- The document describes a unified power flow controller (UPFC) which consists of two voltage source converters connected respectively in series and shunt with a transmission line, with a common DC link.
- It proposes modeling the UPFC using a discrete simulator in MATLAB with 12-pulse converters to reduce voltage harmonics, and controlling the series and shunt converters separately while coordinating them.
- Simulation results showed the UPFC model reflected static and dynamic characteristics, and harmonics analysis was performed on the output during different system conditions including faults.
Optimal Location of Statcom for Power Flow ControlIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
Reparation of Inductive Power in Power System by the use of FACTS devicesIJMTST Journal
This paper presents a shunt type FACTS device connected across the load to improve the power flow and
to maintain the reactive power in real data transmission line power system using MiPower software. The
main objective of this work is to maintain the voltage stability of steady-state bus voltages and reactive
power flows in transmission system with and without FACTS controller. FACTS devices are capable of
controlling the active and reactive power flows in a transmission line by controlling its series and shunt
parameters. This paper presents a steady state model of Static VAR Compensator (SVC) controller in the
power system for stability enhancement. Benefits of FACTS controllers to power system are also discussed.
In this work real data system has been considered for load flow analysis and also to incorporate the SVC
controller in the system
Small Signal Modeling Of Controller For Statcom Used In Distribution System F...IJERA Editor
In this paper non-linear model of the STATCOM is linearized and the following strategies have been adopted .
Hence, a small signal model is adopted here. Here, the grid voltage lags the fundamental component of the
STATCOM converter terminal voltage with a phase angle difference
' '
. Small signal modeling of the phase
angle
' '
and modulation index
' m '
is also done. A single PI-controller for the reactive component current of
the STATCOM has been designed. In this model, the DC-link capacitor voltage is held constant without using a
separate controller. The STATCOM are designed using SVPWM technique. Through adjustment of the
modulation index, fast modulation of the STATCOM reactive power output can be achieved due to high
sensitivity of the same with respect to the output voltage of the STATCOM VSC. The model, with PI controllers
has been simulated in MATLAB/SIMULINK environment with variation of the pre-charge voltage on the DClink
capacitor with linear loads (inductive). Improvement of the power factor of the grid current is achieved for
linear loads.
Static Synchronous Series Compensator (SSSC) with Superconducting Magnetic En...IDES Editor
Static Synchronous Series Compensator (SSSC) has
been designed with Superconducting Magnetic Energy Storage
(SMES) system. A closed loop control scheme has been
proposed with PI controller and real and reactive powers are
taken as references. A 48 pulse voltage source inverter is
designed for the SSSC. Control scheme for the chopper circuit
of SMES coil is also designed. A three area system is taken as
the test system and the operation of SSSC with SMES is
analysed for various transient disturbances. Test results under
different disturbances and operating conditions show the
proposed SSSC with SMES is effective in damping out the
power system oscillations.
POWER SYSTEM STABILITY OF MULTI MACHINE BY USING STATIC SYNCHRONOUS SERIES CO...ijiert bestjournal
In this paper the problem of modeling and simulati on of voltage stability is improved using Static Synchronous Series Compensator (SSSC). Due t o the continuous demand in electric power system,the system is heavily loaded,this ca uses to voltage instability. In this work,a static synchronous series compensator (SSSC) is use d to minimize the effect of this device in controlling active and reactive powers as well as d amping power system oscillations in transient mode. The PI controller is used to achiev e the zero signal error. The result is obtained from simulation using MATLAB. In short whe n any disturbances occur in transmission line,if SSSC is connected then distur bance in the system is minimized & system will reach the steady state condition very quickly.
Simulation Of Interline Power Flow Controller in Power Transmission Systemijsrd.com
The interline power flow controller (IPFC) is one of the latest generation flexible AC transmission systems (FACTS) controller used to control power flows of multiple transmission lines. The IPFC is the multifunction device, such as power flow control, voltage control, oscillation damping. This paper presents an overview and study and mathematical model of Interline Power Flow Control. The simulations of a simple power system of 500kV/230kV in MATLAB and simulation results are carried out on it. The results without and with IPFC are compared in terms of voltages, active and reactive power flows to demonstrate the performance of the IPFC model.
Optimal Location of Statcom for Power Flow ControlIJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
Reparation of Inductive Power in Power System by the use of FACTS devicesIJMTST Journal
This paper presents a shunt type FACTS device connected across the load to improve the power flow and
to maintain the reactive power in real data transmission line power system using MiPower software. The
main objective of this work is to maintain the voltage stability of steady-state bus voltages and reactive
power flows in transmission system with and without FACTS controller. FACTS devices are capable of
controlling the active and reactive power flows in a transmission line by controlling its series and shunt
parameters. This paper presents a steady state model of Static VAR Compensator (SVC) controller in the
power system for stability enhancement. Benefits of FACTS controllers to power system are also discussed.
In this work real data system has been considered for load flow analysis and also to incorporate the SVC
controller in the system
Small Signal Modeling Of Controller For Statcom Used In Distribution System F...IJERA Editor
In this paper non-linear model of the STATCOM is linearized and the following strategies have been adopted .
Hence, a small signal model is adopted here. Here, the grid voltage lags the fundamental component of the
STATCOM converter terminal voltage with a phase angle difference
' '
. Small signal modeling of the phase
angle
' '
and modulation index
' m '
is also done. A single PI-controller for the reactive component current of
the STATCOM has been designed. In this model, the DC-link capacitor voltage is held constant without using a
separate controller. The STATCOM are designed using SVPWM technique. Through adjustment of the
modulation index, fast modulation of the STATCOM reactive power output can be achieved due to high
sensitivity of the same with respect to the output voltage of the STATCOM VSC. The model, with PI controllers
has been simulated in MATLAB/SIMULINK environment with variation of the pre-charge voltage on the DClink
capacitor with linear loads (inductive). Improvement of the power factor of the grid current is achieved for
linear loads.
