The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
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.
LOW VOLTAGE RIDE - THROUGH CAPABILITY OF WIND FARMSEditor IJMTER
Nowadays wind turbines are generally required to offer ancillary services similar to those
provided by conventional generators. One of the most important services wind turbines must offer is
to stay connected to the grid in fault situations delivering the reactive current specified in the recent
grid codes. In this paper, FACTS solutions for fixed speed wind farms such as DVR (Dynamic
Voltage Restorer) are presented as well as classic control and crowbar solutions for variable speed
wind turbines.
Mitigation of Voltage Sag/Swell with Fuzzy Control Reduced Rating DVRIJERD Editor
Power quality has been an issue that is becoming increasingly pivotal in industrial electricity
consumers point of view in recent times. Modern industries employ Sensitive power electronic equipments,
control devices and non-linear loads as part of automated processes to increase energy efficiency and
productivity. Voltage disturbances are the most common power quality problem due to this the use of a large
numbers of sophisticated and sensitive electronic equipment in industrial systems is increased. This paper
discusses the design and simulation of dynamic voltage restorer for improvement of power quality and
reduce the harmonics distortion of sensitive loads. Power quality problem is occurring at non-standard
voltage, current and frequency. Electronic devices are very sensitive loads. In power system voltage sag,
swell, flicker and harmonics are some of the problem to the sensitive load. The compensation capability
of a DVR depends primarily on the maximum voltage injection ability and the amount of stored
energy available within the restorer. This device is connected in series with the distribution feeder at
medium voltage. A fuzzy logic control is used to produce the gate pulses for control circuit of DVR and the
circuit is simulated by using MATLAB/SIMULINK software.
This slide presents about the basic and importance about load shedding in smart microgrid distribution systems. Later of the class i will discuss about in detail on the process of executing the load shedding.
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.
Low Voltage Ride-through for Doubly Fed Induction Generator Using Battery-Sto...IJPEDS-IAES
In this paper, enhanced field oriented control technique (EFOC) was adopted
in Rotor Side Control (RSC) of DFIG converter for improved response
during severe faults. The work is intended to damp pulsations in
electromagnetic torque, improve voltage mitigation and limit surge currents
and to enhance the operation of DFIG during voltage sags. The converter
topology uses a battery energy storage system with capacitor storage system
to further enhance operation of DFIG during faults. The battery and capacitor
system in coordination provide additional real and reactive power support
during faults and nearly constant voltage profile at stator and rotor terminals
and limit overcurrents. For EFOC technique, rotor flux reference changes its
value from synchronous speed to zero during fault for injecting current at the
rotor slip frequency. In this process DC-Offset component of flux is
controlled, decomposition during overvoltage faults. The offset
decomposition of flux will be oscillatory in a conventional FOC, whereas in
EFOC it will damp quickly. A comparison is made with proposed
methodology with battery energy storage system and a conventional system.
Later the system performance with under voltage of 50% the rated voltage
with fault at PCC during 0.8 to 1.2 seconds is analysed using simulation
studies.
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.
LOW VOLTAGE RIDE - THROUGH CAPABILITY OF WIND FARMSEditor IJMTER
Nowadays wind turbines are generally required to offer ancillary services similar to those
provided by conventional generators. One of the most important services wind turbines must offer is
to stay connected to the grid in fault situations delivering the reactive current specified in the recent
grid codes. In this paper, FACTS solutions for fixed speed wind farms such as DVR (Dynamic
Voltage Restorer) are presented as well as classic control and crowbar solutions for variable speed
wind turbines.
Mitigation of Voltage Sag/Swell with Fuzzy Control Reduced Rating DVRIJERD Editor
Power quality has been an issue that is becoming increasingly pivotal in industrial electricity
consumers point of view in recent times. Modern industries employ Sensitive power electronic equipments,
control devices and non-linear loads as part of automated processes to increase energy efficiency and
productivity. Voltage disturbances are the most common power quality problem due to this the use of a large
numbers of sophisticated and sensitive electronic equipment in industrial systems is increased. This paper
discusses the design and simulation of dynamic voltage restorer for improvement of power quality and
reduce the harmonics distortion of sensitive loads. Power quality problem is occurring at non-standard
voltage, current and frequency. Electronic devices are very sensitive loads. In power system voltage sag,
swell, flicker and harmonics are some of the problem to the sensitive load. The compensation capability
of a DVR depends primarily on the maximum voltage injection ability and the amount of stored
energy available within the restorer. This device is connected in series with the distribution feeder at
medium voltage. A fuzzy logic control is used to produce the gate pulses for control circuit of DVR and the
circuit is simulated by using MATLAB/SIMULINK software.
This slide presents about the basic and importance about load shedding in smart microgrid distribution systems. Later of the class i will discuss about in detail on the process of executing the load shedding.
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.
Low Voltage Ride-through for Doubly Fed Induction Generator Using Battery-Sto...IJPEDS-IAES
In this paper, enhanced field oriented control technique (EFOC) was adopted
in Rotor Side Control (RSC) of DFIG converter for improved response
during severe faults. The work is intended to damp pulsations in
electromagnetic torque, improve voltage mitigation and limit surge currents
and to enhance the operation of DFIG during voltage sags. The converter
topology uses a battery energy storage system with capacitor storage system
to further enhance operation of DFIG during faults. The battery and capacitor
system in coordination provide additional real and reactive power support
during faults and nearly constant voltage profile at stator and rotor terminals
and limit overcurrents. For EFOC technique, rotor flux reference changes its
value from synchronous speed to zero during fault for injecting current at the
rotor slip frequency. In this process DC-Offset component of flux is
controlled, decomposition during overvoltage faults. The offset
decomposition of flux will be oscillatory in a conventional FOC, whereas in
EFOC it will damp quickly. A comparison is made with proposed
methodology with battery energy storage system and a conventional system.
Later the system performance with under voltage of 50% the rated voltage
with fault at PCC during 0.8 to 1.2 seconds is analysed using simulation
studies.
The Direct Power Contro; has many advantages like it avoids the usage of integration of PWM voltages which leads to stable operation even at zero rotor frequency, it is position sensor less and hence will not depend on machine parameters like stator or rotor resistance. In case of network unbalance, if the system is operated with constant active and reactive powers, it leads to oscillations in the electromagnetic torque and currents exchange with the grid will become non- sinusoidal, which is not good for the system as it increases the mechanical stress. In this paper, both the rotor connected converter and grid connected converter are fed with DPC strategy along with that a Torque Oscillations Cancellation scheme is applied to RSC and Proportional Integral control based power references generation strategy without calculating the sequence components and with elimination of DC bus voltage oscillations is applied to stator-side converter in order to achieve non-oscillating torque accompanied by quality improved current exchange with the grid. The simulation results of Doubly Fed Induction Generator with and without fault clearly shows that the performance of the proposed scheme is validated.
These slides present about islanding detection techniques in microgrid systems. Later on the classes other aspects of microgrid protection will be discussed in more detail
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
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.
Sag mitigation in distribution system by using Dynamic voltage Restorer (DVR)IJERA Editor
Power quality is most important concern in the current age. It’s now a day’s necessary with the refined devices, where performance is very perceptive to the quality of power supply. Power quality crisis is an incidence manifest as a typical voltage, current or frequency that results in a failure of end use equipments. One of the major crises dealt here is the power sag. Perceptive industrial loads and distribution networks suffer from different types of service interruptions and outages which results in a major financial loss. To improve the power quality, custom power-devices are used. The device considered in this work is Dynamic Voltage Restorer. This paper shows modelling, analysis and simulation of a DVR test systems using MATLAB.
I have considered single line to ground fault for linear load. The role of DVR is to “compensate load voltage” is examined during the different fault conditions like voltage sag, single phase to ground faults.
This article proposes a novel scheme to improve the doubly-fed induction generator (DFIG) behavior during grid fault. The DFIG’s are sensitives to voltage variations when abrupt variations of the wind velocity arrive. For enhancing DFIG behavior, protecting the converters, and smoothing the fluctuations power output of the DFIG under sag voltage; a novel hybrid energy storage system scheme and its controller are proposed. The main advantages of our approach are a faster response and suppressing overvoltage on DC bus and globally less stress in the storage system. The control structure decreases the tiredness on the battery and restores the DC bus voltage rapidly, globally the battery system operating time increases. The results obtained by simulations in MATLAB validate the benefits of the suggested control.
These slides present the introduction to FACTS devices. Later we will discuss about its modelling and control aspect applications. This comes under the topic on power electronics application in smart and microgrid systems.
Seamless Transitions between Grid-Connected and Stand-Alone Operations of Dis...IJERD Editor
Control of the Distributed Generation (DG) system is important in both grid-connected and standalone
modes and the system stability becomes very crucial during the transfer between these two modes. If the
system does not have a proper transfer procedure, severe transient voltages or currents will occur, which may
damage the entire system. A seamless transfer can ensure smooth operation and quick attainment of steady state.
In order to solve these transition problems, this paper presents the development and test of a control strategy for
DG capable of working in grid-connected and intentional islanding connection modes with seamless transitions
from both operational modes.
