With the growing integration into power grids, wind power plants are very important for
power system. According to the grid codes wind power plants should have the ability to perform
voltage control and reactive power compensation at the Point of Common Coupling (PCC). In
general, the entire wind farm operates within a power factor range of 0.95 leading and lagging. This
operation drastically under utilizes the reactive output of the machine. The results offered in this
paper demonstrates enhancement of reactive power capability of Doubly Fed Induction Generator
(DFIG). This additional reactive power supports to improve the post fault voltage and reduces the
overall system losses and also reduces the cost of the generation. The utilization of extended reactive
limits in voltage control may prevent system collapse.
improved reactive power capability of grid connected doubly fed induction gen...vinay kumar mali
The document discusses issues related to doubly fed induction generators (DFIGs) used in wind turbines remaining connected to the power grid during faults. It notes that grid codes now require renewable generators to provide ancillary services like reactive power during faults to support voltage and frequency. While DFIGs are sensitive to voltage dips, various protection methods like crowbar circuits, energy storage, and dynamic voltage restorers can help DFIGs ride through faults by limiting current surges. The document examines different control strategies and protection devices that allow DFIG wind turbines to meet grid code low voltage ride-through requirements.
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.
The document reports on a study of the dynamic behavior of doubly fed induction generators (DFIGs) during three-phase voltage dips. DFIGs are commonly used in large wind turbines. While they provide benefits, they are very sensitive to grid disturbances like voltage dips. The paper develops a theoretical analysis of the machine's behavior during voltage dips to better understand the problem. Experimental results agree with the theoretical analysis, validating the proposed model. The analysis provides insight that can help improve protections and solutions for DFIGs during grid faults.
The document presents a study of the dynamic behavior of a doubly fed induction generator (DFIG) system during three-phase voltage dips. The DFIG system uses a rotor side controller and grid side controller. The objective is to measure the three-phase grid output and stator side flux under simulated voltage dips. The proposed system model includes a wind turbine, asynchronous motor representing the generator, and rotor side and grid side control systems. The output will analyze the three-phase voltage and stator flux after various voltage dips are applied.
Performance of Doubly-Fed Induction Generator by changing various system para...AM Publications
This paper describes the behaviour of a doubly-fed induction generator (DFIG) driven by wind turbine.
The work has been carried out with the main objective to study dynamic performance of wind driven, grid connected
doubly fed induction generator by formulating appropriate mathematical models. Further, performance of doubly fed
induction generator is observed by changing various system parameters like base wind speed, line length and grid
voltage. A MATLAB computer simulation study was undertaken and results on wind turbine are presented.
The document summarizes research on Low Voltage Ride Through (LVRT) capability for wind power systems. It discusses LVRT requirements specified in grid codes that require wind turbines to remain connected during faults and provide reactive power support. It then reviews different wind turbine generator topologies and their responses to faults. Several control strategies and technologies to enable LVRT capability are presented, including chopper resistors, energy storage, and derated generator operation. Simulation results validating one control scheme are shown through various graphs. The conclusion states that combining multiple technologies can help implement LVRT and connect wind power systems to the grid more effectively.
The presentation includes the objective, operation, characteristics , simulation, results and waveforms of Doubly Fed Induction Generator connected to variable speed Wind Turbine. which is published and presented in IEEE international conference in Technological advancements of Power and Energy which was held in Amrita Vishwa Vidyapeetam, Amritapuri, Kerala.
improved reactive power capability of grid connected doubly fed induction gen...vinay kumar mali
The document discusses issues related to doubly fed induction generators (DFIGs) used in wind turbines remaining connected to the power grid during faults. It notes that grid codes now require renewable generators to provide ancillary services like reactive power during faults to support voltage and frequency. While DFIGs are sensitive to voltage dips, various protection methods like crowbar circuits, energy storage, and dynamic voltage restorers can help DFIGs ride through faults by limiting current surges. The document examines different control strategies and protection devices that allow DFIG wind turbines to meet grid code low voltage ride-through requirements.
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.
The document reports on a study of the dynamic behavior of doubly fed induction generators (DFIGs) during three-phase voltage dips. DFIGs are commonly used in large wind turbines. While they provide benefits, they are very sensitive to grid disturbances like voltage dips. The paper develops a theoretical analysis of the machine's behavior during voltage dips to better understand the problem. Experimental results agree with the theoretical analysis, validating the proposed model. The analysis provides insight that can help improve protections and solutions for DFIGs during grid faults.
The document presents a study of the dynamic behavior of a doubly fed induction generator (DFIG) system during three-phase voltage dips. The DFIG system uses a rotor side controller and grid side controller. The objective is to measure the three-phase grid output and stator side flux under simulated voltage dips. The proposed system model includes a wind turbine, asynchronous motor representing the generator, and rotor side and grid side control systems. The output will analyze the three-phase voltage and stator flux after various voltage dips are applied.
Performance of Doubly-Fed Induction Generator by changing various system para...AM Publications
This paper describes the behaviour of a doubly-fed induction generator (DFIG) driven by wind turbine.
The work has been carried out with the main objective to study dynamic performance of wind driven, grid connected
doubly fed induction generator by formulating appropriate mathematical models. Further, performance of doubly fed
induction generator is observed by changing various system parameters like base wind speed, line length and grid
voltage. A MATLAB computer simulation study was undertaken and results on wind turbine are presented.
The document summarizes research on Low Voltage Ride Through (LVRT) capability for wind power systems. It discusses LVRT requirements specified in grid codes that require wind turbines to remain connected during faults and provide reactive power support. It then reviews different wind turbine generator topologies and their responses to faults. Several control strategies and technologies to enable LVRT capability are presented, including chopper resistors, energy storage, and derated generator operation. Simulation results validating one control scheme are shown through various graphs. The conclusion states that combining multiple technologies can help implement LVRT and connect wind power systems to the grid more effectively.
The presentation includes the objective, operation, characteristics , simulation, results and waveforms of Doubly Fed Induction Generator connected to variable speed Wind Turbine. which is published and presented in IEEE international conference in Technological advancements of Power and Energy which was held in Amrita Vishwa Vidyapeetam, Amritapuri, Kerala.
This document describes research on controlling the operation of a doubly fed induction generator (DFIG) for wind turbines under grid voltage disturbances. In Phase I, a current loop controller was added that reduced harmonic distortion and power fluctuations in the generator output. Phase II compared the performance of a DFIG using a proportional-integral current controller versus a fractional-order proportional-integral-derivative current controller. The fractional-order controller provided better performance with lower total harmonic distortion.
Modeling and simulation of dfig to grid connected wind power generation using...IAEME Publication
This document summarizes a study on modeling and simulating a doubly fed induction generator (DFIG) connected to the power grid using MATLAB. It begins with an introduction to DFIGs and their advantages over other wind turbine generator types. It then describes the components and control of a DFIG system, including the AC/DC/AC converter. The document outlines the modeling of wind turbine and DFIG components in MATLAB/Simulink. It presents equations for calculating wind power capture and discusses modeling the variable speed capability of DFIGs. Finally, it summarizes simulation results showing DFIG operation and integration with the electric grid.
This document discusses wind energy conversion systems and types of wind energy systems. It introduces variable speed wind turbine systems using doubly fed induction generators and fully variable systems using voltage source converters. Two papers are referenced that discuss control of a wind turbine using a doubly fed induction generator system and maximum power point tracking algorithms. The conclusion states that doubly fed induction generators and Z-source inverters can provide improved efficiency and control of active and reactive power from wind energy systems.
This report gives an overview of patenting activity around Doubly-fed Induction Generators (DFIG) used in the horizontal axis wind turbines for efficient power generation. Patents were categorized as per key DFIG technologies and analyzed for generating different trends within PatSeer Project.
This document summarizes research on controlling a doubly-fed induction generator (DFIG) for variable-speed wind power generation. A DFIG allows power production at a constant voltage and frequency while the rotor speed varies, making it suitable for wind power applications. The control scheme uses stator flux orientation for the rotor side converter and grid voltage vector control for the grid side converter. Simulation and laboratory tests were performed to validate the control approach under different wind conditions.
