This document describes a proposed 6-pulse HVDC transmission system that could transmit power over long distances. It provides background on the history and development of HVDC technology, including the progression from early DC systems using rotating machinery to modern implementations using thyristor valves or voltage source converters. The proposed system uses a 6-pulse rectifier with IGBTs to transmit 500MW of power over 300km from a 315kV AC network to an inverter, with reactive power provided by filter capacitors. Control is achieved through a synchronized 6-pulse generator and PI current regulator.
High Voltage Direct Current Transmission System ReportNadeem Khilji
The development of HVDC (High Voltage Direct Current) transmission system dates back to the 1930s when mercury arc rectifiers were invented. Since the 1960s, HVDC transmission system is now a mature technology and has played a vital part in both long distance transmission and in the interconnection of systems. Transmitting power at high voltage and in DC form instead of AC is a new technology proven to be economic and simple in operation which is HVDC transmission. HVDC transmission systems, when installed, often form the backbone of an electric power system. They combine high reliability with a long useful life. An HVDC link avoids some of the disadvantages and limitations of AC transmission. HVDC transmission refers to that the AC power generated at a power plant is transformed into DC power before its transmission. At the inverter (receiving side), it is then transformed back into its original AC power and then supplied to each household. Such power transmission method makes it possible to transmit electric power in an economic way.
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.
Modeling and control of HVDC grids: a key challenge for the future power systemPower System Operation
HVDC technology is developing fast and HVDC
grids are increasingly seen as a possible and feasible solution
to manage the future power system with large amounts of
renewables in a secure and cost-effective manner. However,
systems with significant amounts of DC transmission behave
in a fundamentally different manner when compared to the
traditional AC power system. The integration of HVDC systems
introduces new fast dynamics on different time frames and adds
controllability to the combined system. As a result, the modeling
and control of the entire interconnected system needs to be reevaluated
in order to accurately compute the system behavior,
both from the AC and DC system.
This survey paper gives an overview of the current research
in the field of HVDC grids focusing on the interaction of the AC
and DC system. The converters and their behavior are discussed
in greater detail. A second component which is discussed is the
DC breaker. Both devices operate fundamentally different than
their AC counterparts. The fast interaction between AC and DC
systems requires changes in the manner in which the modeling
and computation of the system is done, both at the DC and
the AC side. Although these considerations are needed within all
relevant time frames, two relevant cases are specifically addressed
in this paper: the connection of offshore wind power through a
HVDC system and the optimal operation of the power system
with a strong presence of HVDC.
Control and Analysis of VSC Based High Voltage DC Transmissionijsrd.com
High Voltage Direct Current system based on Voltage Source Converters (VSC-HVDC) is becoming a more effective, solution for long distance power transmission especially for off-shore wind plants and supplying power to remote regions Confronting with an increasing demand of power, there is a need to explore the most efficient and reliable bulk power transmission system. Rapid development in the field of power electronics devices especially Insulated Gate Bipolar Transistors (IGBTs) has led to the High Voltage Direct Current (HVDC) transmission based on Voltage Source Converters (VSCs).Since VSCs do not require commutating voltage from the connected ac grid, they are effective in supplying power to isolated and remote loads. Due to its advantages, it is possible that VSC-HVDC will be one of the most important components of power systems in the future. The VSC based HVDC transmission system mainly consists of two converter stations connected by a DC cable. This paper presents the performance analysis of VCS based HVDC transmission system. In this paper a 75kM long VSC HVDC system is simulated for various faults on the ACSide of the receiving station using MATLAB/SIMULINK. The data has been analyzed and a method is proposed to classify the faults by using back propagation algorithm. The simulated results presented in this paper are in good agreement with the published work.
High Voltage Direct Current Transmission System ReportNadeem Khilji
The development of HVDC (High Voltage Direct Current) transmission system dates back to the 1930s when mercury arc rectifiers were invented. Since the 1960s, HVDC transmission system is now a mature technology and has played a vital part in both long distance transmission and in the interconnection of systems. Transmitting power at high voltage and in DC form instead of AC is a new technology proven to be economic and simple in operation which is HVDC transmission. HVDC transmission systems, when installed, often form the backbone of an electric power system. They combine high reliability with a long useful life. An HVDC link avoids some of the disadvantages and limitations of AC transmission. HVDC transmission refers to that the AC power generated at a power plant is transformed into DC power before its transmission. At the inverter (receiving side), it is then transformed back into its original AC power and then supplied to each household. Such power transmission method makes it possible to transmit electric power in an economic way.
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.
Modeling and control of HVDC grids: a key challenge for the future power systemPower System Operation
HVDC technology is developing fast and HVDC
grids are increasingly seen as a possible and feasible solution
to manage the future power system with large amounts of
renewables in a secure and cost-effective manner. However,
systems with significant amounts of DC transmission behave
in a fundamentally different manner when compared to the
traditional AC power system. The integration of HVDC systems
introduces new fast dynamics on different time frames and adds
controllability to the combined system. As a result, the modeling
and control of the entire interconnected system needs to be reevaluated
in order to accurately compute the system behavior,
both from the AC and DC system.
This survey paper gives an overview of the current research
in the field of HVDC grids focusing on the interaction of the AC
and DC system. The converters and their behavior are discussed
in greater detail. A second component which is discussed is the
DC breaker. Both devices operate fundamentally different than
their AC counterparts. The fast interaction between AC and DC
systems requires changes in the manner in which the modeling
and computation of the system is done, both at the DC and
the AC side. Although these considerations are needed within all
relevant time frames, two relevant cases are specifically addressed
in this paper: the connection of offshore wind power through a
HVDC system and the optimal operation of the power system
with a strong presence of HVDC.
Control and Analysis of VSC Based High Voltage DC Transmissionijsrd.com
High Voltage Direct Current system based on Voltage Source Converters (VSC-HVDC) is becoming a more effective, solution for long distance power transmission especially for off-shore wind plants and supplying power to remote regions Confronting with an increasing demand of power, there is a need to explore the most efficient and reliable bulk power transmission system. Rapid development in the field of power electronics devices especially Insulated Gate Bipolar Transistors (IGBTs) has led to the High Voltage Direct Current (HVDC) transmission based on Voltage Source Converters (VSCs).Since VSCs do not require commutating voltage from the connected ac grid, they are effective in supplying power to isolated and remote loads. Due to its advantages, it is possible that VSC-HVDC will be one of the most important components of power systems in the future. The VSC based HVDC transmission system mainly consists of two converter stations connected by a DC cable. This paper presents the performance analysis of VCS based HVDC transmission system. In this paper a 75kM long VSC HVDC system is simulated for various faults on the ACSide of the receiving station using MATLAB/SIMULINK. The data has been analyzed and a method is proposed to classify the faults by using back propagation algorithm. The simulated results presented in this paper are in good agreement with the published work.
HVDC System a Need for Future Power Transmissionijtsrd
The continuously increasing demand for electric power and the economic access to remote renewable energy sources such as off-shore wind power or solar thermal generation in deserts have revived the interest in high-voltage direct current HVDC multiterminal systems networks . A lot of work was done in this area, especially in the 1980s, but only two three-terminal systems were realized. Since then, HVDC technology has advanced considerably and, despite numerous technical challenges, the realization of large-scale HVDC networks is now seriously discussed and considered. For the acceptance and reliability of these networks, the availability of HVDC circuit breakers CBs will be critical, making them one of the key enabling technologies. Numerous ideas for HVDC breaker schemes have been published and patented, but no acceptable solution has been found to interrupt HVDC short-circuit currents. This paper aims to summarize the literature, especially that of the last two decades, on technology areas that are relevant to HVDC breakers. By comparing the mainly 20 years old, state-of-the art HVDC CBs to the new HVDC technology, existing discrepancies become evident. Areas where additional research and development are needed are identified and proposed. for the couple of well-known applications are discussed. Mohd Liaqat "HVDC System: a Need for Future Power Transmission" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-2 , February 2019, URL: https://www.ijtsrd.com/papers/ijtsrd20318.pdf
Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/20318/hvdc-system-a-need-for-future-power-transmission/mohd-liaqat
This paper analyzes the behaviour of a Voltage Source Converter Based HVDC system under DC pole to ground fault & AC faults for 2-level VSC-HVDC & 12-pulse VSC-HVDC system in order to better understand the system under such faults. DC line faults on HVDC systems utilising Voltage Source Converters (VSC) are a major issue for HVDC systems in which complete isolation of the faulted system is not a viable option. The occurrence of pole-to-ground faults on DC link is the most common fault in HVDC system. It was observed that with the occurrence of DC pole to ground faults leads to substantial over current in the AC grid system which may lead to damage of the converter valve. Simulation of 2-level VSC-HVDC under AC fault is carried out. The fault current magnitude is attempted with the mathematical analysis & which was found to be the same as the simulated result. This paper also compares the performance of the conventional 12-pulse (CSC) HVDC system with the PWM based 2-level VSC-HVDC & 12-pulse VSC-HVDC system.
