This document summarizes a research paper that proposes a method for enhancing power system stability by controlling high-voltage direct current (HVDC) power flow through existing alternating current (AC) transmission lines. The method involves converting existing double circuit AC lines into composite AC-DC lines by allowing the lines to simultaneously carry AC power and superimposed DC power. This is done without requiring any changes to the conductors, insulators, or towers of the original AC line. The addition of controlled DC power flow improves stability and allows the lines to be loaded closer to their thermal limits. Simulation and experimental studies were carried out to validate the coordinated and independent control of AC and DC power flows through the converted lines.
Microcontroller Based Novel Dc-to-Ac Grid Connected Inverter TopologyIDES Editor
The conventional line commutated ac-to-dc
converters/ inverters have square-shaped line current which
contains higher-order harmonics. Moreover, it requires a
costly and bulky dc inductor or choke. The line current with
the high harmonic contents generates EMI and therefore it
causes more heating of the core of distribution or power
transformers. Alternatively, PWM based inverters using
MOSFET/IGBT switches can be used for the above purpose.
However, apart from higher switching losses, the power
handling capability and reliability of these devices are quite
low in comparison to thyristors/ SCR. A thyristor based forced
commutated inverters are not suitable for PWM applications
due to the problems of commutation circuits. A pure sinusoidal
voltage output or waveform with low harmonic contents is
most desirable in the conversion from dc to ac. In the present
work, a novel two pulse line commutated inverter is been
proposed with control signal generated from PIC 16F 877A. It
improves the wave shape hence it reduces the total harmonic
distortion (THD) of the grid interactive-inverter. The
simulation of the circuit is done using SIMULINK. Moreover,
the performance of the proposed circuitry is far better than
the conventional line-commutated inverter. It reduces THD,
number of thyristors and dispenses with the bulky dc inductor/
choke. A prototype model is developed for discontinuous line
current mode. The results are also compared with the
simulation results in SIMULINK/ MATLAB.
1 ijaems oct-2015-3-design and development of novel matrix converter performanceINFOGAIN PUBLICATION
Matrix converter is a direct AC-AC converter topology that directly converts energy from an AC source to an AC load without the need of a bulky and limited lifetime energy storage element. Due to the significant advantages offered by matrix converter, such as adjustable power factor, capability of regeneration and high quality sinusoidal input/output waveforms. Matrix converter has been one of the AC–AC topologies that hasreceived extensive research attention for being an alternative to replace traditional AC-DC-AC converters in the variable voltage and variable frequency AC drive applications. In the present paper an indirect space vector modulated matrix converter is proposed. The basic idea of an indirect modulation scheme is to separately apply SVM to the rectification and inversion stages, before combining their switching states to produce the final gating signals. The paper encompasses development of a laboratory prototype of 230V, 250VA three phase to three phase DSP controlled matrix converter fed induction motor drive. The observations and real time testings have been carried out to evaluate and improve the stability of system under various typical abnormal input voltage conditions
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Microcontroller Based Novel Dc-to-Ac Grid Connected Inverter TopologyIDES Editor
The conventional line commutated ac-to-dc
converters/ inverters have square-shaped line current which
contains higher-order harmonics. Moreover, it requires a
costly and bulky dc inductor or choke. The line current with
the high harmonic contents generates EMI and therefore it
causes more heating of the core of distribution or power
transformers. Alternatively, PWM based inverters using
MOSFET/IGBT switches can be used for the above purpose.
However, apart from higher switching losses, the power
handling capability and reliability of these devices are quite
low in comparison to thyristors/ SCR. A thyristor based forced
commutated inverters are not suitable for PWM applications
due to the problems of commutation circuits. A pure sinusoidal
voltage output or waveform with low harmonic contents is
most desirable in the conversion from dc to ac. In the present
work, a novel two pulse line commutated inverter is been
proposed with control signal generated from PIC 16F 877A. It
improves the wave shape hence it reduces the total harmonic
distortion (THD) of the grid interactive-inverter. The
simulation of the circuit is done using SIMULINK. Moreover,
the performance of the proposed circuitry is far better than
the conventional line-commutated inverter. It reduces THD,
number of thyristors and dispenses with the bulky dc inductor/
choke. A prototype model is developed for discontinuous line
current mode. The results are also compared with the
simulation results in SIMULINK/ MATLAB.
1 ijaems oct-2015-3-design and development of novel matrix converter performanceINFOGAIN PUBLICATION
Matrix converter is a direct AC-AC converter topology that directly converts energy from an AC source to an AC load without the need of a bulky and limited lifetime energy storage element. Due to the significant advantages offered by matrix converter, such as adjustable power factor, capability of regeneration and high quality sinusoidal input/output waveforms. Matrix converter has been one of the AC–AC topologies that hasreceived extensive research attention for being an alternative to replace traditional AC-DC-AC converters in the variable voltage and variable frequency AC drive applications. In the present paper an indirect space vector modulated matrix converter is proposed. The basic idea of an indirect modulation scheme is to separately apply SVM to the rectification and inversion stages, before combining their switching states to produce the final gating signals. The paper encompasses development of a laboratory prototype of 230V, 250VA three phase to three phase DSP controlled matrix converter fed induction motor drive. The observations and real time testings have been carried out to evaluate and improve the stability of system under various typical abnormal input voltage conditions
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Improvement in Power Transmission Capacity by Simultaneous AC-DC Transmissiontheijes
Now days in power transmission systems mainly the high voltage three phase AC or HVDC transmission lines for greater efficiency at very long distances are used. In this paper, we have to show the scheme of AC and DC power transmission system which can be developed by converting double circuit ac line into composite AC and DC power transmission line and also comparing simulation results with the simple EHVAC transmission system and HVDC transmission system having six pulses PWM generator. The main object of thesis is to show that by superimposing DC in AC transmission, the capacity of the transmission line can be increased by nearly 70 % of that if only AC is transmitted. In our existing transmission system, long extra high voltage (EHV) AC lines cannot be loaded to their thermal limits in order to keep sufficient margin against transient instability. With the scheme proposed in this project, it is possible to load these lines close to their thermal limits. The conductors are allowed to carry usual ac along with dc superimposed on it, without altering the original line conductors, tower structures, and insulator strings has been presented.
Development of a Novel Three Phase Grid-Tied Multilevel Inverter TopologyIAES-IJPEDS
The conventional line-commutated ac-to-dc converters/ inverters have square-shaped line current. It contains higher-order harmonics which generates EMI and it causes more heating of the core of distribution or power transformers. PWM based inverters using MOSFET/IGBT have higher switching losses, and the power handling capability and reliability are quite low in comparison to thyristors/ SCR. A thyristor based forced commutated inverters are not suitable for PWM applications due to the problems of commutation circuits. A pure sinusoidal voltage output or waveform with low harmonic contents is most desirable for ac load using dc to ac conversion. This paper presents a new multilevel inverter topology in which three phase ac- to-dc converter circuits are used in inversion mode by controlling the switching angle. Due to natural commutation, no separate circuit is required for synchronization. In this paper simulation and analysis are done for grid-tied three-phase 6-pulse, Two three-phase, 3-pulse and 12-pulse converter. These converters are analysed for different battery voltage and different switching angle combinations in order to reduce the total harmonic distortion (THD). Three-phase harmonic filters are further added to the grid side to reduce the harmonic content in the line current. A comparative study of these converters is also presented in this paper.
