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Wind turbine: Difference between revisions
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[[file:Vestas-V90-power-curve.png|thumb|Power curve (power generation versus wind speed) for two Vestas V90 models. The cut-in speed is 4 m/s (9 mph). The rated speeds are ~11–12 m/s (25–27 mph). The cut-out speed is 25 m/s (56 mph).]] | [[file:Vestas-V90-power-curve.png|thumb|Power curve (power generation versus wind speed) for two Vestas V90 models. The cut-in speed is 4 m/s (9 mph). The rated speeds are ~11–12 m/s (25–27 mph). The cut-out speed is 25 m/s (56 mph).]] | ||
Every wind turbine has a range of wind speeds at which it is operational, from the “cut-in” to the “cut-out” speed. When the wind is close to “cut-in” speed, the generator is used as a motor to start the blades turning in anticipation. As the wind speed increases, the blades are able to overcome the power flowing in from the grid and begin to push power out. When the model’s “rated” wind speed is reached, the turbine is able to produce at its rated capacity, e.g., a 2-MW turbine is generating power at 2 MW. As the wind speed increases further, the blades are increasingly pitched (rotated on their axis) to capture less of its energy to keep their rotation speed fairly constant. At the cut-out wind speed, the blades are completed “feathered” to stop spinning, and at higher wind speeds they are braked to prevent damage. | Every wind turbine has a range of wind speeds at which it is operational, from the “cut-in” to the “cut-out” speed. When the wind is close to “cut-in” speed, the generator is used as a motor to start the blades turning in anticipation. As the wind speed increases, the blades are able to overcome the power flowing in from the grid and begin to push power out. When the model’s “rated” wind speed is reached, the turbine is able to produce at its rated capacity, e.g., a 2-MW turbine is generating power at 2 MW. As the wind speed increases further, the blades are increasingly pitched (rotated on their axis) to capture less of its energy to keep their rotation speed fairly constant (see also: [[Efficiency]]. At the cut-out wind speed, the blades are completed “feathered” to stop spinning, and at higher wind speeds they are braked to prevent damage. | ||
Because of the variable power generation with wind speed, over time a wind turbine produces only 25%–35% of the energy implied by its [[Capacity factor|rated capacity]]. And because of the steep slope of power generation as the wind rises and falls between the cut-in and rated speeds, a wind turbine generates electricity at or above its average rate (25%–35%) only about 40% of the time. | Because of the variable power generation with wind speed, over time a wind turbine produces only 25%–35% of the energy implied by its [[Capacity factor|rated capacity]]. And because of the steep slope of power generation as the wind rises and falls between the cut-in and rated speeds, a wind turbine generates electricity at or above its average rate (25%–35% of capacity) only about 40% of the time. | ||
==See also== | ==See also== | ||