HVDC 2010 april Power engg paper

 

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

        M.Tech I Semester Regular Examinations March/April 2010

                                 HVDC TRANSMISSION

                    (ELECTRICAL POWER ENGINEERING)

                           Time: 3hours Max.Marks:60

                                Answer any five questions

                            All questions carry equal marks

- - -

1. a) Discuss the various applications of HVDC transmission.

b) What are the factors to be considered in planning for HVDC transmission?

2. How is a suitable voltage level chosen for HVDC transmission?

3. Define pulse number, thyristor PIV rating and index of valve utilization and

transformer utilization factor.

4. Derive a formula for average DC voltage of Graetz circuit taking overlap into

account.

5. a) Discuss briefly the principle of DC link control.

b) Explain firing schemes adopted in firing angle control along with their relative

merits and demerits.

6. Discuss the starting and stopping techniques of DC link in a HVDC transmission

system.

7. How are the signals derived from AC system used to control the DC link to

improve the overall performance?

8. Discuss the causes of over voltages in HVDC converter station and methods to

protect the system against them?