Concept of HVDC transmission system and why it is necessary these days.

1. Presented by: Guided by:
 Vinay Vishwakarma Er. Gaurav Kumar Mishra
 Yogesh Mishra Head of Electrical Engg.
 Devesh Pandey
 Ashish Tiwari
 Ravi Mishra
 Amit Shukla
Department Of Electrical Engineering
6th Semester

3. 1. INTRODUCTION
2. HISTORY OF HVDC
3. PROCESS DIAGRAM
4. THE LINK BETWEEN RIHAND TO DADRI
SUBSTATION
5. COMPONENT USED
6. WHY HVDC IS NECESSARY OVER AC
7. LIMITATION OF HVDC
8. APPLICATION OF HVDC
9. THE FUTURE PROSPECTS
10. CONCLUSION

4. • A high-voltage, direct current (HVDC) electric power
transmission system uses direct current for the bulk
transmission of electrical power.
• For long-distance transmission, HVDC systems may be less
expensive and suffer lower electrical losses.
• High voltage is used for electric power transmission to reduce
the energy lost in the resistance of the wires.
• Recent developments in conversion equipment have reduced
their size and cost and improved their reliability.
• The major components of a HVDC transmission system are
converter stations where conversion from AC to DC and from
DC to AC are performed.

5. • Firstly HVDC between Swedish and Gotland in 1954.
• In North America, total HVDC transmission capacity in
1987 was 14,000MW.
• First HVDC is commissioned in India in 1990 at Rihand to
Dadri(near Delhi).
• Distance between stations is 814 km.
• It transfer the power at ±500 KV and 1500 MW.

7. 6V/12V---12V AC to 12V DC—transmission– 12V DC to 12V AC---
12V/6V– sub transmission– 6V/3V--- distribution and lightning.

8. • Converter Transformer
Step up Transformer ( at Generation Station).
Step up Transformer (at Substation).
Step down Transformer (at Distribution).
• Rectifier is a static device which converts AC into Pulsating
DC voltage.
• Filter is used to make the ripple free supply (pure DC).
• Invertor is a static device which converts DC into AC voltage
with desired frequency.
• Power LEDs is used for lightning a plant.

9. The reasons for selecting HVDC instead of HVAC are :-
1. Lower cost at operating condition.
2. Lower transmission losses.
• As only two conductor are required in HVDC hence I2R losses are
low for same power transfer.
3. Cheaper in cost.
• Require two wire for transmission but AC needs Three wire.
• Size of Pole, Insulators, Cross Arm are to be reduced.
• The phase to phase clearance, phase to ground clearance and tower size
are smaller in case of DC transmission.
4. Asynchronous interconnections.
• A DC link can be used to inter-connect two AC systems of different
frequency.

10. 6. No Skin effect:
 There is no skin effect in DC, because skin effect is directly
proportion to frequency and hence there is uniform distribution of
current over the cross-section of the conductor.
7. Better voltage regulation.
• Because there is no inductance and capacitance therefore voltage
regulation is 0%.
7. Absence of charging current.
8. Low short circuit currents.
9. Direct Current saves forest and lands.

12. ADVANTAGES OF HVDC

13. 1. Costly terminal equipments.
• The convertors required at both the ends are more
expensive.
• The convertors produce a lot of harmonics both on DC and
AC sides and may cause Radio Interference.
• To remove ripples from the DC output, filtering &
smoothening equipments are to be provided.
2. More maintenance of insulators is required in HVDC
system.
3. Complexity of control.
4. Voltage transformation is not easier in case of DC system.

14. 1. For long distance high power transmission.
2. For interconnection (tie lines) between two or more AC
systems having their own load frequency control.
3. For back to back asynchronous tie substation where two AC
systems are interconnected by a convertor substation without
any AC transmission line in between.
4. For underground or submarine cable transmission over long
distances at high voltage.

15. There are the following future aspects of the project as:
1. The complete system from generation to distribution is in the
from of DC i.e. possible by using power electronics circuits.
2. By using DC Choppers in place of transformers, we have
resolved complete system into DC system.

16. • Availability of non- renewable resources is limited.
• HVDC is used for increasing the efficiency of transmission
lines.
• Dependency of source from foreign countries are to be reduced.
• HVDC transmission line gives the Reliable, Economical and
Stable supply as compares to AC.

17. ANY QUERY……