Implementation of Fuzzy Controlled Photo Voltaic Fed Dynamic Voltage Restorer...ijfls
Power Quality(PQ) has become an area of concern in the electrical distribution system. Dynamic Voltage
Restorer(DVR) restores load voltage to a nominal balanced sinusoidal voltage, when the source voltage
has harmonic distortions, sag, swell and unbalances. In this paper a Photo Voltaic(PV) fed DVR is
proposed to mitigate PQ problems. The PV system can supply the maximum power to the load at a
particular operating point known as Maximum Power Point (MPP), at which the entire PV system operates
with maximum efficiency. A Fuzzy Controller based MPPT is implemented to generate the optimal voltage
from the photovoltaic system by modulating the duty cycle applied to the boost converter. The DVR is
implemented using a Fuzzy Logic Controller based voltage source inverter with Photovoltaic system. The
test system has been simulated and the efficacy of the proposed PV based Fuzzy controlled DVR is
compared with Proportional Integral (PI) controlled DVR.
Fault Ride-Through capability of DSTATCOM for Distributed Wind Generation SystemIJPEDS-IAES
In this paper, fault ride through analysis of a low voltage distribution system
augmented with distributed wind generation using squirrel cage induction
generator and distribution static compensator (DSTATCOM) is carried out
through modeling and simulation study in MATLAB. The impact of
unbalanced (single line to ground) fault in a low voltage distribution system
in normal and severe conditions is studied and analyzed in details. Analysis
on system instability is also shown in case of sever fault condition. A
distribution Static Compensator (DSTATCOM) is used to improve fault ride
through (FRT) capability of wind generation system by compensating
positive sequence voltage. A comparison of dynamic response of the system
with and without DSTATCOM and effects of DSTATCOM on voltage and
generator speed are presented. The simulation results shows that
DSTATCOM is capable of reducing the voltage dips and improving the
voltage profiles by providing reactive power support to distributed wind
generation system under unbalanced fault condition and enhances the fault
ride through capability of the wind generator.
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.
Comparison of upqc and dvr in wind turbine fed fsig under asymmetric faultselelijjournal
This paper presents the mitigation of faults in wind turbine connected fixed speed induction generator using unified power quality conditioner and static compensator. The UPQC consists of shunt and series converters connected back-to-back through a dc-to-dc step up converter. The presence of the dc-to-dc step converter permits the UPQC to compensate faults for long duration. The series converter is connected to the supply side whereas the shunt converter is connected to the load side. The control system of the proposed UPQC is based on Id-Iq theory. The DVR consists of shunt and series converters connected back-to-back through a dc-to-dc step up converter. The presence of the dc-to-dc step converter permits the DVR to compensate faults for long duration. The series converter is connected to the supply side whereas the shunt converter is connected to the load side. The control system of the proposed DVR is based on
hysteresis voltage controlThe proposed wind turbine fed fixed speed induction generator is evaluated and simulated using MATLAB/SIMULINK environment with UPQC and DVR under asymmetric faults
Performance Assessment of IPFC with IDVR for Two Feeder Transmission systemsIJMER
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.
Low Voltage Ride-through Capability Enhancement of Doubly Fed Induction Gener...IJPEDS-IAES
Based on the advantages of doubly fed induction generator (DFIG)-based
wind turbine (WT). This paper proposes a new control strategy to improve
the ride-through capability of DFIG-based WTs in the event of a grid fault.
The proposed method is performed by using the DFIG converters control and
the addition of the damping resistances connected to the DC circuit, to follow
the requirements defined by the grid codes. The proposed ride-through
solution limits the peak values of the DC link voltage, the rotor inrush
current, electromagnetic torque and DFIG transient response at the times of
occurrence and clearing the fault. The proposed solution is simulated and
compared with the crowbar solution using MATLAB/Simulink environment.
Concept of energy transmission & distribution ZunAib Ali
Downlaod is NOW Allowed (08/06/2016)
for more help: email me at zunaib_91@yahoo.com
Purpose of Electrical Transmission System
Main Parts of Power System
One-Line Diagram of Generating Station
Main Parts of Generating Station
Components of a Transmission Line
In modern society every sector needs continuous power on demand. To achieve this voltage,
current and frequency, these parameters of the power system should be at rated values. Because of
remote generation, transmission and distribution, we are failing to receive the reliable power. To
overcome this problem, the Distribution energy sources (DES) become more suitable solution. This
generated power from DES is supplied to local loads and this can be connected to the main grid
through the Micro-Grid (MG). Micro-grids will operate in two modes, A Grid-connected mode and in
an Islanded mode. During islanding mode, one Distributed Generation (DG) unit should share output
generation power with other unit in exact accordance with the load. Need to control Real and Reactive
power effectively for the load to operate without disturbance. Hence in the present work, Voltage
Source Inverter (VSI) and Proportional Integral Derivative(PID) controller in power conversion
process to get required real and reactive power for the normal operation of micro-grid. The proposed
method has been applied to a designed test Simulink model for different types of Grid connected and
Isolated modes. The simulation results obtained show that, this method can improves the reliability and
smooth operation of the micro-grid system.
These slides presents at introductory level to Micro-grid Stability and Control Modes. Later classes the mathematical representations and simulation ideas will be presented.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
International Refereed Journal of Engineering and Science (IRJES)irjes
The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
The Direct Power Contro; has many advantages like it avoids the usage of integration of PWM voltages which leads to stable operation even at zero rotor frequency, it is position sensor less and hence will not depend on machine parameters like stator or rotor resistance. In case of network unbalance, if the system is operated with constant active and reactive powers, it leads to oscillations in the electromagnetic torque and currents exchange with the grid will become non- sinusoidal, which is not good for the system as it increases the mechanical stress. In this paper, both the rotor connected converter and grid connected converter are fed with DPC strategy along with that a Torque Oscillations Cancellation scheme is applied to RSC and Proportional Integral control based power references generation strategy without calculating the sequence components and with elimination of DC bus voltage oscillations is applied to stator-side converter in order to achieve non-oscillating torque accompanied by quality improved current exchange with the grid. The simulation results of Doubly Fed Induction Generator with and without fault clearly shows that the performance of the proposed scheme is validated.
These slides present about islanding detection techniques in microgrid systems. Later on the classes other aspects of microgrid protection will be discussed in more detail
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
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.
Sag mitigation in distribution system by using Dynamic voltage Restorer (DVR)IJERA Editor
Power quality is most important concern in the current age. It’s now a day’s necessary with the refined devices, where performance is very perceptive to the quality of power supply. Power quality crisis is an incidence manifest as a typical voltage, current or frequency that results in a failure of end use equipments. One of the major crises dealt here is the power sag. Perceptive industrial loads and distribution networks suffer from different types of service interruptions and outages which results in a major financial loss. To improve the power quality, custom power-devices are used. The device considered in this work is Dynamic Voltage Restorer. This paper shows modelling, analysis and simulation of a DVR test systems using MATLAB.
I have considered single line to ground fault for linear load. The role of DVR is to “compensate load voltage” is examined during the different fault conditions like voltage sag, single phase to ground faults.
This article proposes a novel scheme to improve the doubly-fed induction generator (DFIG) behavior during grid fault. The DFIG’s are sensitives to voltage variations when abrupt variations of the wind velocity arrive. For enhancing DFIG behavior, protecting the converters, and smoothing the fluctuations power output of the DFIG under sag voltage; a novel hybrid energy storage system scheme and its controller are proposed. The main advantages of our approach are a faster response and suppressing overvoltage on DC bus and globally less stress in the storage system. The control structure decreases the tiredness on the battery and restores the DC bus voltage rapidly, globally the battery system operating time increases. The results obtained by simulations in MATLAB validate the benefits of the suggested control.
These slides present the introduction to FACTS devices. Later we will discuss about its modelling and control aspect applications. This comes under the topic on power electronics application in smart and microgrid systems.
Seamless Transitions between Grid-Connected and Stand-Alone Operations of Dis...IJERD Editor
Control of the Distributed Generation (DG) system is important in both grid-connected and standalone
modes and the system stability becomes very crucial during the transfer between these two modes. If the
system does not have a proper transfer procedure, severe transient voltages or currents will occur, which may
damage the entire system. A seamless transfer can ensure smooth operation and quick attainment of steady state.
In order to solve these transition problems, this paper presents the development and test of a control strategy for
DG capable of working in grid-connected and intentional islanding connection modes with seamless transitions
from both operational modes.
Implementation of Fuzzy Controlled Photo Voltaic Fed Dynamic Voltage Restorer...ijfls
Power Quality(PQ) has become an area of concern in the electrical distribution system. Dynamic Voltage
Restorer(DVR) restores load voltage to a nominal balanced sinusoidal voltage, when the source voltage
has harmonic distortions, sag, swell and unbalances. In this paper a Photo Voltaic(PV) fed DVR is
proposed to mitigate PQ problems. The PV system can supply the maximum power to the load at a
particular operating point known as Maximum Power Point (MPP), at which the entire PV system operates
with maximum efficiency. A Fuzzy Controller based MPPT is implemented to generate the optimal voltage
from the photovoltaic system by modulating the duty cycle applied to the boost converter. The DVR is
implemented using a Fuzzy Logic Controller based voltage source inverter with Photovoltaic system. The
test system has been simulated and the efficacy of the proposed PV based Fuzzy controlled DVR is
compared with Proportional Integral (PI) controlled DVR.