Static Synchronous Series Compensator (SSSC) with Superconducting Magnetic En...IDES Editor
Static Synchronous Series Compensator (SSSC) has
been designed with Superconducting Magnetic Energy Storage
(SMES) system. A closed loop control scheme has been
proposed with PI controller and real and reactive powers are
taken as references. A 48 pulse voltage source inverter is
designed for the SSSC. Control scheme for the chopper circuit
of SMES coil is also designed. A three area system is taken as
the test system and the operation of SSSC with SMES is
analysed for various transient disturbances. Test results under
different disturbances and operating conditions show the
proposed SSSC with SMES is effective in damping out the
power system oscillations.
POWER SYSTEM STABILITY OF MULTI MACHINE BY USING STATIC SYNCHRONOUS SERIES CO...ijiert bestjournal
In this paper the problem of modeling and simulati on of voltage stability is improved using Static Synchronous Series Compensator (SSSC). Due t o the continuous demand in electric power system,the system is heavily loaded,this ca uses to voltage instability. In this work,a static synchronous series compensator (SSSC) is use d to minimize the effect of this device in controlling active and reactive powers as well as d amping power system oscillations in transient mode. The PI controller is used to achiev e the zero signal error. The result is obtained from simulation using MATLAB. In short whe n any disturbances occur in transmission line,if SSSC is connected then distur bance in the system is minimized & system will reach the steady state condition very quickly.
Simulation Of Interline Power Flow Controller in Power Transmission Systemijsrd.com
The interline power flow controller (IPFC) is one of the latest generation flexible AC transmission systems (FACTS) controller used to control power flows of multiple transmission lines. The IPFC is the multifunction device, such as power flow control, voltage control, oscillation damping. This paper presents an overview and study and mathematical model of Interline Power Flow Control. The simulations of a simple power system of 500kV/230kV in MATLAB and simulation results are carried out on it. The results without and with IPFC are compared in terms of voltages, active and reactive power flows to demonstrate the performance of the IPFC model.
Power System Stability Enhancement Using Static Synchronous Series Compensato...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
Control of Active And reactive power flow in transmission line and power Osci...AM Publications
the continuous demand in electric power system network has caused the system to be heavily loaded
leading to voltage instability. This paper describe the active approach to series line compensation, in which static
voltage sourced converter, is used to provide controllable series compensation. This compensator is called as Static
synchronous series compensator (SSSC). It injects the compensating voltage in phase quadrature with line current, it
can emulate as inductive or capacitive reactance so as to influence the power flow in the line. With DC power supply it
can also compensate the voltage drop across the resistive component of the line impedance. In addition, the series
reactive compensation can greatly increase the power oscillation damping.
Simulations have been done in MATLAB SIMULINK. Simulation results obtained for selected bus-2 in two machine
power system. From the result we can investigate the effect of this device in controlling active and reactive power as
well as damping power system oscillations in transient mode.
An Improved UPQC Controller to Provide Grid-Voltage RegulationIJMTST Journal
In this paper presents an improved controller for the dual topology of the Unified Power Quality Conditioner (UPQC) extending its capability in power quality compensation, as well as in micro-grid applications. By the use of this controller, beyond the conventional UPQC power quality features including voltage sag/swell compensation, the iUPQC will also compensate reactive power support to regulate not only the load-bus voltage, but also the voltage at the grid-side bus. We can say, the iUPQC will work as a STATCOM at the grid side, while providing also the conventional UPQC compensations at the load terminal or micro-grid side. Experimental results are provided to verify the new functionality of the equipment.
This paper investigates the performance of line commutated converter (LCC) based monopolar
HVDC transmission system feeding a weak AC network with hybrid reactive power compensators (RPC’s) at the
inverter AC side. The hybrid compensator is an equal mix of any two of the following compensators:
synchronous compensator (SC); static var compensator (SVC); static synchronous compensator (STATCOM).
The HVDC transmission system model is implemented in the Matlab with the firefly algorithm based optimal
proportional integral (PI) controller for rectifier and inverter control. The transient performances of hybrid
RPC’s (SC+SVC, SVC+STATCOM and SC+STATCOM) are judged under various fault conditions and the
outcomes are compared with the performance of the SC, SVC and STATCOM to highlight the supremacy of the
hybrid compensators. The simulation results validate that the equal mix of SC and STATCOM has a steady and
fastest response. The results also demonstrate the superiority of the firefly algorithm based optimal PI
controller over the conventional PI controller. The harmonic analysis is also carried out under steady state
operation to assure the quality of power supply on the inverter AC side
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
In this article, we have proposed a new control of a PV system connected to the grid. The goal is
to reduce current and voltage harmonicsfor increasing the quality of delivered energy. First, we have
modeled a PV panel. Then we have dimensioned the BOOST converter by finding L and C values. Next,
we have used Perturb and Observe (P&O) Maximum Power Point Control (MPPT) to improve energy
efficiency. Finally, We have developed a control of single-phase H-bridge inverter in order to eliminate the
3rd,5th,7th and 9th harmonics order, and added an LCLTo connect the PV inverter to the grid, an LCL
betweenthe inverter and the grid. Theperformance of the proposed system was tested by computing
spectrum and THD usingMatlab/Simulink software. The proposed architecture provides better Total
Harmonic Distortion (THD) which satisfy the EN50160 requirement the THD must be less than 4.66%. We
found that THD was decreased from 61.93% to 0.04%.
A High Performance PWM Voltage Source Inverter Used for VAR Compensation and ...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
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
POWER QUALITY IMPROVEMENT BY SSSC AND STATCOM USING PI CONTROLLERJournal For Research
This paper presents the enhancement of voltage stability using Static Synchronous compensator (STATCOM) and Static Synchronous series compensator (SSSC). In recent past years, along with the rapid increasing electrical power requirement has caused system to be heavily loaded leading to voltage instability. Under this condition there may be insufficient reactive power causing voltage to drop at various buses. The result would be the occurrence of voltage collapse which leads to total blackout of the whole system. FACT controllers have been used for solving various stability control problems. In this paper, SSSC and STATCOM are used to investigate the effect of these devices in controlling active and reactive powers to maintain voltage stability. The PI Controller is used to tune the circuit and to provide the zero signal error. Simulation results have been presented in MATLAB/Simulink environment for two machines four buses system.
