This document reviews research on using Flexible AC Transmission System (FACTS) devices to enhance power system transient stability. It discusses different FACTS devices such as SVC, TCSC, UPFC, and their control capabilities. The document also reviews developments in semiconductor technologies that have improved FACTS devices, such as GTO, IGBT, and IGCT. It analyzes locations and feedback signals important for FACTS controllers to maximize stability enhancement. In conclusion, UPFC is identified as the most effective FACTS device for improving transient stability by providing independent control of voltage, impedance, and power flows.
This document compares the performance of a star-connected cascaded STATCOM using five different PWM techniques: Sinusoidal Phase Shifted Carrier (SPSC) PWM, Sinusoidal Phase Disposition (SPD) PWM, Third Harmonic Injected Phase Shifted Carrier (THIPSC) PWM, Space Vector Phase Shifted Carrier (SVPSC) PWM, and Space Vector Phase Disposition (SVPD) PWM. The STATCOM performance is simulated in MATLAB for different load changes. Parameters like DC link voltage balancing, total harmonic distortion of STATCOM currents and voltages, and reactive power supplied by the STATCOM are compared for each control strategy.
This document summarizes several FACTS (Flexible AC Transmission Systems) devices that can be installed in power systems to better control power flows. It discusses both shunt and series FACTS controllers, including the Static VAR Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC), Thyristor Controlled Phase Angle Regulator (TCPAR), Static Synchronous Compensator (STATCOM), Static Synchronous Series Compensator (SSSC), Unified Power Flow Controller (UPFC), Interline Power Flow Controller (IPFC) and others. It provides an overview of how these devices work and their benefits, such as increasing transmission capacity, improving stability, and allowing for more optimal
The electricity supply industry is undergoing a profound transformation worldwide. Market forces, scarcer natural resources, and an ever-increasing demand for electricity are some of the drivers responsible for such unprecedented change. Against this background of rapid evolution, the expansion programs of many utilities are being thwarted by a variety of well-founded, environment, land-use, and regulatory pressures that prevent the licensing and building of new transmission lines and electricity generating plants.
A REVIEW PAPER ON A D-FACTS CONTROLLER: ENHANCED POWER FLOW CONTROLLERDHEERAJ DHAKAR
This document provides a review of distributed FACTS (D-FACTS) controllers, specifically the Enhanced Power Flow Controller (EPFC). The EPFC is a D-FACTS controller that functions similarly to a thyristor controlled series compensator (TCSC) but is distributed along transmission lines in small modules every 5-10 km. D-FACTS controllers offer advantages over conventional FACTS devices by being more cost effective, reliable, and not requiring breaks in transmission lines for installation. The EPFC works by injecting series impedance into lines using single turn transformers to control power flow without significantly increasing costs or complexity compared to traditional FACTS controllers.
Application of Multilevel Voltage-Source-Converter in FACTS Devices for Power...IJMER
This document discusses a study on applying a multilevel voltage-source converter (VSC) in flexible AC transmission systems (FACTS) devices for power system voltage control and reactive power compensation. Specifically, it proposes a sixty pulse VSC STATCOM design that combines a twelve pulse converter with a five-level voltage source inverter (VSI) to improve performance. The study finds that the multilevel VSI STATCOM is able to provide satisfactory reactive power flow control and respond quickly to changes in reactive current reference. THD is also maintained within acceptable limits. FACTS devices using power electronics, such as STATCOMs, help enhance power transfer capability, flexibility and stability in transmission networks.
Modern FACTS controllers are being used to control the power through the current power transmission system.
The power transfer can be controlled by using these devices in an efficient and effective manner in transmission
lines. FACTS controllers are having some downsides i.e. their bulky size, higher cost, reliability and break-in
the transmission line, which makes it obsolete to use in modern power system network. These downsides can be
fulfilled by a new compound which is scalable, light weighted and cost effective devices that are distributed-
FACTS (D-FACTS). D-FACTS controllers are distributed version of conventional lumped FACTS controllers
and their cost is low due to lower ratings of component and reliability also increases due to redundancy of
devices. Enhanced Power Flow Controller (EPFC) is all a D-FACTS device which is a distributed version of
thyristor controlled series controller. This paper discusses extensive review about the EPFC and its application.
The document provides an overview of flexible AC transmission systems (FACTS) controllers. It discusses that FACTS controllers use power electronics to control parameters like impedance, voltage, and phase angle to enhance power flow controllability and transmission capacity. FACTS devices allow for better utilization of existing transmission systems and include series controllers that inject voltage in series with transmission lines and shunt controllers that inject current. The benefits of FACTS are more efficient power transfer, increased reliability and grid stability, and delayed investment in new transmission infrastructure.
This document compares the performance of a star-connected cascaded STATCOM using five different PWM techniques: Sinusoidal Phase Shifted Carrier (SPSC) PWM, Sinusoidal Phase Disposition (SPD) PWM, Third Harmonic Injected Phase Shifted Carrier (THIPSC) PWM, Space Vector Phase Shifted Carrier (SVPSC) PWM, and Space Vector Phase Disposition (SVPD) PWM. The STATCOM performance is simulated in MATLAB for different load changes. Parameters like DC link voltage balancing, total harmonic distortion of STATCOM currents and voltages, and reactive power supplied by the STATCOM are compared for each control strategy.
This document summarizes several FACTS (Flexible AC Transmission Systems) devices that can be installed in power systems to better control power flows. It discusses both shunt and series FACTS controllers, including the Static VAR Compensator (SVC), Thyristor Controlled Series Capacitor (TCSC), Thyristor Controlled Phase Angle Regulator (TCPAR), Static Synchronous Compensator (STATCOM), Static Synchronous Series Compensator (SSSC), Unified Power Flow Controller (UPFC), Interline Power Flow Controller (IPFC) and others. It provides an overview of how these devices work and their benefits, such as increasing transmission capacity, improving stability, and allowing for more optimal
The electricity supply industry is undergoing a profound transformation worldwide. Market forces, scarcer natural resources, and an ever-increasing demand for electricity are some of the drivers responsible for such unprecedented change. Against this background of rapid evolution, the expansion programs of many utilities are being thwarted by a variety of well-founded, environment, land-use, and regulatory pressures that prevent the licensing and building of new transmission lines and electricity generating plants.
A REVIEW PAPER ON A D-FACTS CONTROLLER: ENHANCED POWER FLOW CONTROLLERDHEERAJ DHAKAR
This document provides a review of distributed FACTS (D-FACTS) controllers, specifically the Enhanced Power Flow Controller (EPFC). The EPFC is a D-FACTS controller that functions similarly to a thyristor controlled series compensator (TCSC) but is distributed along transmission lines in small modules every 5-10 km. D-FACTS controllers offer advantages over conventional FACTS devices by being more cost effective, reliable, and not requiring breaks in transmission lines for installation. The EPFC works by injecting series impedance into lines using single turn transformers to control power flow without significantly increasing costs or complexity compared to traditional FACTS controllers.