Fault Ride-Through capability of DSTATCOM for Distributed Wind Generation SystemIJPEDS-IAES
In this paper, fault ride through analysis of a low voltage distribution system
augmented with distributed wind generation using squirrel cage induction
generator and distribution static compensator (DSTATCOM) is carried out
through modeling and simulation study in MATLAB. The impact of
unbalanced (single line to ground) fault in a low voltage distribution system
in normal and severe conditions is studied and analyzed in details. Analysis
on system instability is also shown in case of sever fault condition. A
distribution Static Compensator (DSTATCOM) is used to improve fault ride
through (FRT) capability of wind generation system by compensating
positive sequence voltage. A comparison of dynamic response of the system
with and without DSTATCOM and effects of DSTATCOM on voltage and
generator speed are presented. The simulation results shows that
DSTATCOM is capable of reducing the voltage dips and improving the
voltage profiles by providing reactive power support to distributed wind
generation system under unbalanced fault condition and enhances the fault
ride through capability of the wind generator.
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.
Comparison of upqc and dvr in wind turbine fed fsig under asymmetric faultselelijjournal
This paper presents the mitigation of faults in wind turbine connected fixed speed induction generator using unified power quality conditioner and static compensator. The UPQC consists of shunt and series converters connected back-to-back through a dc-to-dc step up converter. The presence of the dc-to-dc step converter permits the UPQC to compensate faults for long duration. The series converter is connected to the supply side whereas the shunt converter is connected to the load side. The control system of the proposed UPQC is based on Id-Iq theory. The DVR consists of shunt and series converters connected back-to-back through a dc-to-dc step up converter. The presence of the dc-to-dc step converter permits the DVR to compensate faults for long duration. The series converter is connected to the supply side whereas the shunt converter is connected to the load side. The control system of the proposed DVR is based on
hysteresis voltage controlThe proposed wind turbine fed fixed speed induction generator is evaluated and simulated using MATLAB/SIMULINK environment with UPQC and DVR under asymmetric faults
Performance Assessment of IPFC with IDVR for Two Feeder Transmission systemsIJMER
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.
Low Voltage Ride-through Capability Enhancement of Doubly Fed Induction Gener...IJPEDS-IAES
Based on the advantages of doubly fed induction generator (DFIG)-based
wind turbine (WT). This paper proposes a new control strategy to improve
the ride-through capability of DFIG-based WTs in the event of a grid fault.
The proposed method is performed by using the DFIG converters control and
the addition of the damping resistances connected to the DC circuit, to follow
the requirements defined by the grid codes. The proposed ride-through
solution limits the peak values of the DC link voltage, the rotor inrush
current, electromagnetic torque and DFIG transient response at the times of
occurrence and clearing the fault. The proposed solution is simulated and
compared with the crowbar solution using MATLAB/Simulink environment.
Concept of energy transmission & distribution ZunAib Ali
Downlaod is NOW Allowed (08/06/2016)
for more help: email me at zunaib_91@yahoo.com
Purpose of Electrical Transmission System
Main Parts of Power System
One-Line Diagram of Generating Station
Main Parts of Generating Station
Components of a Transmission Line
In modern society every sector needs continuous power on demand. To achieve this voltage,
current and frequency, these parameters of the power system should be at rated values. Because of
remote generation, transmission and distribution, we are failing to receive the reliable power. To
overcome this problem, the Distribution energy sources (DES) become more suitable solution. This
generated power from DES is supplied to local loads and this can be connected to the main grid
through the Micro-Grid (MG). Micro-grids will operate in two modes, A Grid-connected mode and in
an Islanded mode. During islanding mode, one Distributed Generation (DG) unit should share output
generation power with other unit in exact accordance with the load. Need to control Real and Reactive
power effectively for the load to operate without disturbance. Hence in the present work, Voltage
Source Inverter (VSI) and Proportional Integral Derivative(PID) controller in power conversion
process to get required real and reactive power for the normal operation of micro-grid. The proposed
method has been applied to a designed test Simulink model for different types of Grid connected and
Isolated modes. The simulation results obtained show that, this method can improves the reliability and
smooth operation of the micro-grid system.
These slides presents at introductory level to Micro-grid Stability and Control Modes. Later classes the mathematical representations and simulation ideas will be presented.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
International Refereed Journal of Engineering and Science (IRJES)irjes
The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
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.
International Refereed Journal of Engineering and Science (IRJES)irjes
The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications
International Refereed Journal of Engineering and Science (IRJES)irjes
The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
International Refereed Journal of Engineering and Science (IRJES)irjes
The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
International Refereed Journal of Engineering and Science (IRJES)irjes
The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
International Refereed Journal of Engineering and Science (IRJES)irjes
The core of the vision IRJES is to disseminate new knowledge and technology for the benefit of all, ranging from academic research and professional communities to industry professionals in a range of topics in computer science and engineering. It also provides a place for high-caliber researchers, practitioners and PhD students to present ongoing research and development in these areas.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
The voltage dip and doubly fed induction generator with considering uncertain...journalBEEI
The paper presents the transient behavior of the doubly fed induction generator (DFIG) in the wind turbine (WT) in the normal and voltage dip condition. When voltage dip occurs in to the grid, the rotor current increases and the DC-link voltage increases too and start to oscilate. In this paper, the proportional integral (PI) controllers are used to control the DFIG-basedwind farms for regulating the electronic devices including rotor side converter (RSC) and grid side converter (GSC) to control the active and reactive power of DFIG. The PI parameters are tuned by imperialist competitive algorithm (ICA). So, the transient behavour of the DFIG-based WF is explors when the voltage dip occurs. Hence, the induced electric motive force in to the rotor is measured. Also, an existed uncertainty for mutual inductance is considered caused by saturated curve during three-phase fault conditions and the bahavour of DFIG-based WT is examined and analyzed. All of simulation is done by Matlab/Simulink®.
Improved Control Strategy for Low Voltage Ride Through Capability of DFIG wit...ecij
This paper deals with a protection and control strategy to enhance the low voltage ride through capability of a wind turbine driven doubly fed induction generator (DFIG). As the wind power penetration continues to increase, wind turbines are required to provide Low Voltage Ride-Through (LVRT) capability. Crowbars are commonly used to protect the power converters during voltage dips and their main drawback is that the DFIG absorbs reactive power from the grid during grid faults. According to emergency grid code requirements, wind farms should have the ability to stay connected and continue generation under external voltage failure conditions, that is, wind turbines have to keep in connection with grid and own continue reactive power supply. This paper proposes a hysteresis current control strategy for the crowbar protection
and a reactive power control to satisfy the grid code requirements. Consequently, the dynamic model of double fed wind turbines is established to study the transient behavior of DFIG. Simulation results are presented to show the effectiveness of the proposed control scheme.
Most of generators utilized in wind turbines are the Doubly-Fed Induction Generator (DFIG). Indirect matrix converter (IMC) is a candidate for substituting the traditional back-to-back converter in the future due to advantages gained by elimination of electrolytic capacitor. Starting DFIG wind turbines and synchronizing to the grid is a challenge in practice because of large inrush currents that could damage switches. Synchronizing the DFIG wind turbine controlled by the IMC is presented in this paper. Also, maximum power point tracking algorithm performance of this configuration is examined. A laboratory scale prototype of the proposed configuration is built. Experimental results have confirmed effectiveness of this configuration.
Improved reactive power capability with grid connected doubly fed induction g...Uday Wankar
In the past, most national grid codes and standards did not require wind turbines to support the power system during a disturbance. For example during a grid fault or sudden drop in frequency wind turbines were tripped off the system. However, as the wind power penetration continues to increase, the interaction between the wind turbines and the power system has become more important. This is because, when all wind turbines would be disconnected in case of a grid failure, these renewable generators will, unlike conventional power plants, not be able to support the voltage and the frequency of the grid during and immediately following the grid failure. This would cause major problems for the systems stability.
Therefore, wind farms will have to continue to operate during system disturbances and support the network voltage and frequency. Network design codes are now being revised to reflect this new requirement. A special focus in this requirement is drawn to both the fault ride-through capability and the grid support capability. Fault ride-through capability addresses mainly the design of the wind turbine controller in such a way that the wind turbine is able to remain connected to the network during grid faults (e.g. short circuit faults). While grid support capability represents the wind turbine capability to assist the power system by supplying ancillary services, i.e. such as supplying reactive power, in order to help the grid voltage recovery during and just after the clearance of grid faults. Due to the partial-scale power converter, wind turbines based on the DFIG are very sensitive to grid disturbances, especially to voltage dips during grid faults.
Faults in the power system, even far away from the location of the turbine, can cause a voltage dip at the connection point of the wind turbine. The abrupt drop of the grid voltage will cause over-current in the rotor windings and over- voltage in the DC bus of the power converters. Without any protection, this will certainly lead to the destruction of the converters. In addition, it will also cause over-speeding of the wind turbine, which will threaten the safe operation of the turbine. Thus a lot of research works have been carried out on the LVRT ability of DFIG wind turbines under the grid fault. These LVRT strategies can be divided into two main types: the active method by improving control strategies, the passive scheme with additional hardware protective devices.
Improved reactive power capability with grid connected doubly fed induction g...Uday Wankar
In the past, most national grid codes and standards did not require wind turbines to support the power system during a disturbance. For example during a grid fault or sudden drop in frequency wind turbines were tripped off the system. However, as the wind power penetration continues to increase, the interaction between the wind turbines and the power system has become more important. This is because, when all wind turbines would be disconnected in case of a grid failure, these renewable generators will, unlike conventional power plants, not be able to support the voltage and the frequency of the grid during and immediately following the grid failure. This would cause major problems for the systems stability.