Lightning Characteristics and Impulse Voltage.Milton Sarker
Lightning characteristics and standard impulse
waveform are related to each other. But the lack
of realization about the relation between them
would make the solution to produce better
protection against lightning surge becomes
harder. Natural lightning surge waveform has
been compared to standard impulse waveform as
evidence that there have similarity between
them. The standard impulse waveform could be
used to test the strength of electrical equipment
against the lightning. Therefore designing and
simulating the impulse generator are the purpose
of this project beside to get better understanding
about lightning characteristics. This project aims
to develop an impulse generator circuit. The
main objectives of this work are two folds: the
first is the characterization of impulse voltages
and the second is the designing of an impulse
voltage generator. Our working purpose is to
give a concept about Impulse voltages and
impulse generator to the students and
researchers.
EXPERIMENTAL DETERMINATION AND ANALYSIS OF TRANSMISSION LINE PERFORMANCEijiert bestjournal
It is necessary to calculate the voltage,current a nd power at any point on a transmission line provided the values at one point are known. We are aware that in three phase circuit problems it is sufficient to compute results in one phase and subsequently predict results in the other two phases by exploiting the three phase symm etry. Although the lines are not spaced equilaterally and not transposed,the resulting asy mmetry is slight and the phases are considered to be balanced. As such the transmission line calcu lations are also carried out on per phase basis. For that purpose in the transmission line demo pane l we will be designed to �To study the performance of the line.1)e.g. Relation between sen ding end quantity and receiving end quantity,Ferranti effect,efficiency of power line etc.2) To demonstrate fault clearing process using distance relay(Future Scope)
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.
A Narrative Approach to Five Phase Transmission SystemIJMTST Journal
The power demand is increasing day to day and is becoming prime requirement. High Phase Order (HPO)
transmission system is being considered a viable alternative to meet the demand by increasing the power
transmission capability. Mainly the research of HPO systems is going on six and twelve phase transmission
systems since they are multiples of three. But there is no difference in magnitude between the line voltage
and phase voltage. This paper takes the instigation regarding Five Phase transmission system and results
are compared with 132 kV three phase system. This paper investigates the weight of the conductor, sag of
the conductor and spacing between the conductors, Inductance and capacitance calculations required in 132
kV Five Phase transmission system. Also, shows the line model of Five Phase transmission system. So,
industrial loads can be driven with Five Phase supply as a ripple free torque and efficiency will be increased
effectively.
The DC-fault Blocking Capability by a New Hybrid Multilevel Converter in HVDC...Editor IJCATR
This paper explains the working principles, supported by simulation results, of a new converter topology in-tended for HVDC
application, called the Alternate Arm Con-verter (AAC). Modular Multilevel Converters deliver small footprints and efficiencies above
99% in their half-bridge format, but only deliver DC-fault blocking with full-bridge sub-modules, and with an unacceptable penalty in
efficiency. The Alternate Arm Converter (AAC) is a hybrid circuit topology using a mixture of full-bridge sub-modules and director
switches which is capable of current control through DC faults while maintaining good efficiency in normal operation. It is hybrid
between the modular multi-level converter, because of the presence of H-bridge cells, and the 2-level converter, in the form of director
switches in each arm. This converter is able to generate a multi-level AC voltage and, since its stacks of cells consist of H-bridge cells
instead of half-bridge cells, they are able to generate higher AC voltage than the DC terminal voltage. This allows the AAC to operate
at an optimal point, called the “sweet spot”, where the AC and DC energy flows equal. The director switches in the AAC are responsible
for alternating the conduction period of each arm, leading to a significant reduction in the number of cells in the stacks. Furthermore,
the AAC can keep control of the current in the phase reactor even in case of a DC-side fault and support the AC grid, through a
STATCOM mode. Simulation results and loss calculations are presented in this paper in order to support the claimed features of the
AAC
Reactive Power Compensation in 132kv & 33kv Grid of Narsinghpur Areaijceronline
Power Sector is considered to be very important and priority sector as it leads to overall development of country. The cost of installation of new generating units is rising; hence generated electrical energy has to be utilized carefully and efficiently, which changes through each AC cycle. It is proposed to study the effect of group shunt compensation provided for the mix of rural and urban loads, catered from grid sub-stations in the district of Narsinghpur, to assess its adequacy and saving in transmission losses. An optimum combination of compensators which yields maximum benefits in the system shall be worked out. Load Flow Study for the effect of group shunt compensation provided on 132KV bus of 220KV sub-station Narsinghpur and on 33KV buses of 132KV sub stations Srinagar, Narsinghpur, Gadarwara and Burman sub-stations for the mix of rural and urban loads, catered from partial grid network in Narsinghpur district. If reactive power is supplied near the load, the line current can be reduced or minimized, reducing power losses and improving voltage regulation at the load terminals. The leading current drawn by the shunt capacitors compensates the lagging current drawn by the load. The selection of shunt capacitors depends on many factors, the most important of which is the amount of lagging reactive power taken by the load. Objective was to study the effect of group shunt compensation provided for the mix of rural and urban loads, catered from grid sub-stations in the district of Narsinghpur and to assess the adequacy and saving in transmission losses & to work out an optimum combination of compensators which yields maximum benefits in the system. Depending on the stages of 'ON' and 'OFF', operations to be carried out in various permutations and combinations of shunt compensators i.e. switchable capacitor banks provided on 132 KV bus of 220KV substation Narsinghpur and on 33KV buses of 132 KV substations
This paper deals with the design of filters and THD analysis of a low - frequency ac (20Hz) transmission system. The LFAC system is interfaced with the 50Hz main power grid with a cycloconverter. The wind power is collected in dc form,and is connected to the L FAC transmission line with a twelve pulse inverter. The waveforms at the sending end and receiving end of the transmission line are plotted.THD analysis of LFAC system is carried out. The circuit model of LFAC system is simulated in MATLAB/SIMULINK.
I have created this report for my final semester seminar at Poornima college of engineering Jaipur, electrical department. This report covers various chapters and other contents. feel free to download.
Note: some minor editsin format and a quick spelling check might be needed.
**content source is wikipedia and internet**
any thing you would like to suggest please let me know in the comments.
