JNTU Exam Papers,IV B.Tech II Semester Supplimentary Examinations,HVDC Transmission June 2007
1. What is the need for interconnection of systems? Explain the merits of connecting HVAC systems by HVDC tie-lines?
2. Draw the circuit diagram voltage and current wave form of a 3φ, 6 pulse uncontrolled bridge rectifier and derive the expression for
(a) Average DC Voltage
(b) Total VA rating of valves and transformer.
3. With steady state equivalent circuit, explain the principle of control of a Two terminal DC link.
4. Discuss the various sources of reactive power for HVDC converters.
5. (a) Obtain the mathematical models of a d.c. link.
(b) Draw the flowchart of AC/DC load flow.
6. (a) What are the basic principles of over current protection.
(b) Discuss the various faults exist in converter station? Explain.
7. Give reasons for selecting star-star and star-delta transformer configuration instead of two star-star configurations for 12 pulse converter. Derive an equation for primary current.
8. What are the various types of filters that are employed in HVDC converter station? Discuss them in detail.