VSC BASED HVDC SYTEM DESIGN AND PROTECTION AGAINST OVER VOLTAGESIJERD Editor
High Voltage Direct Current system based on voltage source converter (VSC-HVDC) is becoming
more effective solution for offshore wind plants and supplying power to remote regions. In this paper, the
control of a VSC-based HVDC system (VSC-HVDC) is described. Based on this control strategy, appropriate
controllers utilizing PI controllers are designed to control the active and reactive power at each end station.The
operation performance of a voltage source converter (VSC) based HVDC (VSC-HVDC system) system is
explained under some characteristic faulted conditions with and without protection measures. A protection
strategy is proposed to enhance the continuous operation performance of the VSC-HVDC system. The strategy
utilizes a voltage chopper to suppress over-voltages on the DC side of the VSC. Digital simulation is done to
verify the validity of the proposed control strategy and protection strategy
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
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This paper proposes a non-isolated soft-switching bidirectional dc/dc converter for interfacing energy storage in DC microgrid. The proposed converter employs a half-bridge boost converter at input port followed by a LCC resonant tank to assist in soft-switching of switches and diodes, and finally a voltage doubler circuit at the output port to enhance the voltage gain by two times. The LCC resonant circuit also adds a suitable voltage gain to the converter. Therefore, overall high voltage gain of the converter is obtained without a transformer or large number of multiplier circuit. For operation in buck mode, the high side voltage is divided by half with capacitive divider to gain higher step-down ratio. The converter is operated at high frequency to obtain low output voltage ripple, reduced magnetics and filters. Zero voltage turn-on is achieved for all switches and zero current turn-on and turn-off is achieved for all diodes in both modes i.e., buck/boost operation. Voltage stress across switches and diode is clamped naturally without external snubber circuit. An experimental prototype has been designed, built and tested in the laboratory to verify the performance of the proposed converter.
An Improved Single Phase Transformer less Inverter Topology for Cost Effecti...IJMER
In grid connected PV systems, the elimination of isolation transformer introduces common
mode leakage current due to the parasitic capacitance between PV panels and the ground. The common
mode leakage current reduces the efficiency of power conversion stage, affects the quality of grid
current, deteriorate the electric magnetic compatibility and give rise to various safety threats. In order
to eliminate the leakage current, an improved transformer less topology with virtual DC bus concept is
proposed here. By connecting the grid neutral line directly to the negative pole of the DC bus, the stray
capacitance between the PV panels and the ground is bypassed. The topology consists of only five power
switches, two capacitors and the filter section. Therefore, the power electronics cost can be curtailed.
This advanced topology can be modulated with the sinusoidal pulse width modulation (SPWM) to reduce
the output current ripple. The simulation result of the proposed topology using MATLAB/SIMULINK is
presented.
Review of Reduction of Leakage Current in Cascaded Multilevel InverterIJRST Journal
Multilevel inverters are a source of high power, often used in industrial applications and can use either sine or modified sine waves. A multilevel inverter uses a series of semiconductor power converters (usually two to three) thus generating higher voltage. Reverse leakage current in a semiconductor device is the current from that semiconductor device when the device is reverse biased. In earlier method transformer is used for generating multilevel output and grid synchronization. Transformer increases the leakage current. Now transformerless method and sine modulation techniques are presented to reduce the leakage current.
Router 1X3 – RTL Design and VerificationIJERD Editor
Routing is the process of moving a packet of data from source to destination and enables messages
to pass from one computer to another and eventually reach the target machine. A router is a networking device
that forwards data packets between computer networks. It is connected to two or more data lines from different
networks (as opposed to a network switch, which connects data lines from one single network). This paper,
mainly emphasizes upon the study of router device, it‟s top level architecture, and how various sub-modules of
router i.e. Register, FIFO, FSM and Synchronizer are synthesized, and simulated and finally connected to its top
module.
Reducing Corrosion Rate by Welding DesignIJERD Editor
The paper addresses the importance of welding design to prevent corrosion at steel. Welding is
used to join pipe, profiles at bridges, spindle, and a lot more part of engineering construction. The
problems happened associated with welding are common issues in these fields, especially corrosion.
Corrosion can be reduced with many methods, they are painting, controlling humidity, and also good
welding design. In the research, it can be found that reducing residual stress on the welding can be
solved in corrosion rate reduction problem.
Preheating on 500oC and 600oC give better condition to reduce corosion rate than condition after
preheating 400oC. For all welding groove type, material with 500oC and 600oC preheating after 14 days
corrosion test is 0,5%-0,69% lost. Material with 400oC preheating after 14 days corrosion test is 0,57%-0,76%
lost.
Welding groove also influence corrosion rate. X and V type welding groove give better condition to reduce
corrosion rate than use 1/2V and 1/2 X welding groove. After 14 days corrosion test, the samples with
X welding groove type is 0,5%-0,57% lost. The samples with V welding groove after 14 days corrosion test is
0,51%-0,59% lost. The samples with 1/2V and 1/2X welding groove after 14 days corrosion test is 0,58%-
0,71% lost.
HVDC System a Need for Future Power Transmissionijtsrd
The continuously increasing demand for electric power and the economic access to remote renewable energy sources such as off-shore wind power or solar thermal generation in deserts have revived the interest in high-voltage direct current HVDC multiterminal systems networks . A lot of work was done in this area, especially in the 1980s, but only two three-terminal systems were realized. Since then, HVDC technology has advanced considerably and, despite numerous technical challenges, the realization of large-scale HVDC networks is now seriously discussed and considered. For the acceptance and reliability of these networks, the availability of HVDC circuit breakers CBs will be critical, making them one of the key enabling technologies. Numerous ideas for HVDC breaker schemes have been published and patented, but no acceptable solution has been found to interrupt HVDC short-circuit currents. This paper aims to summarize the literature, especially that of the last two decades, on technology areas that are relevant to HVDC breakers. By comparing the mainly 20 years old, state-of-the art HVDC CBs to the new HVDC technology, existing discrepancies become evident. Areas where additional research and development are needed are identified and proposed. for the couple of well-known applications are discussed. Mohd Liaqat "HVDC System: a Need for Future Power Transmission" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-2 , February 2019, URL: https://www.ijtsrd.com/papers/ijtsrd20318.pdf
Paper URL: https://www.ijtsrd.com/engineering/electrical-engineering/20318/hvdc-system-a-need-for-future-power-transmission/mohd-liaqat
This paper analyzes the behaviour of a Voltage Source Converter Based HVDC system under DC pole to ground fault & AC faults for 2-level VSC-HVDC & 12-pulse VSC-HVDC system in order to better understand the system under such faults. DC line faults on HVDC systems utilising Voltage Source Converters (VSC) are a major issue for HVDC systems in which complete isolation of the faulted system is not a viable option. The occurrence of pole-to-ground faults on DC link is the most common fault in HVDC system. It was observed that with the occurrence of DC pole to ground faults leads to substantial over current in the AC grid system which may lead to damage of the converter valve. Simulation of 2-level VSC-HVDC under AC fault is carried out. The fault current magnitude is attempted with the mathematical analysis & which was found to be the same as the simulated result. This paper also compares the performance of the conventional 12-pulse (CSC) HVDC system with the PWM based 2-level VSC-HVDC & 12-pulse VSC-HVDC system.