Application of Multilevel Voltage-Source-Converter in FACTS Devices for Power...IJMER
This document discusses a study on applying a multilevel voltage-source converter (VSC) in flexible AC transmission systems (FACTS) devices for power system voltage control and reactive power compensation. Specifically, it proposes a sixty pulse VSC STATCOM design that combines a twelve pulse converter with a five-level voltage source inverter (VSI) to improve performance. The study finds that the multilevel VSI STATCOM is able to provide satisfactory reactive power flow control and respond quickly to changes in reactive current reference. THD is also maintained within acceptable limits. FACTS devices using power electronics, such as STATCOMs, help enhance power transfer capability, flexibility and stability in transmission networks.
Modern FACTS controllers are being used to control the power through the current power transmission system.
The power transfer can be controlled by using these devices in an efficient and effective manner in transmission
lines. FACTS controllers are having some downsides i.e. their bulky size, higher cost, reliability and break-in
the transmission line, which makes it obsolete to use in modern power system network. These downsides can be
fulfilled by a new compound which is scalable, light weighted and cost effective devices that are distributed-
FACTS (D-FACTS). D-FACTS controllers are distributed version of conventional lumped FACTS controllers
and their cost is low due to lower ratings of component and reliability also increases due to redundancy of
devices. Enhanced Power Flow Controller (EPFC) is all a D-FACTS device which is a distributed version of
thyristor controlled series controller. This paper discusses extensive review about the EPFC and its application.
The document provides an overview of flexible AC transmission systems (FACTS) controllers. It discusses that FACTS controllers use power electronics to control parameters like impedance, voltage, and phase angle to enhance power flow controllability and transmission capacity. FACTS devices allow for better utilization of existing transmission systems and include series controllers that inject voltage in series with transmission lines and shunt controllers that inject current. The benefits of FACTS are more efficient power transfer, increased reliability and grid stability, and delayed investment in new transmission infrastructure.
This document presents information on HVDC transmission and FACTS technology. It discusses the advantages and disadvantages of HVDC transmission, including its ability to transmit power over long distances with lower losses compared to AC transmission. It also introduces various FACTS controllers and their advantages in enhancing power flow control and transmission capacity. While FACTS can improve AC system utilization, HVDC may be less expensive for long distance overhead transmission or submarine cables. Both technologies are complementary with HVDC suitable for interconnecting unsynchronized AC systems and FACTS providing added benefits within AC networks.
Enhancement of Power System Dynamics Using a Novel Series Compensation SchemeIJMER
Phase imbalanced capacitive compensation is a “hybrid” series compensation scheme, where the
series capacitive compensation in one phase is created using a single-phase TCSC in series with a fixed capacitor
(Cc), and the other two phases are compensated by fixed series capacitors (C). The TCSC control is initially set
such that its equivalent compensations at the power frequency combined with the fixed capacitor yield a
resultant compensation equal to the other two phases. Thus, the phase balance is maintained at the power
frequency while at any other frequency, a phase imbalance is created. The effectiveness of the scheme in damping
power system oscillations for various network conditions, namely different system faults and tie-line power flows is
evaluated using the MATLAB/SIMULINK Software
Design Modeling and Simulation of Fuzzy Controlled Svc for Long Over Head Tra...IOSRJEEE
The basic control objectives of a power system are system voltage control, system frequency control, protection and economic operation. Reactive power control is a subset of overall system control and stability. A power system is said to be well designed if it gives a good quality of reliable supply. By good quality is said meant the voltage levels are maintained within the reasonable limits. If the voltage variation is more than a pre specified value, the performance of the equipment suffers and the life of most of the equipment is sacrificed. When power is supplied to a load through transmission line keeping sending end voltage constant, the load voltage undergoes variations depending upon the magnitude of the load. The higher the load greater is the voltage variation. The transmission line distributed parameters through out the line, on light loads or at no loads become predominant and consequently the line supplies charging VAR (generates reactive power). In order to maintain the terminal voltage at the load bus adequate, reactive reserves are needed. FACTS devices like SVC can supply or absorb the reactive power at receiving end bus or at load end bus in transmission system, which helps in achieving better economy in power transfer. The fuzzy control has emerged as one of the most active and fruitful areas for research in the applications of fuzzy set theory. Fuzzy control is based on fuzzy logic – a logical system which is much closer in sprit to human thinking and nature language than traditional logical system. The fuzzy logic controller (FLC) provides a means of converting a linguistic control strategy based on an expert knowledge into an automatic control strategy. Knowledge acquisition in FLC application plays an important role in determining the level of performance of a fuzzy control system. FLC based on the fuzzy model of a process is needed when higher accuracy and reliability are required. Only small efforts have been expended in applying fuzzy
Project is designed to develop a FACTs (Flexible AC Transmission) by TSR (Thyristor Switch Reactance) used in two ways. Read more about this project here.
Steady State Fault Analysis of VSC- HVDC Transmission SystemIRJET Journal
This document summarizes research on modeling and analyzing steady state faults in a voltage source converter (VSC) high voltage direct current (HVDC) transmission system. It presents the following:
1) A dynamic model of a VSC-HVDC back-to-back system is developed including VSC converters, AC and DC filters, and cables. Vector control is used to independently control active and reactive power.
2) Simulation cases demonstrate startup and steady state response, as well as the system's ability to independently control active and reactive power through step changes.
3) Additional cases show the system maintains stability under a voltage sag at one station and a three-phase fault at the other station, recovering quickly
Transmission System Operators and Owners are required to maintain a Black Start and System
Restoration Plan that has been thoroughly verified with studies. Combustion turbines are
typically used as Black Start generators, which then are used to start larger coal and combined
cycle plants. Steady state and transient studies are normally performed to verify whether voltage
and frequency are within limits so as not to interrupt the restoration process, and to ensure
large induction motors associated with the power plants can be started. In recent times, Battery
Energy Storage Systems (BESS) are being considered for black start system restoration, in
lieu of combustion turbines. The models that are currently available for BESS in transmission
planning software are meant to study synchronized operation of BESS, rather than an islanded
operation. In this paper, a modeling technique is presented for evaluating BESS for black start
system restoration. The performance of BESS for black start system restoration is compared
with the performance of a combustion turbine.
IRJET- Improved IUPQC Controller to Provide Grid Voltage as a STATCOMIRJET Journal
This document discusses an improved controller for the integrated Unified Power Quality Conditioner (iUPQC) that expands its capabilities. The iUPQC can now provide reactive power support to regulate both the load bus voltage and grid side bus voltage, allowing it to function as a Static Synchronous Compensator (STATCOM) on the grid side while still providing conventional UPQC compensation on the load side. Experimental results confirm the new functionality of the device. The iUPQC with the enhanced controller provides power quality compensation like a UPQC as well as reactive power and voltage regulation like a STATCOM.
This paper proposes a new voltage frequency converter (VFC) that converts both voltage and frequency to the required level of voltage and frequency in low voltage networks used in various countries. The proposed converter could be used as a universal power supply for sensitive AC loads. The converter is composed of, input voltage and frequency detection circuitry, full bridge boost rectifier and a DC to AC inverter. In addition, to improve the feasibility and performance of the converter, synchronous reference based PI (SRFPI) controller is adopted, where the system behaves similar to a DC-DC converter. The parameter selection of PI controller is done using a recent optimisation technique called Lightning Search Algorithm (LSA). The simulation of VFC is conducted in MATLAB/Simulink environment. The simulation results shows that LSA based PI controller provides better output voltage regulation with respect to the reference value under various load and input conditions.
