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info hunter

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24-09-2010, 11:04 AM

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.

HVDC Light is the newly developed HVDC transmission technology, which is based on extruded DC cables and voltage source converters consisting of Insulated Gate Bipolar Transistors (IGBT’s) with high switching frequency. It is a high voltage, direct current transmission Technology i.e., Transmission up to 330MW and for DC voltage in the ± 150kV range. Under more strict environmental and economical constraints due to the deregulation, the HVDC Light provides the most promising solution to power transmission and distribution. The new system results in many application opportunities and new applications in turn bring up new issues of concern. One of the most concerned issues from customers is the contribution of HVDC Light to short circuit currents. The main reason for being interested in this issue is that the contribution of the HVDC Light to short circuit currents may have some significant impact on the ratings for the circuit breakers in the existing AC systems. This paper presents a comprehensive investigation on one of the concerned issues, which is the contribution of HVDC Light to short circuit currents.

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.pdf   14cd83a92f6a0.pdf (Size: 614.8 KB / Downloads: 452)
.pdf   7360181-HVDC-Transmission-Lines.pdf (Size: 331.32 KB / Downloads: 456)
.pdf   19965158-HVDC-Final.pdf (Size: 620.31 KB / Downloads: 451)
.pdf   27947633-HVDC-Light-Paper.pdf (Size: 221.07 KB / Downloads: 429)
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24-09-2010, 11:09 AM


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.pdf   27947637-Hvdc-Light-Technology.pdf (Size: 240.21 KB / Downloads: 233)
.pdf   29149492-Hvdc-Light.pdf (Size: 278.79 KB / Downloads: 195)
.pdf   36605012-HVDC-for-Beginners.pdf (Size: 5.86 MB / Downloads: 332)
.pdf   Extruded_Cables_for_HVDC_Power_Transmission.pdf (Size: 1.48 MB / Downloads: 198)
.pdf   Short Circuit Current Contribution of.pdf (Size: 149.49 KB / Downloads: 192)
.pdf   Panel-02-1_Overview_of_HVDC_Transmission.pdf (Size: 1.36 MB / Downloads: 201)
.pdf   Power Semiconductors in Transmission and Distribution Applications.pdf (Size: 316.74 KB / Downloads: 187)
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04-10-2010, 04:20 PM

.ppt   HVDC Light.ppt (Size: 1.26 MB / Downloads: 328)

.doc   hvdc.doc (Size: 874 KB / Downloads: 258)
HVDC Light


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. The HVDC (High Voltage Direct Current) technology is used to transmit electricity over long distances by overhead transmission lines or submarine cables. It is also used to interconnect separate power systems. A further development in this technology is HVDC light where HVDC light converters are used for faster and efficient conversion of power.

HVDC Light is a fundamentally new power transmission technology developed recently. It is particularly suitable for medium to small-scale power transmission applications. This new transmission and distribution technology, HVDC Light provides an important role to today’s requirements on our network systems and opens up new opportunities for both investors and environmentalist alike.

HVDC light technology for transmission of electric power is introduced in this paper. Its features, advantages and applications are pointed out. HVDC cables, their design, underground laying, their advantages and applications are also added. The paper also gives a note on the advantages of HDVC light cables over AC underground cables.
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23-12-2010, 04:37 PM


.ppt   HVDC LIGHT.ppt (Size: 1.12 MB / Downloads: 148)

Competition in the electricity power industry, coupled with continued load growth require that the existing transmission system assets are utilised more effectively and some times closer to their technical limits.
One solution would be to simply build new, more powerful AC lines.
It is getting increasingly difficult to obtain permits to build new high voltage overhead transmission lines, the right-of-way occupies valuable land.
People are increasingly concerned about the possible health hazards of living close to overhead lines.

The reforms that have or are being introduced in the electricity sector in many countries have radically changed the business environment of the electricity supply industry .
Recent development efforts in transmission technology have focussed on compact, small weight and cost-effective, so-called voltage source converters (VSC ).
By combining the advances made in VSC and DC cables, a new breed of electricity transmission and distribution technology emerges: The "HVDC Light" technology.

Transmission of electricity over long distances using underground DC cables is both economical and technically advantageous .
Laying an underground cable is an easier process than building an overhead line.
Hvdc light technology is also known as “the invisible power transmission” since it is based on underground cables.
Possible application fields include the feeding of distant loads and the connection of distant generation plants.
In Australia, at Direct Link and Murray link, we have two such examples where HVDC Light technology with underground DC-cables has been implemented in a competitive, market-oriented network service.

HVDC Light is a high voltage, direct current transmission technology and is well suited to meet the demands of competitive power market for transmission up to 330MW and for a DC voltage in the ± 150kV range.
It is a well-proven and environmentally-friendly way to design a power transmission system for a submarine link, an underground cable system or network interconnection.
HVDC Light® can rapidly control both active and reactive power independently of each other, to keep the voltage and frequency stable.
An HVDC Light transmission system can do much more than just transmit power between two points – it can also improve conditions in the connected AC networks.

HVDC Light converter station design is based on a modular concept.
It consists of two AC to DC converter stations and a pair of underground cables interconnecting each converter station .