VSC BASED HVDC SYTEM DESIGN AND PROTECTION AGAINST OVER VOLTAGESIJERD Editor
High Voltage Direct Current system based on voltage source converter (VSC-HVDC) is becoming
more effective solution for offshore wind plants and supplying power to remote regions. In this paper, the
control of a VSC-based HVDC system (VSC-HVDC) is described. Based on this control strategy, appropriate
controllers utilizing PI controllers are designed to control the active and reactive power at each end station.The
operation performance of a voltage source converter (VSC) based HVDC (VSC-HVDC system) system is
explained under some characteristic faulted conditions with and without protection measures. A protection
strategy is proposed to enhance the continuous operation performance of the VSC-HVDC system. The strategy
utilizes a voltage chopper to suppress over-voltages on the DC side of the VSC. Digital simulation is done to
verify the validity of the proposed control strategy and protection strategy
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
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
This paper proposes a non-isolated soft-switching bidirectional dc/dc converter for interfacing energy storage in DC microgrid. The proposed converter employs a half-bridge boost converter at input port followed by a LCC resonant tank to assist in soft-switching of switches and diodes, and finally a voltage doubler circuit at the output port to enhance the voltage gain by two times. The LCC resonant circuit also adds a suitable voltage gain to the converter. Therefore, overall high voltage gain of the converter is obtained without a transformer or large number of multiplier circuit. For operation in buck mode, the high side voltage is divided by half with capacitive divider to gain higher step-down ratio. The converter is operated at high frequency to obtain low output voltage ripple, reduced magnetics and filters. Zero voltage turn-on is achieved for all switches and zero current turn-on and turn-off is achieved for all diodes in both modes i.e., buck/boost operation. Voltage stress across switches and diode is clamped naturally without external snubber circuit. An experimental prototype has been designed, built and tested in the laboratory to verify the performance of the proposed converter.
An Improved Single Phase Transformer less Inverter Topology for Cost Effecti...IJMER
In grid connected PV systems, the elimination of isolation transformer introduces common
mode leakage current due to the parasitic capacitance between PV panels and the ground. The common
mode leakage current reduces the efficiency of power conversion stage, affects the quality of grid
current, deteriorate the electric magnetic compatibility and give rise to various safety threats. In order
to eliminate the leakage current, an improved transformer less topology with virtual DC bus concept is
proposed here. By connecting the grid neutral line directly to the negative pole of the DC bus, the stray
capacitance between the PV panels and the ground is bypassed. The topology consists of only five power
switches, two capacitors and the filter section. Therefore, the power electronics cost can be curtailed.
This advanced topology can be modulated with the sinusoidal pulse width modulation (SPWM) to reduce
the output current ripple. The simulation result of the proposed topology using MATLAB/SIMULINK is
presented.
Review of Reduction of Leakage Current in Cascaded Multilevel InverterIJRST Journal
Multilevel inverters are a source of high power, often used in industrial applications and can use either sine or modified sine waves. A multilevel inverter uses a series of semiconductor power converters (usually two to three) thus generating higher voltage. Reverse leakage current in a semiconductor device is the current from that semiconductor device when the device is reverse biased. In earlier method transformer is used for generating multilevel output and grid synchronization. Transformer increases the leakage current. Now transformerless method and sine modulation techniques are presented to reduce the leakage current.
Router 1X3 – RTL Design and VerificationIJERD Editor
Routing is the process of moving a packet of data from source to destination and enables messages
to pass from one computer to another and eventually reach the target machine. A router is a networking device
that forwards data packets between computer networks. It is connected to two or more data lines from different
networks (as opposed to a network switch, which connects data lines from one single network). This paper,
mainly emphasizes upon the study of router device, it‟s top level architecture, and how various sub-modules of
router i.e. Register, FIFO, FSM and Synchronizer are synthesized, and simulated and finally connected to its top
module.
Reducing Corrosion Rate by Welding DesignIJERD Editor
The paper addresses the importance of welding design to prevent corrosion at steel. Welding is
used to join pipe, profiles at bridges, spindle, and a lot more part of engineering construction. The
problems happened associated with welding are common issues in these fields, especially corrosion.
Corrosion can be reduced with many methods, they are painting, controlling humidity, and also good
welding design. In the research, it can be found that reducing residual stress on the welding can be
solved in corrosion rate reduction problem.
Preheating on 500oC and 600oC give better condition to reduce corosion rate than condition after
preheating 400oC. For all welding groove type, material with 500oC and 600oC preheating after 14 days
corrosion test is 0,5%-0,69% lost. Material with 400oC preheating after 14 days corrosion test is 0,57%-0,76%
lost.
Welding groove also influence corrosion rate. X and V type welding groove give better condition to reduce
corrosion rate than use 1/2V and 1/2 X welding groove. After 14 days corrosion test, the samples with
X welding groove type is 0,5%-0,57% lost. The samples with V welding groove after 14 days corrosion test is
0,51%-0,59% lost. The samples with 1/2V and 1/2X welding groove after 14 days corrosion test is 0,58%-
0,71% lost.
Gold prospecting using Remote Sensing ‘A case study of Sudan’IJERD Editor
Gold has been extracted from northeast Africa for more than 5000 years, and this may be the first
place where the metal was extracted. The Arabian-Nubian Shield (ANS) is an exposure of Precambrian
crystalline rocks on the flanks of the Red Sea. The crystalline rocks are mostly Neoproterozoic in age. ANS
includes the nations of Israel, Jordan. Egypt, Saudi Arabia, Sudan, Eritrea, Ethiopia, Yemen, and Somalia.
Arabian Nubian Shield Consists of juvenile continental crest that formed between 900 550 Ma, when intra
oceanic arc welded together along ophiolite decorated arc. Primary Au mineralization probably developed in
association with the growth of intra oceanic arc and evolution of back arc. Multiple episodes of deformation
have obscured the primary metallogenic setting, but at least some of the deposits preserve evidence that they
originate as sea floor massive sulphide deposits.
The Red Sea Hills Region is a vast span of rugged, harsh and inhospitable sector of the Earth with
inimical moon-like terrain, nevertheless since ancient times it is famed to be an abode of gold and was a major
source of wealth for the Pharaohs of ancient Egypt. The Pharaohs old workings have been periodically
rediscovered through time. Recent endeavours by the Geological Research Authority of Sudan led to the
discovery of a score of occurrences with gold and massive sulphide mineralizations. In the nineties of the
previous century the Geological Research Authority of Sudan (GRAS) in cooperation with BRGM utilized
satellite data of Landsat TM using spectral ratio technique to map possible mineralized zones in the Red Sea
Hills of Sudan. The outcome of the study mapped a gossan type gold mineralization. Band ratio technique was
applied to Arbaat area and a signature of alteration zone was detected. The alteration zones are commonly
associated with mineralization. The alteration zones are commonly associated with mineralization. A filed check
confirmed the existence of stock work of gold bearing quartz in the alteration zone. Another type of gold
mineralization that was discovered using remote sensing is the gold associated with metachert in the Atmur
Desert.
Hearing loss is one of the most common human impairments. It is estimated that by year 2015 more
than 700 million people will suffer mild deafness. Most can be helped by hearing aid devices depending on the
severity of their hearing loss. This paper describes the implementation and characterization details of a dual
channel transmitter front end (TFE) for digital hearing aid (DHA) applications that use novel micro
electromechanical- systems (MEMS) audio transducers and ultra-low power-scalable analog-to-digital
converters (ADCs), which enable a very-low form factor, energy-efficient implementation for next-generation
DHA. The contribution of the design is the implementation of the dual channel MEMS microphones and powerscalable
ADC system.
A Novel Method for Prevention of Bandwidth Distributed Denial of Service AttacksIJERD Editor
Distributed Denial of Service (DDoS) Attacks became a massive threat to the Internet. Traditional
Architecture of internet is vulnerable to the attacks like DDoS. Attacker primarily acquire his army of Zombies,
then that army will be instructed by the Attacker that when to start an attack and on whom the attack should be
done. In this paper, different techniques which are used to perform DDoS Attacks, Tools that were used to
perform Attacks and Countermeasures in order to detect the attackers and eliminate the Bandwidth Distributed
Denial of Service attacks (B-DDoS) are reviewed. DDoS Attacks were done by using various Flooding
techniques which are used in DDoS attack.
The main purpose of this paper is to design an architecture which can reduce the Bandwidth
Distributed Denial of service Attack and make the victim site or server available for the normal users by
eliminating the zombie machines. Our Primary focus of this paper is to dispute how normal machines are
turning into zombies (Bots), how attack is been initiated, DDoS attack procedure and how an organization can
save their server from being a DDoS victim. In order to present this we implemented a simulated environment
with Cisco switches, Routers, Firewall, some virtual machines and some Attack tools to display a real DDoS
attack. By using Time scheduling, Resource Limiting, System log, Access Control List and some Modular
policy Framework we stopped the attack and identified the Attacker (Bot) machines
Influence of tensile behaviour of slab on the structural Behaviour of shear c...IJERD Editor
-A composite beam is composed of a steel beam and a slab connected by means of shear connectors
like studs installed on the top flange of the steel beam to form a structure behaving monolithically. This study
analyzes the effects of the tensile behavior of the slab on the structural behavior of the shear connection like slip
stiffness and maximum shear force in composite beams subjected to hogging moment. The results show that the
shear studs located in the crack-concentration zones due to large hogging moments sustain significantly smaller
shear force and slip stiffness than the other zones. Moreover, the reduction of the slip stiffness in the shear
connection appears also to be closely related to the change in the tensile strain of rebar according to the increase
of the load. Further experimental and analytical studies shall be conducted considering variables such as the
reinforcement ratio and the arrangement of shear connectors to achieve efficient design of the shear connection
in composite beams subjected to hogging moment.
