What does it do?
HVDC transmits great amounts of electrical power over long distances.
Compared to alternating current, the direct current system is less expensive
and loses less energy. HVDC can be transmitted through cables both underground
How does it work?
HVDC transmission utilizes a converter station at either end of the
system. A mercury arc valve or solid state valve (thyristor) is used
for the conversion of AC and DC current. The valve at the beginning
of the system converts alternating current to HVDC, the HVDC travels
to the next location through a cable, and the valve at the end of the
system converts the HVDC back to alternating current.
How will it be used in
HVDC is being considered globally for renewable energy efforts. Since
HVDC allows for more power to travel long distances with fewer lines
and reduced losses, clean energy can efficiently travel to distant locations.
Wind farms located in the
best natural wind areas of the Midwest could deliver power a few hundred
miles by HVDC to Chicago or Denver.
Central Quebec has numerous
hydroelectric generating stations in extremely remote areas which could
send power directly to New York City or Boston.
The first successful HVDC
experimental long distance line (37 miles) was made at Munich, Germany
in 1882 by Oskar Von Miller and fellow engineers. These
same pioneers moved on to work on AC power the next year and did not
do much in the HVDC field after that. Miller and associates pioneered
AC power in the 1883-1890s era. Their important early DC work laid the
foundation for future developments.
Later Work, US and Europe:
Thomas Edison and fellow
engineers worked on HVDC as part of a plan to make a standard DC "grid".
AC power quickly proved to be easier to work with for long distance.
The 1891 Electro-technical Exposition
in Frankfurt, Germany was the definitive end of the war of currents,
however a small number of people continued to develop DC transmission
Albert Hull (General Electric)
Albert Hull (GE) developed
the thyratron, and used it on an experimental HVDC line near
Mechanicville, NY in 1936, meanwhile
in Nazi Germany engineers were making great advances in the field as
After the war companies like
ASEA (today ABB) and Siemens were ahead in development and they developed
the first HVDC lines to cross waterways like that between Sweden and
Denmark. There was more of a market for HVDC in Europe and Japan since
HVDC could deliver power under long waterways when AC could not. ASEA
had also employed some of the original German HVDC pioneers after the
war, giving them an advantage over competition. General Electric also
was involved in making HVDC systems but exited the business in the 1980s.
1940 - First modern
HVDC line was under construction between Dessau and Berlin, it was captured
by the Russians and fully completed in 1951 between Kashira and Moscow.
Some US utilities have been
and still are resistant to HVDC despite the advantage to the customers.
The localized power providers do not want cheap energy coming in from
outside their region. In New York State for example, unions of the local
power production facility workers fight HVDC because it would mean lower
energy prices and this would effect profits of local producers. Despite
this resistance North America still has many HVDC lines and is installing
more as time goes on.
ASEA had developed and implemented
solid state switching in 1962. This was the future of HVDC. Today HVDC
systems are highly advanced, safe, and have efficient solid state switching.
Terms of interest:
Thyristor - a semiconductor
switch allowing power to flow in one direction only. In HVDC thyristors
convert AC to DC power, or back to AC. The term thyristor is usually
used to describe a switch with at least four layers of n and p-type
material. Learn more about semiconductor switches here.
In HVDC thyristors are placed in series in tall stacks, often hung off
the floor in an enclosed building.
Mercury Arc Rectifiers - Glass envelopes which contained mercury,
used for rectifying power. When the temperature would heat up enough
to vaporize the mercury, current would pass through the tube through
the vapor to the other side. It was replaced by the thyristor. Example
uses: They were used to convert AC power to DC for the New York City
subway system, and for early electric car chargers, as well as HVDC
systems before the 1960s. See our page on these devices here.
Node - ending or starting point of an HVDC line
Rectification - the
passing of current in only one direction, thyristors will rectify AC
Written by Breanna Day and M. Whelan Volunteer at the Edison Tech Center
and celebrate engineering past, present, and future!
Glenn Breuer. Edison Tech Center. 2012
NODE: HVDC. by Dutch Research Platform for Sustainable Energy
Deutsches Museum, Munich, Germany
ABB company. Switzerland
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