Flexible AC Transmission System (FACTS):
Alternating current transmission systems incorporating power electronic-based and other static controllers to enhance controllability and increase power transfer capability.
FACTS Controller:
What is FACTS? A power electronic-based system and other static equipment that provide control of one or more AC transmission system parameters.
Basic types of FACTS Controllers Based on the connection, generally FACTS controller can be classified as follows: Series controllers
Shunt controllers
Combined series-series controllers
Combined series-shunt controllers
This document provides information about flexible AC transmission systems (FACTS) including opportunities for FACTS, types of FACTS controllers, and their relative importance. It discusses how FACTS controllers can control parameters like line impedance, phase angle, and voltage injection to regulate power flow. The key types of FACTS controllers are series, shunt, and combined series-series or series-shunt configurations. Series controllers directly impact current and power flow, while shunt controllers control voltage. Combined controllers allow coordinated control and real power transfer between elements.
IRJET- Comparative Study of Common Methods of Frequency Response using MTDC G...IRJET Journal
This document compares different control strategies for exchanging frequency support between AC power systems connected by a multi-terminal HVDC grid. It studies synthetic inertia control using frequency derivative input, classical frequency droop control, and an integrated synthetic inertia emulation control scheme. Time domain simulations show the impact of these controls on both HVDC grid voltage response and AC system frequency stability. Frequency droop control improves one AC system's frequency at the cost of disturbance to the other. Integrated synthetic inertia emulation control facilitates primary frequency reserve exchange similarly to droop control. The control strategies allow artificial coupling of HVDC-connected AC systems for frequency support.
In this paper a grid interconnected system with wind energy source linked with a FACTs based SSFC device ( Static switched filter compensator ) at load for enhancing power quality is considered .Analysis is done for the proposed system by varying Carrier frequency over a wide range and observed system performance at all 3 busses wise Grid bus, Generator Bus and Load Bus. Two regulators are used to organize the FACTS SSFC-device, these are based on a tri-loop dynamic error obsessed inter-coupled input to VSC controller. Investigation is made in MATLAB/SIMULINK Environment for the proposed system ,it is observed that system performance in terms of percentage Total harmonic Distortion is satisfactory along with the Enhanced Power Quality.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
This paper deals with the design of filters and THD analysis of a low - frequency ac (20Hz) transmission system. The LFAC system is interfaced with the 50Hz main power grid with a cycloconverter. The wind power is collected in dc form,and is connected to the L FAC transmission line with a twelve pulse inverter. The waveforms at the sending end and receiving end of the transmission line are plotted.THD analysis of LFAC system is carried out. The circuit model of LFAC system is simulated in MATLAB/SIMULINK.
This paper studies the suitability of a vector based current control which is mostly employed for its faster response in the reactive current applications of static compnesators (STATCOMs). The current control is mostly achieved using proportional-integral (PI) controllers because of the advantage of their good tracking and small variations. However, due to the dependency of PI controllers on the modular multilevel converter (MMC) system dynamics, performance variations arise during steady-state STATCOM non-ideal operations. This paper presents an improved MMC based STATCOM control with a d-q compensation algorithm added to the vector based current control. The algorithm is derived to tackle the effects of the dynamics of the MMC and the STATCOM ideal variations without the use of any additional controller. The control is achieved by providing a power compensation in the d,q-axis which injects currents at the input of the PI controllers in order to improve the steady-state performance of the STATCOM control.
Performance of the dpfc before and during series converter failureIAEME Publication
This document discusses the performance of a Distributed Power Flow Controller (DPFC) before and during the failure of one of its series converters. It begins by describing the configuration and operation of a DPFC, which uses multiple single-phase series converters and a three-phase shunt converter to control power flow without a common DC link like in a UPFC. It then analyzes the DPFC's control capabilities at the fundamental frequency and at the third harmonic frequency used to exchange power between converters. Finally, it discusses adapted control schemes that allow the DPFC to remain stable and suppress negative/zero sequence currents during a single series converter failure.
This document summarizes a research paper that examines using a Unified Power Flow Controller (UPFC) to enhance transient stability in a power system. The paper introduces FACTS devices and describes how UPFC works. It then simulates applying a 3-phase fault to different buses in an IEEE 9-bus test system both without and with UPFC compensation. Without UPFC, the fault severely impacts voltages and power flows at several buses. With UPFC, the paper evaluates its effectiveness at improving the system's performance during fault conditions.
FLC based on static var compensator for power system transient stability enha...TELKOMNIKA JOURNAL
1. The document discusses using a fuzzy logic controller combined with a PI controller to control a static var compensator (SVC) for improving power system transient stability.
2. A two generator, three bus test system is used to compare the performance of the fuzzy-SVC controller versus a conventional PI-SVC controller under different fault conditions.
3. Simulation results show that for a single line to ground fault, both controllers perform similarly. However, for a more severe three line to ground fault, the fuzzy-SVC controller is able to damp oscillations faster and achieve stability more quickly than the PI-SVC controller due to its ability to handle nonlinear system dynamics.
This document discusses power system stability and microgrids. It defines power system stability and classifies it into several types including rotor angle stability, voltage stability, and frequency stability. It also discusses microgrids, their interconnection to main grids for availability and economic benefits, and methods for connecting microgrids using switchgear or static switches. In conclusion, it states that power system stability is important for normal operation and can be improved through devices like capacitors and FACTS controllers, and that microgrids satisfy local loads while reducing transmission losses through local renewable generation.
The document discusses improving power system performance using Flexible AC Transmission System (FACTS) devices. It describes three types of FACTS devices: Static Var Compensator (SVC), Thyristor Controlled Series Compensator (TCSC), and Unified Power Flow Controller (UPFC). The SVC and TCSC are able to control voltage and improve the voltage profile. Simulations showed adding FACTS devices decreased power losses and improved the voltage level. The UPFC can simultaneously control parameters like line impedance, voltage, and phase angle to regulate power flow.
Flexible alternating current transmission systems (FACTs) technology opens up new opportunities for
controlling power flow and enhancing the usable capacity of present, as well as new and upgraded lines. These
FACTs device which enables independent control of active and reactive power besides improving reliability and
quality of the supply. This paper describes the real and reactive power flow control through a short transmission
line and then compensated short transmission line with different FACTs devices are used to selection of FACTs
devices for better reactive power compensation with change in line capacitance/shunt capacitance to observe
power flow. Computer simulation by MATLAB/SIMULINK has been used to determining better reactive power.
TCSC, STATCOM, UPFC and SSSC FACTs controller with different capacitance are tested for controlling
reactive power flow.