Conventional and emerging converter technologies in hvdc power transmission s...Naveed Shahzad
The efficiency of HVDC system is primarily associated with power electronic converters which are playing the key role in transforming AC to DC and vice versa. There have been several converter topologies known and implemented in HVDC system throughout the world, however the major converter topologies are line commutated-current source converters (CSC) and self-commutated voltage source converters (VSC). This presentation provides an overview and comparison of CSC and VSC converters including their applications, advantages, limitations and new technological advancement related to CSC, and VSC including 2 level VSC and 3 level VSC and newer modular multilevel converter (MMC) topologies.
Active Power Exchange in Distributed Power-Flow Controller (DPFC) At Third Ha...IJERD Editor
This paper presents a component within the flexible ac-transmission system (FACTS) family, called
distributed power-flow controller (DPFC). The DPFC is derived from the unified power-flow controller (UPFC)
with an eliminated common dc link. The DPFC has the same control capabilities as the UPFC, which comprise
the adjustment of the line impedance, the transmission angle, and the bus voltage. The active power exchange
between the shunt and series converters, which is through the common dc link in the UPFC, is now through the
transmission lines at the third-harmonic frequency. DPFC multiple small-size single-phase converters which
reduces the cost of equipment, no voltage isolation between phases, increases redundancy and there by
reliability increases. The principle and analysis of the DPFC are presented in this paper and the corresponding
simulation results that are carried out on a scaled prototype are also shown.
Mitigation of Voltage Sag/Swell with Fuzzy Control Reduced Rating DVRIJERD Editor
Power quality has been an issue that is becoming increasingly pivotal in industrial electricity
consumers point of view in recent times. Modern industries employ Sensitive power electronic equipments,
control devices and non-linear loads as part of automated processes to increase energy efficiency and
productivity. Voltage disturbances are the most common power quality problem due to this the use of a large
numbers of sophisticated and sensitive electronic equipment in industrial systems is increased. This paper
discusses the design and simulation of dynamic voltage restorer for improvement of power quality and
reduce the harmonics distortion of sensitive loads. Power quality problem is occurring at non-standard
voltage, current and frequency. Electronic devices are very sensitive loads. In power system voltage sag,
swell, flicker and harmonics are some of the problem to the sensitive load. The compensation capability
of a DVR depends primarily on the maximum voltage injection ability and the amount of stored
energy available within the restorer. This device is connected in series with the distribution feeder at
medium voltage. A fuzzy logic control is used to produce the gate pulses for control circuit of DVR and the
circuit is simulated by using MATLAB/SIMULINK software.
Study on the Fused Deposition Modelling In Additive ManufacturingIJERD Editor
Additive manufacturing process, also popularly known as 3-D printing, is a process where a product
is created in a succession of layers. It is based on a novel materials incremental manufacturing philosophy.
Unlike conventional manufacturing processes where material is removed from a given work price to derive the
final shape of a product, 3-D printing develops the product from scratch thus obviating the necessity to cut away
materials. This prevents wastage of raw materials. Commonly used raw materials for the process are ABS
plastic, PLA and nylon. Recently the use of gold, bronze and wood has also been implemented. The complexity
factor of this process is 0% as in any object of any shape and size can be manufactured.
Spyware triggering system by particular string valueIJERD Editor
This computer programme can be used for good and bad purpose in hacking or in any general
purpose. We can say it is next step for hacking techniques such as keylogger and spyware. Once in this system if
user or hacker store particular string as a input after that software continually compare typing activity of user
with that stored string and if it is match then launch spyware programme.
A Blind Steganalysis on JPEG Gray Level Image Based on Statistical Features a...IJERD Editor
This paper presents a blind steganalysis technique to effectively attack the JPEG steganographic
schemes i.e. Jsteg, F5, Outguess and DWT Based. The proposed method exploits the correlations between
block-DCTcoefficients from intra-block and inter-block relation and the statistical moments of characteristic
functions of the test image is selected as features. The features are extracted from the BDCT JPEG 2-array.
Support Vector Machine with cross-validation is implemented for the classification.The proposed scheme gives
improved outcome in attacking.
Secure Image Transmission for Cloud Storage System Using Hybrid SchemeIJERD Editor
- Data over the cloud is transferred or transmitted between servers and users. Privacy of that
data is very important as it belongs to personal information. If data get hacked by the hacker, can be
used to defame a person’s social data. Sometimes delay are held during data transmission. i.e. Mobile
communication, bandwidth is low. Hence compression algorithms are proposed for fast and efficient
transmission, encryption is used for security purposes and blurring is used by providing additional
layers of security. These algorithms are hybridized for having a robust and efficient security and
transmission over cloud storage system.
Application of Buckley-Leverett Equation in Modeling the Radius of Invasion i...IJERD Editor
A thorough review of existing literature indicates that the Buckley-Leverett equation only analyzes
waterflood practices directly without any adjustments on real reservoir scenarios. By doing so, quite a number
of errors are introduced into these analyses. Also, for most waterflood scenarios, a radial investigation is more
appropriate than a simplified linear system. This study investigates the adoption of the Buckley-Leverett
equation to estimate the radius invasion of the displacing fluid during waterflooding. The model is also adopted
for a Microbial flood and a comparative analysis is conducted for both waterflooding and microbial flooding.
Results shown from the analysis doesn’t only records a success in determining the radial distance of the leading
edge of water during the flooding process, but also gives a clearer understanding of the applicability of
microbes to enhance oil production through in-situ production of bio-products like bio surfactans, biogenic
gases, bio acids etc.
Gesture Gaming on the World Wide Web Using an Ordinary Web CameraIJERD Editor
- Gesture gaming is a method by which users having a laptop/pc/x-box play games using natural or
bodily gestures. This paper presents a way of playing free flash games on the internet using an ordinary webcam
with the help of open source technologies. Emphasis in human activity recognition is given on the pose
estimation and the consistency in the pose of the player. These are estimated with the help of an ordinary web
camera having different resolutions from VGA to 20mps. Our work involved giving a 10 second documentary to
the user on how to play a particular game using gestures and what are the various kinds of gestures that can be
performed in front of the system. The initial inputs of the RGB values for the gesture component is obtained by
instructing the user to place his component in a red box in about 10 seconds after the short documentary before
the game is finished. Later the system opens the concerned game on the internet on popular flash game sites like
miniclip, games arcade, GameStop etc and loads the game clicking at various places and brings the state to a
place where the user is to perform only gestures to start playing the game. At any point of time the user can call
off the game by hitting the esc key and the program will release all of the controls and return to the desktop. It
was noted that the results obtained using an ordinary webcam matched that of the Kinect and the users could
relive the gaming experience of the free flash games on the net. Therefore effective in game advertising could
also be achieved thus resulting in a disruptive growth to the advertising firms.
Hardware Analysis of Resonant Frequency Converter Using Isolated Circuits And...IJERD Editor
-LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region[5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits.
Simulated Analysis of Resonant Frequency Converter Using Different Tank Circu...IJERD Editor
LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region [5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits. The supported simulation
is done through PSIM 6.0 software tool
Amateurs Radio operator, also known as HAM communicates with other HAMs through Radio
waves. Wireless communication in which Moon is used as natural satellite is called Moon-bounce or EME
(Earth -Moon-Earth) technique. Long distance communication (DXing) using Very High Frequency (VHF)
operated amateur HAM radio was difficult. Even with the modest setup having good transceiver, power
amplifier and high gain antenna with high directivity, VHF DXing is possible. Generally 2X11 YAGI antenna
along with rotor to set horizontal and vertical angle is used. Moon tracking software gives exact location,
visibility of Moon at both the stations and other vital data to acquire real time position of moon.
