This document discusses HVDC (high voltage direct current) transmission technology. It begins with an introduction that defines HVDC and explains its use for long distance and submarine cable power transmission. It then categorizes different types of HVDC systems and configurations, including monopolar, bipolar, and homopolar links. Key components of HVDC systems like converters, smoothing reactors, and reactive power supplies are also outlined. The document compares HVDC to HVAC transmission and lists advantages like lower transmission losses over long distances. It concludes by noting that while HVDC has high initial costs, the overall costs are lower than HVAC transmission due to reduced line losses and maintenance needs.

1. HVDC AND LINKS
 BY:G.MOHAMMED MUSTAFA
EEE-THIRD-YEAR
DHAANISH AHMED OF COLLEGE
OF ENGG.

2. INTRODUCTION
HVDC Stands for High Voltage Direct Current and
is today a well-proven technology employed for
power transmission all over the world.
HVDC 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,where traditional alternating current(AC)
connections can not be used.

3. Different Categories of HVDC Transmissions
Non-synchronous
Submarine cable
Long-distance
Overhead lines
Underground cable

4. HVDC System Configuration
HVDC links can be broadly classifield into:
Monopolar links
Bipolar links
Homopolar links

5. Monopolar Links
It uses one conductor
The return path is provided by
ground or water
Use of this system is mainly due
to cost considerations.
A Mettalic return may be used
where earth resistivity is too
high.
This configuration type is the
first step towards a bipolar link

6. Bipolar Links
Each terminal has two
converters of equal rated voltage
,connected in series on the DC
side
The junctions between the
converters is grounded
If one pole is isolated due to
fault,the other pole can operate
with ground and carry half the
rated load.

7. Homopolar Links
It has two or more conductors
all having the 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.

8. Components of HVDC Transmission
Systems
Converters
Smoothing reactors
Harmonic filters
Reactive power supplies
Electrodes
DC lines
AC circuit breakers

9. Control of HVDC systems
Objectives of Control
• Efficient and stable operation .
• Maximum flexibility of power control without
compromising the safety of equipment.
• Principle of operation of various control
systems.
• Implementation and their performance during
normal and abnormal system conditions.

10. WHY TO PREFER HVDC THAN HVAC?
Long distance transmission
Five times more energy transmits than AC
Less losses(no inductance,capacitance)
Cost of transmission medium & land is low
Maintenance & operation cost is low
Intial cost is high but overall cost is low than
AC

11. HVDC Vs HVAC

12. Comparison between the prices and
losses of AC &DC Transmission

13. Advantages
Technical
 Reactive power
requirement.
 Short circuit current.
 Independent control of ac
system.
 Fast change of energy
flow.
 Greater reliability.
Economical
 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 dc lines are
lesser tha ac lines.

14. Disadvantages
The disadvantages of HVDC are in
conversion,switching and control.
Expensive inverters with limited overload
capacity.
Higher losses in static inverters at smaller
transmission distances .
The cost of the inverters may not be offset by
reductions in line construction cost and lower
line loss.

15. Conclusion
HVDC is very important issue in transmission
energy.
Problem of cascade blackout,can be reduced
by application of HVDC.
The data collected from 31 utilities says that
forced unavailability of energy due to the
converter station is 1.72percent.
The scheduled unavailability of energy is
about five percent.

16. QUERIES????

17. THANK YOU
PRESENTED BY:
G.MOHAMMEDMUSTAFA
EEE-THIRD-YEAR
DHAANISH AHMED COOLEGE OF ENGG.