VSC BASED HVDC SYTEM DESIGN AND PROTECTION AGAINST OVER VOLTAGESIJERD Editor
High Voltage Direct Current system based on voltage source converter (VSC-HVDC) is becoming
more effective solution for offshore wind plants and supplying power to remote regions. In this paper, the
control of a VSC-based HVDC system (VSC-HVDC) is described. Based on this control strategy, appropriate
controllers utilizing PI controllers are designed to control the active and reactive power at each end station.The
operation performance of a voltage source converter (VSC) based HVDC (VSC-HVDC system) system is
explained under some characteristic faulted conditions with and without protection measures. A protection
strategy is proposed to enhance the continuous operation performance of the VSC-HVDC system. The strategy
utilizes a voltage chopper to suppress over-voltages on the DC side of the VSC. Digital simulation is done to
verify the validity of the proposed control strategy and protection strategy
Augmentation of Real & Reactive Power in Grid by Unified Power Flow ControllerIJERA Editor
In this paper, a Power Flow Control in transmission line with respect to voltage condition (L-G, L-L-G, L-L)
over come by using unified power flow controller. The existing system employs UPFC with transformer less
connection with both series and shunt converter. This converter have been cascaded with multilevel inverters
which is more complicated to enhance the performance of UPFC.A proposed system consist of three terminal
transformer for shunt converter and six terminal transformer for series converter. Shunt converter & series
converter is coupled with common DC capacitor. DC link capacitor voltage is maintained using PID controller
and synchronous reference frame theory (SRF) is used to generate reference voltage & current signal.
Simulation studies are carried out for (L-G, L-L-G, L-L real & reactive power compensation results will be
shown in this paper)
Power System Stability Enhancement Using Static Synchronous Series Compensato...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
International Journal of Modern Engineering Research (IJMER) covers all the fields of engineering and science: Electrical Engineering, Mechanical Engineering, Civil Engineering, Chemical Engineering, Computer Engineering, Agricultural Engineering, Aerospace Engineering, Thermodynamics, Structural Engineering, Control Engineering, Robotics, Mechatronics, Fluid Mechanics, Nanotechnology, Simulators, Web-based Learning, Remote Laboratories, Engineering Design Methods, Education Research, Students' Satisfaction and Motivation, Global Projects, and Assessment…. And many more.
Control of Active And reactive power flow in transmission line and power Osci...AM Publications
the continuous demand in electric power system network has caused the system to be heavily loaded
leading to voltage instability. This paper describe the active approach to series line compensation, in which static
voltage sourced converter, is used to provide controllable series compensation. This compensator is called as Static
synchronous series compensator (SSSC). It injects the compensating voltage in phase quadrature with line current, it
can emulate as inductive or capacitive reactance so as to influence the power flow in the line. With DC power supply it
can also compensate the voltage drop across the resistive component of the line impedance. In addition, the series
reactive compensation can greatly increase the power oscillation damping.
Simulations have been done in MATLAB SIMULINK. Simulation results obtained for selected bus-2 in two machine
power system. From the result we can investigate the effect of this device in controlling active and reactive power as
well as damping power system oscillations in transient mode.
An Improved UPQC Controller to Provide Grid-Voltage RegulationIJMTST Journal
In this paper presents an improved controller for the dual topology of the Unified Power Quality Conditioner (UPQC) extending its capability in power quality compensation, as well as in micro-grid applications. By the use of this controller, beyond the conventional UPQC power quality features including voltage sag/swell compensation, the iUPQC will also compensate reactive power support to regulate not only the load-bus voltage, but also the voltage at the grid-side bus. We can say, the iUPQC will work as a STATCOM at the grid side, while providing also the conventional UPQC compensations at the load terminal or micro-grid side. Experimental results are provided to verify the new functionality of the equipment.
This paper investigates the performance of line commutated converter (LCC) based monopolar
HVDC transmission system feeding a weak AC network with hybrid reactive power compensators (RPC’s) at the
inverter AC side. The hybrid compensator is an equal mix of any two of the following compensators:
synchronous compensator (SC); static var compensator (SVC); static synchronous compensator (STATCOM).
The HVDC transmission system model is implemented in the Matlab with the firefly algorithm based optimal
proportional integral (PI) controller for rectifier and inverter control. The transient performances of hybrid
RPC’s (SC+SVC, SVC+STATCOM and SC+STATCOM) are judged under various fault conditions and the
outcomes are compared with the performance of the SC, SVC and STATCOM to highlight the supremacy of the
hybrid compensators. The simulation results validate that the equal mix of SC and STATCOM has a steady and
fastest response. The results also demonstrate the superiority of the firefly algorithm based optimal PI
controller over the conventional PI controller. The harmonic analysis is also carried out under steady state
operation to assure the quality of power supply on the inverter AC side
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
In this article, we have proposed a new control of a PV system connected to the grid. The goal is
to reduce current and voltage harmonicsfor increasing the quality of delivered energy. First, we have
modeled a PV panel. Then we have dimensioned the BOOST converter by finding L and C values. Next,
we have used Perturb and Observe (P&O) Maximum Power Point Control (MPPT) to improve energy
efficiency. Finally, We have developed a control of single-phase H-bridge inverter in order to eliminate the
3rd,5th,7th and 9th harmonics order, and added an LCLTo connect the PV inverter to the grid, an LCL
betweenthe inverter and the grid. Theperformance of the proposed system was tested by computing
spectrum and THD usingMatlab/Simulink software. The proposed architecture provides better Total
Harmonic Distortion (THD) which satisfy the EN50160 requirement the THD must be less than 4.66%. We
found that THD was decreased from 61.93% to 0.04%.
