University of Mumbai 2007-7th Sem B.E Electrical and Electronics Engineering HVDC Transmission - Question Paper

Con. 3137-07.    [REVISED COURSEJ    ND-1462

(3 Hours)    [Total Marks:    100

N.B. (1) Question No. 1 is compulsory.    O

(2)    Answer any four out of remaining six questions.    0/

(3)    Figures to the right indicate full marks.

1.    (a) Explain the firing schemes of HVDC valves.    10 (b) Explain the control of HVDC system and their performance during normal and abnormal    10

system condition.

2.    (a) 'Converter consumes reactive power' justify the statement.    10

(b) Explain Single commutation failure and Double commutation faHure.    10

3.    (a) Explain with neat diagram the components of HVDC Transmission system.    10

(b) Explain the influence of AC system strength on AC/DC system interaction.    10

4.    (a) Explain with neat diagrams and waveforms the principle of 12 pulse converter.    10

(b) Explain in brief the starting and stopping of a DC link.    10

5.    (a) What are the classification of HVDC links ? Describe each one with neat diagrams.    10

(b) Describe with waveform the transfer of current to the bypass valve    10

fi) Rectifier operation

(ii) Inverter operation.

6.    (a) What are the causes and effects of faults occurring in a converter station ?    10

(b) Explain the Hierarchical control structure for a d.c. link.    10

7.    (a) Explain the causes of Harmonic generation in HVDC and its effect on the system.    10

Describe different fitters used to eliminate these harmonics.

(b) Write short notes on    10

(i)    Mode stabilization

(ii)    Recent trends in HVDC.