“MS-Extractor: An Innovative Approach to Extract Microsatellites on „Y‟ Chrom...IJERD Editor
Simple Sequence Repeats (SSR), also known as Microsatellites, have been extensively used as
molecular markers due to their abundance and high degree of polymorphism. The nucleotide sequences of
polymorphic forms of the same gene should be 99.9% identical. So, Microsatellites extraction from the Gene is
crucial. However, Microsatellites repeat count is compared, if they differ largely, he has some disorder. The Y
chromosome likely contains 50 to 60 genes that provide instructions for making proteins. Because only males
have the Y chromosome, the genes on this chromosome tend to be involved in male sex determination and
development. Several Microsatellite Extractors exist and they fail to extract microsatellites on large data sets of
giga bytes and tera bytes in size. The proposed tool “MS-Extractor: An Innovative Approach to extract
Microsatellites on „Y‟ Chromosome” can extract both Perfect as well as Imperfect Microsatellites from large
data sets of human genome „Y‟. The proposed system uses string matching with sliding window approach to
locate Microsatellites and extracts them.
Importance of Measurements in Smart GridIJERD Editor
- The need to get reliable supply, independence from fossil fuels, and capability to provide clean
energy at a fixed and lower cost, the existing power grid structure is transforming into Smart Grid. The
development of a smart energy distribution grid is a current goal of many nations. A Smart Grid should have
new capabilities such as self-healing, high reliability, energy management, and real-time pricing. This new era
of smart future grid will lead to major changes in existing technologies at generation, transmission and
distribution levels. The incorporation of renewable energy resources and distribution generators in the existing
grid will increase the complexity, optimization problems and instability of the system. This will lead to a
paradigm shift in the instrumentation and control requirements for Smart Grids for high quality, stable and
reliable electricity supply of power. The monitoring of the grid system state and stability relies on the
availability of reliable measurement of data. In this paper the measurement areas that highlight new
measurement challenges, development of the Smart Meters and the critical parameters of electric energy to be
monitored for improving the reliability of power systems has been discussed.
Study of Macro level Properties of SCC using GGBS and Lime stone powderIJERD Editor
One of the major environmental concerns is the disposal of the waste materials and utilization of
industrial by products. Lime stone quarries will produce millions of tons waste dust powder every year. Having
considerable high degree of fineness in comparision to cement this material may be utilized as a partial
replacement to cement. For this purpose an experiment is conducted to investigate the possibility of using lime
stone powder in the production of SCC with combined use GGBS and how it affects the fresh and mechanical
properties of SCC. First SCC is made by replacing cement with GGBS in percentages like 10, 20, 30, 40, 50 and
by taking the optimum mix with GGBS lime stone powder is blended to mix in percentages like 5, 10, 15, 20 as
a partial replacement to cement. Test results shows that the SCC mix with combination of 30% GGBS and 15%
limestone powder gives maximum compressive strength and fresh properties are also in the limits prescribed by
the EFNARC.
Seismic Drift Consideration in soft storied RCC buildings: A Critical ReviewIJERD Editor
Reinforced concrete frame buildings are becoming increasingly common in urban India. Many such
buildings constructed in recent times have a special feature – the ground storey is left open for the purpose of
parking, i.e., columns in the ground floor do not have any partition walls (of either masonry or
Reinforced concrete) between them. Such buildings are often called open ground storey buildings. The
relative horizontal displacement in the ground storey is much larger than storeys above it. The total horizontal
earthquake force it can carry in the ground storey is significantly smaller than storeys above it. The soft or weak
storey may exist at any storey level other than ground storey level. The presence of walls in upper storeys
makes them much stiffer than the open ground storey. Still Multi storey reinforced concrete buildings are
continuing to be built in India which has open ground storeys. It is imperative to know the behavior of
soft storey building to the seismic load for designing various retrofit strategies. Hence it is important to
study and understand the response of such buildings and make such buildings earthquake resistant based
on the study to prevent their collapse and to save the loss of life and property.
Post processing of SLM Ti-6Al-4V Alloy in accordance with AMS 4928 standardsIJERD Editor
This Research work was done to find out the impact of AMS 4928 standard heat treatment on
Selective Laser Melted (SLM) Ti-6Al-4V Grade 23 alloy. Ti-6Al-4V Grade 23 is an Extra Low Interstitial
version of Ti alloy with lower impurities and is α+β type alloy at room temperature. SLM is one type of method
in Additive Manufacturing based on Powder bed system. Each powder layer of few microns is coated and a laser
beam is scanned to melt the metal powder according to the specification of the part and subsequently moved
downwards layer by layer. The test coupons were first heat treated according to the above mentioned standard.
The tensile testing and the microstructural analysis were done to compare the results with that of mentioned in
the AMS 4928.The yield stress andPercentage elongation in the test coupons achieved are better than the
minimum requirement by AMS 4928 standard. Coarse lamellar grain structures were obtained with no
continuous network of alpha at prior beta grain boundaries.
Treatment of Waste Water from Organic Fraction Incineration of Municipal Soli...IJERD Editor
Evaporation is one of treatment alternatives of waste water from condensation of vapour in flue gas
or from flue gas scrubber system of an incinerator. The waste water contains tar and heavy metals which are
toxic and must be separated, before discharged to environment or recycled. Due to the relatively low efficiency
of the evaporation process, a combination of the evaporation-absorption process is developed to increase the
efficiency. The aim of this research is to study the separation efficiency of tar from the tar-water mixture from
organic fraction incineration of garbage by evaporation-absorption process, and compared it with the
evaporation process. The evaporation process was performed by evaporating the waste water directly, while the
evaporation-absorption process was carried out by evaporating the waste water before it had been mixed with
palm oil as an absorbent. The results showed that the efficiency to separate the heavy tar of the evaporation
process was 73.27% compared to the combination of evaporation-absorption that was 98.82%. Meanwhile, for
the separation of the light tar, the efficiencies of both process types were almost the same. This system can be
integrated with the incinerator for the treatment of flue gases and waste water generated from the burning of
organic fraction of MSW
Content Based Video Retrieval Using Integrated Feature Extraction and Persona...IJERD Editor
Traditional video retrieval methods fail to meet technical challenges due to large and rapid growth of
multimedia data, demanding effective retrieval systems. In the last decade Content Based Video Retrieval
(CBVR) has become more and more popular. The amount of lecture video data on the Worldwide Web (WWW)
is growing rapidly. Therefore, a more efficient method for video retrieval in WWW or within large lecture video
archives is urgently needed. This paper presents an implementation of automated video indexing and video
search in large videodatabase. First of all, we apply automatic video segmentation and key-frame detection to
extract the frames from video. At next, we extract textual keywords by applying on video i.e. Optical Character
Recognition (OCR) technology on key-frames and Automatic Speech Recognition (ASR) on audio tracks of that
video. At next, we also extractingcolour, texture and edge detector features from different method. At last, we
integrate all the keywords and features which has extracted from above techniques for searching
purpose.Finallysearch similarity measure is applied to retrieve the best matchingcorresponding videos are
presented as output from database. Additionally we are providing Re-ranking of results as per users interest in
original result.
Planar Internal Antenna Design for Cellular Applications & SAR AnalysisIJERD Editor
This paper presents a new design of direct-fed Multi band printed Planar Internal Antenna (PIA), for
cellular applications. The PIA antenna is composed of ground plane, meander radiating strip and two other
parasitic strips are printed on a common substrate. The designed antenna has been simulated in CST
environment. The simulated results for the resonant frequency, return loss, radiation pattern and gain are
presented and discussed. The bandwidths for three resonance achieved on the basis of -6 dB return loss.These
Bandwidths can be utilized for GSM 900, GSM 1800, GSM 1900, LTE 2300 and Bluetooth/WLAN as an
acceptable reference in mobile phones applications. Further the antenna was placed in proximity to the SAR
head on CST environment. The simulated results of SAR analysis are presented in this paper with acceptable
range.
Intelligent learning management system startersIJERD Editor
learning management system (lms) is increasingly gaining popularity in the academic community as
a means of delivering e-learning contents. Simply placing lecture notes and videos among other contents on
lmss do not particularly train the best. This situation could be improved with intelligent tutoring systems (itss)
integration into preferred lms to make it more adaptive and effective, through enhanced student participation
and learning. This work aims, therefore, to create a starter model and a model java its integrated preferred lms.