A High Performance PWM Voltage Source Inverter Used for VAR Compensation and ...IJMER
International Journal of Modern Engineering Research (IJMER) is Peer reviewed, online Journal. It serves as an international archival forum of scholarly research related to engineering and science education.
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
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
POWER QUALITY IMPROVEMENT BY SSSC AND STATCOM USING PI CONTROLLERJournal For Research
This paper presents the enhancement of voltage stability using Static Synchronous compensator (STATCOM) and Static Synchronous series compensator (SSSC). In recent past years, along with the rapid increasing electrical power requirement has caused system to be heavily loaded leading to voltage instability. Under this condition there may be insufficient reactive power causing voltage to drop at various buses. The result would be the occurrence of voltage collapse which leads to total blackout of the whole system. FACT controllers have been used for solving various stability control problems. In this paper, SSSC and STATCOM are used to investigate the effect of these devices in controlling active and reactive powers to maintain voltage stability. The PI Controller is used to tune the circuit and to provide the zero signal error. Simulation results have been presented in MATLAB/Simulink environment for two machines four buses system.
VSC BASED HVDC SYTEM DESIGN AND PROTECTION AGAINST OVER VOLTAGESIJERD Editor
High Voltage Direct Current system based on voltage source converter (VSC-HVDC) is becoming
more effective solution for offshore wind plants and supplying power to remote regions. In this paper, the
control of a VSC-based HVDC system (VSC-HVDC) is described. Based on this control strategy, appropriate
controllers utilizing PI controllers are designed to control the active and reactive power at each end station.The
operation performance of a voltage source converter (VSC) based HVDC (VSC-HVDC system) system is
explained under some characteristic faulted conditions with and without protection measures. A protection
strategy is proposed to enhance the continuous operation performance of the VSC-HVDC system. The strategy
utilizes a voltage chopper to suppress over-voltages on the DC side of the VSC. Digital simulation is done to
verify the validity of the proposed control strategy and protection strategy
Augmentation of Real & Reactive Power in Grid by Unified Power Flow ControllerIJERA Editor
In this paper, a Power Flow Control in transmission line with respect to voltage condition (L-G, L-L-G, L-L)
over come by using unified power flow controller. The existing system employs UPFC with transformer less
connection with both series and shunt converter. This converter have been cascaded with multilevel inverters
which is more complicated to enhance the performance of UPFC.A proposed system consist of three terminal
transformer for shunt converter and six terminal transformer for series converter. Shunt converter & series
converter is coupled with common DC capacitor. DC link capacitor voltage is maintained using PID controller
and synchronous reference frame theory (SRF) is used to generate reference voltage & current signal.
Simulation studies are carried out for (L-G, L-L-G, L-L real & reactive power compensation results will be
shown in this paper)
This paper investigates the performance of line commutated converter (LCC) based monopolar HVDC transmission system feeding a weak AC network with hybrid reactive power compensators (RPC’s) at the inverter AC side. The hybrid compensator is an equal mix of any two of the following compensators: synchronous compensator (SC); static var compensator (SVC); static synchronous compensator (STATCOM). The HVDC transmission system model is implemented in the Matlab with the firefly algorithm based optimal proportional integral (PI) controller for rectifier and inverter control. The transient performances of hybrid RPC’s (SC+SVC, SVC+STATCOM and SC+STATCOM) are judged under various fault conditions and the outcomes are compared with the performance of the SC, SVC and STATCOM to highlight the supremacy of the hybrid compensators. The simulation results validate that the equal mix of SC and STATCOM has a steady and fastest response. The results also demonstrate the superiority of the firefly algorithm based optimal PI controller over the conventional PI controller. The harmonic analysis is also carried out under steady state operation to assure the quality of power supply on the inverter AC side.
Transformer-Less UPFC for Wind Turbine ApplicationsIJMTST Journal
In this paper, an innovative technique with a new concept of transformer-less unified power flow controller
(UPFC) is implemented. The construction of the conventional UPFC that consists of two back-to-back inverters
which results in complexity and bulkiness which involves the transformers which are complication for
isolation & attaining high power rating with required output waveforms. To reduce a above problem to a
certain extent, a innovative transformer-less UPFC based on less complex configuration with two cascade
multilevel inverters (CMIs) has been proposed. Unified power flow controller (UPFC) has been the most
versatile Flexible AC Transmission System (FACTS) device due to its ability to control real and reactive power
80w on transmission lines while controlling the voltage of the bus to which it is connected. UPFC being a
multi-variable power system controller it is necessary to analyze its effect on power system operation. The
new UPFC offers several merits over the traditional technology, such as Transformer-less, Light weight, High
efficiency, Low cost & Fast dynamic response. This paper mainly highlights the modulation and control for
this innovative transformer-less UPFC, involving desired fundamental frequency modulation (FFM) for low
total harmonic distortion (THD), independent active and reactive power control over the transmission line,
dc-link voltage balance control, etc. The unique capabilities of the UPFC in multiple line compensation are
integrated into a generalized power flow controller that is able to maintain prescribed, and independently
controllable, real power & reactive power flow in the line. UPFC simply controls the magnitude and angular
position of the injected voltage in real time so as to maintain or vary the real and reactive power flow in the
line to satisfy load demand & system operating conditions. UPFC can control various power system
parameters, such as bus voltages and line flows. The impact of UPFC control modes and settings on the
power system reliability has not been addressed sufficiently yet. Cascade multilevel inverters has been
proposed to have an overview of producing the light weight STATCOM’s which enhances the power quality at
the output levels.When the multilevel converter is applied to STATCOM, each of the cascaded H-bridge
converters should be equipped with a galvanically isolated and floating dc capacitor without any power
source or circuit. This enables to eliminate a bulky, heavy, and costly line-frequency transformer from the
cascade STATCOM. When no UPFC is installed, interruption of either three-phase line due to a fault reduces
an active power flow to half, because the line impedance becomes double before the interruption. Installing
the UPFC makes it possible to control an amount of active power flowing through the transmission system.