This document provides a review of the Unified Power Flow Controller (UPFC), a type of Flexible AC Transmission System (FACTS) device. It discusses the basic components and operating principles of the UPFC, which combines the functions of a STATCOM and SSSC to control active and reactive power flow. The UPFC consists of two voltage source converters connected back-to-back via a DC link. One converter injects a voltage in series with the transmission line to control power flow while the other exchanges reactive power with the line to regulate the DC link voltage. Control schemes for both converters are described. The document also presents Simulink models of the UPFC and concludes it is effective for improving power system stability
This document presents information on HVDC transmission and FACTS technology. It discusses the advantages and disadvantages of HVDC transmission, including its ability to transmit power over long distances with lower losses compared to AC transmission. It also introduces various FACTS controllers and their advantages in enhancing power flow control and transmission capacity. While FACTS can improve AC system utilization, HVDC may be less expensive for long distance overhead transmission or submarine cables. Both technologies are complementary with HVDC suitable for interconnecting unsynchronized AC systems and FACTS providing added benefits within AC networks.
Enhancement of Power System Dynamics Using a Novel Series Compensation SchemeIJMER
Phase imbalanced capacitive compensation is a “hybrid” series compensation scheme, where the
series capacitive compensation in one phase is created using a single-phase TCSC in series with a fixed capacitor
(Cc), and the other two phases are compensated by fixed series capacitors (C). The TCSC control is initially set
such that its equivalent compensations at the power frequency combined with the fixed capacitor yield a
resultant compensation equal to the other two phases. Thus, the phase balance is maintained at the power
frequency while at any other frequency, a phase imbalance is created. The effectiveness of the scheme in damping
power system oscillations for various network conditions, namely different system faults and tie-line power flows is
evaluated using the MATLAB/SIMULINK Software
Design Modeling and Simulation of Fuzzy Controlled Svc for Long Over Head Tra...IOSRJEEE
The basic control objectives of a power system are system voltage control, system frequency control, protection and economic operation. Reactive power control is a subset of overall system control and stability. A power system is said to be well designed if it gives a good quality of reliable supply. By good quality is said meant the voltage levels are maintained within the reasonable limits. If the voltage variation is more than a pre specified value, the performance of the equipment suffers and the life of most of the equipment is sacrificed. When power is supplied to a load through transmission line keeping sending end voltage constant, the load voltage undergoes variations depending upon the magnitude of the load. The higher the load greater is the voltage variation. The transmission line distributed parameters through out the line, on light loads or at no loads become predominant and consequently the line supplies charging VAR (generates reactive power). In order to maintain the terminal voltage at the load bus adequate, reactive reserves are needed. FACTS devices like SVC can supply or absorb the reactive power at receiving end bus or at load end bus in transmission system, which helps in achieving better economy in power transfer. The fuzzy control has emerged as one of the most active and fruitful areas for research in the applications of fuzzy set theory. Fuzzy control is based on fuzzy logic – a logical system which is much closer in sprit to human thinking and nature language than traditional logical system. The fuzzy logic controller (FLC) provides a means of converting a linguistic control strategy based on an expert knowledge into an automatic control strategy. Knowledge acquisition in FLC application plays an important role in determining the level of performance of a fuzzy control system. FLC based on the fuzzy model of a process is needed when higher accuracy and reliability are required. Only small efforts have been expended in applying fuzzy
Project is designed to develop a FACTs (Flexible AC Transmission) by TSR (Thyristor Switch Reactance) used in two ways. Read more about this project here.
Steady State Fault Analysis of VSC- HVDC Transmission SystemIRJET Journal
This document summarizes research on modeling and analyzing steady state faults in a voltage source converter (VSC) high voltage direct current (HVDC) transmission system. It presents the following:
1) A dynamic model of a VSC-HVDC back-to-back system is developed including VSC converters, AC and DC filters, and cables. Vector control is used to independently control active and reactive power.
2) Simulation cases demonstrate startup and steady state response, as well as the system's ability to independently control active and reactive power through step changes.
3) Additional cases show the system maintains stability under a voltage sag at one station and a three-phase fault at the other station, recovering quickly
Transmission System Operators and Owners are required to maintain a Black Start and System
Restoration Plan that has been thoroughly verified with studies. Combustion turbines are
typically used as Black Start generators, which then are used to start larger coal and combined
cycle plants. Steady state and transient studies are normally performed to verify whether voltage
and frequency are within limits so as not to interrupt the restoration process, and to ensure
large induction motors associated with the power plants can be started. In recent times, Battery
Energy Storage Systems (BESS) are being considered for black start system restoration, in
lieu of combustion turbines. The models that are currently available for BESS in transmission
planning software are meant to study synchronized operation of BESS, rather than an islanded
operation. In this paper, a modeling technique is presented for evaluating BESS for black start
system restoration. The performance of BESS for black start system restoration is compared
with the performance of a combustion turbine.
IRJET- Improved IUPQC Controller to Provide Grid Voltage as a STATCOMIRJET Journal
This document discusses an improved controller for the integrated Unified Power Quality Conditioner (iUPQC) that expands its capabilities. The iUPQC can now provide reactive power support to regulate both the load bus voltage and grid side bus voltage, allowing it to function as a Static Synchronous Compensator (STATCOM) on the grid side while still providing conventional UPQC compensation on the load side. Experimental results confirm the new functionality of the device. The iUPQC with the enhanced controller provides power quality compensation like a UPQC as well as reactive power and voltage regulation like a STATCOM.
This paper proposes a new voltage frequency converter (VFC) that converts both voltage and frequency to the required level of voltage and frequency in low voltage networks used in various countries. The proposed converter could be used as a universal power supply for sensitive AC loads. The converter is composed of, input voltage and frequency detection circuitry, full bridge boost rectifier and a DC to AC inverter. In addition, to improve the feasibility and performance of the converter, synchronous reference based PI (SRFPI) controller is adopted, where the system behaves similar to a DC-DC converter. The parameter selection of PI controller is done using a recent optimisation technique called Lightning Search Algorithm (LSA). The simulation of VFC is conducted in MATLAB/Simulink environment. The simulation results shows that LSA based PI controller provides better output voltage regulation with respect to the reference value under various load and input conditions.
Flexible AC Transmission System (FACTS):
Alternating current transmission systems incorporating power electronic-based and other static controllers to enhance controllability and increase power transfer capability.
FACTS Controller:
What is FACTS? A power electronic-based system and other static equipment that provide control of one or more AC transmission system parameters.
Basic types of FACTS Controllers Based on the connection, generally FACTS controller can be classified as follows: Series controllers
Shunt controllers
Combined series-series controllers
Combined series-shunt controllers
This document provides information about flexible AC transmission systems (FACTS) including opportunities for FACTS, types of FACTS controllers, and their relative importance. It discusses how FACTS controllers can control parameters like line impedance, phase angle, and voltage injection to regulate power flow. The key types of FACTS controllers are series, shunt, and combined series-series or series-shunt configurations. Series controllers directly impact current and power flow, while shunt controllers control voltage. Combined controllers allow coordinated control and real power transfer between elements.
