Hvdc transmission
- 1. HVDC Transmission INTRODUCTION •Now a days large blocks of power are Technical Seminar Presentation needed to be transmitted. •There arises some technical problems of transmitting power to such a long distance using ac. •In the view of the draw backs of ac the HVDC transmission has come into picture. SAMBIT DAS EE200118302 1
- 2. HVDC Transmission •The first dc link was set up in 1954 in Technical Seminar Presentation between Swedish main land and the island of Gotland. •The use of an HVDC link in an ac system requires converter stations at each end of the line. SAMBIT DAS EE200118302 2
- 3. HVDC Transmission ADVANTAGES Technical Seminar Presentation Advantages of dc transmission Technical Economic Advantages Advantages SAMBIT DAS EE200118302 3
- 4. HVDC Transmission Technical Advantages Technical Seminar Presentation • Reactive power requirement • System stability • Short Circuit Current • Independent Control of ac system • Fast change of energy flow • Lesser Corona Loss and Radio interference • Greater Reliability. SAMBIT DAS EE200118302 4
- 5. HVDC Transmission •No limits in transmitted distance Technical Seminar Presentation •Direction of power flow can be changed very quickly SAMBIT DAS EE200118302 5
- 6. HVDC Transmission Economic advantages Technical Seminar Presentation •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. SAMBIT DAS EE200118302 6
- 7. HVDC Transmission Technical Seminar Presentation SAMBIT DAS EE200118302 7
- 8. HVDC Transmission Comparison between the prices of AC & DC Transmission Technical Seminar Presentation SAMBIT DAS EE200118302 8
- 9. HVDC Transmission Technical Seminar Presentation Types of DC links Monopolar Homopolar Bipolar SAMBIT DAS EE200118302 9
- 10. HVDC Transmission Monopolar link Technical Seminar Presentation SAMBIT DAS EE200118302 10
- 11. HVDC Transmission Bipolar Link Technical Seminar Presentation SAMBIT DAS EE200118302 11
- 12. HVDC Transmission Incorporating HVDC into AC systems • Two terminal DC link point to point Technical Seminar Presentation transmission. • Back to Back DC link • DC line in Parallel with AC link. • Multi-Terminal DC link. SAMBIT DAS EE200118302 12
- 13. HVDC Transmission CONVERTER STATION EQUIPMENT Technical Seminar Presentation • Thyristor valves • Converter Transformer • DC Reactor • Harmonics Filtering Equipment • Control Equipment • Reactive power compensation SAMBIT DAS EE200118302 13
- 14. HVDC Transmission GROUND RETURN • Most dc transmission lines use ground return for reasons Technical Seminar Presentation of economy and reliability • Ground return are used by the monopolar and the bipolar link for carrying the return current. • The ground path has a low resistance and, therefore low power loss as compared to a metallic conductor path provided the ground electrodes are properly designed. • The resistance of the ground path is independent of the depth of the line. SAMBIT DAS EE200118302 14
- 15. HVDC Transmission PROBLEMS Technical Seminar Presentation • The Design of grounding electrodes for low cost of installation and maintenance • Location and screening of electrodes so that ground currents cause negligible electrolytic corrosion of buried and immersed metallic structures. SAMBIT DAS EE200118302 15
- 16. HVDC Transmission EARTH ELECTRODE Technical Seminar Presentation • HVDC system requires a properly designed earth electrode at each station. • The electrode is situated at a safe distance (5 to 30 km) from the station. • The earth electrode at one of the station acts as a anode and at the other end acts as a cathode. SAMBIT DAS EE200118302 16
- 17. HVDC Transmission RECENT ADVANCES Technical Seminar Presentation • GTO’s have come into use. • Use of active ac and dc filters. • Advanced fully digital control systems using optical fibers. SAMBIT DAS EE200118302 17
- 18. HVDC Transmission CONCLUSION Technical Seminar Presentation • Recent studies indicate that HVDC systems are very reliable. • The data collected from 31 utilities says that forced unavailability of energy due to the converter station is 1.62% • The scheduled unavailability of energy is about 5.39%. SAMBIT DAS EE200118302 18
- 19. HVDC Transmission Technical Seminar Presentation Thank you! SAMBIT DAS EE200118302 19