Wind turbines use power electronics like doubly fed induction generators (DFIGs) consisting of wound rotors, induction generators, and AC/DC/AC converters. DFIGs allow variable speed operation, reduce converter size/cost, and enable reactive power control. They work by converting the turbine's mechanical energy to electrical energy. The stator is directly connected to the grid while the rotor is fed at variable frequency by the converter. The converter controls the rotor speed and active/reactive power flow. DFIGs offer advantages like low losses, compact design, and speed regulation from ±20-25% but have disadvantages like slip ring maintenance and complex control.
This document discusses wind turbine generator technologies. It describes the typical components of a wind turbine, including the gearbox and different methods for mechanical speed regulation. It then summarizes the four main types of wind turbine generator technologies presently used: squirrel cage induction generators, induction generators with variable external rotor resistance, doubly fed induction generators, and synchronous or induction generators with full converter interfaces. It provides details on doubly fed induction generators, including their control and protection systems. The document discusses the impact of large wind power plants on power system dynamics and stability.
Analysis of PMSG in Wind Integration using T Source Inverter with Simple Boos...IJTET Journal
The Analysis of PMSG in wind integration using a T-source Inverter with the Simple Boost Control technique for
improving voltage gain is proposed. The Permanent Magnet Synchronous Generator (PMSG) offers higher performance than other
generators because of its higher efficiency with less maintenance. Since they don’t have rotor current, can be used without a gearbox,
which also implies a reduction of the weight of the nacelle with a reduction of costs. T-Source Inverter has high frequency, low
leakage inductance transformer and one capacitance this is the main difference from the Z-source Inverter. It has low active
components in compare with conventional ZSI. The T source network has an ability to perform DC to AC power conversion. It
provides buck boost operation in a single stage, but the traditional Inverter cannot provide such feature. All the components of the
wind turbine and the grid-side converter are developed and implemented in MATLAB/Simulink.
DFIG control of WECS using indirect matrix converter Kuldeep Behera
The connection and operation of wind power plants produce some problems that are rising partly owing to large changeability of environment conditions, influencing the electrical energy supply from these sources. To be possible to study phenomena that are connected with wind power plants and impacts of their operation on the operation of distribution and transmission systems, it is necessary to do such as in other branches, different computer simulations. A grid connected wind power generation scheme using doubly fed induction generator is studied. The aim is modelling and simulation of DFIG operating in two quadrants (torque-speed) by a suitable control technique to control the rotor current. This method will also replace the conventional converter by Indirect Matrix Converter.
Open-End-Winding Permanent Magnet Synchonous Generator for Wind Energy Conver...Naila Syed
Recent trend in Wind energy conversion system which helps in understanding how the control systems and power energy systems can be interfaced to make the best use of wind energy.
Grid Connected Wind Turbine Generator with Real and Reactive Power ControlIRJET Journal
This document proposes a grid-connected wind turbine system with a permanent magnet synchronous generator (PMSG) for variable speed operation. A diode bridge rectifier converts the AC voltage from the PMSG to DC, which is fed to a boost converter for voltage regulation. The output of the boost converter feeds a three-phase inverter to inject real and reactive power into the grid using PI controllers with grid current and voltage feedback. Maximum power point tracking (MPPT) is achieved by varying the turbine pitch angle using a voltage-controlled technique to extract maximum power for varying wind speeds. Simulation results in MATLAB/Simulink demonstrate the performance of the system.
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.
Study on power control of doubly fed induction generatorIRJET Journal
This document summarizes a study on controlling power from a doubly fed induction generator (DFIG) for wind turbine systems. A DFIG allows variable speed operation through the use of an AC-DC-AC converter connected to its rotor. The converter controls both active and reactive power independently of generator speed. The study examines control strategies for the rotor side converter to regulate speed and power, and the grid side converter to control DC bus voltage and power flow. Simulation results show the DFIG control system can maintain stable power output despite fluctuating wind speed.
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.
www.irjes.com
This document presents a two-stage model for daily volt/var control (VVC) of distribution systems that includes distributed energy resources (DERs) like wind turbines and synchronous machine-based distributed generations. The first stage is a day-ahead market that minimizes electrical energy costs and gas emissions from generation units to determine an initial schedule. The second stage examines this schedule from an operational perspective to determine optimal daily dispatches of VVC devices while minimizing losses, adjustment of scheduled active powers, and depreciation costs. It uses Benders decomposition to solve the mixed integer nonlinear programming problem, and tests the approach on two distribution test networks.
IRJET- Improvement of Wind Turbine DFIG using Fault Ride Through Capability T...IRJET Journal
This document discusses techniques for improving the fault ride-through capability of doubly fed induction generator (DFIG) wind turbines. It begins with an introduction to DFIG wind turbines and discusses challenges during grid faults. It then presents an active crowbar protection system to reduce high rotor currents and voltages during faults. The crowbar works by bypassing the rotor circuit when faults are detected. Fault detection methods like current threshold monitoring are also examined. Simulation results show the crowbar technique helps DFIG wind turbines stay connected to the grid during faults and resume normal operation quickly after faults clear. The paper concludes the crowbar protection and control strategies improve the low voltage ride-through capability of DFIG wind turbines.
The document describes a control scheme for a stand-alone hybrid wind-battery energy system. The system includes a 4 kW wind turbine connected to a 5.4 hp squirrel cage induction generator. A 400 Ah lead-acid battery bank provides backup power storage. The control scheme uses maximum power point tracking (MPPT) to charge the batteries from the wind turbine. A pitch controller varies the blade pitch to regulate the turbine speed and electrical parameters. The batteries charge in constant current (CC) mode until fully charged, then switch to constant voltage (CV) mode to maintain the battery voltage without overcharging. Simulation results show the system can successfully regulate parameters and supply uninterrupted power under various wind speed conditions.
Study of DFIG Connected to Grid using Wind Energy SystemIRJET Journal
This document summarizes a study on connecting a doubly fed induction generator (DFIG) driven by a wind turbine to the electric grid. It begins by introducing DFIGs, which are commonly used in large wind farms because they can supply power at constant voltage and frequency despite fluctuations in wind speed. A DFIG has grid-connected stator windings and rotor windings connected to the grid via a back-to-back converter. This converter, consisting of a rotor side converter and grid side converter linked by a DC bus, controls the rotor currents to maintain constant grid frequency regardless of rotor speed variations from changing wind. The document then discusses issues with integrating wind power, such as voltage variations and stability, before describing the basic components
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.
The document discusses the implications of load angle and excitation on generator stability. It explains that the load angle is the angle between the generator induced EMF and terminal voltage. It increases as the generator transfers power from no load to load conditions. The generator operates stably when the derivative of power with respect to load angle is positive, up to a load angle of 90 degrees. Boosting excitation can reduce the load angle and increase power output at a given load angle, as long as excitation limits are respected. The generator capability curve depicts the stability limits imposed by the load angle, rotor current, and stator current limiters.
##CONTENT##
Introduction
Voltage control
Power system control
Control of reactive power and power factor
Interconnected control and frequency ties
Supervisory control
Line compensation
Series compensation
Series and shunt compensation schemes for ac transmission system
This document describes research on controlling the operation of a doubly fed induction generator (DFIG) for wind turbines under grid voltage disturbances. In Phase I, a current loop controller was added that reduced harmonic distortion and power fluctuations in the generator output. Phase II compared the performance of a DFIG using a proportional-integral current controller versus a fractional-order proportional-integral-derivative current controller. The fractional-order controller provided better performance with lower total harmonic distortion.
Modeling and simulation of dfig to grid connected wind power generation using...IAEME Publication
This document summarizes a study on modeling and simulating a doubly fed induction generator (DFIG) connected to the power grid using MATLAB. It begins with an introduction to DFIGs and their advantages over other wind turbine generator types. It then describes the components and control of a DFIG system, including the AC/DC/AC converter. The document outlines the modeling of wind turbine and DFIG components in MATLAB/Simulink. It presents equations for calculating wind power capture and discusses modeling the variable speed capability of DFIGs. Finally, it summarizes simulation results showing DFIG operation and integration with the electric grid.
This document discusses wind energy conversion systems and types of wind energy systems. It introduces variable speed wind turbine systems using doubly fed induction generators and fully variable systems using voltage source converters. Two papers are referenced that discuss control of a wind turbine using a doubly fed induction generator system and maximum power point tracking algorithms. The conclusion states that doubly fed induction generators and Z-source inverters can provide improved efficiency and control of active and reactive power from wind energy systems.
This report gives an overview of patenting activity around Doubly-fed Induction Generators (DFIG) used in the horizontal axis wind turbines for efficient power generation. Patents were categorized as per key DFIG technologies and analyzed for generating different trends within PatSeer Project.