IRJET- Comparative Study of Common Methods of Frequency Response using MTDC G...IRJET Journal
This document compares different control strategies for exchanging frequency support between AC power systems connected by a multi-terminal HVDC grid. It studies synthetic inertia control using frequency derivative input, classical frequency droop control, and an integrated synthetic inertia emulation control scheme. Time domain simulations show the impact of these controls on both HVDC grid voltage response and AC system frequency stability. Frequency droop control improves one AC system's frequency at the cost of disturbance to the other. Integrated synthetic inertia emulation control facilitates primary frequency reserve exchange similarly to droop control. The control strategies allow artificial coupling of HVDC-connected AC systems for frequency support.
In this paper a grid interconnected system with wind energy source linked with a FACTs based SSFC device ( Static switched filter compensator ) at load for enhancing power quality is considered .Analysis is done for the proposed system by varying Carrier frequency over a wide range and observed system performance at all 3 busses wise Grid bus, Generator Bus and Load Bus. Two regulators are used to organize the FACTS SSFC-device, these are based on a tri-loop dynamic error obsessed inter-coupled input to VSC controller. Investigation is made in MATLAB/SIMULINK Environment for the proposed system ,it is observed that system performance in terms of percentage Total harmonic Distortion is satisfactory along with the Enhanced Power Quality.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
This paper deals with the design of filters and THD analysis of a low - frequency ac (20Hz) transmission system. The LFAC system is interfaced with the 50Hz main power grid with a cycloconverter. The wind power is collected in dc form,and is connected to the L FAC transmission line with a twelve pulse inverter. The waveforms at the sending end and receiving end of the transmission line are plotted.THD analysis of LFAC system is carried out. The circuit model of LFAC system is simulated in MATLAB/SIMULINK.
This paper studies the suitability of a vector based current control which is mostly employed for its faster response in the reactive current applications of static compnesators (STATCOMs). The current control is mostly achieved using proportional-integral (PI) controllers because of the advantage of their good tracking and small variations. However, due to the dependency of PI controllers on the modular multilevel converter (MMC) system dynamics, performance variations arise during steady-state STATCOM non-ideal operations. This paper presents an improved MMC based STATCOM control with a d-q compensation algorithm added to the vector based current control. The algorithm is derived to tackle the effects of the dynamics of the MMC and the STATCOM ideal variations without the use of any additional controller. The control is achieved by providing a power compensation in the d,q-axis which injects currents at the input of the PI controllers in order to improve the steady-state performance of the STATCOM control.
Performance of the dpfc before and during series converter failureIAEME Publication
This document discusses the performance of a Distributed Power Flow Controller (DPFC) before and during the failure of one of its series converters. It begins by describing the configuration and operation of a DPFC, which uses multiple single-phase series converters and a three-phase shunt converter to control power flow without a common DC link like in a UPFC. It then analyzes the DPFC's control capabilities at the fundamental frequency and at the third harmonic frequency used to exchange power between converters. Finally, it discusses adapted control schemes that allow the DPFC to remain stable and suppress negative/zero sequence currents during a single series converter failure.
This document summarizes a research paper that examines using a Unified Power Flow Controller (UPFC) to enhance transient stability in a power system. The paper introduces FACTS devices and describes how UPFC works. It then simulates applying a 3-phase fault to different buses in an IEEE 9-bus test system both without and with UPFC compensation. Without UPFC, the fault severely impacts voltages and power flows at several buses. With UPFC, the paper evaluates its effectiveness at improving the system's performance during fault conditions.
FLC based on static var compensator for power system transient stability enha...TELKOMNIKA JOURNAL
1. The document discusses using a fuzzy logic controller combined with a PI controller to control a static var compensator (SVC) for improving power system transient stability.
2. A two generator, three bus test system is used to compare the performance of the fuzzy-SVC controller versus a conventional PI-SVC controller under different fault conditions.
3. Simulation results show that for a single line to ground fault, both controllers perform similarly. However, for a more severe three line to ground fault, the fuzzy-SVC controller is able to damp oscillations faster and achieve stability more quickly than the PI-SVC controller due to its ability to handle nonlinear system dynamics.
This document discusses power system stability and microgrids. It defines power system stability and classifies it into several types including rotor angle stability, voltage stability, and frequency stability. It also discusses microgrids, their interconnection to main grids for availability and economic benefits, and methods for connecting microgrids using switchgear or static switches. In conclusion, it states that power system stability is important for normal operation and can be improved through devices like capacitors and FACTS controllers, and that microgrids satisfy local loads while reducing transmission losses through local renewable generation.
The document discusses improving power system performance using Flexible AC Transmission System (FACTS) devices. It describes three types of FACTS devices: Static Var Compensator (SVC), Thyristor Controlled Series Compensator (TCSC), and Unified Power Flow Controller (UPFC). The SVC and TCSC are able to control voltage and improve the voltage profile. Simulations showed adding FACTS devices decreased power losses and improved the voltage level. The UPFC can simultaneously control parameters like line impedance, voltage, and phase angle to regulate power flow.
Flexible alternating current transmission systems (FACTs) technology opens up new opportunities for
controlling power flow and enhancing the usable capacity of present, as well as new and upgraded lines. These
FACTs device which enables independent control of active and reactive power besides improving reliability and
quality of the supply. This paper describes the real and reactive power flow control through a short transmission
line and then compensated short transmission line with different FACTs devices are used to selection of FACTs
devices for better reactive power compensation with change in line capacitance/shunt capacitance to observe
power flow. Computer simulation by MATLAB/SIMULINK has been used to determining better reactive power.
TCSC, STATCOM, UPFC and SSSC FACTs controller with different capacitance are tested for controlling
reactive power flow.
This document provides a review of the Unified Power Flow Controller (UPFC), a type of Flexible AC Transmission System (FACTS) device. It discusses the basic components and operating principles of the UPFC, which combines the functions of a STATCOM and SSSC to control active and reactive power flow. The UPFC consists of two voltage source converters connected back-to-back via a DC link. One converter injects a voltage in series with the transmission line to control power flow while the other exchanges reactive power with the line to regulate the DC link voltage. Control schemes for both converters are described. The document also presents Simulink models of the UPFC and concludes it is effective for improving power system stability
International Refereed Journal of Engineering and Science (IRJES) is a peer reviewed online journal for professionals and researchers in the field of computer science. The main aim is to resolve emerging and outstanding problems revealed by recent social and technological change. IJRES provides the platform for the researchers to present and evaluate their work from both theoretical and technical aspects and to share their views.
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IRJET- Enhancement of Power Flow Capability in Power System using UPFC- A RevieWIRJET Journal
This document reviews the use of a Unified Power Flow Controller (UPFC) to enhance power flow capability in power systems. The UPFC is a flexible AC transmission system (FACTS) device that can control both real and reactive power flows on a transmission line. It consists of two voltage source converters connected by a DC link: a static synchronous compensator (STATCOM) and a static synchronous series compensator (SSSC). The STATCOM controls reactive power and the DC link voltage, while the SSSC injects a controlled AC voltage in series with the transmission line to vary the transmission line impedance and power flow. Simulation results show that a UPFC installed on the IEEE 5 bus test system can control power flows and
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
This paper presents a method to improve transient stability and damping of low frequency oscillations in a multi-machine power system using adaptive neuro-fuzzy control of FACTS devices. A Simulink model of a three generator power system equipped with a UPFC is developed. Simulation results show that a UPFC controlled using an adaptive neuro-fuzzy inference system controller more effectively improves transient stability and damps power oscillations compared to using SSSC. The neuro-fuzzy controller is trained using a hybrid learning algorithm to tune its parameters online based on generator speed deviation and acceleration as inputs.