The its integrated lms starter model was proposed through augmentation and a fluid iterative cycle of
awareness, suggestion, development, evaluation and conclusion. Known open/inexpensive, tried and tested
popular lmss were evaluated at cms matrix site, and complemented. Java its integrated moodle (preferred),
employing certain architectural framework of its integrated lms, was created following the spiral model of
software development
VAT Registration Outlined In UAE: Benefits and Requirementsuae taxgpt
Vat Registration is a legal obligation for businesses meeting the threshold requirement, helping companies avoid fines and ramifications. Contact now!
https://viralsocialtrends.com/vat-registration-outlined-in-uae/
Putting the SPARK into Virtual Training.pptxCynthia Clay
This 60-minute webinar, sponsored by Adobe, was delivered for the Training Mag Network. It explored the five elements of SPARK: Storytelling, Purpose, Action, Relationships, and Kudos. Knowing how to tell a well-structured story is key to building long-term memory. Stating a clear purpose that doesn't take away from the discovery learning process is critical. Ensuring that people move from theory to practical application is imperative. Creating strong social learning is the key to commitment and engagement. Validating and affirming participants' comments is the way to create a positive learning environment.
Implicitly or explicitly all competing businesses employ a strategy to select a mix
of marketing resources. Formulating such competitive strategies fundamentally
involves recognizing relationships between elements of the marketing mix (e.g.,
price and product quality), as well as assessing competitive and market conditions
(i.e., industry structure in the language of economics).
[Note: This is a partial preview. To download this presentation, visit:
https://www.oeconsulting.com.sg/training-presentations]
Sustainability has become an increasingly critical topic as the world recognizes the need to protect our planet and its resources for future generations. Sustainability means meeting our current needs without compromising the ability of future generations to meet theirs. It involves long-term planning and consideration of the consequences of our actions. The goal is to create strategies that ensure the long-term viability of People, Planet, and Profit.
Leading companies such as Nike, Toyota, and Siemens are prioritizing sustainable innovation in their business models, setting an example for others to follow. In this Sustainability training presentation, you will learn key concepts, principles, and practices of sustainability applicable across industries. This training aims to create awareness and educate employees, senior executives, consultants, and other key stakeholders, including investors, policymakers, and supply chain partners, on the importance and implementation of sustainability.
LEARNING OBJECTIVES
1. Develop a comprehensive understanding of the fundamental principles and concepts that form the foundation of sustainability within corporate environments.
2. Explore the sustainability implementation model, focusing on effective measures and reporting strategies to track and communicate sustainability efforts.
3. Identify and define best practices and critical success factors essential for achieving sustainability goals within organizations.
CONTENTS
1. Introduction and Key Concepts of Sustainability
2. Principles and Practices of Sustainability
3. Measures and Reporting in Sustainability
4. Sustainability Implementation & Best Practices
To download the complete presentation, visit: https://www.oeconsulting.com.sg/training-presentations
Tata Group Dials Taiwan for Its Chipmaking Ambition in Gujarat’s DholeraAvirahi City Dholera
The Tata Group, a titan of Indian industry, is making waves with its advanced talks with Taiwanese chipmakers Powerchip Semiconductor Manufacturing Corporation (PSMC) and UMC Group. The goal? Establishing a cutting-edge semiconductor fabrication unit (fab) in Dholera, Gujarat. This isn’t just any project; it’s a potential game changer for India’s chipmaking aspirations and a boon for investors seeking promising residential projects in dholera sir.
Visit : https://www.avirahi.com/blog/tata-group-dials-taiwan-for-its-chipmaking-ambition-in-gujarats-dholera/
Attending a job Interview for B1 and B2 Englsih learnersErika906060
It is a sample of an interview for a business english class for pre-intermediate and intermediate english students with emphasis on the speking ability.
What is the TDS Return Filing Due Date for FY 2024-25.pdfseoforlegalpillers
It is crucial for the taxpayers to understand about the TDS Return Filing Due Date, so that they can fulfill your TDS obligations efficiently. Taxpayers can avoid penalties by sticking to the deadlines and by accurate filing of TDS. Timely filing of TDS will make sure about the availability of tax credits. You can also seek the professional guidance of experts like Legal Pillers for timely filing of the TDS Return.
Discover the innovative and creative projects that highlight my journey throu...dylandmeas
Discover the innovative and creative projects that highlight my journey through Full Sail University. Below, you’ll find a collection of my work showcasing my skills and expertise in digital marketing, event planning, and media production.
RMD24 | Debunking the non-endemic revenue myth Marvin Vacquier Droop | First ...BBPMedia1
Marvin neemt je in deze presentatie mee in de voordelen van non-endemic advertising op retail media netwerken. Hij brengt ook de uitdagingen in beeld die de markt op dit moment heeft op het gebied van retail media voor niet-leveranciers.
Retail media wordt gezien als het nieuwe advertising-medium en ook mediabureaus richten massaal retail media-afdelingen op. Merken die niet in de betreffende winkel liggen staan ook nog niet in de rij om op de retail media netwerken te adverteren. Marvin belicht de uitdagingen die er zijn om echt aansluiting te vinden op die markt van non-endemic advertising.
Falcon stands out as a top-tier P2P Invoice Discounting platform in India, bridging esteemed blue-chip companies and eager investors. Our goal is to transform the investment landscape in India by establishing a comprehensive destination for borrowers and investors with diverse profiles and needs, all while minimizing risk. What sets Falcon apart is the elimination of intermediaries such as commercial banks and depository institutions, allowing investors to enjoy higher yields.
International Journal of Engineering Research and Development (IJERD)
1. International Journal of Engineering Research and Development
e-ISSN: 2278-067X, p-ISSN: 2278-800X, www.ijerd.com
Volume 7, Issue 7 (June 2013), PP. 37-44
37
HVDC Transmission System Using 6-Pulse IGBT
Converter
Manvendra Nandan1
, Arun Pachori2
, Nitin Saxsena3
1
ME (HIGH VOLTAGE) Student of JEC Jabalpur Engineering College Jabalpur
2,3
Professor Dept. of Electrical Engineering. JEC Engineering College Jabalpur
Abstract: - High Voltage Direct Current (HVDC) technology has characteristics which makes it especially
attractive in certain transmission applications. The number of HVDC projects committed or under consideration
globally has increased in recent years reflecting a renewed interest in this field proven technology. New HVDC
converter designs and improvements in conventional HVDC design have contributed to this trend. This paper
proposes a simple 6-Pulse HVDC transmission system which can cater to the need of agricultural applications in
India. It also provides an overview of the rationale for selection of HVDC technology and describes some of the
latest technical developments.
Keywords: - HVDC, Six-pulse rectifiers, SCR, IGBT, GTO, IGCT.
I. INTRODUCTION
High Voltage Direct Current (HVDC) technology has characteristics which makes it especially
attractive for certain transmission applications. HVDC transmission is widely recognized as being advantageous
for long-distance, bulk power delivery, asynchronous interconnections and long submarine cable crossings. The
number of HVDC projects committed or under consideration globally has increased in recent years reflecting a
renewed interest in this mature technology. New converter designs have broadened the potential range of HVDC
transmission to include applications for underground, offshore, economic replacement of reliability-must-run
generation, and voltage stabilization. Developments include higher transmission voltages up to ± 800 kV,
capacitor-commutated converters (CCC) for weak system applications and voltage-sourced converters (VSC)
with dynamic reactive power control. This broader technology range has increased the potential HVDC
applications and contributed to the recent growth of HVDC transmission.
The rationale behind selection of HVDC for transmission is it reduces loss of power. Power does not
rely only on voltage, but is equal of voltage times current.
P=VI………………. (1)
For a given power a low voltage requires a higher current and a higher voltage requires a lower current.
However, since metal conducting wires have a certain resistance, some power is wasted, and dissipated as heat.
The power losses in a conductor on the other hand are proportional to the square of current and resistance of
conductor.
P=I2
R………………. (2)
Now power is proportional to voltage also, so it can be concluded that higher voltage implies decrease
in current level which in turn results in lower power loss. Although power loss can also be reduced by
decreasing resistance i.e. either by increasing diameter of conductor or using material with lower resistivity but
it in turn results in higher economical costs.
High voltage transmission is used to reduce lost of power, but it cannot be used for lightning system or
for supplying to motors. High voltage level has to be adjusted in accordance with the receivers. In AC
transformers are used for decreasing or increasing voltage to required level. In DC such possibility does not
exist. In case of DC manipulation is possible but in a more complicated way. To change level of voltage
electronic devices such as mercury arc valves, semiconductors devices, thyristors, insulated-gate bipolar
transistors (IGBTs), high power capable MOSFETs (power metal–oxide–semiconductor field-effect transistors)
and gate turn-off thyristors (GTOs).
In AC voltage conversion is simple, and demand little maintenance. Further three-phase generator is
superior to DC generator in many aspects. These reasons causes that AC technology is today common in
production, transmission and distribution of electrical energy. However alternative current transmission has also
drawback which can be compensated in
2. HVDC Transmission System Using 6-Pulse IGBT Converter
38
DC links. So the main reasons why DC technology is chosen instead of AC can be summarized as
under:
־ Inductive and capacitive elements of lines put limits to the transmission capacity and transmission
distance.