This document summarizes research on controlling a doubly-fed induction generator (DFIG) for variable-speed wind power generation. A DFIG allows power production at a constant voltage and frequency while the rotor speed varies, making it suitable for wind power applications. The control scheme uses stator flux orientation for the rotor side converter and grid voltage vector control for the grid side converter. Simulation and laboratory tests were performed to validate the control approach under different wind conditions.
Wind turbines use power electronics like doubly fed induction generators (DFIGs) consisting of wound rotors, induction generators, and AC/DC/AC converters. DFIGs allow variable speed operation, reduce converter size/cost, and enable reactive power control. They work by converting the turbine's mechanical energy to electrical energy. The stator is directly connected to the grid while the rotor is fed at variable frequency by the converter. The converter controls the rotor speed and active/reactive power flow. DFIGs offer advantages like low losses, compact design, and speed regulation from ±20-25% but have disadvantages like slip ring maintenance and complex control.
This document discusses wind turbine generator technologies. It describes the typical components of a wind turbine, including the gearbox and different methods for mechanical speed regulation. It then summarizes the four main types of wind turbine generator technologies presently used: squirrel cage induction generators, induction generators with variable external rotor resistance, doubly fed induction generators, and synchronous or induction generators with full converter interfaces. It provides details on doubly fed induction generators, including their control and protection systems. The document discusses the impact of large wind power plants on power system dynamics and stability.
Analysis of PMSG in Wind Integration using T Source Inverter with Simple Boos...IJTET Journal
The Analysis of PMSG in wind integration using a T-source Inverter with the Simple Boost Control technique for
improving voltage gain is proposed. The Permanent Magnet Synchronous Generator (PMSG) offers higher performance than other
generators because of its higher efficiency with less maintenance. Since they don’t have rotor current, can be used without a gearbox,
which also implies a reduction of the weight of the nacelle with a reduction of costs. T-Source Inverter has high frequency, low
leakage inductance transformer and one capacitance this is the main difference from the Z-source Inverter. It has low active
components in compare with conventional ZSI. The T source network has an ability to perform DC to AC power conversion. It
provides buck boost operation in a single stage, but the traditional Inverter cannot provide such feature. All the components of the
wind turbine and the grid-side converter are developed and implemented in MATLAB/Simulink.
DFIG control of WECS using indirect matrix converter Kuldeep Behera
The connection and operation of wind power plants produce some problems that are rising partly owing to large changeability of environment conditions, influencing the electrical energy supply from these sources. To be possible to study phenomena that are connected with wind power plants and impacts of their operation on the operation of distribution and transmission systems, it is necessary to do such as in other branches, different computer simulations. A grid connected wind power generation scheme using doubly fed induction generator is studied. The aim is modelling and simulation of DFIG operating in two quadrants (torque-speed) by a suitable control technique to control the rotor current. This method will also replace the conventional converter by Indirect Matrix Converter.
Open-End-Winding Permanent Magnet Synchonous Generator for Wind Energy Conver...Naila Syed
Recent trend in Wind energy conversion system which helps in understanding how the control systems and power energy systems can be interfaced to make the best use of wind energy.
Grid Connected Wind Turbine Generator with Real and Reactive Power ControlIRJET Journal
This document proposes a grid-connected wind turbine system with a permanent magnet synchronous generator (PMSG) for variable speed operation. A diode bridge rectifier converts the AC voltage from the PMSG to DC, which is fed to a boost converter for voltage regulation. The output of the boost converter feeds a three-phase inverter to inject real and reactive power into the grid using PI controllers with grid current and voltage feedback. Maximum power point tracking (MPPT) is achieved by varying the turbine pitch angle using a voltage-controlled technique to extract maximum power for varying wind speeds. Simulation results in MATLAB/Simulink demonstrate the performance of the system.
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.
Study on power control of doubly fed induction generatorIRJET Journal
This document summarizes a study on controlling power from a doubly fed induction generator (DFIG) for wind turbine systems. A DFIG allows variable speed operation through the use of an AC-DC-AC converter connected to its rotor. The converter controls both active and reactive power independently of generator speed. The study examines control strategies for the rotor side converter to regulate speed and power, and the grid side converter to control DC bus voltage and power flow. Simulation results show the DFIG control system can maintain stable power output despite fluctuating wind speed.
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.
www.irjes.com
This document presents a two-stage model for daily volt/var control (VVC) of distribution systems that includes distributed energy resources (DERs) like wind turbines and synchronous machine-based distributed generations. The first stage is a day-ahead market that minimizes electrical energy costs and gas emissions from generation units to determine an initial schedule. The second stage examines this schedule from an operational perspective to determine optimal daily dispatches of VVC devices while minimizing losses, adjustment of scheduled active powers, and depreciation costs. It uses Benders decomposition to solve the mixed integer nonlinear programming problem, and tests the approach on two distribution test networks.
IRJET- Improvement of Wind Turbine DFIG using Fault Ride Through Capability T...IRJET Journal
This document discusses techniques for improving the fault ride-through capability of doubly fed induction generator (DFIG) wind turbines. It begins with an introduction to DFIG wind turbines and discusses challenges during grid faults. It then presents an active crowbar protection system to reduce high rotor currents and voltages during faults. The crowbar works by bypassing the rotor circuit when faults are detected. Fault detection methods like current threshold monitoring are also examined. Simulation results show the crowbar technique helps DFIG wind turbines stay connected to the grid during faults and resume normal operation quickly after faults clear. The paper concludes the crowbar protection and control strategies improve the low voltage ride-through capability of DFIG wind turbines.
The document describes a control scheme for a stand-alone hybrid wind-battery energy system. The system includes a 4 kW wind turbine connected to a 5.4 hp squirrel cage induction generator. A 400 Ah lead-acid battery bank provides backup power storage. The control scheme uses maximum power point tracking (MPPT) to charge the batteries from the wind turbine. A pitch controller varies the blade pitch to regulate the turbine speed and electrical parameters. The batteries charge in constant current (CC) mode until fully charged, then switch to constant voltage (CV) mode to maintain the battery voltage without overcharging. Simulation results show the system can successfully regulate parameters and supply uninterrupted power under various wind speed conditions.
Study of DFIG Connected to Grid using Wind Energy SystemIRJET Journal
This document summarizes a study on connecting a doubly fed induction generator (DFIG) driven by a wind turbine to the electric grid. It begins by introducing DFIGs, which are commonly used in large wind farms because they can supply power at constant voltage and frequency despite fluctuations in wind speed. A DFIG has grid-connected stator windings and rotor windings connected to the grid via a back-to-back converter. This converter, consisting of a rotor side converter and grid side converter linked by a DC bus, controls the rotor currents to maintain constant grid frequency regardless of rotor speed variations from changing wind. The document then discusses issues with integrating wind power, such as voltage variations and stability, before describing the basic components
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.
The document discusses the implications of load angle and excitation on generator stability. It explains that the load angle is the angle between the generator induced EMF and terminal voltage. It increases as the generator transfers power from no load to load conditions. The generator operates stably when the derivative of power with respect to load angle is positive, up to a load angle of 90 degrees. Boosting excitation can reduce the load angle and increase power output at a given load angle, as long as excitation limits are respected. The generator capability curve depicts the stability limits imposed by the load angle, rotor current, and stator current limiters.
##CONTENT##
Introduction
Voltage control
Power system control
Control of reactive power and power factor
Interconnected control and frequency ties
Supervisory control
Line compensation
Series compensation
Series and shunt compensation schemes for ac transmission system
This document discusses synchronous motors and their characteristics. It describes the different types of synchronous motors including 3-phase, 1-phase, reluctance, hysteresis, permanent magnet, and inductor motors. It then discusses their key characteristics such as high operating efficiency, smooth starting and acceleration, versatile power factor control, constant speed, and higher cost compared to induction motors. The document also covers torque-angle characteristics of synchronous motors under no-load and full-load conditions and how damper windings are used to reduce torque fluctuations. It describes methods for starting synchronous motors including using a pony motor or applying a low starting frequency. Finally, it discusses how synchronous motors can be used for power factor correction by varying their excitation.