Results has been shown through MATLAB Simulink
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
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
Simulation of D-STATCOM to study Voltage Stability in Distribution systemijsrd.com
This paper presents the simulation of D-statcom to understand the improvement of voltage stability [1] of distribution system. The power circuits of the D-STATCOM and distribution networks are made up of simpower system blocks, while the control circuits made with the simulink blocks The STATCOM is applied to regulate transmission voltage to allow greater power flow in a voltage limited transmission network, in the same manner as a static var compensator (SVC), the STATCOM has further potential by giving an inherently faster response and greater output to a system with depressed voltage and offers improved quality of supply. The main applications of the STATCOM are; Distribution STATCOM (D-STATCOM) exhibits high speed control of reactive power to provide voltage stabilization and other type of system control. The DSTATCOM protects the utility transmission or distribution system from voltage sag and /or flicker caused by rapidly varying reactive current demand. During the transient conditions the D-STATCOM provides leading or lagging reactive power to active system stability, power factor correction and load balancing.
POWER STABILITY ANALYSIS OF A TRANSMISSION SYSTEM WITH A UNIFIED POWER FLOW C...IJITE
The unified power quality conditioner is the equipment used for regulated voltage distortion and voltage
unbalance in a power system. UPFC can enhance the power to flow through the transmission system by
controlling the power flow and voltage stability of the transmission line within their limits. This paper
presents a control scheme and Theoretical derivation of the unified power flow conditioner and the
simulation results are compared and contrasted in detail. UPFC is a combination of shunt Active and
series active power filters. UPFC contains a DC link capacitor in a single-phase voltage source inverter
with two back to back connected, three-phase three-wire and three-phase four-wire are arranged. The
fundamental target of this work is to determine the causes and impacts of power quality problems,
specifically voltage sag, voltage swell, power factor, and Total Harmonics Distortion (THD) and enhance
the power quality of a transmission system by UPFC based Transformative Intrinsic Algorithm (TIA). The
Simulation of the proposed method is developed by Mat lab Simulink software, and the simulation result
shows, the proposed method gives better solutions to control the power imbalance in the distribution
system with its cost-effectiveness.
Control and Analysis of VSC Based High Voltage DC Transmissionijsrd.com
High Voltage Direct Current system based on Voltage Source Converters (VSC-HVDC) is becoming a more effective, solution for long distance power transmission especially for off-shore wind plants and supplying power to remote regions Confronting with an increasing demand of power, there is a need to explore the most efficient and reliable bulk power transmission system. Rapid development in the field of power electronics devices especially Insulated Gate Bipolar Transistors (IGBTs) has led to the High Voltage Direct Current (HVDC) transmission based on Voltage Source Converters (VSCs).Since VSCs do not require commutating voltage from the connected ac grid, they are effective in supplying power to isolated and remote loads. Due to its advantages, it is possible that VSC-HVDC will be one of the most important components of power systems in the future. The VSC based HVDC transmission system mainly consists of two converter stations connected by a DC cable. This paper presents the performance analysis of VCS based HVDC transmission system. In this paper a 75kM long VSC HVDC system is simulated for various faults on the ACSide of the receiving station using MATLAB/SIMULINK. The data has been analyzed and a method is proposed to classify the faults by using back propagation algorithm. The simulated results presented in this paper are in good agreement with the published work.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
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Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
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4. Demo
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Knowledge engineering: from people to machines and back
H04945260
1. IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org
ISSN (e): 2250-3021, ISSN (p): 2278-8719
Vol. 04, Issue 09 (September. 2014), ||V4|| PP 52-60
International organization of Scientific Research 52 | P a g e
Unified Power Flow Controller: Modeling And Dynamic Characteristic Ho Dac Loc Hochiminh City University of Technology (HUTECH), Hochiminh City Abstract: - Unified power flow controller (UPFC) consists two converters. There are three purposes of this paper, firstly to illustrate the UPFC device based VSC designs, then to describe a decoupling method the UPFC’s controller into two separate control systems of the shunt and the series converters respectively in realizing an appropriate co-ordination between them. Finally, using the Matlab tool to build a discrete simulator for the UPFC with 12 pulse converters. The simulation results show that the developed UPFC model is reflected the static and dynamic characteristics of the UPFC. The harmonics of the output of the model are analyzed. Using the simple power system with UPFC as an example, the dynamics characteristics are studied. The fault status of the system with UPFC is analyzed too. Keyword list: - Times Roman, image area, acronyms, references
I. INTRODUCTION
The developing interest in tools for power flow control in a power system has increased significantly during the last 10 years. Demand for research in this field is motivated by rapid transformations in both technology and organization of the power system industry [1]. The deregulation and competitive environment in the contemporary power networks will imply a new scenario in terms of load and power flows condition and so causing problems of line transmission capacity. For this reason, Flexible AC Transmission System (FACTS) controllers has rapidly developed to meet the need for increasing transmission capacity and controlling power flows through predefined transmission corridors. Especially, the improvements in the field of power electronics have had a major impact on the development of this technology. The devices of new FACTS generation are based on the use of high power electronic components such as GTO (Gate Turn-Off Thyristor) and IGBT (Insulated Gate Bipolar Transistor) which makes them respond quickly to the control requirements. It is called by the FACTS technologies based on Voltage Sourced Converter (VSC) designs. The wider application of FATCS leads to numerous benefits for electrical transmission system infrastructure, including increased capacity at minimum cost; enhanced reliability through proven performance; higher levels of security by means of sophisticated control & protection; and improved system controllability with state-of-the-art technology concepts. Thereby, these FACTS devices are able to act almost instantaneously to changes in power system [2]. The most powerful in family of FACTS devices is the Unified Power Flow Controller (UPFC), because it can control simultaneously all three parameters of transmission power line (line impedance, voltage and phase angle). In practice, the UPFC device consists of two Voltage Source Converters (VSC) connected respectively in shunt and in series with the transmission line, and connected to each other by a common DC link including a storage capacitor. The shunt converter is used for voltage regulation at the point of connection injecting an opportune reactive power flow into the line and to balance the real power flow exchanged between the series converter and the transmission line. The series converter can be used to control the real and reactive line power flow inserting an opportune voltage with controllable magnitude and phase in series with the transmission line. Thereby, the UPFC can perform functions of reactive shunt compensation, active and reactive series compensation and phase shifting [3]. There are many different UPFC models have been investigated by several authors [4-6]. The three main purposes of the paper are firstly to illustrate the UPFC configuration based on VSC’s, and then describe a decoupling method the UPFC’s controller into two separate control systems of the shunt and the series converters respectively in realizing an appropriate co-ordination between them, and finally to simulate a new discrete UPFC model based on 12-pulse VSC using Matlab Power Block/Simulink as simulation program. Besides, PWM method is applied to decrease total of voltage harmonics in simulation output of converters.