Therefore, wind farms will have to continue to operate during system disturbances and support the network voltage and frequency. Network design codes are now being revised to reflect this new requirement. A special focus in this requirement is drawn to both the fault ride-through capability and the grid support capability. Fault ride-through capability addresses mainly the design of the wind turbine controller in such a way that the wind turbine is able to remain connected to the network during grid faults (e.g. short circuit faults). While grid support capability represents the wind turbine capability to assist the power system by supplying ancillary services, i.e. such as supplying reactive power, in order to help the grid voltage recovery during and just after the clearance of grid faults. Due to the partial-scale power converter, wind turbines based on the DFIG are very sensitive to grid disturbances, especially to voltage dips during grid faults.
Faults in the power system, even far away from the location of the turbine, can cause a voltage dip at the connection point of the wind turbine. The abrupt drop of the grid voltage will cause over-current in the rotor windings and over- voltage in the DC bus of the power converters. Without any protection, this will certainly lead to the destruction of the converters. In addition, it will also cause over-speeding of the wind turbine, which will threaten the safe operation of the turbine. Thus a lot of research works have been carried out on the LVRT ability of DFIG wind turbines under the grid fault. These LVRT strategies can be divided into two main types: the active method by improving control strategies, the passive scheme with additional hardware protective devices.
ENHANCED CONTROL OF DFIG IN WIND ENERGY CONVERSION SYSTEMIjorat1
The doubly-fed induction generator (DFIG) wind turbine is a variable speed wind turbine widely used
in the modern wind power industries. At present, commercial DFIG wind turbines primarily make use of the
technology that was developed a decade ago. But, it is found in the paper that there is limitations conventional
control method. This project presents a fuzzy-logic approach to control the DFIG. Based on which fuzzy-logic
approach is controlled for real power, reactive power flow and electromagnetic torque of the wind turbine. A
direct current vector control strategy is developed to control the rotor side voltage source converter. This scheme
of direct current vector control strategy allows the independent control of the generated active and reactive
power as well as the rotor speed. In this project, a fuzzy-logic approach is proposed to control the DFIG. The
active and reactive power is controlled by rotor voltage, which goes through back-to-back voltage source
converter and DC-link voltage is also maintained stable. The conventional control approach is compared with the
proposed control techniques for DFIG wind turbine control under both steady and gusty wind conditions. A
MATLAB based simulation system was build to validate the effectiveness of the proposed method. The proposed
method waveforms of real power, reactive power, DC link voltage and generator speed are compared with
conventional method. This paper shows that under the fuzzy-logic approach control techniques, a DFIG system
have a superior performance in various aspects.
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.
Fault Ride-Through of DFIG Wind Turbine by DVR Using Synchronous Reference Fr...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Control of DFIG Stator Voltage on Autonomous Micro Hydro Power PlantIJPEDS-IAES
An autonomous micro hydro power plant was proposed to utilize the small
hydro power potency as a run-of-river. It consisted of a PMSG, a DFIG, and
a converter and should be operated in the off-grid configuration. In a
previous research, the DFIG stator voltages couldn’t be controlled. In this
paper, the novel control algorithm that is able to maintain the DFIG stator
voltages of the autonomous micro hydro power plant in the off-grid
configuration is proposed. The control algorithm was proposed to use the
actual DFIG stator voltages and currents as feedback signals. The controller
was tested by varying three input signals, i.e. the DC-link voltage, the DFIG
stator voltage reference, and the external stator load which simulated the offgrid
configuration. The result of the simulation showed that the DFIG stator
voltages could be controlled and were always in accordance with the
reference.
Enhanced Crowbar Protection for Fault Ride through Capability of Wind Generat...IAES-IJPEDS
Due to increasing demand in power, the integration of renewable sources like
wind generation into power system is gaining much importance nowadays.
The heavy penetration of wind power into the power system leads to many
integration issues mainly due to the intermittent nature of the wind and the
desirability for variable speed operation of the generators. As the wind power
generation depends on the wind speed, its integration into the grid has
noticeable influence on the system stability and becomes an important issue
especially when a fault occurs on the grid. The protective disconnection of a
large amount of wind power during a fault will be an unacceptable
consequence and threatens the power system stability. With the increasing
use of wind turbines employing Doubly Fed Induction Generator (DFIG)
technology, it becomes a necessity to investigate their behavior during grid
faults and support them with fault ride through capability. This paper
presents the modeling and simulation of a doubly fed induction generator
according to grid code compatibility driven by a wind turbine connected to
the grid. This paper analyses the voltage sag due to a three-phase fault in the
wind connected grid. A control strategy including a crowbar circuit has been
developed in MATLAB/SIMULINK to bypass the rotor over currents during
grid fault to enhance the fault ride through capability and to maintain system
stability. Simulation results show the effectiveness of the proposed control
strategies in DFIG based grid connected wind turbine system.
Cars are a very important part of this modern world because they give luxury and comfort. Even
though they are comfortable, some problems always keep arising on the safety side. After a lot of research they
rectified certain problems using air bags, auto parking, turbo charger, pedal shift…, etc.
And now we are going to discuss about one such problem that arises on the safety side. An unsuspected
accident occurs when people smash their fingers in between the car doors. Due to this kind of accident around
120,000 people are injured every year. But this was not taken as a very major safety concern for the customer.
To avoid this kind accident due to car doors, we are introducing “SAFETY DOOR LOCK SYSTEM”
with the help of “HYDRAULIC PISTON AND IR SENSORS”.
The major working process of the “SAFETY DOOR LOCK SYSTEM”is, when a person places his/her
hand or fingers in the gap between the door and the outer panel, at the time when the closing action of the door
takes place, the Sensors start to transmit the Infra Red Rays to the Receivers at the
other end, and so even if someone closes the door without anybody‟s knowledge the hydraulic piston will
automatically come out and stop the door from closing and prevent the person from the unsuspected accident
and minor injuries by the car door and ensure maximum safety to the customer.
Extrusion can be defined as the process of subjecting a material to compression so that it is forced to
flow through an opening of a die and takes the shape of the hole. Multi-hole extrusion is the process of
extruding the products through a die having more than one hole. Multi-hole extrusion increases the production
rate and reduces the cost of production. In this study the ram force has calculated experimentally for single hole
and multi-hole extrusion. The comparison of ram forces between the single hole and multi-hole extrusion
provides the inverse relation between the numbers of holes in a die and ram force. The experimental lengths of
the extruded products through the various holes of multi-hole die are different. It indicates that the flow pattern
is dependent on the material behavior. The micro-hardness test has done for the extruded products of lead
through multi-hole die. It is observed that the hardness of the extruded lead products from the central hole is
found to be more than that of the products extruded from other holes. The study suggests that multi-hole
extrusion can be used for obtaining the extruded products of lead with varying hardness. The micro-structure
study has done for the lead material before and after extrusion. It is observed that the size of grains of lead
material after extrusion is smaller than the original lead.
Analysis of Agile and Multi-Agent Based Process Scheduling Modelirjes
As an answer of long growing frustration of waterfall Software development life cycle concepts,
agile software development concept was evolved in 90’s. The most popular agile methodologies is the Extreme
Programming (XP). Most software companies nowadays aim to produce efficient, flexible and valuable
Software in short time period with minimal costs, and within unstable, changing environments. This complex
problem can be modeled as a multi-agent based system, where agents negotiate resources. Agents can be used to
represent projects and resources. Crucial for the multi-agent based system in project scheduling model, is the
availability of an effective algorithm for prioritizing and scheduling of task. To evaluate the models, simulations
were carried out with real life and several generated data sets. The developed model (Multi-agent based System)
provides an optimized and flexible agile process scheduling and reduces overheads in the software process as it
responds quickly to changing requirements without excessive work in project scheduling.
Effects of Cutting Tool Parameters on Surface Roughnessirjes
This paper presents of the influence on surface roughness of Co28Cr6Mo medical alloy machined
on a CNC lathe based on cutting parameters (rotational speed, feed rate, depth of cut and nose radius).The
influences of cutting parameters have been presented in graphical form for understanding. To achieve the
minimum surface roughness, the optimum values obtained for rpm, feed rate, depth of cut and nose radius were
respectively, 318 rpm, 0,1 mm/rev, 0,7 mm and 0,8 mm. Maximum surface roughness has been revealed the
values obtained for rpm, feed rate, depth of cut and nose radius were respectively, 318 rpm, 0,25 mm/rev, 0,9
mm and 0,4 mm.
Possible limits of accuracy in measurement of fundamental physical constantsirjes
The measurement uncertainties of Fundamental Physical Constants should take into account all
possible and most influencing factors. One from them is the finiteness of the model that causes the existence of
a-priori error. The proposed formula for calculation of this error provides a comparison of its value with the
actual experimental measurement error that cannot be done an arbitrarily small. According to the suggested
approach, the error of the researched Fundamental Physical Constant, measured in conventional field studies,
will always be higher than the error caused by the finite number of dimensional recorded variables of physicalmathematical
models. Examples of practical application of the considered concept for measurement of fine
structure constant, speed of light and Newtonian constant of gravitation are discussed.