A DC-DC Converter with Ripple Current Cancellation Based On Duty Cycle SelectionIJMER
In this paper a boost dc-dc converter is proposed based on the concept of ripple current cancellation. This proposed system has the novel capability of cancelling the input current ripple at an arbitrarily preselected duty cycle. This is accomplished without increasing the count of the number of components in contrast to other solutions available in the conventional system. In addition to this, the converter also features a high voltage gain without utilizing extreme values of duty cycle or boosting transformers. These features make the converter ideal to process electric power coming from low-voltage power-generating sources, such as renewables. This system also provides details on the principle of operation via topological considerations and a mathematical model. The key factor of reactive component sizing is also discussed in detail. The proposed boost dc-dc converter is evaluated by simulating in MATLAB/Simulink software.
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.
Guiding Principles in Selecting AC To DC Converters For Power Factor Correcti...IJERA Editor
The ac to dc converters’ power factors correction in ac transmission system were investigated. The studies include: phase-controlled converter; pulse width modulated (PWM) converter and ac input current shaped converter. Using Fourier series, power factors of these converters were calculated and simulated using MATLAB. The resulting curves are displayed in the hard copies for practical guides in the choice of converters; and comparatively, current shaped type is the best.
A Modern Technique of Deduction in Leakage Current in Resonant Bi-directional...IJMTST Journal
This Paper Presents A whole New resonant twin active bridge(DAB) topology, that uses a tuned inductor-capacitor-inductor(LCL) network. As compared to ancient DAB topologies, the planned topologies significantly reduced the bridge current, lowering every physical phenomenon and alter losses and conjointly VA rating associated with the bridges. The performance of the DAB is investigated using a mathematical model at a lower place varied operational conditions. Experiment results of a model is reduced the outflow current of the circuit. are presented with discussion to demonstrate the improved performance of the LCL DAB topology. Result clearly that the planned DAB Topology provide higher efficiency over an oversized vary of every input voltage and as compared to ancient DAB topology
Improvement in Power Transmission Capacity by Simultaneous AC-DC Transmissiontheijes
Now days in power transmission systems mainly the high voltage three phase AC or HVDC transmission lines for greater efficiency at very long distances are used. In this paper, we have to show the scheme of AC and DC power transmission system which can be developed by converting double circuit ac line into composite AC and DC power transmission line and also comparing simulation results with the simple EHVAC transmission system and HVDC transmission system having six pulses PWM generator. The main object of thesis is to show that by superimposing DC in AC transmission, the capacity of the transmission line can be increased by nearly 70 % of that if only AC is transmitted. In our existing transmission system, long extra high voltage (EHV) AC lines cannot be loaded to their thermal limits in order to keep sufficient margin against transient instability. With the scheme proposed in this project, it is possible to load these lines close to their thermal limits. The conductors are allowed to carry usual ac along with dc superimposed on it, without altering the original line conductors, tower structures, and insulator strings has been presented.
Development of a Novel Three Phase Grid-Tied Multilevel Inverter TopologyIAES-IJPEDS
The conventional line-commutated ac-to-dc converters/ inverters have square-shaped line current. It contains higher-order harmonics which generates EMI and it causes more heating of the core of distribution or power transformers. PWM based inverters using MOSFET/IGBT have higher switching losses, and the power handling capability and reliability are quite low in comparison to thyristors/ SCR. A thyristor based forced commutated inverters are not suitable for PWM applications due to the problems of commutation circuits. A pure sinusoidal voltage output or waveform with low harmonic contents is most desirable for ac load using dc to ac conversion. This paper presents a new multilevel inverter topology in which three phase ac- to-dc converter circuits are used in inversion mode by controlling the switching angle. Due to natural commutation, no separate circuit is required for synchronization. In this paper simulation and analysis are done for grid-tied three-phase 6-pulse, Two three-phase, 3-pulse and 12-pulse converter. These converters are analysed for different battery voltage and different switching angle combinations in order to reduce the total harmonic distortion (THD). Three-phase harmonic filters are further added to the grid side to reduce the harmonic content in the line current. A comparative study of these converters is also presented in this paper.
Lightning Characteristics and Impulse Voltage.Milton Sarker
Lightning characteristics and standard impulse
waveform are related to each other. But the lack
of realization about the relation between them
would make the solution to produce better
protection against lightning surge becomes
harder. Natural lightning surge waveform has
been compared to standard impulse waveform as
evidence that there have similarity between
them. The standard impulse waveform could be
used to test the strength of electrical equipment
against the lightning. Therefore designing and
simulating the impulse generator are the purpose
of this project beside to get better understanding
about lightning characteristics. This project aims
to develop an impulse generator circuit. The
main objectives of this work are two folds: the
first is the characterization of impulse voltages
and the second is the designing of an impulse
voltage generator. Our working purpose is to
give a concept about Impulse voltages and
impulse generator to the students and
researchers.
EXPERIMENTAL DETERMINATION AND ANALYSIS OF TRANSMISSION LINE PERFORMANCEijiert bestjournal
It is necessary to calculate the voltage,current a nd power at any point on a transmission line provided the values at one point are known. We are aware that in three phase circuit problems it is sufficient to compute results in one phase and subsequently predict results in the other two phases by exploiting the three phase symm etry. Although the lines are not spaced equilaterally and not transposed,the resulting asy mmetry is slight and the phases are considered to be balanced. As such the transmission line calcu lations are also carried out on per phase basis. For that purpose in the transmission line demo pane l we will be designed to �To study the performance of the line.1)e.g. Relation between sen ding end quantity and receiving end quantity,Ferranti effect,efficiency of power line etc.2) To demonstrate fault clearing process using distance relay(Future Scope)
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.
A Narrative Approach to Five Phase Transmission SystemIJMTST Journal
The power demand is increasing day to day and is becoming prime requirement. High Phase Order (HPO)
transmission system is being considered a viable alternative to meet the demand by increasing the power
transmission capability. Mainly the research of HPO systems is going on six and twelve phase transmission
systems since they are multiples of three. But there is no difference in magnitude between the line voltage
and phase voltage. This paper takes the instigation regarding Five Phase transmission system and results
are compared with 132 kV three phase system. This paper investigates the weight of the conductor, sag of
the conductor and spacing between the conductors, Inductance and capacitance calculations required in 132
kV Five Phase transmission system. Also, shows the line model of Five Phase transmission system. So,
industrial loads can be driven with Five Phase supply as a ripple free torque and efficiency will be increased
effectively.