A transformer is a device that changes alternating current (ac) electric power at one voltage level to ac power at another voltage level through magnetic induction. It consists of two or more coils wound around a core and linked by a magnetic field. An ideal transformer has no losses and the power input equals the power output. Real transformers have losses due to winding resistance, core losses, and leakage fluxes. The performance of real transformers can be modeled using an equivalent circuit with parameters determined from open-circuit and short-circuit tests. Transformer voltage regulation and efficiency are important performance metrics.
1) Voltage collapse is a major cause of recent blackouts due to increased reliance on remote generation and lack of transmission expansion. As transmission lines trip, reactive power losses increase, reducing voltage.
2) Generators provide reactive power (VARs) to support system voltage through their automatic voltage regulators (AVRs). During low voltage events, AVRs and generator protection systems may not be able to maintain stable operation.
3) Undervoltage load shedding is used to prevent total system collapse by automatically removing certain loads if voltage drops below a threshold for a set time period. This helps restore the balance between generation and load.
This document discusses synchronous generator capability curves. It provides 3 key points that define the capability curve: (1) the stator copper loss which sets a maximum phase current and apparent power limit, (2) the rotor copper loss which sets a maximum field current and equivalent voltage limit, and (3) the prime mover's power limit which sets the maximum real power limit. The capability curve graphs the generator's ability to supply various combinations of real and reactive power based on these three limits.
Excitation System & capability curve of synchronous generatorMANOJ KUMAR MAHARANA
Excitation systems perform control and protective functions essential to the satisfactory performance of the power system.
The amount of continuous reactive power a generator can supply is restricted by various limits. In the over-excitation region limits are imposed by rotor heating or amount of field current and second is the stator current. In the under excitation region the limits are imposed by load angle. So in steady state the generator should always operate within this region and the loci of the various limiters are called the capability curve of the generator.
Synchronous motors operate at a constant synchronous speed determined by the number of poles and frequency of the power supply. They have high efficiency and provide smooth constant torque but are more expensive than induction motors. The rotor is either wound similarly to an induction motor or contains permanent magnets. Methods to provide starting torque include using a pony motor, applying a reduced voltage and frequency to the rotor windings to make it operate like an induction motor initially, or using damper windings. Synchronous motors are commonly used for power factor correction by varying the field excitation to control the phase relationship between voltage and current.
The document discusses synchronous motors, including their construction, operation principles, starting methods, and characteristics under different excitations. Some key points covered include:
- Synchronous motors operate in synchronism with the frequency of the power source, maintaining a constant speed. Their speed is determined by the number of poles and line frequency.
- They are constructed similarly to alternators and have constant speed between no load and full load. Damper windings or an external prime mover are needed for starting.
- Under normal excitation the induced emf equals the supply voltage. Under-excitation leads to induced emf below supply voltage, while over-excitation induces emf above supply voltage.
- Applications
The document discusses excitation in generators and loss of excitation (LOE). It begins by explaining what excitation is, why it is required, and how it is provided in generators of different sizes. It then discusses what will happen if excitation is lost, including potential overspeeding, abnormal heating, and loss of synchronization. Several protection schemes for LOE are presented, including impedance-based R-X schemes which monitor changes in generator terminal impedance during LOE. Settings for typical LOE relays are also calculated and described.
Power factor improvement of an induction motorIIT Roorkee
This document discusses power factor improvement of an induction motor through the use of static capacitors. It begins with introductions to induction motors, power factor, and why power factor correction is important. It then covers motor load characteristics, phasor diagrams showing how capacitors improve power factor, and considerations for proper capacitor sizing to avoid self-excitation of the motor. The document proposes a project to measure an induction motor's internal impedance, efficiency, and power factor at different loads, calculate the optimal capacitor size, observe the improved power factor and efficiency, and calculate potential cost savings.
The document summarizes different types of excitation systems used for synchronous generators. It describes the components and operation of static excitation systems, which are now widely used. Static excitation systems provide fast acting voltage control using thyristor bridges and power electronics. They allow high response ratios of 3-5 compared to older systems like DC excitation. The key components of a static excitation system are the rectifier transformer, SCR bridges, excitation start up equipment, field discharge equipment, and regulator/control circuits.
This document discusses different types of DC generators, including permanent magnet, separately excited, and self-excited generators. It focuses on self-excited DC generators, which can be series wound, shunt wound, or compound wound. The document provides details on the magnetic or open circuit characteristic curve, which shows the relationship between field current and generated voltage without a load. It also discusses the internal and external characteristic curves when the generator is loaded, accounting for voltage drops due to armature reaction and ohmic losses. Characteristics of series wound and shunt wound generators are covered as well.
IRJET- Performance Enhancement of DFIG based Wind Farms Integrated in Power S...IRJET Journal
This document discusses improving the performance of doubly fed induction generator (DFIG) based wind farms integrated into power systems under voltage dips. It proposes coordinating the automatic voltage regulator (AVR) and power system stabilizer (PSS) of synchronous generators using fuzzy logic. A fuzzy coordinator is designed to eliminate harmful interactions between AVR and PSS during faults by adjusting their gains based on rotor angle and terminal voltage deviations. Simulation results on the IEEE 10-machine 39-bus system show the fuzzy coordinator helps transmit voltage at the point of common coupling and reduces DFIGs' reactive power needs under faults, enhancing system performance.
This paper reviews technologies for enhancing the low voltage ride through (LVRT) capability of wind farms using induction generators. It analyzes how FACTS controllers like STATCOMs or MERs can improve LVRT capability compared to thyristor controlled static var compensators (SVCs). It proposes using transient stability margin as an indicator of LVRT capability and describes a torque slip characteristic approach for estimating the rating of compensation devices needed to ensure stability after a fault. The paper also discusses different wind generator types, LVRT technologies like active crowbars and energy storage, and the role of grid codes in technical requirements for connecting wind farms to the grid.
This paper reviews technologies for enhancing the low voltage ride through (LVRT) capability of wind farms using induction generators. It analyzes how FACTS controllers like STATCOMs or MERs can improve LVRT capability compared to thyristor controlled static var compensators (SVCs). It proposes using transient stability margin as an indicator of LVRT capability and describes a torque slip characteristic approach for estimating the rating of compensation devices needed to ensure stability after a fault. The paper also discusses different wind generator types, LVRT technologies like active crowbars and energy storage, and the role of grid codes in technical requirements for connecting wind farms to the grid.
Integration of a Wind Turbine Based Doubly Fed Induction Generator Using STAT...IJERA Editor
This document summarizes research on integrating a wind turbine driven doubly fed induction generator (DFIG) into the power grid using a static synchronous compensator (STATCOM) and crowbar protection to improve transient stability. A DFIG consists of a wound rotor induction generator connected to the grid via a partial-scale power converter. During faults, a crowbar is used to protect the converter by short-circuiting the rotor, while a STATCOM senses voltage sags and provides quick compensation. Simulation results in MATLAB/Simulink show that using STATCOM and DFIG control schemes can improve power quality and grid stability by regulating voltage and reactive power during disturbances.
Application of crowbar protection on dfig based wind turbine connected to grid-2IAEME Publication
This document summarizes a research paper about providing voltage stability support for doubly fed induction generator (DFIG) wind turbines connected to weak power grids. It introduces DFIG technology and describes the modeling and control of the DFIG, including its rotor side converter control strategy. It then analyzes the short circuit current contribution of DFIG wind turbines during faults using crowbar and DC chopper protection. The objectives are to analyze fault current, investigate voltage profiles during subtransmission and medium voltage faults, and develop methods to improve voltage support from wind farms during grid disturbances.
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.
Optimized servo-speed control of wind turbine coupled to doubly fed inductio...IJECEIAES
Optimal control of any variable speed wind turbine needs maximum power point tracking (MPPT) coupled to doubly fed induction generator (DFIG) for better power generation. This paper offers a novel direct power servo-speed control of wind turbine. This latter is based on DFIG optimal hysteresis MPPT inverter current control combined with space voltage modulation (SVM) inverter voltage technique, thus providing a stable and continuous energy flow to power grid. In this design, the asynchronous machine stator is directly connected to the grid. Bidirectional power converter, acting as frequency converter, is rotor circuit located. Rectifier supplies rotor windings with voltages and reference frequency resulting from control procedure of the power exchange between the stator and grid. Inverter is directly controlled by means of SVM technique to maintain direct current (DC) bus voltage constant. Simulation results show that the proposed configuration improves power converters efficiency due that rotor circuit needs less power than stator circuit which is injected into the grid.
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.
