HVDC TRANSMISSION ghjghbin yjuhyhi. Hhuj

Nil

1. “HVDC TRANSMISSION ” J SIVA RANJITH YOGESH M A. JEBA ROSHAN

2. INTRODUCTION : With the increasing of requirement of electrical power supply the facilities have to be increased in that transmission plays an important role. Here HVDC (high voltage direct current) transmission plays major role in power transmission. First HVDC transmission linked between gotland and mainland in sweden in 1954. The HVDC transmission has many advantages over HVAC transmission .

3. HVDC MEANS….. HVDC stands for H igh Voltage Direct Current and is today a well-proven technology all over the world. Two AC systems having different frequencies can be linked up together by means of HVDC link. HVDC technology is used to transmit electricity over long distances.

4. WHY DC TRANSMISSION ? Losses are less in DC transmission while comparing to AC transmission . Only two conductors are required for DC with positive and negative polarities. DC overhead lines or cables are less expensive. DC lines are useful for long distances above 500km. ?

5. Comparison of HVAC and HVDC Conventionally power transmission is affected through HVAC systems all over the world. HVAC transmission is having several limitations like, line length , uncontrolled power flow, over/low voltages during lightly / over loaded conditions, stability problems, fault isolation etc … But HVDC have low transmission losses and it requires only two conductors.

6. Comparison between the prices of AC & DC Transmission

7. Wind Power AC Transmission Line Converter Station Inverter Station AC Transmission Line Distribution Line HVDC Transmission Line HVDC transmission system

8. Converters Smoothing reactors Harmonic filters Reactive power source Electrodes Dc lines Ac circuit breakers Components of hvdc transmission

9. Components of hvdc transmission

10. Homopolar link Monopolar link Bipolar link HVDC Transmission can be broadly classified into:- HVDC system configuration

11. It uses one conductor. The return path is provided by ground or water. Use of this system is due to cost considerations. A metallic return may be used where earth resistivity is too high Monopolar link

12. Each terminal has two converters of equal rated voltage, connected in series on DC side. The junctions between converters is grounded. If one pole is isolated due to fault, the other pole can operate with ground and carry half the rated load ( or more using overload capabilities of its converter line.) bipolar link

13. It has two conductors each having 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. Homopolar link

14. Basic Transmissions of HVDC Back to Back Transmission. Point to point Overhead line Transmission. Point to point Underground Cable Transmission. Point to point Sub marine Transmission.

15. Needs for HVDC The losses which occurs in the systems are comparatively low at all the stages (i.e.) at generation , transmission & distribution level . The losses at transmission level can be highly reduced by HVDC transmission.

16. Advantages of HVDC Technical Advantages Economic Advantages Advantages of HVDC

17. Lesser Corona Loss and Radio interference. The voltage regulation problem is much less serious for DC, since only the IR drop is involved. For the same reason steady state stability is no longer a major problem. No skin and proximity and Ferranti effect Asynchronous operation possible between regions having different electrical parameters. TECHNICAL Advantages

18. 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 a DC line are lower than the losses in an AC lines. Economical Advantages

19. The disadvantages of HVDC are in conversion, switching, control, availability and maintenance. There is nothing like DC transformer which can change the voltage level in a simple way. Voltage transformation has to be provided on the AC sides of the system. The required converter stations are expensive and have limited overload capacity. DISAdvantages of HVDC

20. Rihand-delhi and chandrapur-padghe were the first long distance hvdc projects in India. In 1990 ,rihand-delhi (singrauli) thermal power complex with a combined power generation of Several thousand MW was put in to service. it covers over a distance of 814 km. T he 1500 MW transmission chandrapur-padghe was put in to service. it covers over distance of 736 km. HIGH VOLTAGE DIRECT CURRENT APPLICATIONS OF HVDC TRANSMISSION IN INDIA :

21. Conclusion Recent studies indicate that HVDC systems are very reliable. Very large investments Eg. In China and India shows that High Voltage Direct Current will very important in the future, especially in big and new-industries countries.

22. THANK YOU………………