Performance Comparison of Energy Detection Based Spectrum Sensing for Cogniti...irjes
With the rapid deployment of new wireless devices and applications, the last decade has witnessed a growing
demand for wireless radio spectrum. However, the policy of fixed spectrum assignment produces a bottleneck for more
efficient spectrum utilization, such that a great portion of the licensed spectrum is severely under-utilized. So the concept of
cognitive radio was introduced to address this issue.The inefficient usage of the limited spectrum necessitates the
development of dynamic spectrum access techniques, where users who have no spectrum licenses, also known as secondary
users, are allowed to use the temporarily unused licensed spectrum. For this purpose we have to know the presence or
absence of primary users for spectrum usage. So spectrums sensing is one of the major requirements of cognitive radio.Many
spectrum sensing techniques have been developed to sense the presence or absence of a licensed user. This paper evaluates
the performance of the energy detection based spectrum sensing technique in noisy and fading environments.The
performance of the energy detection technique will be evaluated by use of Receiver Operating Characteristics (ROC) curves
over additive white Gaussian noise (AWGN) and fading channels.
Comparative Study of Pre-Engineered and Conventional Steel Frames for Differe...irjes
In this paper, the conventional steel frames having triangular Pratt truss as a roofing system of 60 m
length, span 30m and varying bay spacing 4m, 5m and 6m respectively having eaves level for all the portals is at
10m and the EOT crane is supported at the height of 8m from ground level and pre-engineered steel frames of
same dimensions are analyzed and designed for wind zones (wind zone 2, wind zone 3, wind zone 4 and wind
zone 5) by using STAAD Pro V8i. The study deals with the comparative study of both conventional and preengineered
with respect to the amount of structural steel required, reduction in dead load of the structure.
Flip bifurcation and chaos control in discrete-time Prey-predator model irjes
The dynamics of discrete-time prey-predator model are investigated. The result indicates that the
model undergo a flip bifurcation which found by using center manifold theorem and bifurcation theory.
Numerical simulation not only illustrate our results, but also exhibit the complex dynamic behavior, such as the
periodic doubling in period-2, -4 -8, quasi- periodic orbits and chaotic set. Finally, the feedback control method
is used to stabilize chaotic orbits at an unstable interior point.
Energy Awareness and the Role of “Critical Mass” In Smart Citiesirjes
A Smart City could be depicted as a place, logical and physical, in which a crowd of heterogeneous
entities is related in time and space through different types of interactions. Any type of entity, whether it is a
device or a person, clustered in communities, becomes a source of context-based data.
Energy awareness is able to drive the process of bringing our society to limit energy waste and to optimize
usage of available resources, causing a strong environmental and social impact. Then, following social network
analysis methodologies related to the dynamics of complex systems, it is possible to find out, emergent and
sometimes hidden new habits of electricity usage. Through an initial Critical Mass, involving a multitude of
consumers, each related to more contexts, we evaluate the triggering and spreading of a collective attitude. To
this aim, in this paper, we propose a novel analytical model defining a new concept of critical mass, which
includes centrality measures both in a single layer and in a multilayer social network.
A Firefly Algorithm for Optimizing Spur Gear Parameters Under Non-Lubricated ...irjes
Firefly algorithm is one of the emerging evolutionary approaches for complex and non-linear
optimization problems. It is inspired by natural firefly‟s behavior such as movement of fireflies based on
brightness and by overcoming the constraints such as light absorption, obstacles, distance, etc. In this research,
firefly‟s movement had been simulated computationally to identify the best parameters for spur gear pair by
considering the design and manufacturing constraints. The proposed algorithm was tested with the traditional
design parameters and found the results are at par in less computational time by satisfying the constraints.
The Effect of Orientation of Vortex Generators on Aerodynamic Drag Reduction ...irjes
One of the main reasons for the aerodynamic drag in automotive vehicles is the flow separation
near the vehicle’s rear end. To delay this flow separation, vortex generators are used in recent vehicles. The
vortex generators are commonly used in aircrafts to prevent flow separation. Even though vortex generators
themselves create drag, but they also reduce drag by delaying flow separation at downstream. The overall effect
of vortex generators is more beneficial and proved by experimentation. The effect depends on the shape,size and
orientation of vortex generators. Hence optimized shape with proper orientation is essential for getting better
results.This paper presents the effect of vortex generators at different orientation to the flow field and the
mechanism by which these effects takes place.
An Assessment of The Relationship Between The Availability of Financial Resou...irjes
The availability of financial resources is an important element in impacting the success of a planning
process for an effective physical planning. The extent to which however, they are articulated in the process
remained elusive both in scholarly and public discourse. The objective of this study wastherefore, to examine
the extent to which financial resources affect physical planning. In doing so, the study examinedwhether
financial resources were adequate or not to facilitate planning processes in Paidha. According to the study
findings,budget prioritization and ceilings are still a challenge in Paidha Town Council. This is partly due
limited level of knowledge of physical planning among the officials of Paidha Town Council. As a result, there
were no dedicated budget line for routine inspection of physical development plan compliance and enforcement
tools in Paidha. In conclusion, in addressing uncoordinated patterns of physical development that characterize
Uganda‟s urban centres, a critical starting point ought to be the analysis of physical planning process. The
research of this kind is not only significant to other emerging urban centres facing poor a road network,
mushrooming informal settlements and poor social services including poor pattern of residential and commercial
developments but also to all institutions that are involved in planning these towns. Knowing the extent of need
for financial influences in planning may assist local authorities to take the processes of planning seriously which
will help enhance the sustainable development of emerging urban centres including Paidha.
The Choice of Antenatal Care and Delivery Place in Surabaya (Based on Prefere...irjes
- Person's desire to do a pregnancy examination is determined by the service place that suits the tastes
and facilities owned by it. Until now, the utilization of antenatal care by pregnant women is still low (Mardiana,
2014). The purpose of the study is to analyze factors affecting the utilization of antenatal care and delivery place
in Surabaya city based on the preferences and choice theory.
Type of survey research is cross sectional approach, the population is mothers who have children aged 1-
12 months in Surabaya. The large sample of 250 mothers who have children aged 1-12 months in 2013 is taken
by simple random sampling technique. Variables of the research are the preference elements and steps, choice
elements and steps, utilization of antenatal care and delivery place. Data were collected through questionnaires
and secondary data were then analyzed with descriptive statistics in the form of a frequency distribution, shown
by the schematic diagram.
The result showed that the preference elements and steps showed almost half (42.9%) desire to give birth
in a health care because of information got from someone else, while the choice element and step shows the
bulk (57.1%) of the criteria of delivery place chosen is a safe, comfortable and cheap delivery place, the labor
place which is the main choice most (57.1%) is cheap, comfortable, close.
Conclusion of the research based on the preferences and choice theory can be found three (3) new
theories, they are preferences become choice, preferences do not become choice, choice is preceded by
preferences
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Taurus Zodiac Sign_ Personality Traits and Sign Dates.pptxmy Pandit
Explore the world of the Taurus zodiac sign. Learn about their stability, determination, and appreciation for beauty. Discover how Taureans' grounded nature and hardworking mindset define their unique personality.
Unveiling the Secrets How Does Generative AI Work.pdfSam H
At its core, generative artificial intelligence relies on the concept of generative models, which serve as engines that churn out entirely new data resembling their training data. It is like a sculptor who has studied so many forms found in nature and then uses this knowledge to create sculptures from his imagination that have never been seen before anywhere else. If taken to cyberspace, gans work almost the same way.
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[Note: This is a partial preview. To download this presentation, visit:
https://www.oeconsulting.com.sg/training-presentations]
Sustainability has become an increasingly critical topic as the world recognizes the need to protect our planet and its resources for future generations. Sustainability means meeting our current needs without compromising the ability of future generations to meet theirs. It involves long-term planning and consideration of the consequences of our actions. The goal is to create strategies that ensure the long-term viability of People, Planet, and Profit.
Leading companies such as Nike, Toyota, and Siemens are prioritizing sustainable innovation in their business models, setting an example for others to follow. In this Sustainability training presentation, you will learn key concepts, principles, and practices of sustainability applicable across industries. This training aims to create awareness and educate employees, senior executives, consultants, and other key stakeholders, including investors, policymakers, and supply chain partners, on the importance and implementation of sustainability.
LEARNING OBJECTIVES
1. Develop a comprehensive understanding of the fundamental principles and concepts that form the foundation of sustainability within corporate environments.
2. Explore the sustainability implementation model, focusing on effective measures and reporting strategies to track and communicate sustainability efforts.
3. Identify and define best practices and critical success factors essential for achieving sustainability goals within organizations.
CONTENTS
1. Introduction and Key Concepts of Sustainability
2. Principles and Practices of Sustainability
3. Measures and Reporting in Sustainability
4. Sustainability Implementation & Best Practices
To download the complete presentation, visit: https://www.oeconsulting.com.sg/training-presentations
Personal Brand Statement:
As an Army veteran dedicated to lifelong learning, I bring a disciplined, strategic mindset to my pursuits. I am constantly expanding my knowledge to innovate and lead effectively. My journey is driven by a commitment to excellence, and to make a meaningful impact in the world.