II. THE UPFC CONFIGURATION– BASED VOLTAGE SOURCE CONVERTER
1. VSC design concept
The single-line diagram of the UPFC is a combination of two VSC configurations shown in Figures 1. As shown in Figures 1, VSC designs are composed of two basic configurations: A) Shunt Connected VSC System, and
2. Unified Power Flow Controller: Modeling And Dynamic Characteristic
International organization of Scientific Research 53 | P a g e
B) Series Connected VSC System
Figure 1 – the UPFC configuration. A basic schematic diagram of the VSC design is illustrated in Figure 2. As a typical configuration, the VSC is a six-pulse converter consisting of six power semiconductor switching devices (GTO, GCT, IGBT, etc) with anti-parallel connected diode together with heat sinks and auxiliary equipment for gating, monitoring and grading. In a high power converter, a number of semiconductor devices may be connected in series or in parallel. Some advanced configurations, for example connecting cascade of two six-pulse converters to twelve- pulse converter, have developed to reduce total of voltage harmonics of converter outputs in Fig. 3.
Figure 2 – Basic VSC Schematic Diagram From a point of D.C. voltage source, provided by a charged capacitor CS, the converter produces a set of controllable three-phase output voltages at the fundamental harmonic frequency of the A.C. system voltage. The output voltage waveform may be a square waveform (Figure 4.a) or a pulse width modulated (PWM) waveform (Figure 4.b), depending on circuit topology and pulse modulation method.
Figure 3 – 12 Pulse-VSC Schematic Diagram
Shunt Converter
Series Converter
Shunt Transformer
Series Transformer
Power transmission line
Power transmission line
DC capacitor
UPFC
F
F
A
B
VDC
vA
vB
vC
iA
iB
iC
iDC
VDC
v’A
v’B
v’C
v’’A
v’’B
V’’C
vA
vB
vC
3. Unified Power Flow Controller: Modeling And Dynamic Characteristic
International organization of Scientific Research 54 | P a g e
In order to eliminate harmonic content from the output voltage, various techniques can be adopted. A
multiple-pulse arrangement by combining the output of cascade or parallel VSCs can be adopted as a solution
using a multi-winding transformer or inter-phase transformer magnetic. The pulse width modulation (PWM)
technique can be implemented to control harmonic content from the output voltage too. Moreover, harmonic
filters can be also adopted in combination with the above techniques. In this paper PWM control is utilized,
allowing for simplified two winding interconnecting transformer designs.
Figure 4 – VSC Output Voltage Waveforms
In the configuration of UPFC, there are two independent VSCs interconnected via coupling capacitor as Shunt
converter and Series converter.
Shunt Connected VSC – the VSC is connected to the power system via a shunt connected transformer. By
varying the amplitude and the phase of the output voltages produced, the active power and the reactive power
exchange between the converter and the A.C. system can be controlled in a manner similar to that of a rotating
synchronous machine. If the amplitude of the output voltage is increased above that of the AC system voltage,
the VSC generates reactive power to the power system. If the amplitude of the output voltage is decreased below
that of the AC system voltage, the VSC absorbs reactive power from the power system.
Series Connected VSC – the VSC is connected to the power system in series via a series connected
transformer. By varying the amplitude and the phase of the output voltages produced, the magnitude and the
angle of the injected voltage can be controlled. The VSC output voltage injected in series with the line acts as an
AC voltage source. The current flowing through the VSC corresponds to the line current. The VA rating of the
VSC is determined by the product of the maximum injected voltage and the maximum line current.
2. Instantaneous power flow delivered by a VSC into a power system
A converter connected to a power system, which is able of power exchange between the power system
and the DC storage capacitor, can be represented by a three symmetrical sinusoidal voltage sources. A
symmetrical three-phase system can be transformed into a synchronously-rotating orthogonal system. A new
coordinate system, having the axes rotating at the synchronous angular speed of the fundamental network
voltage , is defined on the basis of the d-q transformation. In the Fig. 2 the VSC is supplied by a voltage
system vector VS = (VSA, VSB, VSC), with R and L are respectively the transformer equivalent resistances and
inductances. The d-q transformation of the supply voltage system VS is made using the following equations:
1 1 V
V 1 SA
SD 2 2
V
V 3 3 SB SQ 0 V 2 2 SC
(1)
where :
SQ
SD
d
;
dt
V
arct g( )
V
On the basis of this d-q transformation, the instantaneous active and reactive power flowing into the power
system delivered by the VSC [6], neglecting transformer losses and balanced condition; and choose VSD
=VSA, VSQ =0 are :
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International organization of Scientific Research 55 | P a g e
SD SD
SD SQ
3
P(t) V xI
2
3
Q(t) V xI
2
(2)
where VSD , VSQ, ISD, ISQ are vectors of d-q transition voltage and current respectively.