A New approach for controlling the power flow in a transmission system using ...IJMER
Electrical power systems is a large interconnected network that requires a careful design to maintain the system with continuous power flow operation without any limitation. Flexible Alternating Current Transmission System (FACTS) is an application of a power electronics device to control the power flow and to improve the system stability of a power system. Unified Power Flow Controller (UPFC) is a new concept for the compensation and effective power flow control in a transmission system.Through common DC link, any inverters within the UPFC is able to transfer real power to any other and there by facilitate real power transfer among the line. In this paper a test system is simulated in MATLAB/SIMULINK and the results of the network with and without UPFC are compared and when the voltage sag is compensated, reactive power is controlled and transmission line efficiency is improved.
The significance of power factor correction (PFC) has long been visualized as a technology requirement for improving the efficiency of a power system network by compensating for the fundamental reactive power generated or consumed by simple inductive or capacitive loads. With the Information Age in full swing, the growth of high reliability, low cost electronic products have led utilities to escalate their power quality concerns created by the increase of such “switching loads.” These products include: entertainment devices such as Digital TVs, DVDs, and audio equipment; information technology devices such as PCs, printers, and fax-machines; variable speed motor drives for HVAC and white goods appliances; food preparation and cooking products such as microwaves and cook tops; and lighting products, which include electronic ballasts, LED and fluorescent lamps, and other power conversion devices that operate a variety of lamps. The drivers that have resulted in this proliferation are a direct result of the availability of low-cost switch-mode devices and control circuitry in all major end-use segments: residential, commercial, and industrial.
Enhancement of Power Quality by an Application FACTS DevicesIAES-IJPEDS
1) The document discusses the use of Flexible AC Transmission Systems (FACTS) devices like Thyristor Controlled Series Capacitor (TCSC) and Thyristor Controlled Reactor (TCR)-based Static VAR Compensator (SVC) to enhance power quality and transmission capability.
2) It presents simulation models of TCSC and TCR-SVC developed using MATLAB/Simulink. The simulations show that these FACTS devices can effectively reduce voltage drops, electrical losses in long transmission lines, and improve stability.
3) Student feedback indicates the models are easy to use and effective for learning about controlled reactor compensators, series capacitor compensators, and reactive power/voltage
An Overview of FACTS Controllers for Power Quality Improvementtheijes
Large penetration of non-conventional sources of energy (such as wind and solar) into the utility grid usually leads to power quality deterioration of the net system due to the intermittency nature associated with such energy sources. Power quality parameters that may likely be disturbed by such interconnection include voltage profile, frequency waveform, power factor, as well as active and reactive power of the power system. However, grid operators and consumers at all level of usage requires a perfectly balanced three phase a.c power of constant frequency and magnitude with smooth sinusoidal wave shape. In order to compensate for such disturbances, Flexible A.C Transmission System (FACTS) controllers were developed. This paper presents a technological review of different types of FACTS controllers and their application for power quality improvement in a grid network composing of conventional and non-conventional energy sources.
This document is a project report submitted by four students for their Bachelor of Engineering degree. The project investigates the optimal location of Interline Power Flow Controllers (IPFC) in power transmission systems. The objectives are to maintain voltage profiles and real and reactive power flows. The scope involves improving voltage profiles and power transfer capabilities using IPFCs. Recently, FACTS devices like IPFCs have attracted interest for applications like congestion management and cost reduction. The problem is that few publications have investigated IPFC locations in power systems and their effects. The report is organized into chapters covering theory, location determination methods, IPFC performance simulation and results.
International Journal of Computational Engineering Research(IJCER) ijceronline
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Efficacy of Facts in Power Oscillation Damping and Renewable IntegrationIOSRJEEE
This document summarizes research on using flexible AC transmission system (FACTS) devices to improve power oscillation damping and facilitate renewable energy integration. It discusses how power oscillations can lead to instability if not controlled and how FACTS devices like STATCOM and SVC can enhance stability. It presents simulations of the IEEE 14-bus system that demonstrate improved damping from these controllers. Eigenvalue analysis shows STATCOM shifts modes further into the stable region than SVC. Both STATCOM and SVC integration helps renewable sources by mitigating power quality issues to allow more distributed generation on the grid.
This presentation provides an overview of Flexible AC Transmission Systems (FACTS) devices. It defines FACTS as power electronics-based static equipment used to improve power transfer capability and enhance controllability of AC transmission systems. The presentation categorizes FACTS devices based on their connection type to the transmission network and technology. It describes common first and second generation FACTS devices such as SVC, STATCOM, SSSC, TCSC, and UPFC; and their technical benefits regarding load flow control, voltage control, and stability. Potential applications and future enhancements of FACTS are also discussed, along with benefits, operation, and maintenance.
This document discusses Flexible AC Transmission Systems (FACTS) which use power electronics-based devices to improve control of the electric grid and increase power transfer capacity. It covers the history and types of FACTS controllers including series, shunt, and combined configurations. Series controllers inject voltage in series with transmission lines while shunt controllers inject current. FACTS provide benefits like improved power flow control, voltage regulation and transient stability while also involving high costs. Their applications include power flow control, reactive power compensation and improving transmission capability.
Facts controllers for power flow control a brief reviewDHEERAJ DHAKAR
This paper provides a review of FACTS devices. The value of these FACTS is the improvement of security and efficiency of power transmission networks. Fast controllability in emergency situation provides increased flexibility and therefore stability and security advantages. The flexibility in control allows operating closer to stability limits and improve the efficiency of existing networks
This document discusses modeling and analysis of a Thyristor Controlled Series Capacitor (TCSC) in a power system. It begins with background on TCSC and its benefits for power flow control. It then describes modeling a TCSC circuit using MATLAB Simulink. The model includes components like voltage sources, RLC branches, meters, and a thyristor block. Waveforms are analyzed for the TCSC in capacitive and inductive modes by varying the firing pulse delay. The response stabilizes after a few seconds. Fourier analysis shows the fundamental frequency reaching a new steady-state value with a change in firing angle. In conclusion, the modeling provides insights into the transient behavior and operation of a TCSC.