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"𝑩𝑬𝑮𝑼𝑵 𝑾𝑰𝑻𝑯 𝑻𝑱 𝑰𝑺 𝑯𝑨𝑳𝑭 𝑫𝑶𝑵𝑬"
𝐓𝐉 𝐂𝐨𝐦𝐬 (𝐓𝐉 𝐂𝐨𝐦𝐦𝐮𝐧𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬) is a professional event agency that includes experts in the event-organizing market in Vietnam, Korea, and ASEAN countries. We provide unlimited types of events from Music concerts, Fan meetings, and Culture festivals to Corporate events, Internal company events, Golf tournaments, MICE events, and Exhibitions.
𝐓𝐉 𝐂𝐨𝐦𝐬 provides unlimited package services including such as Event organizing, Event planning, Event production, Manpower, PR marketing, Design 2D/3D, VIP protocols, Interpreter agency, etc.
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International Refereed Journal of Engineering and Science (IRJES)
1. International Refereed Journal of Engineering and Science (IRJES)
ISSN (Online) 2319-183X, (Print) 2319-1821
Volume 2, Issue 12 (December 2013), PP. 08-17
Fault Ride Through of a Dfig Wind Turbine Using Dvr
with Modified Control Scheme
Harikrishna Parsa1, Dr.Narasimham R.L2
1
PG-Scholar, Dept. of Electrical And Electronics, TKR Engg. College, Hyderabad, India
Prof and Dean (RPD), Dept. of Electrical And Electronics, TKR Engg. College, Hyderabad, India
2
Abstract:- This paper presents the application of a Dynamic Voltage Restorer (DVR) connected to a wind
turbine driven Doubly Fed Induction Generator (DFIG) is investigated. This setup allows the wind turbine
system an uninterruptible fault ride-through of voltage dips. The DVR can compensate the faulty line voltage,
while the DFIG wind turbine can continue its nominal operation as demanded in actual grid codes. Simulation
results for a 2 MW wind turbine are presented, especially for asymmetrical grid faults. They show the
effectiveness of the DVR in comparison to the low-voltage ride-through of the DFIG using a crowbar that does
not allow continuous reactive power production. A modified control scheme for the DVR will improve the fault
ride through behavior of the wind turbine in terms of harmonics and settling time.
Keywords:- Doubly Fed Induction Generator (DFIG), Dynamic Voltage Restorer (DVR), Fault Ride Through ,
Voltage sag.
I.
INTRODUCTION
With the increase of grid connected power generation from the wind energy systems, fault ride through
capability is demanded for Doubly Fed Induction Generator (DFIG) to decrease the adverse effect on stability of
power system. Fault ride through (FRT) refers the operation during grid voltage faults, wind turbines must stay
connected to the grid and should support the grid by generating reactive power to support and restore quickly
the grid voltage after the fault. A detailed analysis has given in [1].
It requires grid code requirements to maintain a stable and safe operation of the power system network.
The actual grid codes stipulate that wind farms should contribute to power system control like frequency and
voltage to behave similar to conventional power stations. A detailed review of grid code technical requirements
regarding the connection of wind farms to the electrical power system is given in [2]. Among wind turbine
concepts, turbines using the DFIG are dominant due to its variable-speed operation, its separately controllable
active and reactive power, and its partially rated power converter. But there are some issues should be concerned
when the wind farms with DFIGs are connected to the grid.
(1) Power quality induced by fluctuant power
(2) Operation of DFIG during grid faults
But the reaction of DFIGs to grid voltage disturbances is sensitive i.e., faults far away from the location of the
turbine can cause a voltage dip at the connection point of the wind turbine. The dip in the grid voltage will result
an increase of the current in the stator windings of DFIG, which will induce the over current in the rotor circuit
and the power electronic converter. To improve the Low Voltage Ride through (LVRT) capability of wind farms
several approaches have been proposed. They can be divided into three categories.
(1) Improvement of the control of the power converter,
(2) Installation of additional hardware and
(3) Determination of the optimal Point of Common Coupling (PCC).
Conventionally, a resistive network called Crowbar is connected in case of rotor over currents or DClink over voltages to the rotor circuit, and the rotor side converter (RSC) is disabled. But the machine draws a
high short circuit current when the Crowbar is activated, resulting in a large amount of reactive power drawn
from the power network, which is not acceptable when considering actual grid code requirements. Thus, other
protection methods have to be investigated to ride-through grid faults safely and fulfill the grid codes.
There are other proposed solutions using additional hardware for fault ride-through of a DFIG using
additional hardware like a series dynamic resistance in the rotor or in the stator or using a series Line Side
Converter (LSC) topology as in [3]. Other approaches focus on limiting the rotor currents during transient grid
voltage by changing the control of the RSC in order to avoid additional hardware in the system. The RSC can be
protected by feed forward of the faulty stator voltage, by considering the stator flux linkage or by using the
measured stator currents as reference for the rotor current controllers [4]. Other publications focus on the
improved performance during unsymmetrical grid voltage conditions. A demagnetizing current is used to
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2. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
protect the converter in, but it becomes clear that during deep transient dips, Crowbar activation cannot be
avoided, and thus, continuous reactive power control cannot be guaranteed.
If an external power electronic device is used to compensate the faulty grid voltage, any protection
method in the DFIG system can be left out. Such a system is introduced in this paper i.e., dynamic voltage
restorer (DVR) that is a voltage source converter connected in series to the grid to correct faulty line voltages.
The advantages of such an external protection device are thus the reduced complexity in the DFIG system. The
disadvantages are the cost and complexity of the DVR. Note that a DVR can be used to protect already installed
wind turbines that do not provide sufficient fault ride-through behavior or to protect any distributed load in a
micro grid. Control structures based on resonant controllers to compensate unsymmetrical voltages are
presented.
In this paper, the application of a DVR that is connected to a wind-turbine-driven DFIG to allow
uninterruptible fault ride through of voltage dips fulfilling the grid code requirements is investigated. The DVR
can compensate the faulty line voltage, while the DFIG wind turbine can continue its nominal operation as
demanded in actual grid codes. Here, asymmetrical faults are investigated; detailed analysis of DFIG behavior
and DVR control is given here.
The understanding of rotor over currents during symmetrical grid voltage dip using a DFIG wind
turbine is described in Section II. Only if the RSC can provide a sufficient voltage level, controllability of rotor
currents can be obtained. If the rotor voltage exceeds the converter voltage, high currents will flow through the
diodes into the dc-link capacitor, damaging the Insulated Gate Bipolar Transistor (IGBT) or the DC capacitor.
An analysis of rotor voltage dynamics during transient symmetrical voltage dip and a description of the control
structure and conventional crowbar protection are given. The DVR electrical system and control using
controllers are described in Section III. Simulation results for a 2MWwind turbine in Section IV show the
effectiveness of the proposed technique in comparison to the low-voltage ride-through of the DFIG using a
Crowbar. A conclusion closes the analysis.
II.
DOUBLY FED INDUCTION GENERATOR
2.1 Introduction
In variable-speed wind turbine with full converter, the generator can be a squirrel-cage induction or a
synchronous generator which is connected to the grid via a power electronic converter as shown in Fig.1 The
whole power output from generator goes through the converter and therefore the converter is rated at full power.
Among wind turbine concepts, turbines using DFIG are described in [5].
A power electronic converter is used in the variable-speed wind turbine with doubly fed induction
generator as shown in Fig.2. The converter is connected to the generator rotor and the stator is directly
connected to the grid. Compared to the one with full converter, this type is more suitable for high power wind
turbines since only a fraction (typically 20-30%) of the total power goes through the converter. This gives
possibility to design the converter with smaller size, and as a result, lower cost and lower power electronic
losses.
Fig.1. Full converter wind turbine
The investigated wind turbine system, as shown in Fig. 2, consists of the basic components like the
turbine, a gear (in most systems), a DFIG, and a back-to-back voltage source converter with a DC link. A dc
chopper to limit the dc voltage across the dc capacitor and a crowbar are included. The back-to-back converter
consists of a RSC and a LSC, connected to the grid by a line filter to reduce the harmonics caused by the
converter. A DVR is included to protect the wind turbine from voltage disturbances. Due to the short period of
time of voltage disturbances, the dynamics of the mechanical part of the turbine will be neglected and the
mechanical torque brought in by the wind is assumed to be constant.
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3. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
Fig.2. Schematic diagram of DFIG wind turbine system with DVR.
2.2 Rotor Voltage Dynamics
A precise knowledge about amplitude and frequency of the rotor voltage is necessary to design and
control the RSC. Therefore, equations for the rotor voltage in normal operation and under symmetrical stator
voltage dip are derived in the following. Afterwards, the rotor converter rating is taken into account.
From the per-phase equivalent circuit of the DFIG in a static stator- oriented reference frame, the following
stator and rotor voltage and flux equations can be derived:
=
+
………………………….. (1)
=
+
-j
…………....……. (2)
=
……………….....……. (3)
=
……………………… (4)
Where , , and represent the flux, voltage, and current vectors, respectively. Subscripts s and r
denote the stator and rotor quantities, respectively. Ls = Lsσ + Lh and Lr = Lrσ + Lh represent the stator and rotor
inductance, Lh is the mutual inductance, Rs and Rr are the stator and rotor resistances, and Ω is the electrical
rotor frequency.
By introducing the leakage factor σ = 1− (Lh2/LsLr ), the rotor flux can be described in dependence of
the rotor current and the stator flux
r=
s+
σLr r …………………………. (5)
By substituting (5) in (2), an equation for the rotor voltage can be obtained
r=
( -j )
s
+ (Rr+ σ Lr(
-j ))
r ….