The DC-fault Blocking Capability by a New Hybrid Multilevel Converter in HVDC...Editor IJCATR
This paper explains the working principles, supported by simulation results, of a new converter topology in-tended for HVDC
application, called the Alternate Arm Con-verter (AAC). Modular Multilevel Converters deliver small footprints and efficiencies above
99% in their half-bridge format, but only deliver DC-fault blocking with full-bridge sub-modules, and with an unacceptable penalty in
efficiency. The Alternate Arm Converter (AAC) is a hybrid circuit topology using a mixture of full-bridge sub-modules and director
switches which is capable of current control through DC faults while maintaining good efficiency in normal operation. It is hybrid
between the modular multi-level converter, because of the presence of H-bridge cells, and the 2-level converter, in the form of director
switches in each arm. This converter is able to generate a multi-level AC voltage and, since its stacks of cells consist of H-bridge cells
instead of half-bridge cells, they are able to generate higher AC voltage than the DC terminal voltage. This allows the AAC to operate
at an optimal point, called the “sweet spot”, where the AC and DC energy flows equal. The director switches in the AAC are responsible
for alternating the conduction period of each arm, leading to a significant reduction in the number of cells in the stacks. Furthermore,
the AAC can keep control of the current in the phase reactor even in case of a DC-side fault and support the AC grid, through a
STATCOM mode. Simulation results and loss calculations are presented in this paper in order to support the claimed features of the
AAC
Reactive Power Compensation in 132kv & 33kv Grid of Narsinghpur Areaijceronline
Power Sector is considered to be very important and priority sector as it leads to overall development of country. The cost of installation of new generating units is rising; hence generated electrical energy has to be utilized carefully and efficiently, which changes through each AC cycle. It is proposed to study the effect of group shunt compensation provided for the mix of rural and urban loads, catered from grid sub-stations in the district of Narsinghpur, to assess its adequacy and saving in transmission losses. An optimum combination of compensators which yields maximum benefits in the system shall be worked out. Load Flow Study for the effect of group shunt compensation provided on 132KV bus of 220KV sub-station Narsinghpur and on 33KV buses of 132KV sub stations Srinagar, Narsinghpur, Gadarwara and Burman sub-stations for the mix of rural and urban loads, catered from partial grid network in Narsinghpur district. If reactive power is supplied near the load, the line current can be reduced or minimized, reducing power losses and improving voltage regulation at the load terminals. The leading current drawn by the shunt capacitors compensates the lagging current drawn by the load. The selection of shunt capacitors depends on many factors, the most important of which is the amount of lagging reactive power taken by the load. Objective was to study the effect of group shunt compensation provided for the mix of rural and urban loads, catered from grid sub-stations in the district of Narsinghpur and to assess the adequacy and saving in transmission losses & to work out an optimum combination of compensators which yields maximum benefits in the system. Depending on the stages of 'ON' and 'OFF', operations to be carried out in various permutations and combinations of shunt compensators i.e. switchable capacitor banks provided on 132 KV bus of 220KV substation Narsinghpur and on 33KV buses of 132 KV substations
This paper deals with the design of filters and THD analysis of a low - frequency ac (20Hz) transmission system. The LFAC system is interfaced with the 50Hz main power grid with a cycloconverter. The wind power is collected in dc form,and is connected to the L FAC transmission line with a twelve pulse inverter. The waveforms at the sending end and receiving end of the transmission line are plotted.THD analysis of LFAC system is carried out. The circuit model of LFAC system is simulated in MATLAB/SIMULINK.
I have created this report for my final semester seminar at Poornima college of engineering Jaipur, electrical department. This report covers various chapters and other contents. feel free to download.
Note: some minor editsin format and a quick spelling check might be needed.
**content source is wikipedia and internet**
any thing you would like to suggest please let me know in the comments.
A DC-DC Converter with Ripple Current Cancellation Based On Duty Cycle SelectionIJMER
In this paper a boost dc-dc converter is proposed based on the concept of ripple current cancellation. This proposed system has the novel capability of cancelling the input current ripple at an arbitrarily preselected duty cycle. This is accomplished without increasing the count of the number of components in contrast to other solutions available in the conventional system. In addition to this, the converter also features a high voltage gain without utilizing extreme values of duty cycle or boosting transformers. These features make the converter ideal to process electric power coming from low-voltage power-generating sources, such as renewables. This system also provides details on the principle of operation via topological considerations and a mathematical model. The key factor of reactive component sizing is also discussed in detail. The proposed boost dc-dc converter is evaluated by simulating in MATLAB/Simulink software.
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.
Guiding Principles in Selecting AC To DC Converters For Power Factor Correcti...IJERA Editor
The ac to dc converters’ power factors correction in ac transmission system were investigated. The studies include: phase-controlled converter; pulse width modulated (PWM) converter and ac input current shaped converter. Using Fourier series, power factors of these converters were calculated and simulated using MATLAB. The resulting curves are displayed in the hard copies for practical guides in the choice of converters; and comparatively, current shaped type is the best.
A Modern Technique of Deduction in Leakage Current in Resonant Bi-directional...IJMTST Journal
This Paper Presents A whole New resonant twin active bridge(DAB) topology, that uses a tuned inductor-capacitor-inductor(LCL) network. As compared to ancient DAB topologies, the planned topologies significantly reduced the bridge current, lowering every physical phenomenon and alter losses and conjointly VA rating associated with the bridges. The performance of the DAB is investigated using a mathematical model at a lower place varied operational conditions. Experiment results of a model is reduced the outflow current of the circuit. are presented with discussion to demonstrate the improved performance of the LCL DAB topology. Result clearly that the planned DAB Topology provide higher efficiency over an oversized vary of every input voltage and as compared to ancient DAB topology
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.
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.
Reusability is an only one best direction to increase developing productivity and maintainability of application. One must first search for good tested software component and reusable. Developed Application software by one programmer can be shown useful for others also component. This is proving that code specifics to application requirements can be also reused in develop projects related with same requirements. The main aim of this paper proposed a way for reusable module. An process that takes source code as a input that will helped to take the decision approximately which particular software, reusable artefacts should be reused or not.
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.
Enhanced Seamless Handoff Using Multiple Access Points in Wireless Local Area...IJERA Editor
The Mobility in wireless cellular communication systems is its backbone so as to enhance the quality of service and maintain the continuous service. Handoff is an important task in maintaining the continuity of call in cellular systems and its failure can result in ongoing call termination. In cellular mobile networks, the coverage region is divided into smaller cells in order to achieve high system capacity. Each cell has a Base-Station (BS), which provides the service to the Mobile Terminals (MTs), i.e. users equipped with phones, within its region. Before a mobile user can communicate with other user(s) in the network, a group of the frequency bands or channels should usually be assigned. The MTs is free to move across cells. When the mobile user crossing a cell boundary or by deterioration in quality of the signal in the current channel, handoff process is initiated. The scope of this project is to design 802.11 handoff schemes to solve the handoff problems in closely-spaced WLANs.The major problem in multiple WLANs are so many users trying to use same access point(AP), and interferences from nearby WLAN. The better hand off scheme based on signal strength and velocity of the nodes is proposed. The simulation results show that the proposed handoff scheme significantly reduces packet losses compared with existing handoff schemes.
Dynamics of Motivation strategies for KnowledgeworkerIJERA Editor
The article is a study and analysis paper attempting to evaluate a strategy to motivate knowledge worker as a
part of improving the performance of an organisation as well as Knowledge Management (KM) activities). To
establish a good knowledge management system in a firm, human resources are vital tool. The productivity of
the firm and to remain competitive in the field, human resources are fore most important. The challenge lies
with the conversion of tacit knowledge residing in the human resources has to be brought out in code able form
by means of training, documents, lecture etc.
