HVDC TRANSMISSION TECHNOLOGY HISTORY NEED WORKING TYPES COMPONENTS ADV AND DISADV FUTURE PROSPECT CONCLUSION

1. Submitted to:
Dr. Dinesh Birla Sir
Head of Department
A presentation on
HIGH VOLTAGE DIRECT CURRENT TRANSMISSION
RAJASTHAN TECHNICAL UNIVERSITY, KOTA
Submitted by:
Anil Saini
20/279
Session 2022-23
Department of Electrical Engineering

2. CONTENTS
S. No. Name Slide No.
1 Introduction 3
2 Need of HVDC transmission 6
3 Losses and investment cost 7
4 Working OF HVDC Transmission System 9
5 Types of DC Links 11
6 Components of HVDC Transmission System 15
7 Advantages And Disadvantages 23
8 The Future Prospect 25
9 Conclusion 26
10 Reference 27

3. INTRODUCTION
• The HVDC technology uses direct current for the bulk transmission of electrical power.
• For long-distance power transmission, HVDC lines are less expensive, and losses are less
as compared to AC transmission.

4. • The first DC link was set up in 1954 in between Swedish main land and the Island of Gotland.
HISTORY
• In 1987, the total HVDC transmission capacity in North America was 14,000 MW.
• First HVDC was set up in India in 1990 at Rihand to Dadri. It transfers the power of 500 KV
and 1500 MW.
Gotland project DC cables
Gotland HVDC project
Image source: hitachienergy.com

5. • HVAC system have more electrical losses compared to HVDC systems over long distance.
• The absence of skin effect and corona losses in DC transmission reduces power losses
marginally, which makes HVDC more economical.
• Renewable energies like solar can be directly transmitted to electrical grid without converting it
to AC.
Need to shift on HVDC system
Subsea cables

6. • HVDC terminal station are more expensive due to the fact that they must perform the
conversion from AC to DC, and DC to AC.
• But over a certain distance, the so called “break-even distance”(approx. 600-800km), the
HVDC alternative will always provide the lowest cost
Lower Transmission Cost
Image source: circuitglobe.com

7. The diagram shows a comparison of the losses in 1,200MW overhead line transmissions using AC
and HVDC.
Lower losses

8. WORKING
• In generating substation, AC power is generated which can be converted into DC by
using a rectifier.
• In HVDC substation rectifiers and inverters are placed at both the ends of a line.
• The rectifier terminal changes the AC to DC, while the inverter terminal converts DC
to AC.
• The power remains the same at the sending and receiving ends of the line.

9. Block diagram of HVDC System Operation
Image source: https://www.ti.com

10. 1. Transformer
2. Converters
3. Filters
4. Smoothing Reactor
5. DC Transmission Lines or Cables
6. Reactive Power Source
7. AC Switchgear
Components of an HVDC Transmission System

11. • The step-up transformer is used to increase the voltage level at sending end and the step-down
transformer is used to decrease the voltage level at receiving end of the line.
Transformers

12. • the converters are used in both ends of the transmission line. The rectifier is used to convert AC
to DC at sending end of the line. And the inverter is used to convert DC to AC at receiving end
of the line.
Converters

13. AC Switchgear
• The converter station consists of various protection equipment like a circuit breaker, grounding
switch, isolating switch, and lighting arresters.
• The circuit breaker is used to protect the converts against overheating. The lightning arrester is
used to protect the converter station from a lightning surge on the AC system.
• It also consists of an instrument transformer for measurement as well as control and protection
purposes.

14. Types of
DC LINKS
MONOPOLAR DC LINK
ONE CONDUCTOR & EARTH
RETURN PATH; MORE
ECONOMICAL
BIPOLAR DC LINK
TWO CONDUCTORS.
MORE RELIABLE
HOMOPOLAR DC LINK
TWO
CONDUCTORS
Same polarity

15. • One of the terminals of the converter is connected to the transmission line, while the other
terminal is connected to the ground.
• It uses only a single conductor. Hence, the design is very simple.
• It requires less maintenance.
• When a fault occurs on the conductor the entire transmission system is shut down.
Monopolar Link
MONOPOLAR LINK

16. • There are two pole/conductors. One operates at positive polarity and other is on negative
polarity.
• The Bipolar link seems to be costlier than Monopolar, but it is more reliable than Monopolar.
• The advantage of bipolar is that whenever one of the poles fails; the system operates as
Monopolar link with the ground as return path.
• Corona and radio interference is more when compared with a homo-polar link.
Bipolar Link
BIPOLAR LINK

17. • These links also use two conductors but of the same polarity. Usually of negative polarity.
• When a fault occurs on the conductor the converters of the healthy pole are quite enough to
feed the remaining conductors. Which are able to supply more than 50% of the power.
• In this type of link, the earth is used as a return conductor. It also acts as a monopolar link
during faulty conditions.
Homo Polar Link
Multi terminal Link

18. HVDC in INDIA

19. Image source: powerline magazine

20. HVDC in World
Image source: powerline magazine

21. ADVANTAGES
• More economical for very large distance transmission over HVAC.
• Less Electrical losses.
• Lesser number of conductors and insulators, therefore reduced overall cost.
• Due to the absence of the frequency factor on DC link,there is no skin effect.
• HVDC allows power transmission between unsynchronized AC transmission systems.
• The power flow through an HVDC link can be controlled independently under the
steady state condition.

22. LIMITATIONS & DISADVANTAGES
• Due to commutation problem, electrical power can’t be produced at High (DC) Voltage.
• The level of DC voltage can not be changed easily. So we can not get desired voltage for Electrical and
electronic appliances ( such as 5 volts, 9 volts, 15 volts, 22 volts etc) directly from transmission system.
• 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.
• High voltage DC circuit breakers are difficult to build.

23. The Future Prospects
• In HVDC system, reducing initial investment cost and making it more economical for shorter
distance are the 2 major challenges.
• According to Guidehouse Insights’ report Transmission System Upgrades for Renewable
Energy Integration, global HVDC revenue is expected to grow at a compound annual growth
rate of 9.5% from 2016 to 2025 and reach $12.7 billion by 2025.

24. • The development of a UHVDC transmission system is one of the latest advancements in the
HVDC transmission technology, which allows DC voltage transmission of at least 800 kV.
Which will help countries to increase electrical power supply trade opportunities.
• Renewable energy systems, such as solar and wind power projects, are often highly volatile
and located in remote areas. The ever-evolving HVDC technology is gaining ground in the new
energy economy with long-haul HVDC transmission lines that can transport power with
maximum efficiency and power minimal losses.
• HVDC lines are becoming the “electricity superhighways”, which are expediting the future of
renewable power generation systems in three ways—interconnecting existing power plants,
developing new solar power stations, and integrating offshore wind energy projects.

25. CONCLUSIONS
• Considering all the advantages of DC, it seems that HVDC lines are more proficient than AC
lines.
• But, the initial cost of HVDC substation is very high and their substation equipment is quite
complicated.
• For long distance transmission it is preferable.
• This system is economical and also improves the efficiency of the system.

26. REFERENCES
1. C.L. Wadhwa - Electrical Power System
2. I.J. Nagrath and D.P. Kothari - Power System Engineering
3. Ashfaq Hussain - Electrical Power Systems
4. Circuitglobe.com
5. Ti.com
6. powerline magazine

27. QUERIES

28. Thank You