Flexible Alternating Current Transmission Systems

1. International Journal of Trend in International Open Access Journal International Open Access Journal | www.ijtsrd.com International Journal of Trend in Scientific Research and Development (IJTSRD) Research and Development (IJTSRD) www.ijtsrd.com ISSN No: 2456 - 6470 6470 | Volume - 3 | Issue – 1 | Nov – Dec 2018 Dec 2018 Flexible Alternating Current Flexible Alternating Current Transmission Systems Matthew N. O. Sadiku, Adedamola A. Omotoso, Sarhan M. Musa, Adebowale E. Shadare Engineering, Prairie View A&M University, Prairie View Transmission Systems Matthew N. O. Sadiku, Adedamola A. Omotoso, Sarhan M. Musa, Adebowale E. Shadare Matthew N. O. Sadiku, Adedamola A. Omotoso, Sarhan M. Musa, Adebowale E. Shadare Roy G. Perry College of Engineering Prairie View, Texas 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 length overheating, 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 in FACS 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 an transmission 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. The concept of FACTS was introduced by Hingorani in 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 include 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 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 a transistors and thyristors). FACTS power 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 for power 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 device can provide capacitive or inductive compensatio It has the same power electronic topology as STATCOM except that it is incorporated through STATCOM except that it is incorporated through Flexible AC Transmission System (FACTS) refers to 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 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. 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 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, 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 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 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 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 The static synchronous series compensator based serial FACTS device that can provide capacitive or inductive compensation. It has the same power electronic topology as 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 @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 809

2. International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456 International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456 International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470 ?It facilitates the connection of the renewable generation to the grid Other benefits of FACTs include cost (which outweighs other consideration), convenien environmental 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 devices have prevented their deployment the electric transmission system of 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 FAC deployed, the coordination problem comp increases [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 are to 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 https://en.wikipedia.org/wiki/Flexible_AC_transm ission_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/~rhabas LG4125FACTS.pdf 4.A. Abu-Siada, “Review transmission systems; enabling technologies for future smart grids,” Proceedings of International Conference on High Voltage Engineering and Conference on High Voltage Engineering and 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 provide simultaneous 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 po it is more effective when it is located at some optimal location. Other FACTS devices include thyristor contr series capacitor (TCSC), thyristor control shifting 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, improvement, and interconnection of renewable and distributed power generation. BENEFITS Using FACTS devices in power systems number 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 It facilitates the connection of the renewable The unified power flow controller (UPFC) ich can provide Other benefits of FACTs include cost (which outweighs other consideration), convenience, and 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 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 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, on problem complexity Proper placement of the FACTS controllers is crucial in order to obtain good FACTS devices have been used for controlling the and phase angle of high voltage They can be used to increase transient 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]. 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 power quality quality improvement, and interconnection of renewable and Flexible AC transmission system,” Wikipedia, the free https://en.wikipedia.org/wiki/Flexible_AC_transm encyclopedia encyclopedia in power systems provides a , “Power electronics in electric utilities: Role of power electronics in future power Proceedings of IEEE Special Issue on , April 1988. the reliability of AC grids transmission capability and “ELG4125: Flexible AC transmission systems http://www.site.uottawa.ca/~rhabash/E It provides dynamic reactive power support and It improves power quality and transmission Siada, “Review of of flexible flexible AC AC It reduces operation and transmission investment transmission systems; enabling technologies for Proceedings of International @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 810

3. International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456 International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456 International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470 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, a Transmission Systems: Modeling and Control. Berlin, Germany: Springer 10.N. G. Hingorani and L. Gyugyi, FACTS: Concepts and Tec Transmission Systems. Wiley Wiley-IEEE Press, 1999. 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. , Bali, Indonesia, October 2017, pp. S. L. Nilsson, “Security aspects of flexible AC transmission systems Controller applications,” Electrical Power & Energy Systems, vol. 17, no. R. G. Zaher, “Flexible AC Proceedings of X. P. Zhang, C. Rehtanz, and B. Pal., Flexible AC Transmission Systems: Modeling and Control. Berlin, Germany: Springer-Verlag, 2006 International Conference on New Concepts in and Private “Flexible AC Power Engineering 286. N. G. Hingorani and L. Gyugyi, Understanding FACTS: Concepts and Technology of Flexible AC et al., “Overview of series connected flexible AC transmission systems (FACTS), North September 2013. Figure 1 Figure 1 Major FACTS devices [4]. @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 811