As a human resource development activities, the knowledge worker has to be picked up based on the
performance as desired by the firm. Subsequently to retain the knowledge level and further growth of the firm,
proper training, sharing of the knowledge, motivating the knowledge workers by different techniques to
felicitate knowledge management activities are essential. Different motivational methods applicable for different
knowledge level workers are brought out. The dynamics of the motivational strategies for knowledge workers
depending upon the organisational culture and human behavioral aspects are brought out.
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.
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.
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.
The Development of Financial Information System and Business Intelligence Usi...IJERA Editor
One of the most emerging technologies is finance, becoming more amenable to data-driven modeling as large sets of financial data become available everywhere. So we are applying the data mining techniques in financial information system with Business Intelligence. A Business Intelligence System (BIS) can be described as an interactive, computer-based system designed to help decision-makers to solve unstructured problems. Using a combination of models, analytical techniques, and information retrieval, such systems help develop and evaluate appropriate alternatives.
Shortest Tree Routing With Security In Wireless Sensor NetworksIJERA Editor
We propose STR to resolve the main reasons of overall network performance degradation of ZTR, which are the detour path problem and the traffic concentration problem. Second, we prove that the 1-hop neighbor nodes used by STR improve the routing path efficiency and alleviate the traffic load concentrated on tree links in ZTR. Third, we analyze the performance of ZTR, STR, and AODV by differentiating the network conditions such as network density, ZigBee network constraints, traffic types, and the network traffic. For modification security purpose we are also encrypting the data packets during transmission. So that the intermediate nodes are not able to view the data during transmission. For Encryption process, we are using RC4 Algorithm. Short cut tree routing is used for minimizing the routing path from source to destination.
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.
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.
Investigation on Growth and Optical Properties of LVCC Single CrystalsIJERA Editor
L-valine cadmium chloride (LVCC) single crystals were grown by slow evaporation technique with different
concentrations (0.25, 0.5, 0.75 and 1.0 mole) of CdCl2. All the grown crystals were subjected to single crystal
X-ray diffraction analysis. Solid state parameters were calculated for the grown crystals. The optical properties
of the crystals were investigated by UV-Vis. absorption spectroscopy. The results revealed that, the wider
bandgap and large transparency in the visible region along with higher polarizability of the grown crystals are
highly useful in optoelectronic devices. Also according to our needs, one can tune the optical and electrical
properties of LVCC crystals by adjusting the concentration of CdCl2 in LVCC.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
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.
Power Quality Improvement Using Cascaded H-Bridge Multilevel Inverter Based D...IJERA Editor
Cascaded multilevel configuration of the inverter has the advantage of its simplicity and modularity over the
configurations of the diode-clamped and flying capacitor multilevel inverters. This paper presents a threephase,
five-level and seven level cascaded multilevel voltage source inverter based active filter for power line
conditioning to improve power quality in the distribution network. The DSTATCOM helps to improve the
power factor and eliminate the Total Harmonics Distortion (THD) drawn from a Non-Liner Diode Rectifier
Load (NLDRL). The compensation process is based on concept of p-q theory. A CHB Inverter is considered for
shunt compensation of a 11 kV distribution system. Finally a level shifted PWM (LSPWM) and phase shifted
PWM (PSPWM) techniques are adopted to investigate the performance of CHB Inverter. The results are
obtained through Matlab/Simulink software package.
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.
Design and implementation a novel single switch high gain DC-DC converter ba...IJECEIAES
A novel high-gain and high-efficiency direct current to direct current
(DC-DC) converter is introduced in this paper. The presented converter is suitable for low-voltage renewable energy resources such as photovoltaic (PV) and fuel cell (FC). The existence of series inductance with the input source ensures continuous and low-ramp input current, which is important for extracting maximum power from resources. Using coupled inductor technology and an intermediate capacitor in the suggested converter leads to a high gain voltage. In the presented topology for recovering energy from the leakage inductor, reducing voltage stress on the power switch, and so decreasing overall converter losses, a passive clamp circuit is used. The suitable operation range of duty cycle in the converter, besides the leakage inductor, decreases the problem of reverse recovery in diodes. The low value of the leakage inductor and the low volume and cost of the proposed converter are due to the low turn ratio of the coupled inductor. Details of the operation principles of the proposed converter have been discussed in this paper. The presented simulation and laboratory prototype results verify the theoretical analysis and performance of the suggested topology.
Coupled Inductor Based High Step-Up DC-DC Converter for Multi Input PV SystemIJERA Editor
With the shortage of the energy and ever increasing of the oil price, research on the renewable and green energy
sources, especially the solar arrays and the fuel cells, becomes more and more important. How to achieve high
step-up and high efficiency DC/DC converters is the major consideration in the renewable power applications
due to the low voltage of PV arrays and fuel cells. In this paper a coupled inductor dc-dc converter for photovoltaic
system is proposed. The circuit configuration of the proposed converter is very simple. Thus, the
proposed converter has higher step-up and step-down voltage gains than the conventional bidirectional dc–dc
boost/buck converter. Under same electric specifications for the proposed converter and the conventional
bidirectional boost/buck converter, the average value of the switch current in the proposed converter is less than
the conventional bidirectional boost/buck converter. The operating principles have been applied to multi input
photovoltaic system and outputs have been observed.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
The Solar System[c] is the gravitationally bound system of the Sun and the objects that orbit it. The largest of such objects are the eight planets, in order from the Sun: four terrestrial planets named Mercury, Venus, Earth and Mars, two gas giants named Jupiter and Saturn, and two ice giants named Uranus and Neptune. The terrestrial planets have a definite surface and are mostly made of rock and metal. The gas giants are mostly made of hydrogen and helium, while the ice giants are mostly made of 'volatile' substances such as water, ammonia, and methane. In some texts, these terrestrial and giant planets are called the inner Solar System and outer Solar System planets respectively.
A hybrid DC/DC/AC converter connected to the grid without a three-phase transformer is controlled. The decentralized control method is applied to the hybrid DC-DC converter such that the maximum power of PV flows to the grid side. This controller must charge and discharge the battery at the proper time. It must also regulate DC-link voltage. An additional advantage of the proposed control is that the three-phase inverter does not need a separate controller such as PWM and SPWM. A simple technique is used for creating the desired phase shift in the three-phase inverter, which makes the active and reactive power of the inverter controllable. A new configuration is also proposed to transmit and manage the generation power of PV. In this scheme, the battery and fuel cell are employed as an auxiliary source to manage the generation power of PV. Finally, a real-time simulation is performed to verify the effectiveness of the proposed controller and system by considering the real characteristics of PV and FC.
