Hi. I am trying to understand the basic operation of the doubly-fed synchronous generator used for a wind turbine. All i understand is that the rotor windings are fed from a back-to-back inverter. Is that the main property of this machine. Or am I mixing things up?

 

If the rotor windings are energised via the inverter at a controlled slip frequency such that the stator output frequency is the same as the grid frequency you have a variable input speed drive generator with constant output frequency. This allows synchronous power generation back into the grid from a variable speed drive - such as one has with wind turbines.

The inverter fed slip frequency is controlled according to the varying turbine speed.

 

Nice. Great explanation. Thanks.