The site areas needed for converter stations is also minimal.
The AC to DC converters employ the latest in power semiconductor technology, the IGBT (Insulated Gate Bipolar Transistor).
This technology provides the HVDC Light converter with a switching speed 27 times faster than a traditional HVDC, thyristor controlled converter.
This fast control makes it possible to create any phase angle or amplitude which can be done almost instantaneously providing independent control of both active and reactive power.
While the transmitted active power is kept constant the HVDC Light converter can automatically control the voltage of the connected AC network by compensating the generation and consumption of reactive power within the capacity of its rating .
The HVDC Light cable is a new design triple extruded, polymeric insulated DC-cable, which has been successfully type tested to150kV DC, following a comprehensive R & D program .
The cables are operated in bipolar mode, one cable with positive polarity and one cable with negative polarity.

By operating the cables with anti-parallel currents, the overall magnetic field of the cables is nearly eliminated, which is another positive aspect of HVDC Light technology.
The main advantage of ‘HVDC Light’ cables over their HVAC counterparts is their reduced weight and dimensions, which result in a higher power density.
This strength and flexibility make the HVDC Light cables perfect for severe installation conditions:
The land cables can be installed less costly with ploughing technique.
The submarine cables can be laid in deeper waters and on rough seabeds.
HVDC cables can also be installed as overhead cables.

Conventional HVDC converter technology is based on the use of line-commutated or phase-commutated converters (PCC). With the appearance of high switching frequency components, such as IGBT’s (Insulated Gate Bipolar Transistor) it becomes advantageous to build VSC (Voltage Source Converters) using PWM (Pulse Width Modulation) Technology.
HVDC Light uses Pulse Width Modulation to generate the fundamental voltage.
It controls the magnitude and phase of the voltage freely and almost instantaneously and allows independent and very fast control of active and reactive power flows.

The key part of the HVDC Light converter consists of an IGBT valve bridge.
No special converter transformers are necessary between the valve bridge and the AC-grid
A converter reactor can separate the fundamental frequency from the raw PWM waveform.
If the desired DC voltage does not match the AC system voltage, a normal AC transformer may be used in addition to the reactor.
A small shunt AC-filter is placed on the AC-side of the reactor.
On the DC-side there is a DC capacitor that serves as a DC filter.

The fundamental voltage across the converter reactor defines the power flow between the AC and DC sides.
Changing the phase angle between the fundamental frequency voltage generated by the converter and the voltage on the AC bus controls the active power flow between the converter and the network.
The reactive power flow is controlled by the width of the pulses from the converter bridge.
A VSC transmission system will be a very valuable asset during a grid restoration which is exposed to the blackout
It will be available almost instantly after the blackout and does not need any short circuit capacity in order to become connected to the grid.


Once it's installed the cable route can be replanted with Native vegetation.
Reduced environmental impact.
Underground cables rarely meet with public opposition and often receive political support.
The system reliability is enhanced with reduced risk of damage from natural causes such as storms, wind, earthquakes and fire. You simply bury it and forget it.
Operation and maintenance costs of the transmission easement are virtually eliminated.
The width of the corridor to install the underground cable can be as narrow as 4 metres, which will give greater flexibility with the selection of a transmission route.
Connection to a wind farm
Connection of small dispersed electricity generators to a grid
Delivery of electricity to islands
Feeding electric power to large and rapidly growing cities
Feeding of electric power to remotely located loads

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23-06-2011, 08:08 PM

please sent me more details on the abve mentioned topic of HVDC Transmission.
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30-08-2011, 09:52 AM

.pdf   HVDC trnasmission using voltage..pdf (Size: 873.14 KB / Downloads: 98)
Rapid developments in the field of power electronic devices with turn off capability like insulated gate bipolar transistors (IGBT) and gate turn off transistors (GTO), makes the voltage source converters (VSC) getting more and more attractive for High voltage direct current transmission (HVDC).This new innovative technology provides substantial technical and economical advantages for direct applications compared to conventional HVDC transmission systems based on thyristor technology. VSC Application for HVDC systems of high power rating (up to 200MW) which are currently in discussion for several project and implimentations are mentioned. The underlying technology of VSC based HVDC systems, its Characteristics and the working principle of VSC based HVDC system are also presented. This paper concludes with a brief set of guidelines for choosing VSC based HVDC systems in today’s electricity system development.
The development of power semiconductors, especially IGBT's has led to the small power HVDC transmission based on Voltage Source Converters (VSCs). The VSC based HVDC installations has several advantages compared to conventional HVDC such as, independent control of active and reactive power, dynamic voltage support at the converter bus for enhancing stability possibility to feed to weak AC systems or even passive loads, reversal of power without changing the polarity of dc voltage (advantageous in multi terminal dc systems) and no requirement of fast communication between the two converter stations .Each converter station is composed of a VSC. The amplitude and phase angle of the converter AC output voltage can be controlled simultaneously to achieve rapid, independent control of active and reactive power in all
four quadrants. The control of both active and reactive power is bi-directional and continuous across the operating range. For active power balance, one of the converters operates on dc voltage control and other converter on active power control. When dc line power is zero, the two converters can function as independent STATCOMs. Each VSC has a minimum of three controllers for regulating active and reactive power outputs of individual VSC.
The world of converters may be divided in to two groups that are to be distinguished by their operational principle.
One group needs an AC system to operate and called as line commutated coverters.Conventional HVDC systems employ line commutated converters.
The second group of converters does not need an AC system to operate and is therefore called as self commutated converters. Depending on the design of the DC circuits this group can be further divided in to current source converters and voltage source converters. A current source converter operates with a smooth DC current provided by a reactor, while a VSC operates with a smooth DC voltage provided by storage capacitor. Among the self commutated converters it is especially the VSC that has big history in the lower power range for industrial drive applications.
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05-03-2012, 09:50 AM

to get information about the topic HVDC TRANSMISSION SYSTEMS full report ppt and related topic refer the link bellow





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