This paper introduces the modelling of a novel three phase AC-AC converter with indirect use of a capacitor as DC voltage link. The proposed converter has high efficiency because it uses Space Vector PWM (SVPWM) technique at both rectificier and inverter stages to operate the pulse width modulation in IGBT switches. The novel converter is equipped with a power factor control to shape the rectifier input current waveform to be sinusoidal and to be in phase with the input voltage. To keep the DC voltage stable, the converter utilizes PI controllers. Simulations are conducted for output voltage from 120 to 300 Volts with output frequency ranging from 30 Hz to 60 Hz. The simulation results show that the converter is able to maintain stable the DC voltage and current. Furthermore, the model demonstrates the benefits of proposed converter in terms of acquiring high input power factor and sinusoidal current waveform at the output side of the inverter.
Alternating current (AC) is the main driving force in the industries and residential areas, but for the long transmission line (more than 650 KM) AC transmission is more expensive than that of direct current (DC). Technically, AC transmission line control is more complicated because of the frequency. DC transmission does not have these limitations, which has led to build long HVDC transmission lines over the last 40 years. HVDC technology made possible to transfer bulk power over long distances.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
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1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
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UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
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This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
DevOps and Testing slides at DASA ConnectKari Kakkonen
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The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
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Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
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LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
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- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...
B044040916
1. T. Satish Babu et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 4( Version 4), April 2014, pp.09-16
www.ijera.com 9 | P a g e
Stability Enhancement of Power System by Controlling Hvdc
Power Flow through the Same Ac Transmission Line
P. Upendra Kumar*
, T. Satish Babu**
, P. Divakar**
, T. Ravi Teja Kumar**
, G. Rama Raju**
*Associate Professor, Dept Of Eee, Lendi Institute Of Engineering And Technology, Vizianagaram, A.P., India.
**Ug Students, Dept Of Eee, Lendi Institute Of Engineering And Technology, Vizianagaram, A.P., India.
ABSTRACT
Long extra high voltage (EHV) ac lines cannot be loaded to their thermal limits in order to keep sufficient
margin against transient instability. With the scheme proposed in this paper, it is possible to load these lines
very close to their thermal limits. The conductors are allowed to carry usual ac along with dc superimposed on
it. The added dc power flow does not cause any transient instability.
This paper presents the feasibility of converting a double circuit ac line into composite ac–dc power
transmission line to get the advantages of parallel ac–dc transmission to improve stability and damping out
oscillations. Simulation and experimental studies are carried out for the coordinated control as well as
independent control of ac and dc power transmissions. No alterations of conductors, insulator strings, and
towers of the original line are needed. Substantial gain in the loadability of the line is obtained. Master current
controller senses ac current and regulates the dc current orders for converters online such that conductor current
never exceeds its thermal limit.
The present paper is implemented by using MATLAB/SIMULINK.
Key word: Extra high voltage (EHV) transmission, flexible ac transmission system (FACTS), simultaneous
ac–dc power transmission.
I. INTRODUCTION
In recent years, environmental, right-of-
way, and cost concerns have delayed the construction
of a new transmission line, while demand of electric
power has shown steady but geographically uneven
growth. The power is often available at locations not
close to the growing load centers but at remote
locations. These locations are largely determined by
regulatory policies, environmental acceptability, and
the cost of available energy. The wheeling of this
available energy through existing long ac lines to
load centers has a certain upper limit due to stability
considerations. Thus, these lines are not loaded to
their thermal limit to keep sufficient margin against
transient instability. The present situation demands
the review of traditional power transmission theory
and practice, on the basis of new concepts that allow
full utilization of existing transmission facilities
without decreasing system availability and security.
The flexible ac transmission system (FACTS)
concepts, based on applying state-of-the-art power
electronic technology to existing ac transmission
system, improve stability to achieve power
transmission close to its thermal limit. Another way
to achieve the same goal is simultaneous ac–dc
power transmission in which the conductors are
allowed to carry superimposed dc current along with
ac current. Ac and dc power flow independently, and
the added dc power flow does not cause any transient
instability. The authors of this paper have earlier
shown that extra high voltage (EHV) ac line may be
loaded to a very high level by using it for
simultaneous ac–dc power transmission as reported
in references. The basic proof justifying the
simultaneous ac–dc power transmission is explained
in reference. In the above references, simultaneous
ac–dc power transmission was first proposed through
a single circuit ac transmission line. In these
proposals Mono-polar dc transmission with ground as
return path was used. There were certain limitations
due to use of ground as return path. Moreover, the
instantaneous value of each conductor voltage with
respect to ground becomes higher by the amount of
the dc voltage, and more discs are to be added in each
insulator string to withstand this increased voltage.
However, there was no change in the conductor
separation distance, as the line-to-line voltage
remains unchanged. In this paper, the feasibility
study of conversion of a double circuit ac line to
composite ac–dc line without altering the original
line conductors, tower structures, and insulator
strings has been presented. In this scheme, the dc
power flow is point to point bipolar transmission
system. Suggested the conversion of ac line to dc line
for substantial power upgrading of existing ac line.
However, this would require major changes in the
tower structure as well as replacement of ac insulator
strings with high creepage dc insulators. The novelty
of our proposed scheme is that the power transfer
enhancement is achieved without any alteration in the
RESEARCH ARTICLE OPEN ACCESS
2. T. Satish Babu et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 4( Version 4), April 2014, pp.09-16
www.ijera.com 10 | P a g e
existing EHV ac line. The main object is to gain the
advantage of parallel ac–dc transmission and to load
the line close to its thermal limit.
II. SIMULTANEOUS AC – DC POWER
TRANSMISSION
2.1 Basic concept
Fig 2.1: Basic Scheme for composite AC-DC
transmission
Fig 2.1 depicts the basic scheme for
simultaneous ac–dc power flow through a double
circuit ac transmission line. The DC power is
obtained through line commutated 12- pulse rectifier
bridge used in conventional HVDC and injected to
the neutral point of the zigzag connected secondary
of sending end transformer and is reconverted to AC
again by the conventional line commutated 12-pulse
bridge inverter at the receiving end. The inverter
bridge is again connected to the neutral of zig-zag
connected winding of the receiving end transformer.
The double circuit AC transmission line carriers both
three-phase AC and DC power. Each conductor of
each line carries one third of the total DC current
along with ac current. Resistance being equal in all
the three phases of secondary winding of zig-zag
transformer as well as the three conductors of the
line, the DC current is equally divided among all the
three phases. The three conductors of the second line
provide return path for the Dc current. Zig-zag
connected winding is used at both ends to avoid
saturation of transformer due to DC current. Two
fluxes produced by the DC current (Id/3) flowing
through each of a winding in each limb of the core of
a zig-zag transformer are equal in magnitude and
opposite in direction. So the net DC flux at any
instant of time becomes zero in each limb of the core.
Thus, the DC saturation of the core is avoided. A
high value of reactor X d is used to reduce harmonics
in DC current. In the absence of zero sequence and
third harmonics or its multiple harmonic voltages,
under normal operating conditions, the AC current
flow through each transmission line will be restricted
between the zig-zag connected windings and the
three conductors of the transmission line. Even the
presence of these components of voltages may only
be able to produce negligible current through the
ground due to high value of X d. Assuming the usual
constant current control of rectifier and constant
extinction angle control of inverter, the equivalent
circuit of the scheme under normal steady-state
operating condition is given in Fig. 2.2.
