When grouped together, wind turbines are usually spaced between five and ten rotor diameters apart in order to reduce interaction between adjacent machines. Even so, when machines are operating downwind of one another there will usually be some loss of output from the downwind turbines.
When this spacing is taken into account, a wind farm of twenty 500 kW turbines will occupy an area of 3-4 km2. Of this, only around 1% is actually taken up by the turbines. The remainder can still be used as farmland.
The power from a wind farm must be delivered to the local grid. This will normally require a substation. For a small wind farm, under 100 MW, connection may be made to the local distribution system. Larger facilities, such as offshore farms, can have capacities of several hundred megawatts, possibly larger. These must be connected to the high-voltage transmission system.
Small wind farms have often relied on the grid to provide them with frequency and voltage stabilisation. However this puts a significant strain on the grid system which cannot support a large wind generation capacity in this way. Future wind farms will need to provide their own frequency and voltage stabilisation. This can be achieved today with standard techniques. However for the future electronic power-conditioning systems which convert the wind farm output to DC and then back to AC at the grid frequency and voltage will probably offer the most stable connection. This will only be cost effective for large wind farms.
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