This document summarizes recent trends in flexible AC transmission systems (FACTS). It discusses the transmission planning process and the role of power electronics in power systems. It introduces various types of FACTS controllers including static var compensators (SVCs), thyristor controlled series capacitors (TCSCs), and unified power flow controllers (UPFCs). SVCs are used for voltage control and stabilization while TCSCs control power flow. UPFCs can independently control active power flow, reactive power flow, and voltage magnitude. FACTS provide benefits like increased transmission capacity, improved power flow control, and enhanced system stability. The document concludes
A New Approach to Powerflow Management in Transmission System Using Interline...IJERA Editor
In this paper a new approach to power flow management in transmission system using interline Power Flow
Controller (IPFC) is proposed and model for IPFC is developed and simulate by MATLAB software. Interline
Power Flow Controller is a versatile device can be used to control power flows of a multi-line system or subnetworks
An Interline Power Flow Controller (IPFC) is a converter based FACTS controller for series
compensation with capability of controlling power flow among multi-lines within the same corridor of the
transmission line. It consists of two or more Voltage Source Converters (VSCs) with a common dc-link. Real
power can be transferred via the common dc-link between the VSCs and each VSC is capable of exchanging
reactive power with its own transmission system
Similar to Ieee transient stability improvement (20)
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A Review of Enhancement of Transient
Stability by FACTS Devices
Rahul Somalwar and Manish Khemariya
Department of Electrical & Electronics Engg.
Datta Meghe Institute of Engg. Technology & Research, LNCT
Wardh, Bhopal
Abstract : In recent years, power demand has increased substantially while the expansion of power generation and
transmission has been severely limited due to limited resources and environmental restrictions. As a consequence, some
transmission lines are heavily loaded and the system stability becomes a power transfer-limiting factor. Flexible AC
transmission systems (FACTS) controllers have been mainly used for solving various power system steady state control
problems. However, recent studies reveal that FACTS controllers could be employed to enhance power system stability in
addition to their main function of power flow control. The literature shows an increasing interest in this subject for the
last three decades, where the enhancement of system stability using FACTS controllers has been extensively investigated.
This paper presents a comprehensive review on the research and developments in the power system stability enhancement
using FACTS Devices. In addition, some of the utility experience, real-world installations, and semiconductor technology
development have been reviewed and summarized & suggested a new technology Based on the advancement in
Semiconductor device .
or to control directly the real and reactive power flow in
I Introduction the line [6].
A unified power flow controller (UPFC) is the most
Development of effective ways to utilize promising device in the FACTS concept. It has the
transmission system to the maximum thermal ability to adjust the three control parameters, i.e. the bus
capabilities has caught much research attention in voltage, transmission line reactance, and phase angle
resent year. This is one direct outcome of the concept of between two buses, either simultaneously or
flexible A.C. transmission system (FACTS) aspects of independently. A UPFC performs this through the
which have become possible due to advances in power control of the in-phase voltage, quadrature voltage, and
electronics. shunt compensation.
Generally, the main objectives of FACTS are to The basic components of the UPFC are two voltage
increase the useable transmission capacity of lines and source inverters (VSIs) sharing a common dc storage
control power flow over designated transmission routes. capacitor, and connected to the power system through
There are two generations for realization of coupling transformers. One VSI is connected in shunt
power electronics-based FACTS controllers: the first to the transmission system via a shunt transformer,
generation employs conventional thyristor-switched while the other one is connected in series through a
capacitors and reactors, and quadrature tap-changing series transformer. A basic UPFC functional scheme is
transformers, the second generation employs gate turn- shown in fig 1
off (GTO) thyristor-switched converters as voltage
source converters (VSCs).
The first generation has resulted in the Static Var
Compensator (SVC), the Thyristor- Controlled Series
Capacitor (TCSC), and the Thyristor-Controlled Phase
Shifter (TCPS) [1;2]. The second generation has
produced the Static Synchronous Compensator
(STATCOM), the Static Synchronous Series
Compensator (SSSC), the Unified Power Flow
Controller (UPFC), and the Interline Power Flow
Controller (IPFC) [3 -5].
The two groups of FACTS controllers have distinctly
different operating and performance characteristics. For the maximum effectiveness of the controllers, the
The Voltage source converter (VSC) can be used selection of installing locations and feedback signals of
uniformly to control transmission line voltage, FACTS-based stabilizers must be investigated. On the
impedance, and angle by providing reactive shunt other hand, the robustness of the stabilizers to the
compensation, series compensation, and phase shifting, variations of power system operating conditions is
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equally important factor to be considered. Also, the contribute even further to the growth of FACTS
coordination among different stabilizers is a vital issue technology. After that A device called the Insulated
to avoid the adverse effects. Additionally, performance Gate Bipolar Transistor (IGBT) has been developed
comparison is an important factor that helps in selection with small gate consumption and small turn-on and
of a specific FACTS device.[24] turn-off times.
S.V.Ravi kumar [25] find the effect of UPFC with The IGBT has bi-directional current carrying
location capabilities. More effective use of pulse width
• The effect of UPFC is more pronounced when modulation techniques for control of output magnitude
the controller is placed near heavily disturbed and harmonic distortion can be achieved by increasing
generator. the switching frequencies to the low kHz range.
• The effect of UPFC is more pronounced when However, IGBT has until recently been restricted to
the controller is placed near faulted bus rather voltages and currents in the medium power range.
than placed at remote locations. Larger devices are now becoming available with typical
• UPFC helps in improving transient stability by ratings on the market being 3.3 kV/1.2 kA (Eupec), 4.5
improving critical clearing time. kV/2 kA (Fuji), and 5.2 kV/2 kA (ABB) [9,10].
• The transient stability is improved by The Integrated Gate Commutated thyristor (IGCT)
decreasing first swing with UPFC and SVC. combines the excellent forward characteristics of the
• SVC helps in improving transient stability by thyristors and the switching performance of a bipolar
improving critical clearing time transistor. In addition, IGCT does not require snubber
circuits and it has better turn-off characteristics, lower
Control systems for FACTS controllers may have to be conducting and switching loss, and simpler gate control
designed by using intelligent, adaptive digital compared with GTO and IGBT [11]. The ratings of
controllers based on information obtained from wide- IGCT reach 5.5 kV/1.8 kA for reverse conducting
area measurement networks. For systems using FACTS IGCTs and 4.5 kV/4 kA for asymmetrical IGCTs [12].
controllers, aiming for high levels of damping may not Currently, typical ratings of IGCTs on the market are
be a safe design goal for wide-area control. Adequate 10 kV/2.3 kA (ABB) and 6 kV/6 kA (Mitsubishi)
damping over the largest realistic range of operating The SSSC is a power electronic -based synchronous
conditions may be a more desirable criterion to fulfill Voltage source that generates three phase ac voltages of
[7]. The coordination of multiple FACTS controllers in controllable magnitude and phase angle. This voltage,
the same system as well as in the adjacent systems must which is injected in series with the transmission line, is
be investigated extensively and implemented to ensure almost in quadrature with the line current and hence
the security of power-system operation. emulates an equivalent inductive or capacitive
Nelson et al. [8] considered four FACTS controllers to reactance in series with the transmission
be evaluated and compared: the SVC, the STATCOM, line.
the TCSC, and the UPFC. The effects of different
controllers are expressed in terms of the critical clearing
time (CCT). The controller parameters are selected with
only consideration of maximizing the CCT. The CCT
obtained for the different controllers are compared.
Among the shunt controllers, the STATCOM performs
better than SVC. The TCSC is more effective than the
shunt controllers, as it offers greater controllability of
the power flow in the line.
