HVDC TRANSMISSION.pptx
- 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