Second International Symposium on Standards for Ultra High Voltage Transmission

1. Second International Symposium on Standards for Ultra High Voltage Transmission 1200kV Transmission System and Status of Development of Substation Equipment/ Transmission Line Material in India By R.N.Nayak Executive Director (R&D), POWERGRID India

2. 1200kV Transmission System in India Background • High Growth rate of Indian Power Sector • Installed capacity is expected to be more than 6,00,000 MW by 2025 from the present capacity of about 1,47,000MW. • To keep pace with generation, an efficient Transmission network required. • Serious difficulty of availability of Right of Way (ROW) necessitate development of system with high power carrying capacity. • POWERGRID planned to develop +800 kV HVDC and 1200 kV AC system. • To develop 1200kV AC technology indigenously, a 1200kV test station is being established at Bina, Madhya Pradesh in central part of India in association with 25 Indian manufacturers.

3. Comparison of Available Technologies

4. Test Station at Bina

5. Layout of Test Station Electric Field shall be maintained below 10.0kV/m. at 1.8 m height as simulated through Computer studies for Bus height of 18.0m by putting E/W at the structure height (~9m).

6. 1200kV AC TRANSMISSION LINE TECHNICAL ARAMETERS

7. Switching Over Voltage

8. Temporary Over-voltages

9. Characteristics of the 850kV Surge Arrester • The salient features of Surge Arrester (SA) are as under: • Rated Voltage as 850kVrms of SA shall take care power frequency voltage upto 1.15 p.u. for 10 seconds and 1.4 p.u. for about 1second. • Switching Impulse Protective level at 2.0kA is 1500kV and hence about 20% protective margin are available for 1200kV Equipments with 1800kV Switching Impulse withstand voltage. • Lightning Impulse Protective Level at 20.0 kA is 1700kV and hence margins for bay equipments with BIL- 2400kV andfor transformers with BIL-2250kV. • Lightning Arresters to be installed at line entry, transformers, reactors and at the bus.

10. T=0 ms T=1520 ms T=1120 ms T=1220 ms T=1140 ms T=120 ms Steady State 1000 ms Dead Time Stuck breaker 300 ms SLG fault Opening of local end CB of faulted phase Opening of remote end CB of faulted phase Closing of local end CB through SPAR Closing of remote end CB through SPAR Opening of CB due to permanent fault LBB Operates and clears the fault Surge Arrester Energy accumulation Surge Arrester Energy T=100ms Calculated Energy Requirements = 35 MJ for TOV + 2 shots of 5 MJ each of class-5 discharges + margins = 55MJ

11. 4 column Surge Arrester

12. FIELD STUDIES • Corona Cage Studies The test was carried out in a Corona cage at UHV test lab at Central Power Research Institute (CRPI), Hyderabad. The size of the cage was 6.1 m (H) x 6.1 m (W) x 21 m (L). The corona cage consisted of three sections, insulated central section of length 18 m and two end sections each of length 1.5m, located on either side of the central section. Eight Bersimis ACSR (Radius 17.5 mm) bundle conductor was strung between two towers such that the bundle was at the centre along the length of the cage. Both the ends of the bundle was connected to the end fittings, corona shields and insulator strings. • Air Gap clearance Studies Air gap clearance optimization studies for 1200kV system have been carried out at CPRI, Hyderabad. Tower top & Tower window have been simulated. • Voltage Distribution studies – under progress

13. Air Gap clearance Studies Tower top Simulation

14. Tower Window simulation

15. 1200kV General Technical Parameters

16. 1200kV Equipment Technical Parameters • Circuit Breakers • Current Transformers • Capacitive Voltage Transformers • Power Transformers • Disconnectors • Bus Post Insulators • Line Materials

17. Status of the Project • All equipment technical parameters have been finalized in association with respective equipment manufacturers. • Prototypes of 1200kV Capacitive Voltage Transformer and Dis-connectors are already developed. • Design of 850kV, 4 column Surge Arresters has been finalized & components are under manufacturing and prototypes shall be ready by Feb, 2009. • 1200kV transmission line towers have been designed and line materials are under manufacturing. • The terminal connectors, spacers, vibration dampers and other accessories have already been developed. • The design of 1200/400kV transformers is under vetting by consultants/ experts. • The Bushings are under manufacturing. • Readiness of the Transformer expected by IIIrd Quarter,2009 • Commissioning by IVth Quarter,2009.

18. 1200kV CVT Make-A

19. 1200 kV CVT - Make B

20. The Way Forward • The detailed field testing shall be taken up for the performance of various equipments by conducting various tests. • The Testing Instrument manufacturers are also participating in this project for condition monitoring of various equipments. • The experience gained on various 1200kV equipments shall help in fine tuning the Technical parameters for 1200kV AC transmission system

21. Thank You for your kind attention please

22. Circuit Breakers

23. Capacitive Voltage Transformer

24. Surge Arresters

26. Current Transformers

27. Dis-connectors

28. Bus Post Insulators

29. Disc Insulators & Hardware

30. Insulator Strings

31. Polymer Long Rod Insulators Strings

32. Corona Cage Studies

33. Air Gap clearance Studies