III. DECOUPLING METHOD OF UPFC MODEL
1. Series and Shunt converter control systems
In the UPFC configuration two converters can work independently of each other by separating the DC side. In
general operating mode of UPFC is possible as follow:
The series converter is operating in Automatic Power Flow Control mode: the reference inputs are value of
P and Q to maintain on the transmission line despite system changes; and
the shunt converter operating in Automatic Voltage Control mode : the goal is to maintain the transmission
voltage line as a reference value.
In this paper it has been chosen a UPFC model in terms of two ideal controllable voltage sources, connected
respectively in series and in shunt to the transmission line as in Fig. 1, to represent respectively the series and
the shunt inverters. So, the two UPFC control systems must be developed in such a way to evaluate the
amplitude and the phase angle of these two voltage sources on the basis of operating functions required UPFC.
On the basis of (2) the instantaneous power flow at the receiving end, assuming VrD equal to the receiving end
voltage amplitude vr and VRq = 0 results:
r rD rD
r rD rQ
3
p (t) v xi
2
3
q (t) v xi
2
(3)
where irD and irQ are the d-q component values of line current. Thereby, the reference parameters of controller is
possibly calculated as follows :
*
* r
rD
rD
*
* r
rQ
rD
2 p
i (t)
3 v
2 q
i (t)
3 v
(4)
with p*
r , and q*r are the instantaneous active and reactive power flow required the receiving end.
At the same way, the instantaneous active and reactive power flows provided by the shunt inverter are:
Sh lD Sh,D
Sh lD Sh,Q
3
p (t) v xi
2
3
q (t) v xi
2
(5)
also assuming VlD equal to the sending end voltage amplitude Vl and VlQ =0, with iSh,D and iSh,Q are the d-q
current components injected by shunt inverter into the transmission line. So, the reference values of these two
current components are evaluated as follows:
*
* Sh
Sh,D
lD
*
* Sh
Sh,Q
lD
2 p
i (t)
3 v
2 q
i (t)
3 v
(6)
where p*
Sh , q*
Sh are the instantaneous active and reactive power flows required to the shunt inverter.
From Fig. 1, the circuit equation of shunt VSC of UPFC can be written in per unit as :
Sh,A * Sh,A SA Sh,A
Sh,B * Sh,B * SB Sh,B
Sh,C Sh,C SC Sh,C
i 1 0 0 i v e
d R 1
i 0 1 0 i v e
dt L L
i 0 0 1 i v e
(7)
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International organization of Scientific Research 56 | P a g e
From [] the output values of controller of Shunt Converter to evaluate the d-q components of equivalent output
voltage source, VSh,D and VSh,Q can be shown as below :
'
Sh
Sh,D lD 1Sh
' '
Sh Sh
Sh,Q lQ 2Sh 2Sh
L
v v y
L L
v v y y
(8)
' Sh
Sh
b
L
L
z
(9)
with assuming that Vl,D = |vl| ; Vl,Q = 0; the LSh = shunt transformer leakage inductance; Zb is the base
impedance. Therefore, the module and displacement angle of equivalent voltage source of shunt converter are
calculated as follows :
2 2
Sh Sh,D Sh,Q
Sh,Q
Sh
Sh,D
V v v
v
arctg
v
(10)
At the same manner, the output variables y1Se , y2Se are used to evaluate the d-q components of series converter
of equivalent voltage source , VSe,D and VSe,Q by following equations :
'
Se
Se,D lD rD 1Se
'
Se
Se,Q lQ rQ 2Se
L
v (v v ) y
L
v (v v ) y
(12)
' 1 Se
Se
b
(L L )
L
z
(13)
2 2
Se Se,D Se,Q
Se,Q
Se
Se,D
V v v
v
arctg
v
(14)
with assuming that Vl,D = |vl| ; Vl,Q = 0; the LSe = shunt transformer leakage inductance, and L1 is the line
inductance. Therefore, the module and displacement angle of equivalent voltage source of shunt converter are
calculated as follows :
2. Converter control technique
On the basic of operation requirements, the scheme of switching the converter’s elements, such as GTO’s or
IGBT’s, may be different. In this paper, as shown above, the PWM switching control technique has been
considered. In this case the three phases of the output converter voltage result:
yA y DC y
0
yB y DC y
0
yB y DC y
1
v m V sin( t )
2
1
v m V sin( t 120 )
2
1
v m V sin( t 240 )
2
(15)
here my , y are the amplitude modulation ratio and phase angle of converter output voltage. These
control variables are the input control signals of converters of UPFC according to PWM switching technique. If
we apply (12) for Shunt converter, then mSh is the index modulation and Sh is the phase displacement angle
with respect to Vl (sending voltage). The same equation to Series converter, mSe is the index modulation and
Se is the phase displacement angle with respect to Vl – Vr (compensation voltage). VDC is the value of voltage
across the storage capacitor.
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International organization of Scientific Research 57 | P a g e
Moreover the following relations are valid:
2 2
yD yQ
y
DC
yQ
y
yD
v v
m 2 2
V
v
arctg
v
(16)
where vyD and vyQ are calculated by (8) and (11) respectively for the series and the shunt inverter.
In both control schemes the PI controllers is applied with parameters in dependence of converter characteristics,
(RSe, LSe), (RSh, LSh) respectively the equivalent impedance of the series and shunt transformer and (Rline, Lline )
the line equivalent impedance.
