Question

1) How is the real power controlled in a grid-connected wind turbine employing a permanent-magnet synchronous generator (PMSG) with rectifier and inverter? *

rotational speed

inverter output current

generator output voltage

rectifier output voltage

inverter output voltage

2) How do you compare the size of power electronics in a grid-connected 1 MW variable-speed wind turbine employing DFIG and PMSG? *

same

no power electronics in DFIG

no power electronics in PMSG

smaller in PMSG

smaller in DFIG

3)What is the real power flow in a grid-connected wind turbine employing a 4-pole doubly-fed induction generator (DFIG) if the generator rotational speed is 1580 rpm? *

power grid --> stator, rotor --> power grid

power grid --> stator, power grid --> rotor

stator --> power grid, power grid --> rotor

stator --> power grid, rotor --> power grid

stator --> power grid, no rotor power

4) What is the azimuth angle at solar noon in a place located at 40^o N and 30^o E for March 21, 2020? *

-120^o

-90^o

45^o

90^o

0^o

5)What is the altitude angle at sunset in a place located at 40^o N and 30^o E for March 21, 2020? *

30^o

60^o

90^o

0^o

45^o

Answer 1

1) How is the real power controlled in a grid-connected wind turbine employing a permanent-magnet synchronous generator (PMSG) with rectifier and inverter? *

Answer: Rectifier output voltage

Permanent magnet synchronous generator (PMSG) used in wind turbine system has its output connected to load or grid through an uncontrolled or controlled rectifier.load side control is achieved through inverter output voltage control by pulse width modulation techniques.

2)How do you compare the size of power electronics in a grid-connected 1 MW variable-speed wind turbine employing DFIG and PMSG? *

Answer: smaller in PMSG

As in DFIG topology, the control of active power is achieved through power electronics converter and the capacity utilisation of converter is only about 30% in DFIG and 100%in PMSG so we need larger size of power electronics converter, or we cam say smaller capacity in PMSG.

3)What is the real power flow in a grid-connected wind turbine employing a 4-pole doubly-fed induction generator (DFIG) if the generator rotational speed is 1580 rpm? *

Answer stator---->power grid, rotor------>power grid

A doubly fed induction motor is a type of machine in which both stator and rotor is connected to AC grid, the rotor delivery to stator and as well as power grid, which is connected to stator.