modern power electronics. A flexible alternating current transmission system(FACTS) consists of static equipment used overcome certain limitations in the static antransmission of electrical energy. IEEE defines FACTS as "a power electronic based system and other static equipment that provide control of one or more AC transmission system parameters to enhance controllability and increase power transfer capability”[1]. In a power system, FACTS devices enable control of active and reactive power flow. Using the devices opens up the potential of reducing power losses of a transmission line.

International Journal of Trend in Scientific Research and Development (IJTSRD)

International Open Access Journal | www.ijtsrd.com

6470 | Volume - 3 | Issue – 1 | Nov – Dec 2018

www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018

Flexible Alternating Current Transmission Systems

Matthew N. O. Sadiku, Adedamola A. Omotoso, Sarhan M. Musa, Adebowale E. ShadareEngineering, Prairie View A&M University, Prairie View

Flexible AC Transmission System (FACTS) refers to based devices designed

to increase power transfer capability of power transmission system. The main objective of FACTS is o obtain AC systems with a high level of flexibility

FACTS uses power electronics for controlling power flow in a

provides a brief introduction to FACTS devices or controllers.

C transmission system, power electronics, voltage source converters

In conventional AC transmission system, the amount of power that can be sent over a transmission line is limited by many factors such as the length of the line,

transient stability it, voltage limit, and short circuit current limit. For

ideal transmission the active power should be equal to the apparent power so that the power factor can be unity. This is where the role of flexible AC

in. The use of FACS devices can potentially overcome the

by using advanced solutions based on

flexible alternating current transmission system consists of static equipment used to

s in the static and dynamic IEEE defines

FACTS as "a power electronic based system and other static equipment that provide control of one or more AC transmission system parameters to enhance

ower transfer capability” In a power system, FACTS devices enable control

of active and reactive power flow. Using the devices opens up the potential of reducing power losses of a

The concept of FACTS was introduced by Hingoraniin 1988 [2]. Since then, FACTS applications have increased significantly. The number of FACTS devices installed in practical power systems has steadily increased. It is expected that play a significant role in the next generation of electric power grids. FEATURE OF FACTS The objectives of FACTS includethe transmission capabilities while maintaining the stability of power systems, (ii) to control power so that if flows on the desired routes, (iii) to increase loading capacity of transmission lines,blackouts. The design of FACTS devices is based on the combination of traditional power system components (such as inductors, capacitors, transformers, and, switches) and power electronics elements (such atransistors and thyristors). FACTSpower systems are illustrated in Figure 1 and explained as follows [4]: � STATCOM: The static sy

(STATCOM) is a shunt-connected FACT device which is used in controlling the bus varying impedance. It is also used forpower compensation of the transmission line.

� SVC: The static VAR compensator (SVC) is the first generation of FACTS controllers.used to stabilize the load voltage in the power system and to improve the power factor of the load.

� SSSC: The static synchronous series compensator (SSSC) is a VSC-based serial FACTS devicecan provide capacitive or inductive compensatioIt has the same power electronic topology as STATCOM except that it is incorporated through

Research and Development (IJTSRD)

www.ijtsrd.com

Dec 2018

Dec 2018 Page: 809

Transmission SystemsMatthew N. O. Sadiku, Adedamola A. Omotoso, Sarhan M. Musa, Adebowale E. Shadare

Prairie View, Texas

The concept of FACTS was introduced by Hingorani Since then, FACTS applications have

The number of FACTS devices installed in practical power systems has

. It is expected that FACTS will play a significant role in the next generation of

The objectives of FACTS include [3]: (i) to increase the transmission capabilities while maintaining the stability of power systems, (ii) to control power so that if flows on the desired routes, (iii) to increase

capacity of transmission lines, (iv) to prevent

The design of FACTS devices is based on the combination of traditional power system components (such as inductors, capacitors, transformers, and, switches) and power electronics elements (such as

FACTS controllers used in are illustrated in Figure 1 and

The static synchronous compensator connected FACT device

which is used in controlling the bus voltage by It is also used for reactive

power compensation of the transmission line. VAR compensator (SVC) is the

first generation of FACTS controllers. It is often used to stabilize the load voltage in the power system and to improve the power factor of the

The static synchronous series compensator based serial FACTS device that

can provide capacitive or inductive compensation. It has the same power electronic topology as STATCOM except that it is incorporated through

International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456


a series coupling transformer instead of the shunt transformer as in the STATCOM.

� UPFC: The unified power flow controller (UPFC) is a versatile FACTS device which can providesimultaneous control of all basic parameters of the power system. It can provide both power flow and voltage control. It can control both the real and the reactive power flow. Although UPFC can be installed in different location in the poit is more effective when it is located at some optimal location.

Other FACTS devices include thyristor contrseries capacitor (TCSC), thyristor controlshifting transformers (TCPST), dynamic flow controller (DFC), and the super conducting magnetic energy storage (SMES) unit. These FACTS controllers are capable of changing the parameters of the transmission lines in a fast and effective manner.They can be connected to the power system in series, shunt or hybrid. APPLICATIONS FACTS devices have been used for controlling the voltage, impedance, and phase angle of high voltage AC lines. They can be used to increase transient stability of the transmission systems and three phase arc furnace loads. Modern FACTS devices are based on using voltage source converter (VSC) to inject a controllable AC waveform into the power system. The VSC is a basic element of the modern FACTS. Other applications include power flow control, reactive power compensation, power quality improvement, and interconnection of renewable and distributed power generation. BENEFITS Using FACTS devices in power systemsnumber of benefits. These include [5]: � It enhances the reliability of AC grids� It increases power transmission capability and

improves transient stability � It provides dynamic reactive power support and

voltage control � It improves power quality and transmission

efficiency � It reduces operation and transmission investment

cost � It reduces power delivery costs



a series coupling transformer instead of the shunt

The unified power flow controller (UPFC) ich can provide

simultaneous control of all basic parameters of the It can provide both power flow and It can control both the real and the

