Introduction to HVDC systems are well explained in it.

1. 1
HVDC SYSTEMS
Prepared By:
INDUBHUSHAN KUMAR
Phd* (NITKKR) , M.Tech (IITR), B.Tech (WBUT)

2. 2
Introduction
To
HVDC Transmission
Systems

3. 3
• Both Electrical Sciences and practical applications of
electricity began with direct current.
•.Electric lighting and power - using DC generators
(run by steam engines).
•First electric station (1882) – By Edison in New York.
- 110V, U/G upto 1 mi.
• With initial supremacy, why ac replaced dc?
• Why again dc is being used for long HV transmission?
•In 1880s & 1890s, Transformers, Induction motors, poly-phase
circuits, steam turbines etc.
• Controversy over supremacy of ac v/s dc arises.
• But due to advantages of ac systems, ac systems became universal.
Gen. Trans. Dist. & Utilization – all ac
If dc needed – by rectification.
• Victory of ac over dc was almost complete.

4. 4
• Despite it, some engineers never forgot the advantages of dc transmission
• They supplemented ac with dc.
- parallel DC link with ac
- interconnected two ac systems with dc line.
 requires converters:
one at sending end & other at receiving end.
 converters of high voltage & power needed.
• Converters – an assembly of controlled switches
• Valves – Devices having inherent un-directional conduction.
Mercury Arc Convertors (1903) – Thyratrons
Silicon Controlled Rectifiers (1960) – Thyristors
• First commercial application – Between Swedish mainland
& Gotland island (1954)
- 20 MW, 90 km underwater link.
• First HVDC system using thyristors - Eel river scheme (1972)
- Between New Brunswick & Quebec (Canada)
- 320 MW back-to-back.

5. • Mercury Arc Valves
– First 25 years (1950- 1975)
• Line Commutated Devices (Thyristor)
– Second 25 years(1975-2000)
• Self Commutated Converters (IGBT, GTO)
– Next 25 years (from 2000)
Developments of HVDC

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Main Applications of HVDC Systems
1. Bulk power transmission over long distances
- AC systems not feasible (> 600 km)due to stability
- Series & Shunt compensation requirements.
- Beyond 600 km, HVDC is the better option.
2. Underwater cables longer than 30 km.
- AC systems impractical
(due to high charging currents)
3. Asynchronous link between two ac systems
- AC link may not be feasible due to
(i) stability problem
(ii) two different operating frequencies.

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(a) AC Transmission System
(b) DC Transmission System
1. Single circuit - 3 conductors
2. Double circuit – for higher reliability
3. Series & Shunt compensation
- Two conductors
- Sometimes only one. Ground as return path.
Two conductor DC line = Double circuit 3φ ac line

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Point-to-Point
(with DC line)
Back-to-Back
(Without DC line)
Two terminal
• Mono-polar
• Bipolar
• Homo-polar
Multi-terminal
Two-terminal links

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10. Mono-polar CSC-HVDC system with 12-pulse converters
Bipolar CSC-HVDC system with one 12-pulse converter per pole
Back-to-back CSC-HVDC system with 12-pulse converters

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Back-to-back Link
(a) Line with parallel tap
Multi-terminal links
(b) HVDC Ring System
(c) Series connected system
Constant voltage scheme
Constant current scheme

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13. HVDC Components
13
Converter Transformer
Converter
DC Smoothing Reactor
AC Filter
DC Filter

15. 15
REFERENCES :
1. E. W. Kimbark, “Direct Current Transmission”, Wiley Interscience, New
York, 1971.
2. E. Uhlmann, “Power Transmission by Direct Current”, Springer-Verlag,
Berlin, 1975.
3. K. R. Padiyar, “HVDC Power Transmission Systems, New Age
International (P) Ltd., New Delhi, 1990 & 2nd Ed., 2010.
4. J. Arrillaga, “High Voltage Direct Current Transmission”, II Ed., IEE
Power Engineering series, London, 1998.
5. P. Kundur, “Power System Stability and Control”, Tata-McGraw Hill,
(Chapter 10), New Delhi, 2006.
6. X-Fan Wang, Y. Song and Malcolm Irving, “Modern Power Systems
Analysis, (Chapter 5), Springer, 2008.
7. S. Kamakshaiah & V Kamaraju, “HVDC Transmission”, McGraw Hill, 2011
8. V. K. Sood, “HVDC and FACTS Controllers: Applications of Static
Converters in Power Systems ”, Kluwer Academic Publishers, New York,
2004.
9. J. Arrillaga, Y. H. Liu and N. R. Watson, “Flexible Power Transmission:
The HVDC Options”, John Wiley and Sons, 2007.
10. Chan-Ki Kim, V. K. Sood, Gil-Soo Jang, Seong-Joe Lim and Seok-Jin Lee,
“HVDC Transmission: Power Conversion Application in Power Systems”,
Wiley, 2009.