3. INTRODUCTION
A high voltage, direct current(HVDC) electric power
transmission system(also called a power super highway)
uses direct current for the bulk transmission of electric
power.
It’s especially useful for long distance and underwater
power transmission.
The longest HVDC link in the world is the Rio Madeira link
in Brazil(2*±600kV,3150MW)
In India, the longest HVDC link is the Talcher-Kolar
transmission link(1450km long) of 500kV,with a rated
capacity of 2500MW.
5. ComparisonbetweenACandDCTransmission
Lower overall
investment cost
for point to point
transmission.
Less conductor
cost due to
absence of skin
effect.
Losses are less as
dc has only active
power.
DC Higher
investment cost.
Higher conductor
cost as three
phases have to
be supported.
Losses are more
as ac has both
active and
reactive power.
AC
9. MONOPOLAR LINK
A monopolar system has only one conductor with
ground as return conductor and it is usually of a
negative polarity.
It is suitable in submarine systems where sea water
can be used as return path.
10. BIPOLAR LINK
A bipolar system has two conductors, one of positive
and other of negative polarity.
The ground point is maintained at the mid-potential.
Each terminal of a bipolar system has two converters
of equal voltage rating connected in series.
11. HOMOPOLAR LINK
Homopolar system has two or more conductors with
same polarity, usually negative and they always operate
with ground return.
In the event of fault in one conductor, the whole
converter can be connected to a healthy pole.
15. HVDC offers powerful alternativeto increase
stability of a power system as well as to improve
system flexibilityand loss reduction.
Inthe present times, the increasingnumber of
HVDC transmissionprojects shows the potential
and scope of HVDC.
CONCLUSION