־ Transmission between two points of different current frequency is not possible.
Therefore electrical engineers have developed a strong research orientation towards developing application of
DC technology which doesn’t have such limitation.
II. HISTORY
The first transmission of direct current was in 1882, it was 50 km long (distance between Miesbach-
Munichbut) and voltage level was only 2 kV. DC transmission was developed by Rene Thury. This scientist
created a method, which based on series-connected generator and was put into practice by 1889 in Italy. System
based on Thury’s idea transmitted 630 kW at 14 kV over distance 120 km. [2] [3]
Fig.1. Scheme of Thury’s installation from 1889 [1]
The next important project was line Moutiers-Lyon in France which was used from about 1906 until
1936. Moutiers power plant had eight generators which were connected in series. The Moutiers-Lyon system
transmitted 8,600 kW of hydroelectric power to a distance of 200 km, including 10 km of underground cable
and voltage between two poles was 150 kV. Fifteen Thury’s systems were in operation by 1913 [4].Other
Thury’s systems operating at up to 100 kV DC operated into the 1930s, but the rotating machinery required high
maintenance and had high energy loss. So Thury’s system was little commercial success.
The next era, was attempts with mercury arc valve. First proposed in 1914 [5], and put into use in 1932
by General Electric, which tested mercury-vapor valves in 12 kV DC line. It could convert current from
frequency of 40 Hz to 60 Hz. This installation worked in Mechanicville, New York. In 1941, a 60.0 MW,
±200 kV, 115 km buried cable link was designed for the city of Berlin using mercury arc valves (Elbe-Project),
but owing to the collapse of the German government in 1945 the project was never completed. Mercury arc
valves were common in systems designed up to 1972.
The replacement of mercury arc valves by solid-state devices in most cases thyristor valves was the
next major development. Development of thyristor valves for HVDC had begun in the late 1960’s. HVDC using
thyristor valves is also known as line-commutated converter (LCC) HVDC [6].
Line-commutated converters have some limitations in their use for HVDC systems, resulting from the
inability of the thyristor to turn off current and its need for a period of reverse voltage after turn-off (turn-off
time). An attempt to address these limitations is the Capacitor-Commutated Converter (CCC) which has been
used in a small number of HVDC systems. However, CCC has remained only a niche application because of the
advent of voltage-source converters (VSC) which completely eliminate the need for an extinction time [7].
Widely used in motor drives since the 1980s, Voltage-source converters started to appear in HVDC in
1997 with the experimental Hellsjon–Grangesberg project in Sweden. By the end of 2011, this technology had
captured a significant proportion of the HVDC market.The development of higher rated insulated gate bipolar
transistors (IGBT), gate turn-off thyristors (GTO) and integrated gate-commutated thyristors (IGCTs), has made
smaller HVDC systems economical.
With time, voltage-source converter systems will probably replace all installed simple thyristor-based
systems, including the highest DC power transmission applications [7].
3. HVDC Transmission System Using 6-Pulse IGBT Converter
39
III. HVDC APPLICATIONS
HVDC transmission applications can be broken down into different basic categories. Although the
rationale for selection of HVDC is often economic, there may be other reasons for its selection. HVDC may be
the only feasible way to interconnect two asynchronous networks, reduce fault currents, utilize long cable
circuits, bypass network congestion, share utility rights-of-way without degradation of reliability and to mitigate
environmental concerns. In all of these applications, HVDC nicely complements the AC transmission system.
A. Long Distance Bulk Power Transmission
HVDC transmission systems often provide a more economical alternative to ac transmission for long-
distance, bulk-power delivery from remote resources such as hydroelectric developments, or large scale wind
farms. Higher power transfers are possible over longer distances using fewer lines with HVDC transmission
than with ac transmission. Typical HVDC lines utilize a bipolar configuration with two independent poles.
The controllability of HVDC links offers firm transmission capacity without limitation due to network
congestion or loop flow on parallel paths. Therefore, the utilization of HVDC links is usually higher than that
for EHV ac transmission lowering the transmission cost per MWh. This controllability can also be very
beneficial for the parallel transmission as well since, by eliminating loop flow, it frees up this transmission
capacity for its intended purpose of serving intermediate load and providing an outlet for local generation.
B. Cable Transmission
Unlike the case for ac cables, there is no physical restriction limiting the distance or power level for
HVDC underground or submarine cables. Underground cables can be used on shared ROW with other utilities
without impacting reliability concerns over use of common corridors. For underground or submarine cable
systems there is considerable savings in installed cable costs and cost of losses when using HVDC transmission.
The lower cost cable installations made possible by the extruded HVDC cables and prefabricated joints
makes long distance underground transmission economically feasible for use in areas with rights-of-way
constraints or subject to permitting difficulties or delays with overhead lines.
C. Asynchronous Ties
With HVDC transmission systems, interconnections can be made between asynchronous networks for
more economic or reliable system operation. The asynchronous interconnection allows interconnections of
mutual benefit while providing a buffer between the two systems. Often these interconnections use back-to-back
converters with no transmission line. Asynchronous HVDC links act as an effective “firewall” against
propagation of cascading outages in one network from passing to another network.
D. Offshore Transmission
Self-commutation, dynamic voltage control and black-start capability allow compact VSC HVDC
transmission to serve isolated loads on islands or offshore production platforms over long distance submarine
cables. This capability can eliminate the need for running expensive local generation or provide an outlet for
offshore generation such as that from wind. The VSC converters can operate at variable frequency to more
efficiently drive large compressor or pumping loads using high voltage motors.
E. Power Delivery to Large Urban Areas
Power supply for large cities depends on local generation and power import capability. Local
generation is often older and less efficient than newer units located remotely. Often, however, the older, less-
efficient units located near the city enter must be dispatched out-of-merit because they must be run for voltage
support or reliability due to inadequate transmission. Air quality regulations may limit the availability of these
units. New transmission into large cities is difficult to site due to right of way limitations and land use
constraints.
Compact VSC-based underground transmission circuits can be placed on existing dual-use rights-of-
way to bring in power as well as to provide voltage support allowing a more economical power supply without
compromising reliability. Furthermore, the dynamic voltage support offered by the VSC can often increase the
capability of the adjacent ac transmission.
IV. CORE HVDC TECHNOLOGIES
Interconnecting HVDC within an AC system requires conversion from AC to DC and inversion from
DC to AC. We refer to the circuits which provide conversion from AC to DC as rectifiers and the circuits which
provide conversion from DC to AC as inverters. The term converter is used to generically refer to both rectifiers
and inverters. Converter technologies are based on use of switching devices collectively referred to in the
HVDC community as valves. Valves may be non-controlled or controlled. A controlled valve comprising
usually of thyristors has a similar characteristic to non-controlled valves except that it requires a gate pulse to
turn on. Two basic converter technologies are used in modern HVDC transmission systems. These are
4. HVDC Transmission System Using 6-Pulse IGBT Converter
40
conventional line- commutated, current source converters (CSC) and self-commutated, voltage-sourced
converters (VSC) [8]-[11].
A. Line-Commutated, Current-Sourced Converter
Conventional HVDC transmission employs line-commutated, current-source converters (CSC) with
thyristor valves. Such converters require a synchronous voltage source in order to operate. The basic building
block used for HVDC conversion is the three-phase, full-wave bridge referred to as a
6-pulse or Graetz bridge. The term 6-pulse is due to six commutations or switching operations per period
resulting in a characteristic harmonic ripple of 6 times the fundamental frequency in the dc output voltage. Each
6-pulse bridge is comprised of 6 controlled switching elements or thyristor valves. Each valve is comprised of a
suitable number of series-connected thyristors to achieve the desired dc voltage rating. Line-commutated current
source converters can only operate with the alternating current lagging the voltage so the conversion process
demands reactive power.
Fig. 2. HVDC thyristor valve arrangement
B. Self-Commutated Voltage-Sourced Converter
HVDC transmission with VSC converters can be beneficial to overall system performance. VSC
converter technology can rapidly control both active and reactive power independently of one another. Reactive
power can also be controlled at each terminal independent of the dc transmission voltage level. This control
capability gives total flexibility to place converters anywhere in the AC network since there is no restriction on
minimum network short circuit capacity. Self commutation with VSC even permits black start, i.e., the
converter can be used to synthesize a balanced set of three phase voltages like a virtual synchronous generator.
