High voltage direct current transmission and its applications

1. Name: Pooja Dubey
Course: EEE
Roll No:120104026

2. HVDC
Transmission
Components
of HVDC
HVDC LINKS
Advantage of HVDC
Comparison of HVDC AND HVAC
Applications of HVDC
CONCLUSION

3. HVDC Transmission
Transmitting power at high voltage and in DC fo
rm instead of AC is a new technology proven to
be economic and simple in operation which is
HVDSCinctera onusrm ission.
primary
source is A.C,
The three
basic
steps are:-
1. Convert AC into DC
(rectifier)
2. Transmit DC
3. Convert DC into AC
(inverter)

4. Wind
Power
AC
Transmision
Line
Converter
Station
Inverter
Station
AC Transmission
Line
Distribution
Line
HVDC
Transmission Line

5. 1) Converters
2) Smoothing reactors
3) Harmonic filters
4) Reactive power source
5) Electrodes
6) Dc lines
7) Ac circuit breakers

7. HVDC Transmission can be broadly classified
into:-
Monopolar link
Bipolar link
Homopolar link

8. It uses one conductor.
The return path is provided by ground or water.
Use of this system is due to cost considerations.
Ametallic return may be used where earth resistivity is too high

9. Each terminal has two converters of equal rated voltage, connected
in series on DC side.
The junctions between converters is grounded.
If one pole is isolated due to fault, the other pole can operate with
ground and carry half the rated load ( or more using overload
capabilities of its converter line.)

10. It has two conductors each having same polarity, usually negative.
Since the corona effect in DC transmission lines is less for
negative polarity, homopolar link is usually operated with negative
polarity.
The return path for such a system is through ground.

11. Advantages of HVDC
Technical
Advantages
Economic
Advantages

12.  Lesser Corona Loss and Radio interference.
 The voltage regulation problem is much less
serious for DC, since only the IR drop is
involved. For the same reason steady state
stability is no longer a major problem.
 No skin and proximity and ferranti effect
 Asynchronous operation possible between
regions having different electrical
parameters.

13.  DC lines and cables are cheaper than AC
lines or cables.
 The towers of the DC lines are narrower,
simpler and cheaper compared to the towers
of the AC lines.
 Line losses in a DC line are lower than the
losses in an AC lines.

14.  The disadvantages of HVDC are in conversion,
switching, control, availability and maintenance.
 There is nothing like DC transformer which can
change the voltage level in a simple way. Voltage
transformation has to be provided on the AC sides of
the system.
 The required converter stations are expensive and
have limited overload capacity.

16.  A 500V, 1500W, 810Km bipolar HVDC transmission line is
set up between Rihand & Delhi.
 In Vindhyachal back to back link is laid for exchange of
power between Northern & Western regions.

 The Talcher–Kolar is a 1450 km,200MW,
500V HVDC transmission connection between the eastern
and southern regions in India. In 2007 the scheme was
upgraded to 2500 MW.
 Undersea cables, where high capacitance causes
additional AC losses. (e.g. 250 km Baltic Cable between
Sweden and Germany) .

21. HVDC offers powerful alternative to increase stability of a
power system, with it power flow can be controlled rapidly
and accurately.
Use of HVDC to interconnect two points in a power grid, in
many cases is the best economic alternative and further
more it has excellent environmental benefits.
Very large investment for example in China and India
shows that HVDC
very important in future especially in big, new industrial
countries.