11. What are the advantages of MHD generator?
Ans: i. Conversion efficiency is around 50%.
ii. Capital cost is less compared with conventional steam plants.
iii. Overall generation cost is less.
iv. Large amount of power is generated.
v. It has no moving parts, so more reliable.
12. Write down the classification of geothermal sources.
Ans: i. Hydro-thermal convective systems.
ii. Geo pressure resources
iii. Petro-thermal or hot dry rocks
iv. Magma resources
v. Volcanoes
13. What are the parts of the transmission system network?
Ans: i. Transmission system
ii. Sub transmission system
iii. Primary distribution system
iv. Secondary distribution system
14. What are the advantages of geothermal energy?
Ans: i. Geothermal energy is versatile in its use.
ii. It is cheaper.
iii. Geothermal power plants have highest annual load factor
iv. Pollution is less.
15. What are the disadvantages of geothermal energy?
Ans: i. Overall efficiency for power production is low; approximately 15%.
ii. Drilling operation is noisy.
iii. Large areas are needed for exploitation of geothermal energy.
16. What are the transmission system voltages used in India?
Ans: 33kV, 66 kV ⇒ For medium high voltage
132 kV, 220 kV ⇒For high voltage
400 kV ⇒For extra high voltage
765 kV ⇒ For Ultra high voltage
17. What are the types of HVDC links?
Ans: i. Monopolar link
ii. Bipolar link
iii. Homopolar link
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18. List the advantages and disadvantages of HVDC transmission system?
Ans: Advantages
i. Asynchronous operation is possible
ii. Less corona loss and radio interference
iii. No compensation problem
iv. Cheaper for long distance transmission
v. No charging current
vi. No technical limit for power transfer except thermal limit
vii. Power control is possible
viii. No reactive power loss
ix. Ground can be used as return conductor
x. No skin and Ferranti effect
xi. No transmission of short circuit power incase of fault
xii. Low short circuit current
xiii. No stability problem
xiv. No switching transient
xv. Require less space compared to ac for same voltage rating and size
xvi. Fast fault clearing time.
Disadvantages
i) Point to point transmission not possible
ii) Introduction of harmonics
iii) Blocking of reactive power
iv) High cost of terminal equipment
19. What are the main components of HVDC transmission system?
Ans: i. Converters
ii. Converter transformers
iii. Smoothing reactors
iv. Reactive power source
v. Harmonic filters
vi. Overhead lines
vii. Earth electrodes
20. What are the applications of HVDC transmission system?
Ans: i. Long distance bulk power transmission
ii. Underground or submarine cables
iii. Asynchronous connection of ac system with different frequencies
iv. Control and stabilize the power system with power flow control