The dynamic support of the ac voltage at each converter terminal improves the voltage stability and can increase
the transfer capability of the sending and receiving end AC systems thereby leveraging the transfer capability of
the DC link.
Fig. 3. HVDC IGBT valve arrangement
V. HVDC CONTROL & OPERATING PRINCIPLES
A. Conventional HVDC
For conventional HVDC transmission one terminal sets the dc voltage level while the other terminal(s)
regulates the (its) dc current by controlling its output voltage relative to that maintained by the voltage setting
terminal. Since the dc line resistance is low, large changes in current and hence power can be made with
5. HVDC Transmission System Using 6-Pulse IGBT Converter
41
relatively small changes in firing angle, alpha. Two independent methods exist for controlling the converter dc
output voltage. These are 1) by changing the ratio between the direct voltage and the ac voltage by varying the
delay angle or 2) by changing the converter ac voltage via load tap changers (LTC) on the converter
transformer. The former method is rapid whereas the latter method is slow due to the limited speed of response
of the LTC.
Fig. 4. Control of conventional HVDC transmission
B. VSC-Based HVDC
Power can be controlled by changing the phase angle of the converter ac voltage with respect to the
filter bus voltage, whereas the reactive power can be controlled by changing the magnitude of the fundamental
component of the converter ac voltage with respect to the filter bus voltage. By controlling these two aspects of
the converter voltage, operation in all four quadrants is possible. This means that the converter can be operated
in the middle of its reactive power range near unity power factor to maintain dynamic reactive power reserve for
contingency voltage support similar to a static var compensator. It also means that the real power transfer can be
changed rapidly without altering the reactive power exchange with the ac network or waiting for switching of
shunt compensation.
Fig. 5. Control of VSC-based HVDC transmission
VI. PROPOSED 6-PULSE HVDC TRANSMISSION SYSTEM MODEL
In the proposed model a 500 MW (250 kV, 2 kA) DC interconnection is used to transmit power from a
315 kV, 5000 MVA AC network. The network is simulated by a LLR damped equivalent (impedance angle of
80 degrees at 60 Hz and 3rd harmonic). The converter transformer and the rectifier are modeled respectively
with the Universal Transformer and Universal Bridge blocks The converter used is a 6-pulse rectifier. It is
connected to a 300 km distributed parameter line through a 0.5 H smoothing reactor LsR. The inverter is
simulated by a simple DC voltage source in series with a diode (to force unidirectional conduction) and
smoothing reactor LsI. The reactive power required by the converter is provided by a set of filters (C bank plus
5th, 7th and high pass filters; total 320 Mvar). The filter toplogy is depicted in Fig.6. The usage of a circuit
breaker allows to application of DC line fault on the rectifier side.
The control system uses two main blocks: the Synchronized 6-pulse generator and a PI Current
Regulator. Voltages sent to the synchronization system are filtered by 2nd order band pass filters. The whole
control system is discretized (Sampling interval = 1/360/64 = 43.4 μsec). The DC line current at the output of
the rectifier is compared with a reference. The PI regulator tries to keep the error at zero and outputs the alpha
6. HVDC Transmission System Using 6-Pulse IGBT Converter
42
firing angle required by the synchronizing unit to maintain minimum error. Inputs of the current regulator allow
to bypass the regulator action and to impose the alpha firing angle.
Fig. 6. AC filter topology (320 Mvar) HVDC
Fig. 7. Proposed model of HVDC Transmission system
VII. SIMULATION RESULTS AND DISCUSSION
The proposed model was simulated using MATLAB version 7.9.0.2601 (R2009b). The system is
programmed to start and reach a steady state. Then, a step is applied on the reference current to observe the
dynamic response of the regulator. Finally a DC fault is applied on the line. The simulation results are shown in
Fig.7.In the figure Trace 1 shows the reference current Idref (magenta) and the variation in measured current Id
(yellow) in per units (pu). Trace 2 shows the alpha firing angle in degree (deg.) required to reach the reference
current. Finally Trace 3 depicts fault current Ifault variation in amperes (A).
For our simulation reference current Idref is initially set to 0.5 pu (1kA).On starting simulation the direct
current Id starts from zero and reaches a steady-state in 0.1 s as depicted in trace 1. Trace 2 shows the alpha
firing angle required to obtain 0.5 pu of reference current is 30 degrees.
Fig. 8. Simulation result of proposed model
Further at t = 0.3 s, the reference current was increased from 0.5 pu (1 kA) to the nominal current 1pu
(2 kA). The current regulator responds in approximately 0.1 s and tries to reach new steady state value. In the
7. HVDC Transmission System Using 6-Pulse IGBT Converter
43
mean time the alpha angle decreases from 30 degrees to 15 degrees. So we can conclude that the model has a
very low response time and the controller starts transition as soon as the reference current is altered.
Now to depict fault management of the model at t = 0.5 s, a DC fault is applied on the line. The fault
current Ifault in trace 3 increases to 5 kA and the Id current increases to 2 pu (4 kA) in 10 ms. Then, the fast
regulator action lowers the current back to its reference value of 1 pu. At approximately t = 0.55 s, the alpha
angle is forced by the protection to reach 165 degrees thereby making the Forced_alpha input of the current
regulator high. The rectifier thus passes in inverter mode and sends the energy stored in the line back to the 345
kV network. As a result, the arc current producing the fault rapidly decreases. The fault is cleared at t = 0.555 s
when the fault current zero crossing is reached. At t = 0.57 s, the regulator is released from inverter mode, it
goes back into rectifier mode and it starts to regulate the DC current again. The steady-state 1 pu current is
finally reached at t = 0.75 s.
The harmonics present on the AC system are (6k±1). Thus the AC harmonic filters are tuned to the 5th,
7th, 11th, and 13th harmonics to reduce the harmonic content in the voltages and currents in the AC network to
acceptable levels. Higher harmonics thus would not penetrate very far into the system. The harmonics are
mainly present in the AC current as the AC voltage is heavily dependent on the system itself. The Harmonics
present on the DC side are mainly on output voltage. These are in multiples of 6 as the waveform repeats itself 6
times. The DC is smoothed by the smoothing reactors.
VIII. ADVANTAGES AND DRAWBACKS
The advantages HVDC transmissions have can be enumerated as:
‾ More power can be transmitted per conductor per circuit.
‾ Use of Ground Return Possible.
‾ Smaller Tower Size.
‾ Higher Capacity available for cables.
‾ No skin effect.
‾ Less corona and radio interference.
‾ No Stability Problem.
‾ Asynchronous interconnection possible.
‾ Lower short circuit fault levels.
The inherent problems associated with HVDC are summarized hereunder:
‾ Expensive convertors.
‾ Reactive power requirement.
‾ Generation of harmonics.
‾ Difficulty of circuit breaking.
‾ Difficulty of voltage transformation.
‾ Difficulty of high power generation.
IX. ECONOMIC COMPARISIONS
The HVDC system has a lower line cost per unit length as compared to an equally reliable AC system
due to the lesser number of conductors and smaller tower size. However, the DC system needs two expensive
convertor stations which may cost around two to three times the corresponding AC transformer stations. Thus
HVDC transmission is not generally economical for short distances, unless other factors dictate otherwise.
Economic considerations call for a certain minimum transmission distance (break-even distance) before HVDC
can be considered competitive purely on cost. Estimates for the break even distance of overhead lines are around
500 km with a wide variation about this value depending on the magnitude of power transfer and the range of
costs of lines and equipment. The breakeven distances are reducing with the progress made in the development
of converting devices.
Fig. 9. Break-even distance for DC transmission
8. HVDC Transmission System Using 6-Pulse IGBT Converter
44
Figure 9 shows the comparative costs of DC and AC links with distance, assuming a cost variation of ±
5% for the AC. link and a variation of ± 10% for the DC link. For cables, the break-even distance is much
smaller than for overhead lines and is of the order of 25 km for submarine cables and 50 km for underground
cables.
X. CONCLUSION
Today HVDC is very important issue in transmission energy. In near future this technology probably
will be developed very intensively. Influence on future may have intensive spread of renewable energy source,
also wind farm which need undersea connections. Also problem of cascade blackout can be reduced by
application of HVDC. To implement the grid that is required for the future, collaborative planning is needed
using a long term, system perspective.
In order to capture the full scale of benefits that high capacity technologies such as 765-kV and HVDC
provide, the system must be examined on an interregional scale that matches the reach of those benefits. Some
keys to success include: adoption of interconnection wide planning criteria and assumptions focusing on broad
system solutions.
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