NET’S
Navodaya institute of technology (NIT)
Department of Electrical and Electronics Engineering
Assignment Questions
Subject: HVDC TRANSMISSION (10EE751)Semester: VII
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Unit 1&2
1. With relevant figures, explain the constitution of EHV-AC and HVDC links.
2. Explain briefly the advantages and disadvantages of a HVDC transmission system.
3 Compare HVAC and HVDC transmission for economics of operation, stability limit, voltage control, and reliability.
4. a)Explain the various types of DC links?
b)Mention the details of the first HVDC link in the world and that in India?
c)Explain the necessity of a back to back HVDC link?
5. Draw the schematic diagram of a typical HVDC converter stations and explain the various components?
6.Enumerate the important applications of DC transmission? List some HVDC links for long distance transmission and back to back control projects installed in India with its features?
Unit 3
1a.Define a) Rating of the valve b) Peak Inverse Voltage c) Rating of the transformer d) Pulse number e) Commutation Group.
1b.Briefly explain the assumption made while studying the properties of converter circuits?
2. Compare three phase one way rectifier and three phase two way rectifier with respect to Peak Inverse Voltage (PIV),Average DC voltage, Volt ampere rating of the transformer bank .Draw neat sketches and derive the expression used in both cases.
3. Derive the expression for average DC voltage Vdoand Peak Inverse Voltage (PIV), Valve utilization factor, and Transformer utilization factor(TUF) for a ‘p’ pulse number, ‘q’ valves in a commutation group where ‘s’ valves in series and ‘r’ valves in parallel. Assume the peak valve of the commutation voltage in ‘Em’
4. Prove that Graetz circuit configuration is the best for 6 pulse converter operation.
5a. Describe with the suitable schematic explain the operation of single phase bridge rectifier.
5b.What is twelve pulse converters? Draw the schematic and state the advantages with respect to six pulse converter circuit?