How those Wind Turbines keep turning
Large wind turbines require a large amount of energy to operate. Other electricity plants generally use their own electricity, and the difference between the amount they generate and the amount delivered to the grid is readily determined. Wind plants, however, use electricity from the grid, which does not appear to be accounted for in their output figures.
Among the wind turbine functions that use electricity are the following:...
....magnetizing the stator -- the induction generators used in most large grid-connected turbines require a "large" amount of continuous electricity from the grid to actively power the magnetic coils around the asynchronous "cage rotor" that encloses the generator shaft; at the rated wind speeds, it helps keep the rotor speed constant, and as the wind starts blowing it helps start the rotor turning (see next item); in the rated wind speeds, the stator may use power equal to 10% of the turbine's rated capacity, in slower winds possibly much more
...using the generator as a motor (to help the blades start to turn when the wind speed is low or, as many suspect, to maintain the illusion that the facility is producing electricity when it is not, particularly during important site tours) -- it seems possible that the grid-magnetized stator must work to help keep the 40-ton blade assembly spinning, along with the gears that increase the blade rpm some 50 times for the generator, not just at cut-in (or for show in even less wind) but at least some of the way up towards the full rated wind speed; it may also be spinning the blades and rotor shaft to prevent warping when there is no wind.
Hat tip to an anonymous commentator who noticed the turbines by the motorway turning on a windless halcyon day.