3. DC-side control
For normal operation of two VSC’s in an UPFC, the DC voltage across the DC storage capacitor CS must be
kept constant. This implies that the active power exchanged
between the UPFC and the power system is zero at steady state operation:
pSe + pSh = 0 (17)
that is, the active power delivered by the shunt inverter pSh is equal to the active power exchange between the
series inverter and the transmission line, pSe. Hence, a DC voltage control system must be realized to keep Vdc
constant by taking the actual value of vdc as the feedback signal against a dc reference signal V*dc []. Moreover,
assuming negligible the losses of the shunt and series converters and coupling transformers the actual value of
the DC capacitor voltage is computed as :
DC Se Sh
DC DC
dv p p
dt C v
(18)
IV. SIMULATION AND RESULTS
All the simulations were made using Matlab Power System Blockset and Simulink. The simulation
results of the discrete UPFC model based 12 pulse-converter are the subject of this section. These results are
obtained based on discrete modulation functions. A simple configuration of power system is applied to validate
the new UPFC model based 12 pulse- converter. The test power system operates at 230 kV and is shown in
Fig.5. The generator is assumed to be an ideal voltage source behind an equivalent Thevenin impedance. The
UPFC model is located at the sending end of the transmission line and is controlled in such a way to follow the
changes in reference values of the line active and reactive power. The Shunt converter and Series converter are
based on 12 pulse-converter with two level ignition signals. Besides, PWM technique with 1080 Hz carrier
frequency, which is modeled by the discrete PWM pulse generator, is used to generate output voltage pulses of
converters. This technique is very suitable for pulse control of UPFC and reduce total harmonic distortion of
output voltage and line current. In those devices, input control variables of converter, such as amplitude
modulation ratio and phase angle are output variables of close-loop power flow controller and close-loop DC
voltage controller.
Fig.5 – Simple test system with UPFC.
The Fig.8 displays DC voltage of UPFC. The real signal shape of DC voltage in discrete simulation is
an oscillation curve around reference value according to pulses of PWM converter. In Fig.9 output voltage of
Series converter is shown. It is a combination of two 6 pulse converters connected cascade together in which
whole output voltage gains a better result of low harmonic content. This has a very important meaning in
practice,….
In Fig.7, line current though UPFC is shown by discrete type.
UPFC Sys
P, Q
Transmission line
VS VR
VIdeal
ILine
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International organization of Scientific Research 58 | P a g e
Moreover, this simulation proved that total harmonic content of line voltage at UPFC bus in new discrete 12
pulse converter model is lower that of conventional 6 pulse converter. This is illustrated in Fig.10.
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
OUTPUT VOLTAGE OF 12 PULSE-SERIES CONVERTER
WITH PWM TECHNIQUE
TIME (ms)
VOLTAGE (pu)
Fig. 6 – Output voltage of 12 pulse series converter
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
LINE CURRENT WITH UPFC
TIME (ms)
CURRENT (pu)
Fig. 7 – Current in transmission line
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
0
0.02
0.04
0.06
0.08
0.1
0.12
DC VOLTAGE OF UPFC
TIME (ms)
VOLTAGE (pu)
Fig.8 - DC voltage of UPFC
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
-1.5
-1
-0.5
0
0.5
1
1.5
TIME (ms)
VOLTAGE (pu)
VOLTAGE OF UPFC BUS
Fig.9 – Voltage in UPFC’ received bus of transmission line
TIME (Sec)
TIME (Sec)
TIME (Sec)
TIME (Sec)
8. Unified Power Flow Controller: Modeling And Dynamic Characteristic
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In particular, the UPFC series inverter is simulated to maintain a power flow at the receiving end at 2
p.u. up to 5/60 sec. and after that at 4 p.u. as in Fig.11, and a reactive power flow is kept at 0.5 p.u. During
simulation the active power exchange between the series converter and the power system is compensated by the
active power exchange of the shunt converter, evaluated by the DC control system, so to maintain the dc voltage
across the storage capacitor constant at the specified value as in Fig. 14.
Fig.10-
Fig.11 – Power flow characteristic of transmission line under dynamic control of UPFC
Fig.12, Fig.13, and Fig.14 are the demonstration of dynamic operating of UPFC with power value reference as
stated above. In these figures, both values and shapes of voltage and current in transmission line are changed
according to changing of modulation control variables adapted with active power references.
0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15
-0.1
-0.05
0
0.05
0.1
0.15
OUTPUT VOLTAGE OF 12 PULSE SERIES CONVERTER
TIME (Sec.)
VOLTAGE (pu)
Fig.12 – Output voltage responses of 12 pulse series converter in dynamic states.
9. Unified Power Flow Controller: Modeling And Dynamic Characteristic
International organization of Scientific Research 60 | P a g e
0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15
-1.5
-1
-0.5
0
0.5
1
1.5
VOLTAGE OF UPFC BUS IN DYNAMIC STATES
TIME (Sec.)
VOLTAGE (pu)
Fig.13 – Voltage characteristic of transmission line under dynamic control of UPFC
0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15
-5
-4
-3
-2
-1
0
1
2
3
4
5
LINE CURRENT OF UPFC BUS
TIME (sec.)
CURRENT (pu)
Fig.14 – Current characteristic of transmission line under dynamic control of UPFC
V. CONCLUSIONS
This paper after a brief summary of the UPFC configuration based converter, illustrates in detail the
control system model of UPFC with two separate control systems for the series and shunt inverters and a control
for their coordination. Finally, a discrete simulation of new UPFC model based 12 pulse converter using
Matlab/Simulink as simulation program is shown and some simulation results are illustrated to validate the
implemented this UPFC model. Especially, the simulation results have provided the practical operating
processes of UPFC and converter. These give us the practical views of action of every part of devices and
responses of power system under UPFC working. The results are obtained for a PWM-based control
technique, but it's very simple to modify the converter control technique such as phase control.
However, this new discrete UPFC model based on 12 pulse converter seems not to be suitable for application in
contingency analysis because it is quite complex in separating control systems of Shunt converter and series
converter properly with maintained control quality A UPFC with matrix converter is useful only for steady
operation modes.
This new discrete 12 pulse converter model will be modified to be able to perform a damping oscillation
operating functions in such a way in the future researches.
REFERENCES
[1] L. Gyugyi, C.D. Shauder, S.L. Williams, T.R. Rietman, D.R. Torgerson, A. Edris. “The unified power
flow controller: A new approach to power transmission control”, IEEE Trans. On Power Delivery,
Vol.10, No.2, April 1995, pp.1085-1097.
[2] H.Fujita, Y. Watanabe, H.Akagi. “Control and analysis of a unified power flow controller”. IEEE Trans.
On Power Electronics, Vol.14, No.6, Nov. 1999.