Fig. 2.2 Equivalent circuit
The dotted lines in the figure show the path of AC
return current only. The second transmission line
carries the return DC current Id , and each conductor
of the line carries Id/3 along with the AC current per
phase. Vdro and Vdio are the maximum values of
rectifier and inverter side DC voltages and are equal
to (3 ) times converter AC input line-to-line
voltage. R, L, and C are the line parameters per phase
of each line. Rcr, Rci are commutating resistances, and
α, are firing and extinction angles of rectifier and
inverter, respectively.
Neglecting the resistive drops in the line conductors
and transformer windings due to DC current,
expressions for AC voltage and current, and for
active and reactive powers in terms of A, B, C, and D
parameters of each line may be written as
Es=AER+BIR (2.1)
IS=CER+DIR (2.2)
PS+JQS=-ESE*R/B*+D*E2
R/B* (2.3)
PR+JQR=-E*SER/B*-A*E2
R/B* (2.4)
Neglecting AC resistive drop in the line and
transformer, the DC power Pdr and Pdi of each
rectifier and inverter may be expressed as
Pdr= Vdr Id (2.5)
Pdi= Vdi Id (2.6)
Reactive powers required by the converters are
Qdr= Pdr r (2.7)
Qdi= Pdi I (2.8)
r= ( α + α+ µr))/2 (2.9)
i= ( α + α+ µi))/2 (2.10)
μr and μi are commutation angles of inverter and
rectifier, respectively, and total active and reactive
powers at the two ends areTransmission loss for each
line is
PL= (PS+Pdr)-(PR+Pdi) (2.11)
3. T. Satish Babu et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 4( Version 4), April 2014, pp.09-16
www.ijera.com 11 | P a g e
Ia being the rms AC current per conductor at any
point of the line, the total rms current per conductor
becomes
I= [Ia
2
+(Id/3)2
]1/2
(2.12)
Power loss for each line PL≈ 3I2
R (2.13)
The net current I in any conductor is
offseted from zero. In case of a fault in the
transmission system, gate signals to all the SCRs are
blocked and that to the bypass SCRs are released to
protect rectifier and inverter bridges. The current in
any conductor is no more offseted. Circuit breakers
(CBs) are then tripped at both ends to isolate the
faulty line. CBs connected at the two ends of
transmission line interrupt current at natural current
zeroes, and no special DC CB is required. Now,
allowing the net current through the conductor equal
to its thermal limit (Ith).
I=[Ia
2
+(Id/3)2
]1/2
(2.14)
Let Vph be per-phase rms voltage of
original ac line. Let Vph also Va be the per-phase
voltage of ac component of composite AC-DC line
with dc Vd voltage superimposed on it. As insulators
remain unchanged, the peak voltage in both cases
should be equal
Vmax = Vph = Vd+ Va (2.15)
Electric field produced by any conductor
possesses a DC component superimpose on it a
sinusoidally varying AC component. However, the
instantaneous electric field polarity changes its sign
twice in a cycle if (Vd/Va < 2) is insured.
Therefore, higher creep age distance requirement for
insulator discs used for HVDC lines are not required.
Each conductor is to be insulated for Vmax, but the
line-to line voltage has no DC component and VLL
max = 6Va. Therefore, conductor-to-conductor
separation distance of each line is determined only by
rated AC voltage of the line. Allowing maximum
permissible voltage offset such that the composite
voltage wave just touches zero in each every cycle;
Vd= Vph/ and Va = Vph/ (2.16)
The total power transfer through the double circuit
line before conversion is as follows:
P’total ≈ 3 Vph
2
1/X (2.17)
Where X is the transfer reactance per phase of the
double circuit line, 1 and is the power angle between
the voltages at the two ends. To keep sufficient
stability margin, 1 is generally kept low for long
lines and seldom exceeds 30o. With the increasing
length of line, the load ability of the line is decreased.
An approximate value of 1 may be computed from
the load ability curve by knowing the values of surge
impedance loading (SIL) and transfer reactance X of
the line.
P’total = 2.M.SIL (2.18)
Where M is the multiplying factor and its
magnitude decreases with the length of line. The
value of M can be obtained from the load ability
curve.
The total power was transfer through the composite
line.
Ptotal = Pac + Pdc = 3Va
2
2/X+2VdId (2.19)
The power angle 2 between the AC
voltages at the two ends of the composite line may be
increased to a high value due to fast controllability of
DC component of power. For a constant value of
total power, Pac may be modulated by fast control of
the current controller of DC power converters.
Approximate value of AC current per phase per
circuit of the double circuit line may be computed as
Ia= V( /2)/X (2.20)
The rectifier DC current order is adjusted online as
Id=3 Ith
*2
-Ia
*2
(2.21)
Preliminary qualitative analysis suggests
that commonly used techniques in HVDC/AC system
may be adopted for the purpose of the design of
protective scheme, filter, and instrumentation
network to be used with the composite line for
simultaneous AC-DC power flow. In case of a fault
in the transmission system, gate signals to all the
SCRs are blocked and that to the bypass SCRs are
released to protect rectifier and inverter bridges. CBs
are then tripped at both ends to isolate the complete
system. A surge diverter connected between the zig-
zag neutral and the ground protects the converter
bridge against any over voltage.
2.2 Economic consideration
To get the advantages of parallel AC–DC
transmission in order to improve stability and
damping oscillations, the conversion of a double
circuit AC line for simultaneous AC–DC power flow
has been considered such that no alterations of
conductor, insulator string and tower structure of the
original line are required. The optimum values of AC
phase and DC voltages of the converted line are 1/2
and 1/√2 times the phase voltage before conversion,
respectively. The cost of transmission line includes
the investment and operational costs. The investment
includes costs of Right of Way (RoW), transmission
tower, conductors, insulators, labour and terminal
equipments. The operational costs include mainly the
cost of losses. Additional costs of compensation and
its terminal equipments also influences the AC line
cost. DC transmission does not require compensation
but the terminal equipment costs are increased due to
the presence of converters and filters. Replacement of
Y-connected transformer in simultaneous AC–DC
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power transmission with zig-zag transformer is not
likely to increase the cost, because it transfers only
25% of total power by transformer action. Also, the
AC voltage reduces to 50% of the original AC
voltage. However, the neutral point of this
transformer needs insulation to withstand DC
voltage. The load ability is observed to get doubled
or even more with the simultaneous AC–DC power
flow for a line with length of 500 km or longer.
When an existing AC line is converted to
simultaneous AC–DC line, instead of adding separate
parallel DC, the additional investment on new DC
line and on AC line compensations are saved.