The UPFC is by far the best controller, as it provides
independent control over the bus voltage and the line
real and reactive power flows.
II Development in FACTS Devices
The technology behind thyristor-based FACTS Fig 2 Static synchronous series compensator
controllers has been present from several decades and is
therefore considered mature. More utilities are likely to When the series injected voltage leads the line current,
adopt this technology in the future as more promising it emulates an inductive reactance causing the power
GTO-based FACTS technology is fast emerging. flow and the line current to decrease. When the line
Further advances in silicon power-switching devices current leads the injected voltage it emulates a
that significantly increase their power ratings will capacitive reactance thereby enhancing the power flow
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over the line. The basic schematic diagram of the static The ideal power switch would switch like an IGBT and
synchronous series compensator with its test system is conduct like a GTO thyristor, and it would have the low
shown in Figure 2. [21] fabrication costs and high yields of the GTO thyristors.
High performance and cost effective high power This is exactly what the IGCT achieves The IGCT has
voltage source inverters (VSI) are a prerequisite for the become the power semiconductor of choice in Medium
realization of SSSC. Since conventional two-pulse Voltage Industrial Applications. Also in the Energy
inverters are not available with higher ratings, multi- Management and the Traction market the versatility of
pulse inverters with higher operating range are used to this power switch has enabled performance
cater the need in SSSC. [22] These multi-pulse improvements and cost savings in a variety of
inverters can be operated at lower switching applications.[20] IGCT are currently being applied to
frequencies, generating symmetrical output voltages such devices as: Medium Voltage Drives (current and
having very low harmonic components. 48-Pulse voltage source), Circuit Breakers, Super-conducting
inverter can be used in high power FACTS controllers, Magnetic Energy Storage Systems (SMES), Dynamic
without AC filters due to its high performance and low Voltage Restorers , STATCOMs, Dynamic
harmonic rate on the AC side. 48-Pulse inverters are Uninterruptible Power Supplies, Power Conditioners,
obtained by combining eight 6-Pulse VSIs with an Induction Heaters, Traction inverters and choppers.
adequate phase shifts between them. Each of the VSI
needs a coupling transformer of which four of them IV Design Rules
require a Y-Y transformer with a turns ratio of 1:1 and
the remaining four require a Delta - Star with a turns A New proposed FACTS control device under
ratio of 1:√3. The output of the phase shifting testing process the, the most important design steps are
transformers is connected in series to cancel out the • The diode turn-off di/dt capability mostly
lower order harmonics.[23,26] determines the size of the di/dt choke.Li ≥
(Vdcmax/(di/dtmax))
III Advance FACTS controller A bigger choke might be chosen in order to
limit switching losses of the diode or to limit
From the very beginning, the development of the surge current stress during shoot-through
power semiconductors was nothing more than a search in a phase leg
for the ideal switch. The lowest on-state and • The clamp circuit parameters, Ccl, and Rs, can
commutation losses, the highest possible commutation be determined after solving the 2nd order
frequency and a simple drive circuit. Power silicon differential equation for the damped parallel
switches have increased steadily in complexity and resonance circuit Li, Ccl, Rs and optimising
capability.[13,14] The first silicon-controlled rectifiers the damping factor to force the diode clamping
could switch power off only at the end of an AC cycle. current to zero as fast as possible without
From the transistor and Darlington to the IGBT, low- succeeding oscillations of significant
voltage applications have benefited all the way along amplitudes, Thereby the influence of the stray
while the medium-voltage user could only look on — inductance, Ls2, of the loop Rs – Ccl– Cdc on
GTO’s and more GTO’s, nothing else . The the voltage overshoot has to be accounted for.
introduction of IGBTs brought faster switching, but at • Safe operating area and turn-off switching
present their switching losses are acceptable only at low losses are valid for a stray inductance value
voltage levels. GTO thyristors consist of thousands of equal to or less than the data sheet value, Lcl
individual switching elements fabricated on a silicon .For applications with higher Lcl values, safe
wafer. Losses occur in all four conditions of operation operating area and switching losses must be
(on, off, switching on, switching off). At medium rechecked.
voltage, GTO’s exhibit very low on-state losses and
reasonable turn-off losses. However, due to switching
V Conclusion
being non-homogeneous, external snubber circuits are
necessary for the switching operation. These snubber
circuits take up more than half the volume of the final In this review, the current status of power system
equipment and account for much of the design stability enhancement using FACTS controllers was
complexity, costs and losses. [19] discussed and scrutinized. The essential features of
The tendency over the years has been for the designers FACTS controllers and their potential to enhance
of all these devices to concentrate mainly on the power system stability was addressed [15 –18]. The location
switching itself, so that little attention has been paid to and feedback signals used for design of FACTS-based
the complexities involved in real-world applications. damping controllers were discussed.
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The coordination problem among different control 450
O n e - m a c h i n e s y s t e m s w i n g c u r ve . F a u l t c l e a r e d a t 0 . 1 3 s
schemes was also considered. Performance comparison 400
of different FACTS controllers has been reviewed. The 350
likely future direction of FACTS technology, especially 300
Delta, degree
in restructured power systems, was discussed as well. In 250
addition, utility experience and major real-world 200
installations and semiconductor technology 150
development have been summarized.
100
50
To investigate the effectiveness of the FACTS 0
controller under different fault condition the equal area 0 0 .2 0 .4 0 .6
t, s e c
0 .8 1 1 .2 1 .4
criteria is applied and simulation is conducted. System is unstable at Pm = 0.91
The result of control algorithm is simple and straight 120
O n e - m a c h in e s y s t e m s w in g c u r ve . F a u lt c le a r e d a t 0 . 1 3
forward that 110
• Without FACTS controller the power system 100
loses synchronism at particular shaft power Ps 90
• With FACTS controller the power system is
Delta, degree
80
stabilized at particular shaft power Ps. 70
Utility of FACTS controller for transmission stability
60
50
enhancement and damping of large oscillation has been 40
elaborated. 30
The stability investigation has been already carried out
0 0.2 0.4 0 .6 0.8 1 1 .2 1.4
t, s ec
and the system is found to be stable after introduction System stable by introducing angle Alpha by Static
of phase shift by FACTS controller . The investigation Phase shifter on same critical time.
has been done by analytical ,graphical & numerical
methods.The scheme of the introduction of the phase VI References
shift after the fault clearance is verified by simulation
and the system which was earlier unstable was found to 1. IEEE Power Engineering Society, FACTS
be stable after the phase shift α is introduced by Overview. IEEE Special Publication 95 TP108,
FACTS controller. 1995.
The new technique is suggested in this paper is 2. IEEE Power Engineering Society, FACTS
advanced FACTS Controller in which new Applications. IEEE Special Publication 96
semiconductor IGCT is used instead of GTO or IGBT TP116-0, 1996.
for designing the FACTS controller . The paper 3. I. A. Erinmez and A. M. Foss, (eds.), Static
analyzed the advantages of IGCT over other power Synchronous Compensator (STATCOM).
electronics switches. The application of this switch is Working Group 14.19, CIGRE Study Committee
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