Although UPFC can be installed in different location in the power system, it is more effective when it is located at some

Other FACTS devices include thyristor controllable thyristor controllable phase-

dynamic flow and the super conducting magnetic

These FACTS the parameters of

in a fast and effective manner. They can be connected to the power system in series,

FACTS devices have been used for controlling the and phase angle of high voltage

They can be used to increase transient systems and for balancing

Modern FACTS devices are based on using voltage source converter (VSC) to inject a controllable AC waveform into the

The VSC is a basic element of the

Other applications include power flow control, power quality

improvement, and interconnection of renewable and

in power systems provides a

the reliability of AC grids transmission capability and

It provides dynamic reactive power support and

It improves power quality and transmission

It reduces operation and transmission investment

� It facilitates the connection of the renewable generation to the grid

Other benefits of FACTs include cost (which outweighs other consideration), convenienenvironmental impact [6]. CHALLENGES Although FACTS devices can solve several power system problems, they have their own challenges and limitations. They are not widely used in the power industry. Their cost and complexity of the deviceshave prevented their deploymentthe electric transmission systemof FACTS devices has raised concern on stability since FACTS increases the stress level of the system. Power flows in a power network are not easily controlled due to the fact that the line parameters are not easily changed. As more FACdeployed, the coordination problem compincreases [8]. Proper placement of controllers is crucial in order to obtain good performance. CONCLUSION FACTS is a technology that is based on power electronics. Advances in power now offer fast FACTS devices. The devices areto enhance transient stability, controllability and power transfer capability of transmission systems. It is expected that FACTS devices will be used in smart grids for various control purposes.information about FACTS, one should consult [9,10 REFERENCES 1. “Flexible AC transmission system,”

the free encyclopediahttps://en.wikipedia.org/wiki/Flexible_AC_transmission_system

2. N. G. Hingorani, “Power electronics in electric utilities: Role of power electronics in future power systems,” Proceedings of IEEE Special Issue on Power Electronics, April 1988.

3. “ELG4125: Flexible AC transmission systems (FACTS),”http://www.site.uottawa.ca/~rhabasLG4125FACTS.pdf

4. A. Abu-Siada, “Review of flexible AC transmission systems; enabling technologies for future smart grids,” Proceedings of International Conference on High Voltage Engineering and

International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470

Dec 2018 Page: 810

It facilitates the connection of the renewable

Other benefits of FACTs include cost (which outweighs other consideration), convenience, and

Although FACTS devices can solve several power system problems, they have their own challenges and

They are not widely used in the power cost and complexity of the devices their deployment and integration into

the electric transmission system [7]. The introduction FACTS devices has raised concern on stability

since FACTS increases the stress level of the system. ower flows in a power network are not easily

controlled due to the fact that the line parameters are As more FACTS technologies are

on problem complexity Proper placement of the FACTS

controllers is crucial in order to obtain good

FACTS is a technology that is based on power Advances in power electronics technology

now offer fast FACTS devices. The devices are used to enhance transient stability, controllability and power transfer capability of transmission systems. It is expected that FACTS devices will be used in smart

ol purposes. For more FACTS, one should consult [9,10].

Flexible AC transmission system,” Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Flexible_AC_transm

, “Power electronics in electric utilities: Role of power electronics in future power

Proceedings of IEEE Special Issue on , April 1988.

“ELG4125: Flexible AC transmission systems http://www.site.uottawa.ca/~rhabash/E

Siada, “Review of flexible AC transmission systems; enabling technologies for

Proceedings of International Conference on High Voltage Engineering and



Power System, Bali, Indonesia, October 2017, pp. 6-11.

5. T. U. Okeke and R. G. Zaher, “Flexible AC transmission systems (FACTS),” Proceedings of the International Conference on New Concepts in Smart Cities: Fostering Public Alliances, December. 2013

6. P. Moore and P. Ashmole, “Flexible AC Transmission Systems,” Power Engineering Journal, December 1995, pp. 282-286.

7. M. Bocovich et al., “Overview of series connected flexible AC transmission systems (FACTS),American Power Symposium, September 2013.

Figure 1



, Bali, Indonesia, October 2017, pp.

R. G. Zaher, “Flexible AC Proceedings of

International Conference on New Concepts in and Private

“Flexible AC Power Engineering

286.

et al., “Overview of series connected flexible AC transmission systems (FACTS), North

September 2013.

8. S. L. Nilsson, “Security aspects of flexible AC transmission systems Controller applications,” Electrical Power & Energy 3, 1995, pp. 173-179.

9. X. P. Zhang, C. Rehtanz, aTransmission Systems: Modeling and Control.Berlin, Germany: Springer

10. N. G. Hingorani and L. Gyugyi,FACTS: Concepts and TecTransmission Systems. Wiley

Figure 1 Major FACTS devices [4].

International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470

Dec 2018 Page: 811

S. L. Nilsson, “Security aspects of flexible AC transmission systems Controller applications,” Electrical Power & Energy Systems, vol. 17, no.

X. P. Zhang, C. Rehtanz, and B. Pal., Flexible AC Transmission Systems: Modeling and Control. Berlin, Germany: Springer-Verlag, 2006

N. G. Hingorani and L. Gyugyi, Understanding FACTS: Concepts and Technology of Flexible AC

Wiley-IEEE Press, 1999.

102 flexible alternating current transmission systems

Documents