When you see conventional power plants, you see an array of wiring feeding a distribution station and/or substation. But, when you see these banks of modern windmills you see…nothing! No wires at all! Why is this?
The cables are there, but they are buried. There are various reasons for this, primarily environmental or aesthetic in nature:
So, I WAG we can assume the power is dumped directly into the existing power grid without a need for additional substations, and the like.
The amount of power provided by each windmill is much less than the total power usually produced by a fossil fuel power plant so the cables can be sized and buried using the same technology as found in neighborhood underground systems. The power is aggregated at a substation somewhere nearby. You may just may have not seen it.
It is also pretty easy to connect a windmill directly to the grid by having it spin an ordinary, cheap induction motor. Phase relationships take care of themselves that way, and you can always feed power into an AC grid with an induction motor this way (we’re talking an induction motor without any salient poles, for instance whatever’s on your table saw or compressor, be it 1 phase or 3). But the windmill has to want to turn the motor faster than whatever its synchronous speed is, or else it becomes a fan. I think it’s worth the investment to have a more complicated and efficient system, but this does represent a kind of lowest common denominator if you’re interested.
It’s a pretty simple matter to add some circuitry to disconnect the windmill when it’s not turning fast enough, in order to prevent needlessly sucking power out of the grid. You also need to disconnect it when the grid itself goes down, lest your eco-friendly wind generator electrocutes some lineman tryng to repair broken equipment.