III.MODELLING OF COMPOSITE AC-DC SYSTEM
Fig 3: Simulink Model of Simultaneous AC-DC Transmission
IV.PROPOSED APPLICATIONS
1. Long EHV ac lines can not be loaded to their
thermal limit to keep sufficient margin against
transient instability and to keep voltage
regulation within allowable limit, the
simultaneous power flow does not imposed any
extra burden on stability of the system, rather it
improves the stability. The resistive drop due to
dc current being very small in comparison to
impedance drop due to ac current, there is also
no appreciable change in voltage regulation due
to superimposed dc current.
2. Therefore one possible application of
simultaneous ac-dc transmission is to load the
line close to its thermal limit by transmitting
additional dc power. Figure3 shows the variation
of Pt/Pac for changing values of k and x at unity
power factor. However, it is to be noted that
additional conductor insulation is to be provided
due to insertion of dc.
3. Necessity of additional dc power transmission
will be experienced maximum during peak load
period which is characterized with lower than
rate voltage. If dc power is injected during the
peak loading period only with V d being in the
range of 5% to 10% of E ph, the same
transmission line without having any enhanced
insulation level may be allowed to be used For
10.2% more power may be transmitted.
4. By adding a few more discs in insulator strings
of each phase conductor with appropriate
modifications in cross-arms of towers insulation
level between phase to ground may be increased
to a high value, which permits proportional
increase in Emax, Therefore higher value of Vd
may be used to increase dc and total power flow
through the line. This modification in the exiting
ac lines is justified due to high cost of a separate
HVDC line.
5. With the very fast electronic control of firing
angle (α) and extinction angle ( ) of the
converters, the fast control of dc power may also
be used to improve dynamic stability and
damping out oscillations in the system similar to
that of the ac-dc parallel transmission lines.
6. Control of α and also controls the rectifier and
inverter VAR requirement and therefore, may be
used to control the voltage profile of the
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transmission line during low load condition and
works as inductive shunt compensation. It may
also be considered that the capacitive VAR of
the transmission line is supplying the whole or
part of the inductive VAR requirement of the
converter system. In pure HVDC system
capacitance of transmission line cannot be
utilized to compensate inductive VAR.
7. The independent and fast control of active and
reactive power associated with dc, superimposed
with the normal ac active and reactive power
may be considered to be working as another
component of FACTS.
8. Simultaneous ac-dc power transmission may find
its application in some special cases of LV and
MV distribution system. When 3-phase power in
addition to dc power is supplied to a location
very near to a furnace or to a work place having
very high ambient temperature, rectification of 3-
phase supply is not possible at that location using
semiconductor rectifier. In such place
simultaneous ac-dc transmission is
advantageous. In air craft 3-phase loads are
generally fed with higher frequency supply of
about 400Hz and separate line is used for dc
loads. Skin effect restricts the optimum use of
distribution wires at high frequency.
Simultaneous ac-dc power transmission reduces
both volume and weight of distributors.
9. Another possible application is the transmission
of dc power generated by PV solar cells directly
to remote dc loads through 3-phase ac line. In all
cases of separate dc supply filter networks are
not required.
V. SIMULATED RESULTS
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Inverter side voltage
Inverter side current
Active power source side
Reactive power source side
Active power
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Reactive power
VI.CONCLUSIONS
The feasibility to convert ac transmission
line to a composite ac–dc line has been demonstrated.
The line is loaded to its thermal limit with the
superimposed dc current. The dc power flow does not
impose any stability problem. The advantage of
parallel ac–dc transmission is obtained. Dc current
regulator may modulate ac power flow. There is no
need for any modification in the size of conductors,
insulator strings, and towers structure of the original
line. The optimum values of ac and dc voltage
components of the converted composite line are 1/2
and times the ac voltage before conversion,
respectively.
References
[1] H. Rahman, B.H. Khan, Power upgrading of
double circuit ac transmission line by
simultaneous ac–dc power transmission, in:
Proceedings The IEEE, PES, Power India,
2006, doi:10.1109/POWERI.2006.1632623.
[2] H. Rahman and B H Khan ―Stability
Improvement of Power Systemby
Simultaneous AC-DC Power Transmission‖
Electric Power System Research Journal,
Elsevier, Paper Editorial ID No. EPSRD-
06-00732, Press Article No. EPSR-2560—
Digital Object.
[3] L. K. Gyugyi, ―Unified power flow concept
for flexible A.C. transmission system,‖ Proc.
Inst. Elect. Eng., p. 323, Jul. 1992.
[4] L. K. Gyugyi et al., ―The unified power flow
controller; a new approach to power
transmission control,‖ IEEE Trans. Power
Del., vol. 10, no. 2, pp. 1085–1097, Apr.
1995.
[5] N. G. Hingorani, ―FACTS—flexible A.C.
transmission system,‖ in Proc. Inst. Elect.
Eng. 5th. Int. Conf. A.C. D.C. Power
Transmission, London, U.K., 1991.
[6] P. S. Kundur, Power System Stability and
Control. New York: Mc-Graw-Hill, 1994.
8. T. Satish Babu et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 4( Version 4), April 2014, pp.09-16
www.ijera.com 16 | P a g e
[7] K. P. Basu and B. H. Khan, ―Simultaneous
ac-dc power transmission,‖ Inst. Eng. (India)
J.-EL, vol. 82, pp. 32–35, Jun. 2001.
[8] H. Rahman and B. H. Khan, ―Enhanced
power transfer by simultaneous transmission
of AC-DC: a new FACTS concept,‖ in Proc.
Inst. Elect. Eng. Conf. Power Electronics,
Machines, Drives, Edinburgh, U.K., Mar.
31–Apr. 2 2004, vol. 1, pp. 186–191.
[9] A. Clerici, L. Paris, and P. Danfors, ―HVDC
conversion of HVAC line to provide
substantial power upgrading,‖ IEEE Trans.
Power Del., vol. 6, no. 1, pp. 324–333, Jan.
1991.
[10] Padiyar, HVDC Power Transmission
System. New Delhi, India: Wiley Eastern,
1993.
[11] E. W. Kimbark, Direct Current
Transmission. New York: Wiley, 1971, vol.
I.
[12] J. Arillaga and N. R.Watson, Computer
Modelling of Electrical Power Systems.
Chichester, U.K.: Wiley, 2003.
[13] M. A. Chaudhry and D. P. Caroll,
―Coordinated active and reactive power
modulation of multiterminal HVDC
system,‖ IEEE Trans. Power App. Syst., vol.
PAS-103, pp. 1480–1485, 1989.
[14] K. R. Padiyar, M. A. Pai, and C.
Radhakrishna, ―Analysis of D.C. link
control for system stabilization,‖ in Proc.
Inst. Elect. Eng. Conf. Publ. No. 205,
London, U.K., 1981, pp. 145–148.
[15] M. Stella, P. K. Dash, and K. P. Basu, ―A
neuro-sliding mode controller for
STATCOM,‖ Elect. Power Compon. Syst.,
vol. 32, pp. 131–147, Feb. 2004.