IRJET - Optimal Scheduling of Solar Wind Bio-Mass Systems and Evaluating the ...IRJET Journal
This document presents a study on optimal scheduling of a solar-wind-biomass hybrid renewable energy system and evaluating its effective load carrying capability. It proposes a multi-source multi-product framework for coupled multi-carrier energy supplies using the hybrid renewable system. The study develops a MATLAB/Simulink model of the hybrid system and analyzes its performance. Key findings include that the hybrid system is able to reliably meet electricity demand by drawing power from multiple renewable sources and energy storage helps balance the intermittent nature of solar and wind power.
IRJET- Optimal Performance of Mechanical Load Factor for the Solar Photovolta...IRJET Journal
1. The paper presents a mathematical formulation to optimize the matching between a photovoltaic generator and an
electromechanical load system.
2. The results show that a system using a permanent magnet motor coupled to a centrifugal pump load has suitable matching
with PV array characteristics.
3. Varying the load factor in the torque-speed relationship can improve matching at different insulation levels and minimize
power drop, helping to optimize system design.
This document discusses performance analysis of a doubly fed induction generator (DFIG) wind turbine system. It begins with an introduction to DFIG wind turbines and their advantages over other wind turbine systems. It then discusses several emerging issues with DFIG systems, such as frequency regulation, harmonic control, fault ride through capability, and maximum power point tracking. It also reviews various control strategies that have been proposed and implemented to address these issues, such as using battery energy storage systems, resonant controllers, dynamic braking resistors, and maximum power point tracking algorithms. In general, the document provides an overview of challenges with DFIG wind turbines and reviews past research on control methods to improve their performance and integration with power grids.
Abstract: Wind energy is becoming the most effective renewable energy source mainly because of the growing concerns over carbon emissions and uncertainties in fossil fuel supplies and the government policy impetus. The increasing penetration of wind power in distribution systems may significantly affect VAR compensation and max. Power tracking of the systems, particularly during wind turbine cut-in and cut-off disturbances.
A DFIG based wind turbine has an ability to generate maximum power with varying and adjustable speed, ability to control active and reactive power by the integration of electronic power converters, low power rating of cost converter components, and so on. This study presents an overview and literature survey over past few decades on the different problems associated due to penetration of WT-DFIG in the power system and control aspects of DFIG.
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.
IRJET- Modelling of a PMSG Wind Turbine with Voltage ControlIRJET Journal
This document summarizes a study that models a wind energy conversion system using a permanent magnet synchronous generator (PMSG) with variable-speed control. It describes the system components, including the wind turbine, PMSG, maximum power point tracking (MPPT) algorithm, and inverters. Mathematical models are presented for the wind turbine, PMSG in a d-q reference frame, and MPPT control. Simulations were performed in MATLAB to verify the system design models for the generator-side inverter, grid-side inverter, MPPT controller, and pitch angle control of the wind turbine. The simulation results validate the autonomous control system design for the PMSG-based wind energy conversion system.
IRJET- Controlling the Stator Flux Linkages to Improve Dynamic Behavior of Gr...IRJET Journal
This document summarizes a research paper that proposes a new control strategy to improve the low voltage ride-through (LVRT) capability of doubly fed induction generator (DFIG) wind turbines during grid faults. The strategy aims to mitigate voltage and current shocks on the rotor side by controlling the stator flux linkages. It does this by applying active control to the DC component of the stator current to accelerate the decay of the stator's DC flux linkage, which induces oscillations on the rotor during faults. Simulation results show the proposed method regulates the DC bus voltage and dampens torque oscillations, improving dynamic behavior compared to conventional control strategies.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
IRJET- Simulation of a Doubly Fed Induction Generator based Wind Energy C...IRJET Journal
This document discusses the simulation of a doubly fed induction generator (DFIG) based wind energy conversion system using MATLAB. Key points:
- DFIGs are commonly used in wind energy systems due to advantages like improved efficiency, active and reactive power control, and reduced converter costs.
- In a DFIG system, the stator is directly connected to the grid while the rotor is connected via power electronic converters. Field oriented control is used to control the DFIG.
- The paper presents the mathematical modeling of a DFIG and simulations run in MATLAB, showing outputs like stator current, rotor current, and output power.
- A floating capacitor bridge topology is proposed to control the voltage across the capacitor
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.
Review of different Fault Ride through (FRT) Control Strategies for a DFIG Wi...IRJET Journal
This document provides a review of different fault ride-through control strategies for a doubly fed induction generator wind turbine. It begins with an abstract that introduces the topic and outlines various techniques used to enhance the fault ride-through capability of fixed-speed induction generator wind turbines. It then provides background on wind energy generation using doubly fed induction generators and discusses issues like their sensitivity to grid disturbances. The document reviews different fault ride-through control strategies like the use of dynamic voltage restorers, static compensators, unified power flow controllers and crowbars to prevent converter tripping and allow uninterrupted operation during grid faults.
Stabilization and Frequency Regulation in Microgrid by Controlling Pitch Angleijtsrd
PID controller based pitch angle controller for the frequency regulation and active power control in a wind turbine and diesel engine powered hybrid power system, is presented in this paper. For testing the prosed controller, variable wind speed pattern is used for realization of real time wind behavior. Furthermore, the variable load is also connected to the hybrid power system to test the efficacy of the prosed controller. The system is modelled and simulated in MATLAB environment and results obtained are compared with and without pitch angle controller. The frequency deviations in PID based pitch angle controller is less than the without controller. Aman Malik | Kavita Sharma "Stabilization and Frequency Regulation in Microgrid by Controlling Pitch Angle" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-6 , October 2020, URL: https://www.ijtsrd.com/papers/ijtsrd33303.pdf Paper Url: https://www.ijtsrd.com/engineering/electrical-engineering/33303/stabilization-and-frequency-regulation-in-microgrid-by-controlling-pitch-angle/aman-malik
Similar to Enhancement of reactive power capability of doubly fed induction generator 2-3 (20)
Submission Deadline: 30th September 2022
Acceptance Notification: Within Three Days’ time period
Online Publication: Within 24 Hrs. time Period
Expected Date of Dispatch of Printed Journal: 5th October 2022
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Living in 21st century in itself reminds all of us the necessity of police and its administration. As more and more we are entering into the modern society and culture, the more we require the services of the so called ‘Khaki Worthy’ men i.e., the police personnel. Whether we talk of Indian police or the other nation’s police, they all have the same recognition as they have in India. But as already mentioned, their services and requirements are different after the like 26th November, 2008 incidents, where they without saving their own lives has sacrificed themselves without any hitch and without caring about their respective family members and wards. In other words, they are like our heroes and mentors who can guide us from the darkness of fear, militancy, corruption and other dark sides of life and so on. Now the question arises, if Gandhi would have been alive today, what would have been his reaction/opinion to the police and its functioning? Would he have some thing different in his mind now what he had been in his mind before the partition or would he be going to start some Satyagraha in the form of some improvement in the functioning of the police administration? Really these questions or rather night mares can come to any one’s mind, when there is too much confusion is prevailing in our minds, when there is too much corruption in the society and when the polices working is also in the questioning because of one or the other case throughout the India. It is matter of great concern that we have to thing over our administration and our practical approach because the police personals are also like us, they are part and parcel of our society and among one of us, so why we all are pin pointing towards them.
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The goal of this study was to see how talent management affected employee retention in the selected IT organizations in Chennai. The fundamental issue was the difficulty to attract, hire, and retain talented personnel who perform well and the gap between supply and demand of talent acquisition and retaining them within the firms. The study's main goals were to determine the impact of talent management on employee retention in IT companies in Chennai, investigate talent management strategies that IT companies could use to improve talent acquisition, performance management, career planning and formulate retention strategies that the IT firms could use. The respondents were given a structured close-ended questionnaire with the 5 Point Likert Scale as part of the study's quantitative research design. The target population consisted of 289 IT professionals. The questionnaires were distributed and collected by the researcher directly. The Statistical Package for Social Sciences (SPSS) was used to collect and analyse the questionnaire responses. Hypotheses that were formulated for the various areas of the study were tested using a variety of statistical tests. The key findings of the study suggested that talent management had an impact on employee retention. The studies also found that there is a clear link between the implementation of talent management and retention measures. Management should provide enough training and development for employees, clarify job responsibilities, provide adequate remuneration packages, and recognise employees for exceptional performance.
