# IV B.Tech II Semester Supplementary Examinations, June 2007

# HVDC TRANSMISSION

# (Electrical & Electronic Engineering)

# SET-I

1. (a) What are the different applications of D.C. transmission system? Explain them in detail.

(b) With neat sketches explain the different kinds of D.C. links available.

2. Draw a schematic of a 6 pulse converter circuit and derive from fundamentals, the expression for voltage and currents for the operation of converter as a rectifier and inverter with relevant waveforms.

3. Write short notes on the following:-

(a) Constant Alpha control

(b) Inverse cosine control.

4. Explain in detail, the concept of reactive power requirement in HVDC converters.

5. Obtain the mathematical model of a d.c. network and d.c. converter, including converter controller.

6. (a) Explain the principle of current interruption in d.c. circuit breakers. What are the various types of possible circuit breakers.

(b) Discus the importance of Corona loss in DC transmission.

7. How do you estimate the harmonic order based upon pulse number of HVDC converter station? Give a detailed harmonic analysis of a 12 pulse converter for characteristic harmonics.

8. What are the various types of filters that are employed in HVDC converter station? Discuss them in detail.