hvdc

HVDC QUIZ

1. What is the basic nature of the power flow in AC/DC systems?

2. How to represent the equivalent circuit of a surge arrester?

3. What is the relation between critical flash over voltage (CFO) and critical withstand voltage (CWS) in a DC line insulator? (where ’μ’ is the standard deviation) ?

4. If ’P’ is the measured sound –pressure level and ’Pr’ is the reference pressure level then  

    what is sound level?

5. The lightning strokes in the AC network causes which type of over voltages?

6. Which filters are designed to filter out characteristic harmonics of single frequency?

7. If ’p’ is the pulse number,’n’ is any integer then what is the order of the harmonics in the converter DC voltage?

8. In designing high pass filter which of the pulse operation will be excluded?

9. What are the following characteristics will be taken into account for the filters?

10. Which of the effect of corona is peculiar to DC lines?

11. The basic protection provided against converter faults?

12. What is the name of failure of two successive commutations in the same cycle?

13. What is the range of Steep front over voltages with front times?

14. A single tuned filter is which circuit?

15. How to define the harmonic distortion individually for a single harmonic?

16. Which transmission reliability is good?

17. Which type of DC link has two conductors?

18. The power transfer in AC lines is dependent on?

19. The AC system is said to be weak if the short circuit ratio is?

20. What is the average DC output voltage across the converter?

21. What is the Peak inverse voltage of the Converter when q valves are odd?

22. When the extinction of current can occur in a valve?

23. What is the impedance of the single tuned filter at the harmonic order ‘h’?

24. How many minimum single tuned filters are required for 12 pulse converters?

 25.  Skin effect is less in which transmission?

26. Monopolar link is usually of what polarity?

27. DC Filter is used to reduce what?

28. The break even distances can vary from what ranges?

29. PPC means?

30. Individual phase control can be achieved by which control ?

31. What is the ratio of short circuit level at the converter bus to the rated DC power is?

32. What is the filter that eliminates both characteristic & low frequency non-

      characteristic harmonics?

33. What is FACTS?

34. What is the purpose of smoothing reactor?

35. The ionization of air surrounding the conductor is

36. The current flowing through the outer surface of the conductor is called?

37. Current controller in HVDC is placed at what side?

38. Which transmission is economical above 400kms?

39. How many conductors are used in DC transmission system?

40. What is the range of Switching over voltages with front times?

41. RI is measured at what frequency?

42. What is ROW?

43. What is formula for SCR?

44. If q is even then what is the maximum inverse voltage with a phase displacement of 180

      degrees?

45. Formula for valve utilization factor?

46. If q is odd then what is the maximum inverse voltage with a phase displacement of   

     180+180/q degrees?

47. The order of characteristic harmonics in ac?

48. IPC means?

49. In Inverse cosine control what is the phase shift of each timing voltage?

50. Twelve pulse converter is used to filter out which order harmonics?

HVDC KEY

1. Steady state                                                         

2. Non-linear resistor                                              

3. CFO=CWS+3μ                                                   

4. dB =20log(P/Pr)                                                 

5. Switching over voltages                               

6. Single tuned filters                                       

7. h= np                                                            

8. Six pulse operation                                      

9. Impedance characterstics                       

10. Space charge field                               

11.  valve group differential protection      

12. double commutation failure

                 

13. 0.3 to 0.3ms

14.   LC circuit

15.   Dn  = (InZn/E1)*100

16.   DC transmission

17.   Bipolar link

18.   Angle difference b/w the voltage phasors

19.   Less than 3

20.   VdoCOSά

   21. 2Em cos 180/2q

22.  Current through it falls below holding current

23.  Zfh=R+j(hwL-1/hwC)

24. At least Two

25. HVDC transmission

                      

 26.Negative polarity

27. Current harmonics

28. 500 to 800 kms

29. Pulse Phase Control

30. Constant ά control & Inverse cosine control

                                    

31. SCR

                                                        

32. Active dc filters                                      

 33.  Flexible AC transmission systems         

  

  34. Filters dc voltage                                   

 

  35.corona  

  36. Skin   effect

  37. Inverter side3

 38. Two conductors

40. More than 100msec 

41. 1 MHZ

42 Right of way

43. Short circuit level at the converter bus/Rated DC power

44.2Em

45.PIV/Vdo

 46. 2Em cos 180/2q

47. hac=np±1

48. Individual phase control

 49.90deg

50.11th & 13th