ATTRITION IN THE IT INDUSTRY DURING COVID-19 PANDEMIC: LINKING EMOTIONAL INTE...IAEME Publication
Globally, Millions of dollars were spent by the organizations for employing skilled Information Technology (IT) professionals. It is costly to replace unskilled employees with IT professionals possessing technical skills and competencies that aid in interconnecting the business processes. The organization’s employment tactics were forced to alter by globalization along with technological innovations as they consistently diminish to remain lean, outsource to concentrate on core competencies along with restructuring/reallocate personnel to gather efficiency. As other jobs, organizations or professions have become reasonably more appropriate in a shifting employment landscape, the above alterations trigger both involuntary as well as voluntary turnover. The employee view on jobs is also afflicted by the COVID-19 pandemic along with the employee-driven labour market. So, having effective strategies is necessary to tackle the withdrawal rate of employees. By associating Emotional Intelligence (EI) along with Talent Management (TM) in the IT industry, the rise in attrition rate was analyzed in this study. Only 303 respondents were collected out of 350 participants to whom questionnaires were distributed. From the employees of IT organizations located in Bangalore (India), the data were congregated. A simple random sampling methodology was employed to congregate data as of the respondents. Generating the hypothesis along with testing is eventuated. The effect of EI and TM along with regression analysis between TM and EI was analyzed. The outcomes indicated that employee and Organizational Performance (OP) were elevated by effective EI along with TM.
INFLUENCE OF TALENT MANAGEMENT PRACTICES ON ORGANIZATIONAL PERFORMANCE A STUD...IAEME Publication
By implementing talent management strategy, organizations would have the option to retain their skilled professionals while additionally working on their overall performance. It is the course of appropriately utilizing the ideal individuals, setting them up for future top positions, exploring and dealing with their performance, and holding them back from leaving the organization. It is employee performance that determines the success of every organization. The firm quickly obtains an upper hand over its rivals in the event that its employees having particular skills that cannot be duplicated by the competitors. Thus, firms are centred on creating successful talent management practices and processes to deal with the unique human resources. Firms are additionally endeavouring to keep their top/key staff since on the off chance that they leave; the whole store of information leaves the firm's hands. The study's objective was to determine the impact of talent management on organizational performance among the selected IT organizations in Chennai. The study recommends that talent management limitedly affects performance. On the off chance that this talent is appropriately management and implemented properly, organizations might benefit as much as possible from their maintained assets to support development and productivity, both monetarily and non-monetarily.
A STUDY OF VARIOUS TYPES OF LOANS OF SELECTED PUBLIC AND PRIVATE SECTOR BANKS...IAEME Publication
Banking regulations act of India, 1949 defines banking as “acceptance of deposits for the purpose of lending or investment from the public, repayment on demand or otherwise and withdrawable through cheques, drafts order or otherwise”, the major participants of the Indian financial system are commercial banks, the financial institution encompassing term lending institutions. Investments institutions, specialized financial institution and the state level development banks, non banking financial companies (NBFC) and other market intermediaries such has the stock brokers and money lenders are among the oldest of the certain variants of NBFC and the oldest market participants. The asset quality of banks is one of the most important indicators of their financial health. The Indian banking sector has been facing severe problems of increasing Non- Performing Assets (NPAs). The NPAs growth directly and indirectly affects the quality of assets and profitability of banks. It also shows the efficiency of banks credit risk management and the recovery effectiveness. NPA do not generate any income, whereas, the bank is required to make provisions for such as assets that why is a double edge weapon. This paper outlines the concept of quality of bank loans of different types like Housing, Agriculture and MSME loans in state Haryana of selected public and private sector banks. This study is highlighting problems associated with the role of commercial bank in financing Small and Medium Scale Enterprises (SME). The overall objective of the research was to assess the effect of the financing provisions existing for the setting up and operations of MSMEs in the country and to generate recommendations for more robust financing mechanisms for successful operation of the MSMEs, in turn understanding the impact of MSME loans on financial institutions due to NPA. There are many research conducted on the topic of Non- Performing Assets (NPA) Management, concerning particular bank, comparative study of public and private banks etc. In this paper the researcher is considering the aggregate data of selected public sector and private sector banks and attempts to compare the NPA of Housing, Agriculture and MSME loans in state Haryana of public and private sector banks. The tools used in the study are average and Anova test and variance. The findings reveal that NPA is common problem for both public and private sector banks and is associated with all types of loans either that is housing loans, agriculture loans and loans to SMES. NPAs of both public and private sector banks show the increasing trend. In 2010-11 GNPA of public and private sector were at same level it was 2% but after 2010-11 it increased in many fold and at present there is GNPA in some more than 15%. It shows the dark area of Indian banking sector.
EXPERIMENTAL STUDY OF MECHANICAL AND TRIBOLOGICAL RELATION OF NYLON/BaSO4 POL...IAEME Publication
An experiment conducted in this study found that BaSO4 changed Nylon 6's mechanical properties. By changing the weight ratios, BaSO4 was used to make Nylon 6. This Researcher looked into how hard Nylon-6/BaSO4 composites are and how well they wear. Experiments were done based on Taguchi design L9. Nylon-6/BaSO4 composites can be tested for their hardness number using a Rockwell hardness testing apparatus. On Nylon/BaSO4, the wear behavior was measured by a wear monitor, pinon-disc friction by varying reinforcement, sliding speed, and sliding distance, and the microstructure of the crack surfaces was observed by SEM. This study provides significant contributions to ultimate strength by increasing BaSO4 content up to 16% in the composites, and sliding speed contributes 72.45% to the wear rate
ROLE OF SOCIAL ENTREPRENEURSHIP IN RURAL DEVELOPMENT OF INDIA - PROBLEMS AND ...IAEME Publication
The majority of the population in India lives in villages. The village is the back bone of the country. Village or rural industries play an important role in the national economy, particularly in the rural development. Developing the rural economy is one of the key indicators towards a country’s success. Whether it be the need to look after the welfare of the farmers or invest in rural infrastructure, Governments have to ensure that rural development isn’t compromised. The economic development of our country largely depends on the progress of rural areas and the standard of living of rural masses. Village or rural industries play an important role in the national economy, particularly in the rural development. Rural entrepreneurship is based on stimulating local entrepreneurial talent and the subsequent growth of indigenous enterprises. It recognizes opportunity in the rural areas and accelerates a unique blend of resources either inside or outside of agriculture. Rural entrepreneurship brings an economic value to the rural sector by creating new methods of production, new markets, new products and generate employment opportunities thereby ensuring continuous rural development. Social Entrepreneurship has the direct and primary objective of serving the society along with the earning profits. So, social entrepreneurship is different from the economic entrepreneurship as its basic objective is not to earn profits but for providing innovative solutions to meet the society needs which are not taken care by majority of the entrepreneurs as they are in the business for profit making as a sole objective. So, the Social Entrepreneurs have the huge growth potential particularly in the developing countries like India where we have huge societal disparities in terms of the financial positions of the population. Still 22 percent of the Indian population is below the poverty line and also there is disparity among the rural & urban population in terms of families living under BPL. 25.7 percent of the rural population & 13.7 percent of the urban population is under BPL which clearly shows the disparity of the poor people in the rural and urban areas. The need to develop social entrepreneurship in agriculture is dictated by a large number of social problems. Such problems include low living standards, unemployment, and social tension. The reasons that led to the emergence of the practice of social entrepreneurship are the above factors. The research problem lays upon disclosing the importance of role of social entrepreneurship in rural development of India. The paper the tendencies of social entrepreneurship in India, to present successful examples of such business for providing recommendations how to improve situation in rural areas in terms of social entrepreneurship development. Indian government has made some steps towards development of social enterprises, social entrepreneurship, and social in- novation, but a lot remains to be improved.
OPTIMAL RECONFIGURATION OF POWER DISTRIBUTION RADIAL NETWORK USING HYBRID MET...IAEME Publication
Distribution system is a critical link between the electric power distributor and the consumers. Most of the distribution networks commonly used by the electric utility is the radial distribution network. However in this type of network, it has technical issues such as enormous power losses which affect the quality of the supply. Nowadays, the introduction of Distributed Generation (DG) units in the system help improve and support the voltage profile of the network as well as the performance of the system components through power loss mitigation. In this study network reconfiguration was done using two meta-heuristic algorithms Particle Swarm Optimization and Gravitational Search Algorithm (PSO-GSA) to enhance power quality and voltage profile in the system when simultaneously applied with the DG units. Backward/Forward Sweep Method was used in the load flow analysis and simulated using the MATLAB program. Five cases were considered in the Reconfiguration based on the contribution of DG units. The proposed method was tested using IEEE 33 bus system. Based on the results, there was a voltage profile improvement in the system from 0.9038 p.u. to 0.9594 p.u.. The integration of DG in the network also reduced power losses from 210.98 kW to 69.3963 kW. Simulated results are drawn to show the performance of each case.