(6)
which consists of two parts. The first part is caused by the stator flux
operation by the constantly rotating vector
s that is given in normal
…………………………… (7)
s=
The second part of (6) is caused by the rotor current r . The rotor resistance Rr and the leakage factor σ
are often small, so the rotor voltage does not differ considerably from the part caused by the stator flux. Thus,
the amplitude of the rotor voltage in normal condition Vr0 can be calculated as
≈ Vs
= Vs
s ………….……… (8)
where s = 1− (Ω/ωs) = ωr/ωs describes the slip and ωr the slip frequency. The rotor voltage induced by
the stator flux increases the most during a full symmetrical stator voltage dip. Under a symmetrical voltage dip,
the stator voltage is reduced from normal amplitude V1 to the faulty amplitude V2 as described in (9)
s
s
……..…… (9)
=
…............. (10)
=
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4. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
Since the stator flux is a continuous value, it cannot follow the step function of the voltage. The
evolution of the stator flux can be derived by solving the differential equation (11) (from (1) and (3), assuming
r = 0 due to its low influence on the rotor voltage)
=
s ………………………………………………...
s-
(11)
The solution consists of two parts. The first part is the steady state stator flux after the voltage dip that
is described by s2 and the second part is the transition of the flux from s1 to s2 that is described by (12)
e-tRs/Ls =
s=
e-t/τs ………………………………….…. (12)
where s0 is the difference of the stator flux before and after the voltage dip, described by (V1−V2)/jωs .
Summarizing, the stator flux is given by the sum of the two parts
s(t)=
+
e−t/τs .……………………………………….. (13)
When the dynamic stator flux from (13) is considered in the rotor voltage equation of (6) (neglecting
and 1/τs ), the dynamic behavior of the rotor voltage under symmetrical voltage dip is described by (15)
r
…………… (14)
r=
……….......… (15)
=
In a reference frame rotating at rotor frequency, the following rotor voltage is obtained:
…… (16)
r=
The results of this analysis show that the rotor voltage during symmetrical voltage dip consists of two
components. The first part is proportional to the slip and the remaining stator voltage; thus, for a deep voltage
dip and a slip usually at − 0.2, it is small. The frequency of the first part is the slip frequency (at a slip of − 0.2,
ωr = 10Hz). The second part of (16) has a high amplitude at t = 0 proportional to (1 − s) and rotates at the
electrical rotor frequency Ω (at a slip of −0.2, Ω = 60Hz). The part is decaying exponentially with the stator
time constant of τs. The maximum rotor voltage during symmetrical voltage dip will occur at the beginning of
the fault (t = 0) and for a full dip (V2 = 0)
Vr,max ≈
……………………………….………... (17)
Note that (17) is an approximation of the maximum rotor voltage under the given circumstances. The
RSC of a DFIG is rated for a part of the stator power, because the rotor power is approximately proportional to
the slip Pr ≈ sPs that is chosen usually between ±0.3. The required amplitude of the rotor voltage is probably
determined [with Lh /Ls ≈ 1 in (8)] by
Vr =
………………………………………..…….…..……. (18)
where Nsr is the stator to rotor turns ratio. The turn’s ratio is usually set at 1/2 or 1/3 in practical windturbine-driven DFIGs to make full use of the dc-link voltage and reduce the converters current rating. The
required dc-link voltage can be determined by
= Vr …………………….…………………….………… (19)
m
where m is the modulation index of the pulse width modulation (PWM) technique. The value of the
modulation index is 1.0 for the carrier-based sinusoidal PWM and 1.15 for the space vector modulation, both
without over modulation techniques. The findings of the section enhance the understanding of rotor over
currents during symmetrical grid voltage dip. Only if the RSC can provide a sufficient voltage level,
controllability of rotor currents can be obtained. If the rotor voltage exceeds the converter voltage, high currents
will flow through the diodes into the dc-link capacitor, damaging the insulated gate bipolar transistor (IGBT) or
the dc capacitor.
2.3 RSC Control
The RSC provides decoupled control of stator active and reactive power. A cascade vector control
structure with inner current control loops is applied. The overall control structure is shown in Fig. 3. When
adopting stator-voltage-oriented (SVO) control, a decomposition in d and q components is performed (Vsq = 0).
Neglecting the stator resistive voltage drop, the stator output active and reactive powers are expressed as
≈
Vsd Ird ………………………………….…………… (20)
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5. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
≈−
…………………… (21)
thus, the stator active and reactive power can be controlled independently, controlling the d and q
components of the rotor current. Based on (20) and (21), the outer power control loops are designed.
2.4 LSC Control
The LSC controls the dc voltage Vdc and provides reactive power support. A voltage-oriented cascade
vector control structure with inner current control loops is applied [see Fig. 3 (right)]. The line current Il can be
controlled by adjusting the voltage drop across the line inductance Ll giving the following dynamics:
Vs = Rl Il + Ll
…………………………….…… (22)
which is used to design the current controller, while the dc voltage dynamics can be expressed by
Cdc
= Idc – Iload ………………………………. (23)
which is used to design the outer dc voltage control loop, where Cdc is the dc capacitance and Idc and Iload are
the dc currents on LSC and RSC side, respectively.
2.5 Crowbar Protection
To protect the RSC from tripping due to over currents in the rotor circuit or overvoltage in the dc link
during grid voltage dips, a crowbar is installed in conventional DFIG wind turbines, which is a resistive network
that is connected to the rotor windings of the DFIG. The crowbar limits the voltages and provides a safe route
for the currents by bypassing the rotor by a set of resistors. When the crowbar is activated, the RSCs pulses are
disabled and the machine behaves like a squirrel cage induction machine directly coupled to the grid. The
magnetization of the machine that was provided by the RSC in nominal condition is lost and the machine
absorbs a large amount of reactive power from the stator, and thus, from the network, which can further reduce
the voltage level and is not allowed in actual grid codes. Triggering of the crowbar circuit also means high stress
to the mechanical components of the system as the shaft and the gear. Detailed analyses on the DFIG behavior
during voltage dip and crowbar protection can be found. Thus, from network and machine mechanical point of
view, a crowbar triggering should be avoided. Anyway, to compare the presented technique here with a
conventional DFIG wind turbine system protected by a crowbar circuit, simulation results including crowbar
protection are examined. Therefore, the crowbar resistance is designed here.
Fig.3. Schematic diagram of DFIG wind turbine and DVR control structure.
There are two constraints that give an upper and a lower limit to the crowbar resistance. As a first
constraint, the crowbar resistance should be high enough to limit the short-circuit rotor current Ir,max. As the
second constraint, the crowbar resistance should be low enough to avoid too high voltage in the rotor circuit. If
the rotor phase voltage across the crowbar rises above the maximum converter voltage given in (18), high
currents will flow through the anti parallel diodes of the converter. A crowbar resistance of Rcrow = 150Rr is used
in the simulations. There are approaches limiting the operation time of the crowbar to return to normal DFIG
operation with active and reactive power control as soon as possible by injecting a demagnetizing current or
using a threshold control.
III.
DYNAMIC VOLTAGE RESTORER
3.1 Introduction
Dynamic Voltage Restorer (DVR) in the literature as their primary application is to compensate for
voltage sags and swells. Their configuration is similar to that of SSSC. However, the control techniques are
different. Also, a DVR is expected to respond fast (less than 1/4 cycle) and thus employs PWM converters using
IGBT devices.
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6. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
The most common disturbances in the source voltages are the voltage sags or swells that can be due to
(i) disturbances arising in the transmission system, (ii) adjacent feeder faults and (iii) fuse or breaker operation.
Voltage sags of even 10% lasting for 5-10 cycles can result in costly damage in critical loads. The voltage sags
can arise due to symmetrical or unsymmetrical faults. In the latter case, negative and zero sequence components
are also present. Uncompensated nonlinear loads in the distribution system can cause harmonic components in
the supply voltages. To mitigate the problems caused by poor quality of power supply, series connected
compensators are used.
Fast variations in the source voltage cannot be ignored, these can affect the performance of critical
loads such as (a) semiconductor fabrication plants (b) paper mills (c) food processing plants and (d) automotive
assembly plants.
3.2 Electrical System
A DVR is a voltage source converter equipped with a line filter (usually LC type). Usually, a coupling
transformer is used in series to the grid in order to correct deteriorated line voltages to reduce possible problems
on a sensitive load or generator. Different transformer-based topologies are compared with respect to the
number of hardware components, switching harmonics, dc-link control, and the ability to inject zero sequence
voltages. Different system topologies are investigated in regard to the connection of the dc link and the rating in
power and voltage. The rating of the DVR system depends mainly on the depth of the voltage fault that should
be compensated. For voltage sags or swells with zero-phase angle jump, the requirement of active power of the
DVR is simply given by
……………………..……. (24)
=
where V1 is the nominal and V2 the faulty line voltage. Note that special focus must be taken on voltage
faults with phase angle jump that can lead to a higher power rating. When the DVR compensates a voltage sag,
the active power of the DFIG is partly fed into the grid and the DVR system that is dependent of the remaining
grid voltage. The active power flowing into the DVR charges its dc link. The excess energy must either be
delivered to an energy storage system or transformed into heat by a dc chopper. Note that for full compensation
of a full voltage dip, the DVR must be rated for the power of the wind turbine, making the solution in
economical. Thus, the solution will probably be implemented to fully compensate the line voltage during partial
voltage dip or swell and to assist during full voltage dip. The injection transformers have a great impact on the
DVR design. To adapt the DVR dc voltage to the compensating voltage, an adequate transformer ratio must be
chosen. The design of the injection transformers differs from normally used shunt transformers. They must be
higher rated to avoid possible saturation effects and lower the risk of high inrush currents that must be handled
by the converter. In practical applications, several security issues must be considered. Since the DVR is
connected in series to the load, bypass switches across the transformers must be included to disconnect the DVR
from the load, to protect the converter from damage in overload situations.
