HVDC Transmission - Exam Paper - Electrical Engineering - 7th Semester, Exams of Electrical Engineering

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312 /p3djobupe Apel OO BE Cé) XL () Con, 2902-09. HVDC, “TRANSMISSION VR-4710 Ye (3 Hours) 0g. 2(D. [Total Marks : 100 he. : (1), Question No. 1 is compulsory. (2) Attempt any four questions out of remaining six questions. (3) Assume 3 any suitable data, if required, _ Wey UEC T roms] Yylsfos (a) Oreinten of the bridge converter with overlap angle in the range between 60° and oe 120° is abnormal. Justify the statement. (b) For a bridge converter with grid contro! and with overlap less than 60° af? Agl Prove that Cos = Cosa - 2-4 Vdo (c) Explain the importance of current margin. (d) Explain with neat diagram ‘Mode Stabilization’. 2. (a) Explain with neat diagram the components of HVDC Transmission System. 10 (b) Explain with neat waveforms single commutation failure. 10 3. (a) Derive the steady state equivalent circuit of HVDC converter, 12 (b) ‘Converter consumes reactive power'— Justify the statement. 8 4, (a) Explain with neat waveforms of voltage and currents, the commutation froma io normally operating rectifier bridge to the by pass valve. (b) Describe with neat diagram different filters used in HVDC Transmission System. i0 5, (a) Explain the problem caused while connecting a weak AC System toa DCG System. io How it can be eliminated ? (b) Explain equidistant pulse control schemes used in HVDC valves, What are its 10 advantages ? 6. (a) Explain power reversal in HVDC system with contro! characteristics. 10 (b) Explain with neat diagram and waveforms the principle of 12 pulse converter. 10 7. Write short notes on any two :— 20 (a) Causes and effect of Harmonics (b) Starting and stopping of a DC link (c) Recent trends in HVDC.