APPLICATION OF FRUGAL APPROACH FOR PRODUCTIVITY IMPROVEMENT - A CASE STUDY OF...IAEME Publication
Manufacturing industries have witnessed an outburst in productivity. For productivity improvement manufacturing industries are taking various initiatives by using lean tools and techniques. However, in different manufacturing industries, frugal approach is applied in product design and services as a tool for improvement. Frugal approach contributed to prove less is more and seems indirectly contributing to improve productivity. Hence, there is need to understand status of frugal approach application in manufacturing industries. All manufacturing industries are trying hard and putting continuous efforts for competitive existence. For productivity improvements, manufacturing industries are coming up with different effective and efficient solutions in manufacturing processes and operations. To overcome current challenges, manufacturing industries have started using frugal approach in product design and services. For this study, methodology adopted with both primary and secondary sources of data. For primary source interview and observation technique is used and for secondary source review has done based on available literatures in website, printed magazines, manual etc. An attempt has made for understanding application of frugal approach with the study of manufacturing industry project. Manufacturing industry selected for this project study is Mahindra and Mahindra Ltd. This paper will help researcher to find the connections between the two concepts productivity improvement and frugal approach. This paper will help to understand significance of frugal approach for productivity improvement in manufacturing industry. This will also help to understand current scenario of frugal approach in manufacturing industry. In manufacturing industries various process are involved to deliver the final product. In the process of converting input in to output through manufacturing process productivity plays very critical role. Hence this study will help to evolve status of frugal approach in productivity improvement programme. The notion of frugal can be viewed as an approach towards productivity improvement in manufacturing industries.
A MULTIPLE – CHANNEL QUEUING MODELS ON FUZZY ENVIRONMENTIAEME Publication
In this paper, we investigated a queuing model of fuzzy environment-based a multiple channel queuing model (M/M/C) ( /FCFS) and study its performance under realistic conditions. It applies a nonagonal fuzzy number to analyse the relevant performance of a multiple channel queuing model (M/M/C) ( /FCFS). Based on the sub interval average ranking method for nonagonal fuzzy number, we convert fuzzy number to crisp one. Numerical results reveal that the efficiency of this method. Intuitively, the fuzzy environment adapts well to a multiple channel queuing models (M/M/C) ( /FCFS) are very well.
Main news related to the CCS TSI 2023 (2023/1695)Jakub Marek
An English 🇬🇧 translation of a presentation to the speech I gave about the main changes brought by CCS TSI 2023 at the biggest Czech conference on Communications and signalling systems on Railways, which was held in Clarion Hotel Olomouc from 7th to 9th November 2023 (konferenceszt.cz). Attended by around 500 participants and 200 on-line followers.
The original Czech 🇨🇿 version of the presentation can be found here: https://www.slideshare.net/slideshow/hlavni-novinky-souvisejici-s-ccs-tsi-2023-2023-1695/269688092 .
The videorecording (in Czech) from the presentation is available here: https://youtu.be/WzjJWm4IyPk?si=SImb06tuXGb30BEH .
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
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By highlighting the potential advantages and challenges of integrating AI with XML development tools and languages, the presentation seeks to inspire thoughtful conversation around the future of XML development. We’ll not only delve into the technical aspects of AI-powered XML development but also discuss practical implications and possible future directions.
Introduction of Cybersecurity with OSS at Code Europe 2024Hiroshi SHIBATA
I develop the Ruby programming language, RubyGems, and Bundler, which are package managers for Ruby. Today, I will introduce how to enhance the security of your application using open-source software (OSS) examples from Ruby and RubyGems.
The first topic is CVE (Common Vulnerabilities and Exposures). I have published CVEs many times. But what exactly is a CVE? I'll provide a basic understanding of CVEs and explain how to detect and handle vulnerabilities in OSS.
Next, let's discuss package managers. Package managers play a critical role in the OSS ecosystem. I'll explain how to manage library dependencies in your application.
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Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
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Ivanti’s Patch Tuesday breakdown goes beyond patching your applications and brings you the intelligence and guidance needed to prioritize where to focus your attention first. Catch early analysis on our Ivanti blog, then join industry expert Chris Goettl for the Patch Tuesday Webinar Event. There we’ll do a deep dive into each of the bulletins and give guidance on the risks associated with the newly-identified vulnerabilities.
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
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- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
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Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
2. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
The precise modelling of DFIG units is important for both static and dynamic analysis of
power system performance. Computation of reactive power is essential to accurately assess the
stability of a system and to prevent voltage violations. The effect of wind speed variation and wind
farm output variability becomes a critical factor, when studying system performance with high
penetration levels [04].
Paper [03] discussed about the generation of capability curve and limitations of machine.
The amount of reactive power reserves at generating stations is a measure of the degree of voltage
stability [05]. Participation factor of each generator in the management scheme are predetermined
based on the voltage-var (V-Q) curve methodology. In the grid impact studies of wind power
integration, voltage stability is the mostly concerned problem that will affect the operation and
security of wind farms and power grid [06].
This paper extends an application of the capability curve to demonstrate economic and
reliability improvements in both static and dynamic power system operation. This work validates that
DFIG wind farm may operate at much lower power factor without incurring additional converter
cost. When we implement the full reactive capability of the DFIG farms, the excess available
reactive power impacts system cost and may justify investment in DFIG generation. This surplus
reactive power improves the voltage stability when faults are occurring in the system. Here, in this
paper we are comparing the operation of DFIG with capability curve and without capability curve
(Restricted Power Factor). Some relevant references are [8-17]. This article organized in seven
sections. In section 1, we introduce the current scenario of the DFIG. The reactive power
characteristics of DFIG been discussed in section 2. Section 3 deals with modelling part of DFIG.
Section 4 provides information about the capability curve of DFIG. Section 5 deals with Voltage
control application. Impact of capability curve on generation and the contingency analysis of the
system been discussed in section 6. Paper is concluded with help of results in section 7.
2. REACTIVE CHARACTERISTICS OF DFIG
Reactive power is essential for the stable operations of the Power system. It facilitates flow of
active power from generation sources to load centers and maintains bus voltages within prescribed
limits. Stable operation of power systems requires the availability of sufficient reactive generation.
Both static and dynamic reactive power source plays an important role in voltage stability.
Traditional wind generation units consisting of Fix Speed Induction Generators (FSIG) does
not allow for reactive support, but are reactive power consumers. To mitigate this reactive demand,
FSIG wind parks are typically equipped with external sources of reactive power. Static sources like
shunt capacitors are relatively inexpensive compared to dynamic resources such as SVCs [04].
The wind farm applying variable speed generator enclosed with power electronics controllers
like DFIG has reactive power capability. The presence of power electronics control in DFIG makes
them a fast acting dynamic reactive resource as compared to direct grid connected synchronous
generators.
In 2005, FERC orders 661 and 661A [04], a key requirement for plant operation is that the
power factor at the point of interconnection (POI) must remain between 0.95 leading and 0.95
lagging. The reason for this ruling is that reactive power capability for a wind plant is a significant
additional cost compared to conventional units which possess inherent reactive capability.
As penetration level continues to increase, the impact from the loss in performance translates
into higher operating costs. Utilization of the capability curve can lead to improved system
performance. This will reduce the amount of committed conventional reactive reserve.
108
3. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM
3. MODELLING OF DFIG
The proper modeling of the machine is necessary
-2014
DFIG wind farm. These machines can be represented using the simplified traditional induction
machine T-model shown in fig.1
Fig.1
In Fig.1, the stator and rotor voltage (
from the machine currents ( ), in (1)
resistance and leakage inductance with
The grid frequency is given by
and
. The RSC size is computed from the ratings of the rotor side Voltage source by combining the
above basic Kirchhoff voltage law (KVL) loop equations with the stator and
Eliminating the stator flux from these equations, expressions for the rotor current, voltage, and
converter MVA rating can be computed.