3.3 DVR Control
For control of the DVR system, a closed-loop control in a rotating dq reference frame is introduced in,
but identified as unsuitable for the compensation of unsymmetrical grid faults. Because the majority of faults on
a power system are unbalanced in nature, which results in unbalanced voltages, appropriate generation of
unsymmetrical compensation voltage components by the DVR is an important feature. Thus, stationary-frame
controllers for DVR implementation are designed to achieve good positive- and negative-sequence voltage
regulation. The cascade control structure includes inner proportional current controllers. As outer voltage
controllers proportional + resonant (P+Res) controllers are compared to H∞-controllers. Both control structures
have good steady-state sinusoidal error tracking of the positive- and negative-sequence voltage components.
Anyway, DVR current control is inadequate if the load is current-controlled too. Therefore, P+Res voltage
controllers that are controlling directly the voltage across the filter capacitors without inner current controllers
are used here. The controller transfer function expressed in terms of inverter voltage reference u* i , measured
filter capacitor voltage uc , and filter capacitor voltage reference u*c is given by
u i* (s)=uc(s)+Gp+Res(s) . (uc*(s)-uc(s)) …………………(25)
where a feed forward of the measured filter capacitor voltage is used. The transfer function of the P+Res voltage
controller is defined as
……………………………… (26)
GP+Res(s)=KP+KI
which has been implemented in the discrete form leading to the following transfer function:
GP+Res(z)= KP+KI
…………………. (27)
Additionally, an anti windup functionality has been added. The control parameters KP and KI were
found by the analysis of bode plots and root loci of the given discrete controller. The inverter system has been
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7. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
discrete modeled consisting of a delay element in series with the transfer function of the LC line filter. The
proposed fuzzy control structure is shown in the following figure.
3.4 Proposed Method
The fuzzy control of DVR will improve the performance is achieved with negligible amount of spikes
and reach the steady state with less time. Thus the proposed Fuzzy Control (FC) has better dynamic behavior
than conventional PI Control. The centroid method is employed for defuzzification. For the proposed FC, the
input signals are error and change in error are properly scaled and fuzzified. Seven membership functions are
used for error, change in error. A rule table relating each one of the 49 input label pairs to respective output label
is shown in above Table 1.
Table 1: Fuzzy rule representation
∆E NB NM NS
Z
PS PM PB
e
Z
NB NB NB NB NB NM NS
Z
PS
NM NB NB NB NM NS
NB NB NM NS
Z
PS PM
NS
NB NM NS
Z
PS PM PB
Z
Z
PS PM PB PB
PS NM NS
Z
PS PM PB PB PB
PM NS
Z
PS PM PB PB PB PB
PB
IV.
RESULTS AND ANALYSIS
Detailed simulation studies carried out on MATLAB/Simulink platform to verify the operating
behavior of the proposed scheme as shown in fig.2 modeled in Simulink is shown in fig.4. Machine parameters
chosen for carrying out the simulation study are provided in Table 2.
Table 2 Simulation Parameters
Simulation Parameters
Symbol
Quantity
Value
Uline
low voltage level (phase-to-phase, rms)
690 V
ωs
Line angular frequency
2π 50 Hz
PDFIG
Wind turbine rated power
2 MW
i
Stator to rotor transmission ratio
1
n
Rated mechanical speed
1800 r/min
Lh
mutual inductance
3.7 mH
Rs
stator resistance
10mΩ
Rcrowbar
Crowbar resistance
0.3 Ω
VDC
DVR DC voltage
560 V
CDC
DVR DC link capacitance
7.5 mF
Fig.4. Simulation block diagram
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8. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
Fig.5. DVR Fuzzy control structure
The converter control and DVR control are designed with the help of control structure given in Fig.3.
The DVR controlled structure is shown in Fig.5. All the simulations are done in MATLAB/Simulink version
7.8.0.347 (R2009a). On the basis of results obtained by simulation, the detailed conclusion is given.
Fig.7. Simulation of DFIG performance with DVR
Fig.6. Simulation of DFIG performance with
protection during two-phase voltage dip.
crowbar protection during two-phase voltage dip.
(a) Line voltage. (b) DVR voltage. (c) Stator voltage. (d) Stator current. (e) RSC current. (f) Crowbar current.
(g) Mechanical speed. (h) Active and reactive stator power. (i) Active and reactive DVR power.
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9. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
The system performance of the DFIG is shown in Fig. 6, protected by the conventional passive
crowbar, and in Fig. 7, protected by the DVR during a two-phase 37 % voltage dip of 100 ms duration [see Figs.
6(a) and 7(a)].The DFIG reacts with high stator currents Is , and thus, high rotor currents are induced in the rotor
circuit. When the rotor currents exceed the maximum level, the crowbar is triggered to protect the RSC from
over currents IRSC [see Fig. 6(e) and (f)]. When the voltage level has been reestablished and transients have
decayed, the crowbar can be deactivated, which is not shown here. When the RSC is in operation, the machine
magnetization is provided by the rotor, but when the crowbar is triggered, the RSC is disabled and the machine
excitation is shifted to the stator. Thus, reactive power control cannot be provided during the voltage dip [see
Fig. 6(h)], which is not acceptable when considering the grid codes. The machine cannot generate enough torque
so that the rotor accelerates, which can lead to disconnection of the turbine due to over speed. The DVR is not
activated in the simulations, as shown in Fig. 6. When the wind turbine system is protected by the DVR, as
shown in Fig. 7, the voltage dip can almost be compensated [see Fig. 7(c)].
Fig.8. Simulations of DFIG performance with DVR
Fig.9. Simulations of DFIG performance with DVR
conventional Control protection during two-phase
Fuzzy control protection during two- phase voltage
voltage dip.
dip.
(d) Stator current. (e) RSC current. (h) Active and reactive stator power. (i) Active and reactive DVR power
The Fig. 8 and Fig.9 shows the comparison of outputs of the DVR control with conventional control
and Fuzzy respectively. The DFIG response is much less critical, which means that lower stator over currents
and rotor over currents are produced so that the crowbar does not have to be triggered [see Fig. 8(d)–(e) and
9(d)-(e)]. There is considerable reduction of over currents can be observed from the Figures 8 and 9. Note that
although the stator voltage dip is fairly well-compensated, a slight distortion in the stator currents (dc
components), and thus, disturbed rotor currents can be observed. Anyway, the RSC remains in operation and
can control stator active and reactive power independently. Thus, the speed is kept constant and a reactive power
production (Qs = 0.5Mvar) during grid fault as demanded in grid codes is performed. Note that a
communication between DVR and DFIG is necessary. In Fig. 8(i) and 9(i), the DVR power to compensate the
voltage dip is shown. It becomes clear that the active and reactive power that cannot be fed into the faulty grid
during grid fault must be consumed by the DVR. The comparison of DVR control with P+Res and Fuzzy are
given in Table 3 and Table 4.
Table 3 Comparison of Current level
Measuring Quantity
Isabc(Stator Current)
Irabc(Rotor Current)
Tolerance
P+Res control
2000 ± 10.5%
2000 ± 25%
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Fuzzy control
2000 ± 1.5%
2000 ± 16%
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10. Fault Ride Through of a Dfig Wind Turbine Using Dvr with Modified Control Scheme
Table 4 Comparison of Settling Time
Settling time
Measuring Quantity
P+Res Control
Fuzzy control
Isabc(Stator Current)
0.15 sec
0.1sec
Irabc(Rotor Current)
0.15 sec
0.05sec
V.
CONCLUSION
Throughout this work, we have shown the effectiveness of the application of DVR control with PI and
Fuzzy comparison with crowbar. In fact, the ripples are minimized in Stator side and rotor side current with the
fuzzy control of DVR which we have shown in simulation. From that we will conclude that fault ride through
capability is improved for wind turbine generator connected to grid. Moreover, it can also be extended to the
installed wind turbines, that do not provide sufficient fault ride through behavior or to protect any distributed
load in a micro grid.
ACKNOWLEDGEMENTS
I have great immense gratitude to my guide Dr.Narasimham R.L for his constant encouragement
throughout this work.
REFERENCES
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[2].
M. Tsili and S. Papathanassiou, “A review of grid code technical requirements for wind farms,”
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[3].
P. Flannery and G. Venkataramanan, “Unbalanced voltage sag ride through of a doubly fed induction
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[4].
F. Lima, A. Luna, P. Rodriguez, E. Watanabe, and F. Blaabjerg, “Rotor voltage dynamics in the doubly
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[5].
S.Muller,M.Deicke, and R.DeDoncker, “Doubly fed induction generator systems for wind turbines,”
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www.ijres.org
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