The converter that excites the DFIG machine is constructed with a back
electronic converter (PEC) that is fed from a dc voltage source. Given the highest ac voltage
connected to the bi-directional converter the dc link voltage can be obtained using the following
relation.
is modulation index.
17 – 19, July 2014, Mysore, Karnataka, India
109
for understanding the reactive capability of
DFIG wind turbine static model
and ) and flux ( s, r) equations can be derived
1)-(4), ( , ) and ( ) are the respective stator and rotor
defining the magnetizing induction;
, the machine slip is s, and
rotor flux equations.
back-to-back power
4. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
110
4. CAPABILITY CURVE OF DFIG
The power output of a generator is usually limited to value within the MVA rating by the
capability of its prime mover. When real power and terminal voltage is fixed, its armature and field
winding heating limits restricts the reactive power generation from the generator. The armature
heating limit is a circle with radius
, centered on the origin
and given by
5. (9)
Fig.2 Capability curve of Generator
The Field heating limit is also a circle, centered at
, radius
given by fig.2
6. (10)
is the voltage at the generator terminal bus, is the steady state armature current, is the
excitation voltage and ! is the synchronous reactance. P and Q are real and reactive power
generation from machine, respectively. The machine rating in MVA is the point of intersection of
two circles. The corresponding real power generation is denoted by #.when P$ % the limit on the
reactive power is imposed by the generator’s field heating limit (10) while when P % the armature
heating limit (9) imposes restricts the generators reactive power output. There is also an under-excitation
limit
'(),to restrict the unit operation in under-excited mode due to localized heating in
the end region of the armature.
In this paper we are comparing the DFIG with fix power factor (restricted power factor) and
DFIG which operate with the actual capability of the machine (based on capability curve).
Fig.3 P-Q curve for fix power factor (0.95pf)
7. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
Fig.4 Capability curve of DFIG
Thus, by utilizing the capability curve in network analysis, additional reactive power and
hence improved power system performance may be attained over a regulated power factor. It is
evident from the figure that at 100% plant output, the use of the capability curve does not give much
additional reactive support compared to the 0.95 leading operation. In contrast, additional reactive
consumption may be realized in lagging operation. Wind parks will very seldom operate
continuously at 100% output, and therefore, in the periods of operation below 100%, there is
significant additional reactive power available that could aid in improved system performance.
111
5. VOLTAGE CONTROL APPLICATION
There are two voltage control strategies that are implemented to demonstrate a comparison
between DFIG wind farm responses on system performance. The first strategy utilizes the *+,-
power factor regulation set forth by all the DFIGs which are used now days. Where reactive limit are
defined by the farms real output.
.
'/. 01234567895+,-:: (11)
The second strategy utilizes the reactive capability that is detailed in developed capability
curve in Fig.4
Control scheme for DFIG was developed for three different areas. Here we use a three
different scheme for generate the reactive power. First was wind emulator, in this scheme we set the
%; and %; as per requirements. In second we generate the own model for another development.
And third power factor regulators, in this pfa control scheme we are generate the reactive power as
per the power factor. The controller design was developed using power word simulator.
Fig.5 Reactive power control scheme
8. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
For this we were use the one machine and infinite bus system. After applying the control
strategy for the gaining of the extra reactive power we got the reactive power more with the use of
capability curve (cc) as compare with fix power factor. In this system we have to do the transient
stability analysis and for that we open the lines and then power flow is possible. In this analysis due
to fault in the system, system voltage goes down. But applying the capability curve analysis we have
to improve the reactive capability of the DFIG.
Fig.6 Transient stability analysis of DFIG for CC
Fig.7 Transient stability analysis of DFIG for fixed power factor (0.95pf)
6. IMPACT OF CAPABILITY CURVE ON GENERATION DISPATCH
The optimal power flow analysis described is used to assess impact of extended reactive
capability on system operating costs. The central goal of using technique is to compare the system
operation with restricted power factor (0.95pf) versus the capability curve. The described system in
Fig. 8 is studied with a load of 392MW and 87 MVAr. At base case the depicted three conventional
generators are online to satisfy this demand the production costs of all generators are assumed to be
the same.
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9. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
Fig.8 Power System with three generators
Additionally, to analyze the impact of increased DFIG wind Penetration, various penetration
levels at 15, 20, 25, and 30% are simulated. In this study, wind penetration is defined as the total
capacity of wind generation compared to the total load:
=4=232?74@=A=B C D)EE;FG()FHIH(J
CK0F (12)
At each penetration level, the total wind generation is simulated at 2, 15, 50, and 100% output
in order to consider various production conditions from cut-in to cut-out wind speeds. Since wind is
not a constant resource, this study aims to capture the effect of wind variability on system operating
costs.
At 2% park output, it is considered that the wind units have just cut-in and the real power
output is at a minimum. When employing the capability curve, the reactive limits of the machines are
the greatest at this output as compared the other output levels studied. As wind speeds increase, the
parks real output increases and consequently the reactive capability of the DFIG wind farm reduces.
In this analysis we have to compare the reactive power generation for different level of penetration
for restricted power factor and capability curve. Here we are use the wind farm capacity of 100MW.
Table.1 Generation of reactive power with different penetration level
113
Penetration
Level
LMNO
MW
PMNO through
Restricted Power Factor
(0.95pf) MVAr
PMNO through Capability
Curve MVAr
100% 100 32.87 37
80% 80 26.29 46.60
60% 60 19.72 57.40
40% 40 13.15 66.60
20% 20 6.57 74
2% 2 0.7 80
At each penetration level, the total system operating costs are computed for each output level.
The system operating costs are comprised of both the cost of generation to meet the demand and
generation cost to satisfy losses. When a unit is unable to meet its local reactive load, remote
10. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
generation compensates this requirement, but the system incurs additional line losses. Since the
demand is fixed the reactive dispatch of the DFIG wind farm results in reduced system losses due to
DFIG generation being able to meet the local reactive requirements. In this study, the cost of system
losses is minute as compared to the cost of generation. Thus, even a substantial reduction in losses
will not reflect a significant savings in total operating costs. Hence, the reduction in system losses is
used as a metric of comparison between the reactive control strategies. With this comparison we
have to reduce the cost of the generation and also reduce the losses of the system
Fig.9 Total hourly cost per MW for CC and RPF
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6.1 CONTIGENCY ANALYSIS
To study the effect of contingencies on system performance, a preliminary analysis of 20%
wind penetration scenario was performed by removing line !Qand ! Q from service (fig7). At the
20% penetration level, it was observed that at 2% and 15% plant output levels, with restricted power
factor, the OPF does not converge. In contrast, operation with the capability curve provides
additional reactive support at these low output levels which leads to OPF convergence. At 50% and
100% outputs, both control schemes have sufficient reactive capability for OPF convergence.
At 2% plant output level, the reactive power of the capability curve is at its maximum
whereas the reactive power of the restricted power factor operation is at its minimum. At 2% real
output, the additional reactive power gained by employing the capability curve over the regulated
power factor control is 80 MVAr. Thus, the investment in shunt capacitance for secure system
operation at a restricted power factor can be avoided by utilizing the capability curve.
DFIG wind farm implementing capability curve control may substantially reduce system
losses, especially at low plant output levels. This control strategy not only facilitates reductions in
operating costs but also avoids the necessity of additional reactive compensation required for secure
operation of the power system. The combined savings in total system costs may help justify
transmission investment for future wind installations
For the analysis point of view we have to analysis of the bus 4 that generator bus (DFIG
connected). In this we have to take a result of generated MW at that bus, generated MVAr and field
voltage at that bus.
11. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
Fig.10 Bus-1 restricted power factor through generation of MW, MVAr, and Field voltage for
penetration level 20%
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Fig.11 Bus-1Improved result with CC for generation of MW, MVAr, Field voltage for penetration of
20%
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7. CONCLUSION
The operation of DFIG wind farm implementing a capability curve paves the way for
regulatory changes. In general guidelines for interconnecting wind farm are used a restricted power
factor. When DFIG work with capability curve, fully utilizing the potential of DFIG wind farm may
be obtain at no extra cost to the wind farm owner, which not only facilities reduced system losses but
also improves the post fault voltage recovery following a disturbance. As the levels of wind
penetration continues to increase the reactive power the certain point it should be in limit. At the
100% penetration the limit of reactive power in both CC and RPF are almost same.
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